Gastrointestinal and renal side effects of bisphosphonates: differentiating between no proof of difference and proof of no difference.

BACKGROUND This study was aimed at comparing the safety of bisphosphonates in women with osteoporosis by application of equivalence testing. METHODS Gastrointestinal and renal side effects were evaluated based on information published in randomized controlled trials. RESULTS The data on gastrointestinal side effects (47 trials) indicated that alendronate, risedronate etidronate, and zolendronate have similar rates of the adverse effects; application of Bayesian network meta-analysis showed that equivalence was demonstrated according to margins around ±10%. The data on renal safety were more sparse and suffered from the use of different outcome measures; hence, a single trial could be evaluated. This trial showed a similar effect of alendronate and risedronate on renal function at 12 months; equivalence was based on differences between the two agents in renal function with margins of less than ±10.4 ml/min. CONCLUSION Our study provided quantitative information to determine to what extent bisphosphonates can be considered equivalent in terms of gastrointestinal and renal side effects.