Hyperbaric oxygen therapy for non-healing ulcers in diabetes mellitus: an evidence-based analysis.
OBJECTIVE
To examine the effectiveness and cost-effectiveness of hyperbaric oxygen therapy (HBOT) to treat people with diabetes mellitus (DM) and non-healing ulcers. This policy appraisal systematically reviews the published literature in the above patient population, and applies the results and conclusions of the review to current health care practices in Ontario, Canada. Although HBOT is an insured service in Ontario, the costs for the technical provision of this technology are not covered publicly outside the hospital setting. Moreover, access to this treatment is limited, because many hospitals do not offer it, or are not expanding capacity to meet the demand.


OBJECTIVE
Diabetes mellitus is a chronic disease characterized by an increase in blood sugar that can lead to many severe conditions such as vision, cardiac, and vascular disorders. The prevalence of DM is difficult to estimate, because some people who have the condition are undiagnosed or may not be captured through data that reflect access to the health care system. The Canadian Diabetic Association estimates there are about 2 million people in Canada with diabetes (almost 7% of the population). According to recent data, the prevalence of DM increased from 4.72% of the population aged 20 years and over in 1995, to 6.19% of the population aged 20 years and over in 1999, or about 680,900 people in 1999. Prevalence estimates expanded to 700,000 in 2003. About 10% to 15% of people with DM develop a foot wound in their lifetimes because of underlying peripheral neuropathy and peripheral vascular disease. This equals between 70,000 and 105,000 people in Ontario, based on the DM prevalence estimate of 700,000 people. Without early treatment, a foot ulcer may fester until it becomes infected and chronic. Chronic wounds are difficult to heal, despite medical and nursing care, and may lead to impaired quality of life and functioning, amputation, or even death.


METHODS
Hyperbaric oxygen therapy has been in use for about 40 years. It is thought to aid wound healing by supplying oxygen to the wound. According to the Hyperbaric Oxygen Therapy Association, HBOT acts as a bactericidal, stops toxin production, and promotes tissue growth to heal difficult wounds. During the procedure, a patient is placed in a compression chamber with increased pressure between 2.0 and 2.5 atmospheres absolute for 60 to 120 minutes, once or twice daily. In the chamber, the patient inhales 100% oxygen. Treatment usually runs for 15 to 20 sessions. Noted complications are rare but may include claustrophobia; ear, sinus, or lung damage due to pressure; temporary worsening of short sightedness; and oxygen poisoning. Careful monitoring during the treatment sessions and follow-up by a trained health care provider is recommended.


METHODS
The aims of this health technology policy appraisal were to assess the effectiveness, safety, and cost-effectiveness of HBOT, either alone, or as an adjunct, compared with the standard treatments for non-healing foot or leg ulcers in patients with DM. The following questions were asked: Alone or as an adjunct therapy, is HBOT more effective than other therapies for non-healing foot or leg ulcers in patients with DM?If HBOT is effective, what is the incremental benefit over and above currently used strategies?When is the best time in a wound treatment strategy to use HBOT?What is the best treatment algorithm with HBOT?The Medical Advisory Secretariat searched for health technology assessments in the published and grey literature. The search yielded 4 reports, which were published from 2000 to 2005. The most recent from the Cochrane Collaboration had a literature review and analysis of randomized control trials to 2003. As an update to this review, as per the standard Medical Advisory Secretariat systematic review strategy, the abstracts of peer-reviewed publications were identified using Ovid MEDLINE, EMBASE, MEDLINE in-process and not-yet-indexed citations, Cochrane Database of Systematic Reviews, Cochrane CENTRAL, and INAHTA using key words and searching from January 1, 2003 to 2004. The criteria for inclusion were as follows: Patients with diabetesLive human studyEnglish-language studyHBOT as adjunctive therapy or aloneRandomized control trialThe number of excluded studies included the following: 2 animal studies13 focus on condition other than DM8 review/protocol for HBOT use3 HBOT not focus of report2 health technology assessments (2)1 non-RCTOutcomes of interest were wound healing and prevention of amputation. The search yielded 29 articles published between 2003 and 2004. All 29 of these were excluded, as shown beside the exclusion criteria above. Therefore, this health technology policy assessment focused exclusively on the most recently published health technology assessments and systematic reviews.


RESULTS
Four health technology assessments and reviews were found. Cochrane Collaboration researchers published the most recent review in 2005. They included only randomized controlled trials and conducted a meta-analysis to examine wound healing and amputation outcomes. They found that, based on findings from 118 patients in 3 studies, HBOT may help to prevent major amputation (relative risk, 0.31; 95% confidence interval [CI], 0.13-0.71) with a number needed to treat (NNT) of 4 (95% CI, 3-11). They noted, however, that the point estimates derived from trials were not well reported, and had varying populations with respect to wound severity, HBOT regimens, and outcome measures. These noted limitations rendered the comparison of results from the trials difficult. Further, they suggested that the evidence was not strong enough to suggest a benefit for wound healing in general or for prevention of minor amputations. The Medical Advisory Secretariat also evaluated the studies that the Cochrane Collaboration used in their analysis, and agreed with their evaluation that the quality of the evidence was low for major and minor amputations, but low to moderate for wound healing, suggesting that the results from new and well-conducted studies would likely change the estimates calculated by Cochrane and others.


CONCLUSIONS
In 2003, the Ontario Health Technology Advisory Committee recommended a more coordinated strategy for wound care in Ontario to the Ministry of Health and Long-term Care. This strategy has begun at the community care and long-term care institution levels, but is pending in other areas of the health care system. There are about 700,000 people in Ontario with diabetes; of these, 10% to 15% may have a foot ulcer sometime in their lifetimes. Foot ulcers are treatable, however, when they are identified, diagnosed and treated early according to best practice guidelines. Routine follow-up for people with diabetes who may be at risk for neuropathy and/or peripheral vascular disease may prevent subsequent foot ulcers. There are 4 chambers that provide HBOT in Ontario. Fewer than 20 people with DM received HBOT in 2003. The quality of the evidence assessing the effectiveness of HBOT as an adjunct to standard therapy for people with non-healing diabetic foot ulcers is low, and the results are inconsistent. The results of a recent meta-analysis that found benefit of HBOT to prevent amputation are therefore uncertain. Future well-conducted studies may change the currently published estimates of effectiveness for wound healing and prevention of amputation using HBOT in the treatment of non-healing diabetic foot ulcers. Although HBOT is an insured service in Ontario, a well conducted, randomized controlled trial that has wound healing and amputation as the primary end-points is needed before this technology is used widely among patients with foot wounds due to diabetes.