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COST-EFFECTIVENESS OF ADJUNCTIVE HYPERBARIC OXYGEN IN THE TREATMENT OF DIABETIC ULCERS

Published online by Cambridge University Press:  21 April 2004

Shien Guo ,
Michael A. Counte ,
Kathleen N. Gillespie  and
Homer Schmitz
Shien Guo
Affiliation:
Saint Louis University
Michael A. Counte
Affiliation:
Saint Louis University
Kathleen N. Gillespie
Affiliation:
Saint Louis University
Homer Schmitz
Affiliation:
Saint Louis University
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Abstract

Objectives: This study estimates the cost-effectiveness (CE) of the adjunctive use of hyperbaric oxygen (HBO2) therapy in the treatment of diabetic ulcers based on the payer's and societal perspectives.

Methods: The study population was a hypothetical cohort of 1,000 patients sixty years of age with severe diabetic foot ulcers. A decision tree model was constructed to estimate the CE of HBO2 therapy in the treatment of diabetic ulcers at years 1, 5, and 12. Scenario and one-way sensitivity analyses were also undertaken to identify parameters that may significantly influence the estimates.

Results: The CE model estimated that the incremental cost per additional quality-adjusted life year (QALY) gained at years 1, 5, and 12, was $27,310, $5,166, and $2,255, respectively.

Conclusions: The study results indicate that HBO2 therapy in the treatment of diabetic ulcers is cost-effective, particularly based on a long-term perspective. However, the results are limited by the clinical studies that provide the basis of the CE estimation.

Keywords

Hyperbaric oxygenDiabetic ulcersCost-effectivenessTechnology assessment
Type
RESEARCH NOTES
Information
International Journal of Technology Assessment in Health Care , Volume 19 , Issue 4 , December 2003 , pp. 731 - 737
Copyright
© 2004 Cambridge University Press

Foot ulcers are a common problem that has adversely affected a large number of diabetic patients (25). Due to a lack of effective treatment, diabetic foot ulcers have been reported to be associated with higher utilization of health care (6;18;23;24) and an elevated risk of lower extremity amputations (LEAs) (25). In addition, patients often experience high mortality and a diminished quality of life after major LEA due to lifelong disability (22). Hyperbaric oxygen (HBO2) therapy is one of the treatment modalities that have been recently found to be beneficial to patients with diabetic foot ulcers (27). Several clinical studies have indicated that the adjunctive use of HBO2 therapy significantly improves wound healing and reduces the risk of lower extremity amputation (8;11;15;17;29).

Although the role of HBO2 therapy in diabetic ulcers remains undefined (28), insurers such as Medicare in the U.S. have been recently considering extending coverage for HBO2 therapy in the treatment of diabetic foot ulcers. Such a coverage decision may benefit a large number of patients with diabetic ulcers, but at the same time, it may also have considerable economic consequences for the health-care system. Currently, little is known about the economic impact of the application of HBO2 therapy in diabetic ulcers. To provide more information for better decision making, this study seeks to estimate the cost-effectiveness (CE) of adjunctive use of HBO2 therapy in the treatment of diabetic ulcers.

METHODS AND RESEARCH DESIGN

The CE Model

The study population was a hypothetical cohort of 1,000 patients with severe diabetic foot ulcers (Wagner's classification III or above) (5). Patients were assumed to be sixty years old. By assumption, there are no patients with contraindications of HBO2 therapy, such as high fever, emphysema, or pneumothorax. Furthermore, it was assumed that both control and treatment groups had similar demographic and etiological characteristics.

A decision tree model (see Figure 1) was constructed to estimate the CE ratio of incremental cost per additional quality adjusted life year (QALY) gained (9) from the adjunctive use of HBO2 therapy. The incremental cost was estimated from the total cost of HBO2 therapy minus averted costs of major and minor LEAs saved. We excluded the costs of treating side effects of HBO2 therapy because major side effects that require medical attention rarely occur (21).

Decision tree diagram for cost-effectiveness analysis of hyperbaric oxygen (HBO2) therapy at year 1 in the treatment of diabetic foot ulcers. LEA, lower extremity amputations.

Because wound care is a standard treatment for both HBO2 and non-HBO2 groups, the cost of wound care treatment was excluded from the analysis, as it will not affect the incremental costs of HBO2 treatment. All costs identified for this analysis were inflated to 2001 dollars. QALYs for each patient were derived from assigning EuroQol weights (22) to four different treatment outcomes (see Figure 1). In addition, QALYs gained from the adjunctive use of HBO2 therapy were based on the difference of total QALYs in both treatment and control groups. A discount rate of 3% (13) was applied to adjust QALYs gained in the future years. The entire analysis was performed primarily based on societal and payers' perspectives (9).

Based on the model, we estimated the CE ratio at three time intervals – 1, 5, and 12 years after HBO2 treatments. The 5-year interval was chosen to represent the private payers' perspective, because 5 years later they will automatically become Medicare beneficiaries. The 12-year interval was selected to represent the societal perspective, because the expected life expectancy for people at age 60 is approximately 20 years (1) and the life expectancy for people with diabetes is approximately 8 years shorter than that of people without diabetes (14). Two assumptions were also made for this analysis: first, the mortality rate was assumed to be constant over the 12-year period; second, foot ulcers would not reoccur once they were healed.

The probabilities of treatment outcomes for both the treatment and control groups were based on the summarized results of four prospective, controlled, clinical studies (Table 1). These studies were selected through a complete MEDLINE search between 1985 and 2001 (February). Five studies (7;17;19;20;26) were excluded from the analysis because they failed to meet one of the inclusion criteria, including prospective controlled design, diabetic etiology and the measure of treatment outcomes as primary healing and healing with minor and major LEAs. Additional model parameters used in this analysis are described in Table 2.

Scenario and Sensitivity Analyses

Scenario analyses (9) were conducted to measure the range of the CE ratios between the least (11) and most (2) efficacious outcomes of HBO2 therapy in the treatment of diabetic ulcers shown in Table 2, holding the remaining parameters constant in the model. In addition, one-way sensitivity analyses (9) were also undertaken to evaluate the impact of each parameter on the CE ratios of the base case estimation in different time periods.

RESULTS

CE Ratios

In the base case estimation, 155 cases of major LEAs are averted (205 LEAs in control group versus 50 LEAs in HBO2 group) and approximately 50.2, 265.3, and 608.7 QALYs are gained at years 1, 5, and 12, respectively, due to the use of HBO2 therapy in the hypothetical cohort. The base model also estimates an increase of forty-five cases of minor LEAs in the HBO2 group (130 LEAs in control group versus 175 LEAs in HBO2 group). As a result, the incremental cost of the adjunctive use of HBO2 therapy is $1,370,965, calculated from ($5,901,500 of HBO2 treatments)+($1,773,780 due to increased number of minor LEAs)−($6,304,315 due to major LEAs averted). This calculation results in an incremental cost per additional QALY gained of approximately $27,310, $5,166, and $2,255 at the 1, 5, and 12-year periods, respectively (Table 3), indicating HBO2 therapy is more cost-effective based on a long-term perspective.

Scenario and Sensitivity Analyses

In the scenario analyses, the CE ratios vary substantially across different scenarios. For example, the CE ratio at year 1 is $142,923, $27,310, and $−72,799 in the worst, base, and best case scenarios, respectively (Table 3). In addition, the broad variation of the CE ratios indicates that the results are very sensitive to the efficaciousness probabilities drawn from the existing clinical studies. Table 3 also shows the results of one-way sensitivity analyses. Based on the analyses, the CE ratios are most sensitive to the quality weights, especially for major LEA. Other parameters such as the number of HBO2 treatments per case, the HBO2 cost per treatment, and the treatment costs of major and minor LEA per case also have a significant impact on the CE ratios (see Table 3). The CE ratios are less sensitive to the mortality rate and discount rate (not shown).

DISCUSSION

CE analysis has been used frequently to improve the allocation of scarce health care resources. Treatment alternatives with lower CE ratios indicate a more effective use of resources than those with higher CE ratios. It has been suggested that medical interventions below the threshold of $50,000 per additional QALY gained are considered to be cost-effective (12). This study suggests that the adjunctive application of HBO2 therapy in diabetic ulcers, as compared with the threshold, is relatively cost-effective based on both the payers' and societal perspectives.

Results of the analysis also have several implications. First, HBO2 therapy is more cost-effective based on a long-term perspective. This finding suggests that HBO2 therapy may become less valuable to payers like HMOs if their enrollees, especially those with diabetes, frequently switch their medical plans in the short-term. Second, the negative CE ratio in the best case scenario suggests that HBO2 therapy not only improves the outcomes but also reduces the overall costs of treating diabetic ulcers. Third, the broad variations in the CE ratios across different scenarios and the significant impact of the number of HBO2 treatments on these ratios suggest that this therapy can be more cost-effective if proper clinical practice guidelines, such as criteria for selecting appropriate patients for HBO2 therapy and systematic evaluation to decide the number of HBO2 treatments needed for each patient, can be clearly established and strictly implemented. Fourth, the variation also suggests that more clinical trials of HBO2 therapy with randomized controlled designs, larger sample sizes, and especially long-term follow-up of patients are needed to improve the estimation.

There are three important limitations that need to be addressed. First, the CE estimation was based on a few, small, and methodologically weak studies (28). Thus, the CE of HBO2 therapy may not be so conclusive. Second, the assumption of no recurrence of foot ulcers in the analysis may have a significant influence on the CE ratios. It would considerably increase the CE ratios if foot ulcers reoccur frequently. Third, the improved speed of wound healing and reduction of the level of wound care utilization from the use of HBO2 therapy was not taken into account in the analysis due to the paucity of such information. If they were included in the analysis, the CE ratios could be much lower. Future research on this subject should make efforts to improve these limitations if information becomes available.

POLICY IMPLICATIONS AND CONCLUSIONS

Although the validity of this study may be seriously limited by the clinical studies that provide the basis of the analysis, we believe, given current inadequate information, this study still provides valuable information for better decision making and guidance for future research. To better estimate the CE of HBO2 therapy, economic evaluation should be incorporated into clinical trials of HBO2 therapy. If such direct measurement is not feasible, more clinical trials of HBO2 therapy with larger sample sizes, randomized controlled designs, and especially long-term follow-up of subjects will be needed to improve its CE estimation.

References

Arias E. 2000 United States life table, Center for Disease Control. Available at: http://www.cdc.gov/nchs/data/nvsr/nvsr51/nvsr51_03.pdf. Accessed February 11, 2003.
Baroni G, Porro T, Faglia E et al. 1987 Hyperbaric oxygen in diabetic gangrene treatment. Diabetes Care. 10: 81- 86.Google Scholar
Blid DE, Stevenson JM. 1992 Frequency of recording of diabetes on U.S. death certificates: Analysis of the 1986 National Mortality Followback Survey. J Clin Epidemiol. 45: 275- 281.Google Scholar
Braddeley RM, Fulford JC. 1965 A trial of conservative amputations for lesions of the feet in diabetes mellitus. Br J Surg. 52: 38- 43.Google Scholar
Cianci P. 1994 Adjunctive hyperbaric oxygen therapy in the treatment of the diabetic foot. J Am Podiatr Med Assoc. 84: 448- 455.Google Scholar
Cianci P, Hunt T. 2001 Adjunctive hyperbaric oxygen therapy in the treatment of the diabetic foot wound. In: Bowker J, Pfeifer M, eds. Levin and O'Neal's the diabetic foot. St. Louis: Mosby; 404- 421.
Ciaravino ME, Friedell ML, Kammerlocher TC. 1996 Is hyperbaric oxygen a useful adjunct in the management of problem lower extremity wounds? Ann Vasc Surg. 10: 558- 562.Google Scholar
Doctor N, Pandya S, Supe A. 1992 Hyperbaric oxygen therapy in diabetic foot. J Postgrad Med. 38: 112- 114.Google Scholar
Drummond MF, O'Brien B, Stoddart GL, Torrance GW. 1997 Methods for the economic evaluation of health care programs. New York: Oxford University Press
Eckman MH, Greenfield S, Mackey W et al. 1995 Foot infections in diabetic patients: Decision and cost-effectiveness analyses. JAMA. 273: 712- 720.Google Scholar
Faglia E, Favales F, Aldeghi A et al. 1996 Adjunctive systemic hyperbaric oxygen therapy in treatment of severe prevalently ischemic diabetic foot ulcer. Diabetes Care. 19: 1338- 1343.Google Scholar
Garber AM, Phelps CE. 1997 Economic foundations of cost-effectiveness analysis. J Health Econ. 16: 1- 31.Google Scholar
Gold MR, Siegel J, Russell LB, Weinstein MC. 1996 Cost-effectiveness in health and medicine. New York: Oxford University Press
Gu K, Cowie CC, Harris MI. 1998 Mortality in adults with and without diabetes in a national cohort of the U.S. population, 1971–1993. Diabetes Care. 21: 1138- 1145.Google Scholar
Hammarlund C, Sundberg T. 1994 Hyperbaric oxygen reduced size of chronic leg ulcers: A randomized double-blind study. Plast Reconstr Surg. 93: 829- 833.Google Scholar
Hyperbaric Oxygen Therapy Association. The costs of hyperbaric oxygen therapy prepared by The Lewin Group. Available at: http://www.uhms.org/legislation/lewin.htm. Accessed June 20, 2002.
Lee SS, Chen CY, Chan YS et al. 1997 Hyperbaric oxygen in the treatment of diabetic foot. Chang Geng Med J. 20: 17- 22.Google Scholar
Ollendorf D, Kotsanos J, Wishner W et al. 1998 Potential economic benefits of lower-extremity amputation prevention strategies in diabetes. Diabetes Care. 21: 1240- 1245.Google Scholar
Oriani G, Meazza D, Favales F et al. 1990 Hyperbaric oxygen therapy in diabetic gangrene. J Hyperb Med. 5: 171- 174.Google Scholar
Oriani G, Michael M, Meazza D et al. 1992 Diabetic foot and hyperbaric oxygen therapy: A ten-year experience. J Hyperb Med. 7: 213- 221.Google Scholar
Plafki C, Peters P, Almeling M et al. 2000 Complications and side effects of hyperbaric oxygen therapy. Aviat Space Environ Med. 71: 119- 124.Google Scholar
Ragnarson-Tennvall G, Apelqvist J. 2000 Health-related quality of life in patients with diabetes mellitus and foot ulcers. J Diabetes Complications. 14: 235- 241.Google Scholar
Ramsey SD, Newton K, Blough D et al. 1999 Incidence, outcomes, and cost of foot ulcers in patients with diabetes. Diabetes Care. 22: 382- 387.Google Scholar
Reiber GE. 2001 Epidemiology of foot ulcers and amputation in the diabetic foot. In: Bowker J, Pfeifer M, eds. Levin and O'Neal's the diabetic foot. St. Louis: Mosby; 13- 32.
Reiber GE, Lipsky BA, Gibbons GW. 1998 The burden of diabetic foot ulcers. Am J Surg. 176: 5s- 10s.Google Scholar
Wattel F, Mathieu D, Coget JM, Billard V. 1990 Hyperbaric oxygen therapy in chronic vascular wound management. Angiology. 41: 59- 65.Google Scholar
Willians RL, Armstrong DG. 1998 Wound healing. Clin Podiatr Med Surg. 15: 117- 128.Google Scholar
Wunderlich RP, Peters EJG, Lavery LA. 2000 Systemic hyperbaric oxygen therapy: Lower-extremity wound healing and the diabetic foot. Diabetes Care. 23: 1551- 1555.Google Scholar
Zamboni WA, Wong HP, Stephenson LL, Pfeifer MA. 1997 Evaluation of hyperbaric oxygen for diabetic wounds: A prospective study. Undersea Hyperb Med. 24: 175- 179.Google Scholar
Figure 0

Decision tree diagram for cost-effectiveness analysis of hyperbaric oxygen (HBO2) therapy at year 1 in the treatment of diabetic foot ulcers. LEA, lower extremity amputations.

Figure 1

Summary of Clinical Studies of HBO2 Therapy in Diabetic Ulcers

Figure 2

Model Parameters Used to Estimate Incremental Cost per QALYs Gained and Additional Major LEA Saved from the Use of HBO2 Therapy in the Treatment of Diabetic Ulcers

Figure 3

Estimated Cost-effectiveness of HBO2 Therapy in Different Scenarios and Results of Sensitivity Analyses