Intermittent claudication (IC) is pain caused by chronic occlusive arterial disease that develops in a limb during exercise and is relieved with rest. Most drug treatments of IC have a limited effect in improving walking distance. Padma 28, a Tibetan herbal preparation, has been used to treat IC, but there is debate as to whether Padma 28 produces a clinical benefit beyond the placebo effect. This is an update of a review first published in 2013.
To determine whether Padma 28 is effective, compared with placebo or other medications, in increasing pain-free and maximum walking distance for patients with intermittent claudication.
For this update the Cochrane Vascular Trials Search Co-ordinator searched the Specialised Register (September 2015), the Cochrane Register of Studies ((CENTRAL) (2015, Issue 8)) and clinical trials databases.
Randomised controlled trials of Padma 28 compared with placebo or other pharmacological treatments in people suffering from IC.
All review authors independently assessed the selected studies and extracted the data. Risk of bias was evaluated independently by two review authors. Depending on the data provided in the individual trials, we extracted mean or median walking distance at the end of the trial, or change in walking distance over the course of the trial, or both. Where not provided, and whenever possible, the statistical significance of differences in these parameters between treatment and placebo groups in individual trials was calculated. Where possible, data were combined by meta-analysis.
No new trials were identified in the search for this review update. In total five trials involving 365 participants were included in this review. All trials compared Padma 28 with placebo for at least 16 weeks of follow-up. Pain-free and maximum walking distances both increased significantly in the groups treated with Padma 28, with no significant change in the placebo group. In general, the studies presented results comparing the treatment arms before and after treatment but made no comparisons between the Padma 28 and placebo groups. Pooled data of maximum walking distance after treatment with Padma 28 and placebo from two studies (193 participants) indicated a higher maximum walking distance (mean difference (MD) 95.97 m, 95% confidence interval (CI) 79.07 m to 112.88 m, P < 0.00001, very low quality evidence) in the Padma 28 group compared with placebo. The clinical importance of these observed changes in walking distance is unclear as no quality of life data were reported. There was no effect on ankle brachial index (ABI): change in ABI values between baseline and six months follow up MD -0.01, 95% CI -0.07 to 0.05, 1 study, 56 participants, P = 0.72, very low quality evidence). Mild side effects, especially gastrointestinal discomfort, tiredness and skin eruption, were reported but this outcome was not different between the Padma 28 and placebo groups (odds ratio 1.09, 95% CI 0.42 to 2.83, four studies, 231 participants, P = 0.86, very low quality evidence).
Some evidence exists from individual trials to suggest that Padma 28 may be effective in increasing walking distances, at least in the short term (four months), in people with IC. Side effects do not appear to be a problem. However, the longer term effects of treatment are unknown and the clinical significance of the improvements in walking distance are questionable. Moreover, the quality of the evidence is limited by the small sample size of the available trials, limited reporting of statistical analyses that compared treatment groups, and relatively high withdrawal rates that were linked to the outcome. That is, patients were withdrawn if they failed to improve walking distance. There was also evidence of publication bias. We therefore feel there is currently insufficient evidence to draw conclusions regards the effectiveness of Padma 28 in the routine management of IC. Further well-designed research would be required to determine the true effects of this herbal preparation.