Statistical analysis comparison of studies investigating the outcome of hyperbaric oxygen therapy in the management of diabetic foot ulceration

Controversial have been reported from studies evaluating the effect of hyperbaric oxygen therapy (HBOT) on diabetic foot ulceration (DFU), and the recommendations are inconsistent. The study objective was to systematically compare differences in methodological quality and conduct between studies favouring HBOT in the treatment of DFU and those that do not favour it. Secondary analysis of prospective comparative studies of the effectiveness of HBOT in DFU was performed. General information and study design were compared. Studies were classified as favouring HBOT if the primary outcome significantly favoured HBOT and non-favouring HBOT otherwise. Differences in various methodological quality domains were assessed using Cochrane risk of bias tool for randomized controlled trials (RCTs) and Newcastle-Ottawa Scale for observational studies. Thirteen of the 18 included studies favoured HBOT. None of the included studies was multi-centre, and most of them (59%, 10/17) either did not mention funding information or reported no funding. RCTs comprised 78% (14/18); their overall methodological quality was moderate. A few studies favouring HBOT reported an intention-to-treat analysis (30%, 3/10), had sham control (31%, 4/13), and stated the adverse effects of HBOT (46%, 6/13). Of the studies that did not favour HBOT, only one reported sample size calculation; however, it employed an inappropriate outcome. Both those favouring and not favouring HBOT for DFU were of inadequate quality to explain the effect of HBOT on DFU. Sufficiently large and high-quality international, multi-centre, randomized controlled clinical trials are required to formally examine the efficacy of HBOT in DFU.