[abstract] THE PLACEBO EFFECT OF HYPERBARIC OXYGEN THERAPY - FACT OR FICTION?

Abstract

BACKGROUND: Patients undergoing hyperbaric oxygen therapy (HBO) frequently report improvement in their health status; however, it is debatable whether this is a true effect of HBO or a placebo. We aimed to investigate the placebo effect of receiving HBO. METHODS: 18 Patients with diabetic foot ulcers were randomised, in a double blind study, either to receive hyperbaric 100percent oxygen (treatment group) or hyperbaric air (placebo group), at 2.4 atmospheres of absolute pressure for 90 minutes daily, for a total of 30 treatments. Two generic health status questionnaires, SF-36 Health Survey and HADS (Hospital Anxiety and Depression Scale) were used to assess the patients before commencing the treatment, and after day 1, day 15 and day 30. RESULTS: HADS detected a significant reduction in the depression score in both groups (p=0.001) and a significant reduction in anxiety levels in the control group (p=0.025). In five of the eight domains of the SF-36, the treatment had no significant effect in either group. Patients in the treatment group reported significant improvement in the General Health domain (p=0.008), in the Vitality domain (p=0.01), in the Mental Health domain (p=0.05), and in their overall Health Transition (p=0.04). In contrast, there was no significant difference in the placebo group in all domains of the SF-36. CONCLUSION: Patients receiving hyperbaric oxygen reported a significant improvement in their health related quality of life. In contrast, the placebo effect of hyperbaric therapy as measured by SF-36 was insignificant. Nevertheless, HADS has detected a significant reduction in both anxiety and depression scores in the placebo group.