Seeing the forest and the trees - getting more value out of systematic reviews of complex interventions

Systematic reviews and meta-analyses of complex interventions raise conceptual and methodological challenges that traditional systematic review and meta-analysis approaches fail to address. We have undertaken a series of systematic reviews of diabetes quality improvement interventions (published in JAMA 2006 (50 trials), Lancet 2012 (142 trials), Cochrane Library in preparation (278 trials)). To enhance the value of the systematic review, we have explored procedural (contacting authors) and statistical (Bayesian hierarchical multivariate analyses) innovations to extract more information for decision makers planning diabetes quality improvement activities.