Introduction
Specific phobia is one of the most common mental disorders in the general population with lifetime and 12-month prevalence estimates in representative population surveys ranging from 7.7 to 12.5% and from 2.0 to 8.8%, respectively (Kessler et al. Reference Kessler, McGonagle, Zhao, Nelson, Hughes, Eshleman, Wittchen and Kendler1994, Reference Kessler, Berglund, Demler, Jin, Merikangas and Walters2005; Bijl et al. Reference Bijl, Ravelli and van Zessen1998; Alonso et al. Reference Alonso, Angermeyer, Bernert, Bruffaerts, Brugha, Bryson, de Girolamo, Graaf, Demyttenaere, Gasquet, Haro, Katz, Kessler, Kovess, Lépine, Ormel, Polidori, Russo, Vilagut, Almansa, Arbabzadeh-Bouchez, Autonell, Bernal, Buist-Bouwman, Codony, Domingo-Salvany, Ferrer, Joo, Martínez-Alonso, Matschinger, Mazzi, Morgan, Morosini, Palacín, Romera, Taub and Vollebergh2004; Wells et al. Reference Wells, Browne, Scott, McGee, Baxter and Kokaua2006; Stinson et al. Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007; Grenier et al. Reference Grenier, Schuurmans, Goldfarb, Préville, Boyer, O'Connor, Potvin and Hudon2011; de Graaf et al. Reference de Graaf, ten Have, van Gool and van Dorsselaer2012). In addition, prospective studies have shown high incidence rates for specific phobia. Angst et al. (Reference Angst, Paksarian, Cui, Merikangas, Hengartner, Ajdacic-Gross and Rössler2016) found a cumulative incidence of 26.9% between the ages of 20 and 50 years. Bijl et al. (Reference Bijl, De Graaf, Ravelli, Smit and Vollebergh2002) found a 1-year incidence rate of 2.20 new cases per 100 person-years. Grant et al. (Reference Grant, Goldstein, Chou, Huang, Stinson, Dawson, Saha, Smith, Pulay, Pickering, Ruan and Compton2009) found a lower 1-year incidence rate of 0.44 new cases per 100 person-years. Interestingly, prevalence rates (e.g. Kessler et al. Reference Kessler, McGonagle, Zhao, Nelson, Hughes, Eshleman, Wittchen and Kendler1994; Bijl et al. Reference Bijl, Ravelli and van Zessen1998; Stinson et al. Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007) and incidence rates (Bijl et al. Reference Bijl, De Graaf, Ravelli, Smit and Vollebergh2002; Angst et al. Reference Angst, Paksarian, Cui, Merikangas, Hengartner, Ajdacic-Gross and Rössler2016) have been found to be higher in females than in males. Also, prevalence rates have been shown to decrease with age (e.g. Stinson et al. Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007; Sigström et al. Reference Sigström, Skoog, Karlsson, Nilsson and Östling2016).
Because of its high prevalence, lifetime persistence (e.g. Goisman et al. Reference Goisman, Allsworth, Rogers, Warshaw, Goldenberg, Vasile, Rodriguez-Villa, Mallya and Keller1998), associated impairment and high lifetime co-morbidity rate with other disorders, specific phobia is important from both an epidemiological and a clinical perspective. Previous work has shown considerable role impairment in those with specific phobia, with 34.2% reporting significant role impairments in their daily life, compared with 26.5% in agoraphobia and 33.5% in social phobia (Magee et al. Reference Magee, Eaton, Wittchen, McGonagle and Kessler1996). Depla et al. (Reference Depla, ten Have, van Balkom and de Graaf2008) showed that up to 59.2% of patients reported interference with their daily life. Using data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), Stinson et al. (Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007) showed that impairment levels in specific phobia were comparable with other anxiety and substance use disorders. However, other studies have found low disability in specific phobia compared with other disorders (e.g. Wells et al. Reference Wells, Browne, Scott, McGee, Baxter and Kokaua2006; Ormel et al. Reference Ormel, Petukhova, Chatterji, Aguilar-Gaxiola, Alonso, Angermeyer, Bromet, Burger, Demyttenaere, de Girolamo, Haro, Hwang, Karam, Kawakami, Lépine, Medina-Mora, Posada-Villa, Sampson, Scott, Ustün, Von Korff, Williams, Zhang and Kessler2008) and it has been suggested that observed functional impairment in specific phobia can be partly explained by high co-occurrence with other disorders (Comer et al. Reference Comer, Blanco, Hasin, Liu, Grant, Turner and Olfson2011). Nevertheless, the restricted lifestyle resulting from fear and avoidance in specific phobia is likely to contribute independently to functional impairment.
Previous surveys have shown that co-morbidity rates between specific phobia and other mental disorders are high (Kessler et al. Reference Kessler, Nelson, McGonagle, Liu, Swartz and Blazer1996, Reference Kessler, Crum, Warner, Nelson, Schulenberg and Anthony1997), with estimated rates of up to 83.4% (Magee et al. Reference Magee, Eaton, Wittchen, McGonagle and Kessler1996). Interestingly, these retrospective studies showed that in the majority of co-morbid cases, the onset of specific phobia precedes the other disorder(s) (Kessler et al. Reference Kessler, Nelson, McGonagle, Liu, Swartz and Blazer1996, Reference Kessler, Crum, Warner, Nelson, Schulenberg and Anthony1997; Magee et al. Reference Magee, Eaton, Wittchen, McGonagle and Kessler1996). Prospective work has shown that specific phobia is associated with a higher odds of later depressive, anxiety and eating disorders (Goodwin, Reference Goodwin2002; Bittner et al. Reference Bittner, Goodwin, Wittchen, Beesdo, Höfler and Lieb2004; Trumpf et al. Reference Trumpf, Margraf, Vriends, Meyer and Becker2010; Lieb et al. Reference Lieb, Miché, Gloster, Beesdo-Baum, Meyer and Wittchen2016) but not of later substance use disorders (Zimmermann et al. Reference Zimmermann, Wittchen, Höfler, Pfister, Kessler and Lieb2003). Grant et al. (Reference Grant, Goldstein, Chou, Huang, Stinson, Dawson, Saha, Smith, Pulay, Pickering, Ruan and Compton2009) showed that specific phobia at baseline was associated with an increased incidence of other anxiety disorders. However, these associations could also be explained by other baseline disorders and sociodemographic factors.
Relatively effective treatments, such as behaviour therapy and cognitive therapy, are available for specific phobia (Choy et al. Reference Choy, Fyer and Lipsitz2007). However, despite specific phobia patients’ need for care, only a minority of patients seek treatment in their lifetime (Magee et al. Reference Magee, Eaton, Wittchen, McGonagle and Kessler1996: 46.6%; Stinson et al. Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007: 8.0%). In addition, it has been shown that specific phobia patients that do seek treatment take much longer to do so compared with other anxiety disorders (Iza et al. Reference Iza, Olfson, Vermes, Hoffer, Wang and Blanco2013; ten Have et al. Reference ten Have, de Graaf, van Dorsselaer and Beekman2013).
Within specific phobia, the Diagnostic and Statistical Manual of Mental Disorders (DSM) distinguishes between different subtypes: animal (e.g. bugs, snakes), natural environment (e.g. heights, weather), blood-injection-injury, situational (e.g. flying on a plane, enclosed spaces) and other (e.g. vomiting, choking). Previously phobia subtypes have been shown to differ in terms of, for example, prevalence, impairment levels and co-morbidity rates (e.g. Fredrikson et al. Reference Fredrikson, Annas, Fischer and Wik1996; Becker et al. Reference Becker, Rinck, Türke, Kause, Goodwin, Neumer and Margraf2007; Depla et al. Reference Depla, ten Have, van Balkom and de Graaf2008; LeBeau et al. Reference LeBeau, Glenn, Liao, Wittchen, Beesdo-Baum, Ollendick and Craske2010). Also, most patients have more than one subtype (Curtis et al. Reference Curtis, Magee, Eaton, Wittchen and Kessler1998; Burstein et al. Reference Burstein, Georgiades, He, Schmitz, Feig, Khazanov and Merikangas2012) and increasing numbers of subtypes have been shown to be associated with more co-morbidity, impairment and treatment-seeking (e.g. Curtis et al. Reference Curtis, Magee, Eaton, Wittchen and Kessler1998; Stinson et al. Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007; Burstein et al. Reference Burstein, Georgiades, He, Schmitz, Feig, Khazanov and Merikangas2012).
Although the above-described findings indicate that specific phobia is a highly relevant condition that deserves attention from both researchers and clinicians, they all come from surveys in Western, high-income countries. This makes it hard to judge the universal relevance of specific phobia as an impairing condition and a marker for increased psychopathology risk. In this study we therefore took a cross-national approach, combining World Mental Health (WMH) population survey data from 22 low-/lower-middle-income, upper-middle-income and high-income countries (n = 124 902) to gain a more complete insight into the epidemiological characteristics of specific phobia around the world.
Method
Sample
Data came from 25 World Health Organization (WHO) WMH surveys, conducted in 22 countries (online Supplementary Appendix Table S1). Of these countries, five are classified by the World Bank (World Bank, 2008) as low-/lower-middle-income countries [Colombia, Iraq, Nigeria, Peru and the People's Republic of China (PRC)], six as upper-middle-income countries [Brazil, Bulgaria, Colombia (Medellín), Lebanon, Mexico and Romania] and 12 as high-income countries (Belgium, France, Germany, Italy, Japan, the Netherlands, New Zealand, Northern Ireland, Poland, Portugal, Spain and the USA). The sample sizes of the surveys ranged from 2357 (Romania) to 12 790 (New Zealand) and the total combined sample size was 124 902. Most surveys were based on nationally representative stratified multistage clustered area probability samples of household residents. All respondents were aged 18 years or older. Response rates ranged from 45.9% (France) to 97.2% (Colombia) and the average weighted response rate across countries was 69.3%. The surveys were conducted face to face by trained lay interviewers. The same standardized procedures for interviewer training, translation of the used study materials and quality control were used in all countries (Kessler & Üstün, Reference Kessler and Üstün2008). To reduce the burden of the interview it was often divided into two parts. In part I, core mental disorders were assessed. In part II, additional disorders and correlates were assessed. All respondents completed part I (n = 124 902). Part II (n = 60 345) was additionally administered to a subsample of respondents meeting criteria for any part I disorder and in a probability subsample of the other part I respondents. Part II responses were weighted by the inverse of their probability of selection into the part II sample to adjust for any differential sampling. All respondents provided informed consent prior to the interview and the study protocols were approved by the institutional review boards of the organizations coordinating the surveys.
Measures
Diagnostic assessments
The lifetime and 12-month prevalence and age of onset (AOO) of specific phobia as defined in the DSM-IV were evaluated with the WHO Composite International Diagnostic Interview (CIDI, Kessler & Üstün, Reference Kessler and Üstün2004). In the screening section, respondents were shown a list of six specific fears [animals, still water/weather events, blood/injuries/medical experiences (BIM), closed spaces, high places, flying] and were asked if they ever had a strong fear of any of these things. If any specific fear was reported in the screening section, the specific phobia section was administered. The CIDI was also used to assess other psychiatric disorders, including mood (major depressive, dysthymic, bipolar-I, bipolar-II and subthreshold bipolar disorder), anxiety (agoraphobia, social phobia, generalized anxiety, panic, post-traumatic stress and separation anxiety), substance use (alcohol and drug abuse, alcohol and drug dependence with abuse) and behaviour disorders (attention-deficit/hyperactivity, oppositional-defiant, conduct, intermittent explosive disorder). The WMH interview translation, back-translation and harmonization were done by culturally competent bilingual clinicians, who reviewed, modified and approved the key phrases describing the assessed symptoms (Harkness et al. Reference Harkness, Pennell, Villar, Gebler, Aguilar-Gaxiola, Bilgen, RC Kessler and Üstün2008). Masked clinical reappraisal with a standardized clinical interview showed fair agreement for specific phobia (area under the receiver operating curve = 0.67; Haro et al. Reference Haro, Arbabzadeh-Bouchez, Brugha, de Girolamo, Guyer, Jin, Lepine, Mazzi, Reneses, Vilagut, Sampson and Kessler2006).
Healthcare use
The services module of the WMH-CIDI v3.0 (Kessler & Üstün, Reference Kessler and Üstün2004) was used to assess if respondents ever received treatment for emotion regulation problems, psychological distress, anxiety or substance use. If respondents reported ever receiving such care, follow-up questions were asked about their age at the first and last treatment and about the treatment they received in the past 12 months. Different sectors of treatment were distinguished. The specialty mental health sector included psychiatrists, psychologists or any other non-psychiatrist mental health specialists (social workers, counsellors in specialty mental health settings, mental health helplines, overnight hospital admissions for mental health or substance-related problems). The general medical sector included general practitioners, other medical doctors, nurses, occupational therapists or any other healthcare professional. The human services sector included religious or spiritual advisors, social workers or counsellors in other settings than the specialty mental health sector. The complementary and alternative medicine sector included any other type of healer (e.g. herbal healers, self-help groups).
Impairment
A modified version of the Sheehan Disability Scales (SDS; Leon et al. Reference Leon, Olfson, Portera, Farber and Sheehan1997) was used to assess 12-month role-functioning. Respondents were asked to remember the month in which their specific phobia was most severe and to rate its interference with functioning in four domains (home management, ability to work, relationships and social life) on a 10-point scale. Those with a score of 7 or higher on one or more SDS domains were classified as severely impaired. Respondents with 12-month specific phobia were also asked how many of the 365 days in the past 12 months they had been totally unable to work or carry out their normal activities because of their specific phobia.
Demographic factors
The following demographic factors were investigated: age group (18–29 years, 30–44 years, 45–59 years and 60+ years), gender, employment status [employed, student, homemaker, retired, other (unemployed, temporarily laid off, maternity leave, illness/sick leave, and disabled)], marital status (currently married, divorced/separated/widowed, never married), education level (no education, some primary, finished primary, some secondary, finished secondary, some college, finished college) and household income (low, low-average, high-average and high). Income categories were based on the quartiles of country-specific gross household income distributions (Levinson et al. Reference Levinson, Lakoma, Petukhova, Schoenbaum, Zaslavsky, Angermeyer, Borges, Bruffaerts, de Girolamo, de Graaf, Gureje, Haro, Hu, Karam, Kawakami, Lee, Lepine, Browne, Okoliyski, Posada-Villa, Sagar, Viana, Williams and Kessler2010).
Statistical analyses
Analyses of prevalence, AOO and impairment were carried out for the cross-national sample, each country-income group, each country survey and cross-national gender groups. Cross-tabulations were used to estimate the lifetime, 12-month and 30-day prevalence. Only lifetime prevalence rates were calculated for subtypes of specific phobia and the prevalence of specific phobia with one to more than four lifetime subtypes.
The 12-month prevalence of specific phobia among lifetime cases was used as an indicator of recurrence or chronicity: e.g. a disorder can have a high lifetime prevalence, but a low level of recurrence as shown by a low 12-month prevalence among lifetime cases. The 30-day prevalence among 12-month cases was calculated as an indicator of disorder duration: e.g. a disorder can have a high 12-month prevalence, but a limited duration, as shown by a low 30-day prevalence. The percentages of lifetime and 12-month co-morbidity in lifetime cases and the percentages of 12-month co-morbidity in 12-month cases were estimated. In addition, the percentages of cases in which specific phobia was the temporally primary disorder were calculated. The percentages of 12-month specific phobia cases with severe role impairment and healthcare use across sectors were calculated with cross-tabulation. The mean number of days out of role was calculated for all 12-month specific phobia cases combined and for subsamples of 12-month cases, split out by their highest reported domain of role impairment. Percentages of lifetime co-morbidity, 12-month impairment and healthcare use were calculated for each subtype and groups with one to more than four lifetime subtypes.
The AOO and the projected risk at age 75 years were estimated with the two-part actuarial method implemented in SAS. The actuarial method assumes a constant conditional risk of onset in a given year of life across cohorts and allows for accurate estimations of the onset timings within a year (Halli et al. Reference Halli, Rao and Halli1992). Associations of lifetime specific phobia with demographic factors were analysed with survival models, adjusted for age cohort, gender, person-years and country. Associations of 30-day specific phobia with demographic factors were analysed with logistic regression models, adjusted for time since specific phobia onset, AOO, gender and country. Associations of demographic factors with recurrence (12-month prevalence among lifetime cases) and duration (30-day prevalence among 12-month cases) were analysed with logistic regression, adjusted for time since specific phobia onset, AOO, gender and country. The distributions of AOO and of sociodemographic variables were calculated for groups with different subtypes and subgroups with one to more than four lifetime subtypes.
All analyses were weighted to adjust for differential selection probabilities within households, to match the samples to population sociodemographic distributions and to adjust for non-response (Kessler & Üstün, Reference Kessler and Üstün2008). Design-adjusted standard errors were estimated using the Taylor series linearization method (Wolter, Reference Wolter1985), implemented in SAS 9.4 (SAS Institute Inc., USA). Design-adjusted Wald χ2 tests were used to test the multivariate statistical significance of sets of predictors.
Results
Prevalence
Lifetime specific phobia prevalence ranged from 2.6% to 12.5% across countries (Table 1) and the averaged cross-national lifetime prevalence was 7.4% for the whole sample [median = 6.8%, interquartile range (IQR) = 4.8–10.2%], 4.9% for the male and 9.8% for the female subsample. The prevalence was 8.0–8.1% in high-income and upper-middle-income countries and 5.7% in the low-/lower-middle-income countries. The overall mean 12-month prevalence was 5.5% in the whole sample (median = 5.0%, IQR = 3.8–7.6%), 3.3% among males and 7.7% among females. The 12-month prevalence differed across countries (1.7–10.6%) and income groups (4.0–6.4%), with the lowest prevalence in the low-/lower-middle-income group (4.0%). The overall mean 30-day prevalence was 3.9% in the total sample, with differences across gender (males: 2.1%; females: 5.5%), countries (0.9–8.8%) and income groups (2.4–4.8%), with the lowest prevalence (2.4%) in the low-/lower-middle-income countries.
Table 1. Prevalence of DSM-IV specific phobia in the World Mental Health surveys
Data are given as percentage (standard error) unless otherwise indicated.
DSM-IV, Diagnostic and Statistical Manual of Mental Disorders, fourth edition; PRC, People's Republic of China.
a χ2 Test of homogeneity to determine if there is variation in prevalence estimates.
* p < 0.05 (two-sided test).
Of specific phobia subtypes (Table 2), animal fear had the highest cross-national lifetime prevalence (3.8%), followed by BIM (3.0%), high places (2.8%) and still water or weather events fear (2.3%). Fear of flying had the lowest prevalence (1.3%). The low-/lower-middle-income countries showed the lowest prevalence rates for all subtypes (0.6–3.4%) and considerably higher prevalence rates in upper-middle-income countries (1.2–4.4%) and high-income countries (1.7–3.7%). The clearest difference was seen for fear of flying, which had an almost three times higher prevalence in high-income (1.7%) than in low-/lower-middle-income (0.6%) countries. All subtypes were most common in females. Of the cross-national sample, 3.4% reported a single subtype, 1.8% reported two subtypes, 1.1% reported three subtypes and 1.1% reported more than four subtypes. Higher numbers of subtypes were more common among females than males.
Table 2. Lifetime prevalence of DSM-IV specific phobia subtypes and cases with different numbers of co-occurring subtypes in the World Mental Health surveys
Data are given as percentage (standard error) unless otherwise indicated.
DSM-IV, Diagnostic and Statistical Manual of Mental Disorders, fourth edition; PRC, People's Republic of China.
a χ2 Test of homogeneity to determine if there is variation in prevalence estimates.
* p < 0.05 (two-sided test).
Recurrence and duration
The averaged prevalence of 12-month specific phobia among lifetime specific phobia cases was 74.2% for the whole cross-national sample (median = 73.0%, IQR = 70.2–81.3%; Table 1). The averaged prevalence of 30-day specific phobia among 12-month cases was 70.2% for the cross-national sample (median = 72.6%, IQR = 67.6–78.3%). Both prevalence rates were higher in females than in males. In addition, the 30-day prevalence among 12-month cases was the only that differed notably across income groups, with the lowest rate in the low-/low-middle-income group (58.7%).
AOO
The median AOO was 8 years (IQR = 5–13 years; online Supplementary Appendix Table S2) and differed slightly across surveys (IQR = 8–9 years). The cross-national projected risk at age 75 years was only 0.7% higher than the observed lifetime prevalence rate (8.1% v. 7.4%), reflecting specific phobia's young AOO distribution. Early AOO was most common for all subtypes, but especially common for fear of still water/weather (Table 3; 37.1%), animals (36.6%) and closed spaces (35.2%). A slightly older-onset distribution was seen for fear of flying and high places. Early-onset rates increased and late-onset rates decreased with the number of fears.
Table 3. Sociodemographic characteristics, impairment, co-morbidity and treatment use for each specific phobia subtype and for groups of patients with different numbers of phobias
Data are given as percentage (standard error) unless otherwise indicated.
DSM-IV, Diagnostic and Statistical Manual of Mental Disorders, fourth edition; SDS, Sheehan Disability Scales.
a Highest severity category across four SDS role domains.
b Specialty mental health care, general medical care, human services or complementary/alternative medicine.
Co-morbidity
In 60.5% of lifetime specific phobia cases, at least one other lifetime disorder was present, with 34.3% having a co-morbid mood disorder, 41.2% an anxiety disorder, 15.9% a substance use disorder and 17.4% an impulse-control disorder (Table 4). In those with 12-month co-morbidity of specific phobia with any other disorder, co-morbid anxiety disorders were most common (29.6%), followed by mood disorders (21.0%). Specific phobia preceded the other disorders in the majority of co-morbid cases (71.6–92.2%). Lifetime co-morbidity with any other disorder ranged from 60.6% to 73.0% across subtypes (Table 3). Co-morbidity was highest with anxiety (range: 41.9–58.3%) and mood disorders (range: 34.7–43.6%). Co-morbidity rates were highest in those with fear of closed spaces and flying and increased with the number of subtypes from 49.7% (one subtype) to 82.1% (four or more subtypes).
Table 4. Co-morbidity of specific phobia with other DSM-IV disorders
Data are given as percentage (standard error) unless otherwise indicated.
DSM-IV, Diagnostic and Statistical Manual of Mental Disorders, fourth edition.
a Respondents with major depressive episode or bipolar disorder (broad).
b Respondents with panic disorder, generalized anxiety disorder, social phobia, agoraphobia, post-traumatic stress disorder or separation anxiety disorder.
c Respondents with intermittent explosive disorder, attention-deficit disorder, conduct disorder, oppositional defiant disorder, binge-eating disorder or bulimia nervosa.
d Respondents with alcohol abuse with or without dependence or drug abuse with or without dependence.
e Respondents with any disorder listed above.
f Percentage of respondents with either lifetime or 12-month specific phobia who also meet lifetime criteria for at least one of the other DSM-IV disorders.
g Percentage of respondents with 12-month specific phobia who also meet 12-month criteria for at least one of the other disorders.
h Percentage of respondents with either lifetime or 12-month specific phobia and at least one of the other disorders, whose age of onset of specific phobia is reported to be younger than the age of onset of all co-morbid disorders under consideration (i.e. either mood, anxiety, substance use, impulse control or any disorder).
Demographic correlates of specific phobia onset
In the combined sample, higher risk of lifetime onset of specific phobia (Table 5) was observed in respondents aged younger than 60 years compared with respondents aged 60 years and older [odds ratio (OR) 1.5–1.8], in women compared with men (OR 2.0), in homemakers and those with ‘other’ employment status compared with employed respondents (OR 1.2–1.4), in previously married compared with currently married (OR 1.2), in those with some college or less education compared with those who completed college (OR 1.3–1.7), and in those with low and low-average income compared with those with a high income (OR 1.1–1.2). When analysed by income group (online Supplementary Appendix Tables S3–S5), the following associations with increased odds of lifetime specific phobia onset were consistently observed: being in the youngest age cohort (OR 1.3–2.0), being female (OR 1.5–2.3), having employment status ‘other’ (OR 1.3–1.5) and having a lower education than finished college (OR 1.2–1.9).
Table 5. Bivariate associations between sociodemographics correlates and DSM-IV specific phobia (all countries combined)
Data are given as odds ratio (95% confidence interval).
DSM-IV, Diagnostic and Statistical Manual of Mental Disorders, fourth edition.
a These estimates are based on logistic regression adjusted for age, gender and country.
b These estimates are based on survival models adjusted for age cohorts, gender, person-years and country.
c These estimates are based on logistic regression adjusted for time since specific phobia onset, age of onset, gender and country.
d χ2 Test of significant differences between blocks of sociodemographic variables.
e Includes, for example, looking for work or being disabled.
f Denominator n: 124 902 = total sample; 5 130 258 = number of person-years in the survival models; 9583 = number of lifetime cases of specific phobia; 7140 = number of 12-month cases of specific phobia.
* p < 0.05 (two-sided test).
The age group distribution varied across subtypes (Table 3), with most young persons in animal and BIM phobia. The percentage of females was highest in all subtype groups and increased with number of subtypes. Employment status showed limited variation across subtypes, but the percentage of working persons was markedly lower (53.1%) in those with four or more subtypes compared with those with one to three subtypes (57.7–60.8%). The percentages of cases with completed college showed some variation across subtypes (8.8–12.3%), but a more striking difference between those with four or more subtypes (7.6%) and those with one to three subtypes (12.1–13.8%). Income group distributions showed limited variation across subtypes, but the percentages of low and low-mid income increased with the number of subtypes.
Demographic correlates of persistence
Among lifetime cases, 12-month specific phobia prevalence (Table 5) was higher in those with early AOO compared with those with late AOO (OR 1.4), in women compared with men (OR 1.8), in those who were retired or had employment status ‘other’ compared with the employed (OR 1.3 and OR 1.5), in those with some college or less compared with those with finished college (OR 1.3–1.7), and in those with low income compared with those with high income (OR 1.4). Only female gender was consistently observed to be associated with an increased odds of 30-day prevalence among 12-month cases (OR 1.5–1.9; online Supplementary Appendix Tables S3–S5).
Impairment
In the combined sample, 18.7% of 12-month specific phobia cases reported severe role impairment in any domain (online Supplementary Appendix Table S6), with the highest percentage of severe impairment in the home domain (10.3%) and the lowest in the relationship domain (7.9%). The percentages of severe impairment differed across income groups on all domains, except for work. The low-/lower-middle-income group, especially Nigeria and PRC Shen Zhen, showed the lowest percentages of severe impairment. The upper-middle-income group showed the highest percentages of severe impairment (range: 9.9–14.4%). The mean number of days out of role in the past year due to 12-month specific phobia was 12.2 (s.e. = 0.9). However, those with severe impairment in any domain reported 29.1 days out of role (online Supplementary Appendix Table S7), with the number of days varying depending on the investigated domain of impairment (34.6–47.9 days). The percentage of cases reporting any impairment varied somewhat across subtypes (52.1–57.3%; Table 3). However, impairment rates increased with the number of fear subtypes, with 11.6% reporting severe impairment in those with one subtype and 20.6% in those with four or more subtypes.
Treatment
Cross-nationally, the percentage of 12-month specific phobia cases reporting any treatment was 23.1%. Treatment was more common in those reporting severe impairment (32.5%) compared with those reporting mild or moderate impairment (21.1% and 22.8%, respectively; online Supplementary Appendix Table S8). Treatment rates differed across income groups, with 9.6% in low-/lower-middle-income, 16.0% in higher-middle-income and 30.1% in high-income countries. Overall treatment use showed some variation across subtypes (Table 3), with the highest rates for fear of flying (28.4%), closed spaces (27.5%) and high places (26.0%). Also, rates of treatment use increased from 16.7% in those with one subtype to 29.2% in those with four or more subtypes.
Discussion
Specific phobia is a common mental disorder with a cross-national lifetime prevalence of 7.4%. Interestingly, the prevalence, impairment and duration of specific phobia were considerably higher in high- and upper-middle-income countries than in low-/lower-middle-income countries. This could be due to cultural differences in the degree to which symptoms of specific phobia are recognized or attributed to a mental disorder and differences in catastrophic cognitions about phobic/anxious symptoms (Hinton & Pollack, Reference Hinton and Pollack2009; Marques et al. Reference Marques, Robinaugh, LeBlanc and Hinton2011; Hofmann & Hinton, Reference Hofmann and Hinton2014). Also, there could be differences in how interview questions are interpreted, social norms, attitudes and stigmas surrounding mental problems (Angermeyer & Dietrich, Reference Angermeyer and Dietrich2006; Lee et al. Reference Lee, Juon, Martinez, Hsu, Robinson, Bawa and Ma2009). For instance, differences in specific phobia duration could be attributed to the reasons above but could also reflect differences in the kinds and/or frequencies of reported phobic stimuli. Although cross-national differences could not be investigated in depth, the results suggest that the phenomenology and underlying processes of specific phobia vary across countries. As observed previously (e.g. Stinson et al. Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007; LeBeau et al. Reference LeBeau, Glenn, Liao, Wittchen, Beesdo-Baum, Ollendick and Craske2010), females showed higher specific phobia prevalence than males.
Young age was also observed to be associated with specific phobia, aligning with previous work (Stinson et al. Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007; Sigström et al. Reference Sigström, Skoog, Karlsson, Nilsson and Östling2016). Those with lower education had higher odds of specific phobia, which has been observed previously (Magee et al. Reference Magee, Eaton, Wittchen, McGonagle and Kessler1996) but not in all surveys (Stinson et al. Reference Stinson, Dawson, Chou, Smith, Goldstein, Ruan and Grant2007). Those with employment status ‘other’ (e.g. disabled, looking for a job) showed higher odds of specific phobia. Magee et al. (Reference Magee, Eaton, Wittchen, McGonagle and Kessler1996) found a similar association, but it has not been investigated in other surveys.
Subtype-specific analyses showed that animal phobia had the highest cross-national prevalence (3.8%; 1.4–8.1% across countries), in line with previous observations (3.3–7.0%; Curtis et al. Reference Curtis, Magee, Eaton, Wittchen and Kessler1998; Depla et al. Reference Depla, ten Have, van Balkom and de Graaf2008; LeBeau et al. Reference LeBeau, Glenn, Liao, Wittchen, Beesdo-Baum, Ollendick and Craske2010). Fear of still water or weather events had a prevalence of 2.3%, aligning with previously reported prevalence rates for ‘water’ phobia (2.2–3.4%) and ‘storm’ phobia (2.0–2.9%; LeBeau et al. Reference LeBeau, Glenn, Liao, Wittchen, Beesdo-Baum, Ollendick and Craske2010). For fear of heights, the cross-national prevalence (2.8%) was somewhat lower than reported previously (3.1–5.3%; LeBeau et al. Reference LeBeau, Glenn, Liao, Wittchen, Beesdo-Baum, Ollendick and Craske2010). The cross-national prevalence of BIM phobia (3.0%) was in line with previously estimated prevalence rates (3.2–4.5%; LeBeau et al. Reference LeBeau, Glenn, Liao, Wittchen, Beesdo-Baum, Ollendick and Craske2010). The cross-national prevalence rates fear of closed spaces (2.2%) and fear of flying (1.3%) were both lower than reported previously (closed spaces: 3.2–3.3%; flying: 2.5–2.9%; LeBeau et al. Reference LeBeau, Glenn, Liao, Wittchen, Beesdo-Baum, Ollendick and Craske2010). Apart from methodological differences, some of the discrepancies between current and previous findings could be explained by variations across countries in culture (see above) and rates of exposure (e.g. flying is less common in low-income countries). Investigation of subtype co-occurrence showed that more than half of patients had two or more lifetime fear subtypes and that those with more subtypes had more severe clinical characteristics (e.g. impairment, co-morbidity), aligning with previous results (e.g. Curtis et al. Reference Curtis, Magee, Eaton, Wittchen and Kessler1998).
The median AOO of specific phobia was found to be young, showing relatively limited variation across surveys (IQR = 5–13 years). In line with this, the projected lifetime risk was only slightly higher than the observed lifetime prevalence rates (range of absolute differences across surveys: 0.1–1.2%; range of proportional differences across surveys: 1.7–22.0%). In line with previous work (e.g. Burstein et al. Reference Burstein, Georgiades, He, Schmitz, Feig, Khazanov and Merikangas2012), the AOO distribution showed some differences across subtypes, with more early AOO for animal and natural phenomena phobias. The observation of a younger AOO distribution in those with multiple fear subtypes also aligns with previous work (Burstein et al. Reference Burstein, Georgiades, He, Schmitz, Feig, Khazanov and Merikangas2012). Lifetime co-morbidity levels in specific phobia were high (60.5%), with some subtypes being associated with higher levels than others. In the majority of co-morbid cases, specific phobia onset preceded the other disorders(s). In addition, co-morbidity became more common with increasing numbers of fear subtypes. Together, these results support the idea that specific phobia is an early-life indicator of psychopathology vulnerability.
Severe role impairment was reported in roughly a fifth of 12-month specific phobia cases, but reported impairment was lower in low-/lower-middle-income countries than in the other countries. The mean number of days out of role in all subjects with 12-month specific phobia was 12.2, but in respondents reporting severe impairment, this number was much higher, often in excess of a month, depending on the domain of severe impairment. Twelve-month impairment increased with the number of reported fear subtypes, aligning with the idea that the presence of multiple lifetime fears marks increased clinical severity. Together, these results suggest that specific phobia can have a severe impact on persons’ lives.
Treatment for specific phobia was threefold higher in high-income countries than in low-/lower-middle-income countries, which could be due to differences in the availability of care and financial resources (Saxena et al. Reference Saxena, Thornicroft, Knapp and Whiteford2007; McBain et al. Reference McBain, Norton, Morris, Yasamy and Betancourt2012), the perceived need for treatment (Andrade et al. Reference Andrade, Alonso, Mneimneh, Wells, Al-Hamzawi, Borges, Bromet, Bruffaerts, de Girolamo, de Graaf, Florescu, Gureje, Hinkov, Hu, Huang, Hwang, Jin, Karam, Kovess-Masfety, Levinson, Matschinger, O'Neill, Posada-Villa, Sagar, Sampson, Sasu, Stein, Takeshima, Viana, Xavier and Kessler2014), knowledge about mental healthcare (Palazzo et al. Reference Palazzo, Dell'Osso, Altamura, Stein and Baldwin2014) and prejudices (Clement et al. Reference Clement, Schauman, Graham, Maggioni, Evans-Lacko, Bezborodovs, Morgan, Rüsch, Brown and Thornicroft2015; Semrau et al. Reference Semrau, Evans-Lacko, Koschorke, Ashenafi and Thornicroft2015). Despite differences in treatment rates, associations between the level of impairment and percentages of reported treatment were comparable across the income groups, with severely impaired cases reporting most treatment. These results indicate that self-reported impairment could be an informative clinical specifier indicating need for care.
The current study had several limitations. First, diagnoses were based on structured lay interviews. However, a previous clinical reappraisal study (Haro et al. Reference Haro, Arbabzadeh-Bouchez, Brugha, de Girolamo, Guyer, Jin, Lepine, Mazzi, Reneses, Vilagut, Sampson and Kessler2006) showed sufficient concordance between CIDI-based and clinical diagnoses of specific phobia. Second, all information about lifetime prevalence and AOO was reported retrospectively. This could have led to recall bias, which has been suggested to lead to underestimated lifetime prevalence rates of common mental disorders (Moffitt et al. Reference Moffitt, Caspi, Taylor, Kokaua, Milne, Polanczyk and Poulton2010). If this bias affected reporting of specific phobia in the current study, the true lifetime prevalence and co-morbidity rates could be higher. Third, the included surveys differed in terms of their response rate and sampling frames. Fourth, not all phobia types were systematically assessed (e.g. fear of choking, vomiting, contacting an illness), which could have led to under-reporting. Finally, the results are based on DSM-IV criteria for specific phobia and using DSM-5 diagnoses could have led to different results. Going from DSM-IV to DSM-5, two important modifications were made to the diagnostic criteria. First, persons above 18 years are no longer required to recognize that their fear/avoidance is excessive/unreasonable. Second, the fear/avoidance should at least last 6 months in all persons. Interestingly, the former modification is likely to increase prevalence, whereas the latter is likely to decrease the prevalence, possibly counteracting each other's effects. Given the fact that the core features have remained the same and the nature of the modifications, strongly differing prevalence estimations would not be expected.
Although cross-national differences were observed in the prevalence, associated impairment and treatment use, the results suggest that specific phobia is associated with considerable impairment across the world and often precedes other disorders. These findings suggest that specific phobia deserves attention of clinicians and researchers in view of its direct effects on the global burden of disease, and its role in the developmental unfolding of psychopathology.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S0033291717000174
Acknowledgements
The WHO WMH Survey Initiative is supported by the National Institute of Mental Health (NIMH; R01 MH070884), the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, the US Public Health Service (R13-MH066849, R01-MH069864 and R01 DA016558), the Fogarty International Center (FIRCA R03-TW006481), the Pan American Health Organization (PAHO), Eli Lilly and Company, Ortho-McNeil Pharmaceutical, GlaxoSmithKline and Bristol-Myers Squibb. None of these funders had any role in the design, analysis, interpretation of results, or preparation of this article. A complete list of all within-country and cross-national WMH publications can be found at http://www.hcp.med.harvard.edu/wmh/. Each WMH country obtained funding for its own survey.
The São Paulo Megacity Mental Health Survey is supported by the State of São Paulo Research Foundation (FAPESP) Thematic Project Grant 03/00204–3.
The Bulgarian Epidemiological Study of common mental disorders EPIBUL is supported by the Ministry of Health and the National Center for Public Health Protection.
The Chinese WMH Survey Initiative is supported by the Pfizer Foundation. The Shenzhen Mental Health Survey is supported by the Shenzhen Bureau of Health and the Shenzhen Bureau of Science, Technology, and Information.
The Colombian National Study of Mental Health (NSMH) is supported by the Ministry of Social Protection. The Mental Health Study Medellín – Colombia was carried out and supported jointly by the Center for Excellence on Research in Mental Health (CES University) and the Secretary of Health of Medellín.
The European Study of the Epidemiology of Mental Disorders (ESEMeD) project is funded by the European Commission (contracts QLG5–1999-01042; SANCO 2004123 and EAHC 20081308), the Piedmont Region (Italy), Fondo de Investigación Sanitaria, Instituto de Salud Carlos III, Spain (FIS 00/0028), Ministerio de Ciencia y Tecnología, Spain (SAF 2000-158-CE), Departament de Salut, Generalitat de Catalunya, Spain, Instituto de Salud Carlos III (CIBER CB06/02/0046, RETICS RD06/0011 REM-TAP), and other local agencies and by an unrestricted educational grant from GlaxoSmithKline.
Implementation of the Iraq Mental Health Survey (IMHS) and data entry were carried out by the staff of the Iraqi Ministry of Health and Ministry of Planning with direct support from the Iraqi IMHS team with funding from both the Japanese and European Funds through the United Nations Development Group Iraq Trust Fund (UNDG ITF).
The WMH Japan (WMHJ) Survey is supported by the Grant for Research on Psychiatric and Neurological Diseases and Mental Health (H13-SHOGAI-023, H14-TOKUBETSU-026, H16-KOKORO-013) from the Japan Ministry of Health, Labour and Welfare.
The Lebanese National Mental Health Survey (L.E.B.A.N.O.N.) is supported by the Lebanese Ministry of Public Health, the WHO (Lebanon), National Institute of Health/Fogarty International Center (R03 TW006481-01), Sheikh Hamdan Bin Rashid Al Maktoum Award for Medical Sciences, anonymous private donations to the Institute for Development, Research, Advocacy and Applied Care (IDRAAC), Lebanon, and unrestricted grants from AstraZeneca, Eli Lilly, GlaxoSmithKline, Hikma Pharmaceuticals, Janssen Cilag, Lundbeck, Novartis and Servier.
The Mexican National Comorbidity Survey (MNCS) is supported by the National Institute of Psychiatry Ramon de la Fuente (INPRFMDIES 4280) and by the National Council on Science and Technology (CONACyT-G30544-H), with supplemental support from the PAHO. C.B. has received funding from the (Mexican) National Council of Science and Technology (grant CB-2010-01-155221).
Te Rau Hinengaro: The New Zealand Mental Health Survey (NZMHS) is supported by the New Zealand Ministry of Health, Alcohol Advisory Council and the Health Research Council.
The Nigerian Survey of Mental Health and Wellbeing (NSMHW) is supported by the WHO (Geneva), the WHO (Nigeria) and the Federal Ministry of Health, Abuja, Nigeria.
The Northern Ireland Study of Mental Health was funded by the Health & Social Care Research & Development Division of the Public Health Agency.
The Peruvian WMH Study was funded by the National Institute of Health of the Ministry of Health of Peru.
The Polish project Epidemiology of Mental Health and Access to Care – EZOP Poland was carried out by the Institute of Psychiatry and Neurology in Warsaw in consortium with the Department of Psychiatry – Medical University in Wroclaw and the National Institute of Public Health-National Institute of Hygiene in Warsaw and in partnership with Psykiatrist Institut Vinderen – Universitet, Oslo. The project was funded by the Norwegian Financial Mechanism and the European Economic Area Mechanism as well as the Polish Ministry of Health. No support from pharmaceutical industry or other commercial sources was received.
The Portuguese Mental Health Study was carried out by the Department of Mental Health, Faculty of Medical Sciences, NOVA University of Lisbon, with collaboration with the Portuguese Catholic University, and was funded by the Champalimaud Foundation, Gulbenkian Foundation, Foundation for Science and Technology (FCT) and the Ministry of Health.
The Romania WMH study projects ‘Policies in Mental Health Area’ and ‘National Study Regarding Mental Health and Services Use’ were carried out by the National School of Public Health & Health Services Management (former National Institute for Research & Development in Health), with technical support of Metro Media Transilvania, the National Institute of Statistics-National Centre for Training in Statistics, SC, Cheyenne Services SRL, Statistics Netherlands and were funded by the Ministry of Public Health (former Ministry of Health) with supplemental support of Eli Lilly Romania SRL.
The South Africa Stress and Health Study (SASH) is supported by the US NIMH (R01-MH059575) and National Institute of Drug Abuse (NIDA) with supplemental funding from the South African Department of Health and the University of Michigan.
The Psychiatric Enquiry to General Population in Southeast Spain – Murcia (PEGASUS-Murcia) Project has been financed by the Regional Health Authorities of Murcia (Servicio Murciano de Salud and Consejería de Sanidad y Política Social) and Fundación para la Formación e Investigación Sanitarias (FFIS) of Murcia.
The Ukraine Comorbid Mental Disorders during Periods of Social Disruption (CMDPSD) study is funded by the US NIMH (RO1-MH61905).
The US National Comorbidity Survey Replication (NCS-R) is supported by the NIMH (U01-MH60220) with supplemental support from the NIDA, the Substance Abuse and Mental Health Services Administration (SAMHSA), the Robert Wood Johnson Foundation (RWJF; grant 044708) and the John W. Alden Trust.
Preparation of this report was supported by a VICI grant (no: 91812607) received by P.d.J. from the Netherlands Research Foundation (NWO-ZonMW). The authors appreciate the helpful contributions to the WMH of Herbert Matschinger, Ph.D.
Declaration of Interest
In the past 3 years, R.C.K. has been a consultant for Hoffman-La Roche, Inc., Johnson & Johnson Wellness and Prevention and Sonofi-Aventis Groupe. R.C.K. has served on advisory boards for Mensante Corporation, Plus One Health Management, Lake Nona Institute and U.S. Preventive Medicine. R.C.K. is a co-owner of DataStat, Inc.
K.D. is on the speaker bureau for Astra Zeneca, Eli Lilly, Lundbeck and Servier and has received research grants from Eli Lilly, from the foundation ‘Ga voor Geluk’ and from the Flemish Research Council. The other authors report no disclosures.
