Meta-analysis and adverse drug reactions

Evelinde Trindade and colleagues raise a number of important issues regarding meta-analysis and the reporting of adverse drug reactions in their article on adverse effects associated with selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants.'

Although meta-analysis has become an accepted method for statistically pooling outcome measurements, the results of such analyses may not uniformly predict the clinical outcomes of randomized controlled trials2 and must be interpreted with caution. Limitations depend upon the selection of articles combined, the outcome criteria chosen, the heterogeneity of the studies included, the statistical technique used to pool the data, duplicate publication and interpretation of results.3,4

Furthermore, meta-analysis was developed primarily to examine treatment efficacy, not safety. Trindade and colleagues report crude occurrence rates of adverse events for 2 classes of antidepressant medications. They found that SSRIs cause significantly more serotonergic events and tricyclic antidepressants more anticholinergic events. Did this outcome warrant the use of metaanalysis? Although the presentation of overall event rates may be useful,5 meta-analysis comparing the adverse events of treatments with widely different side effect profiles is unnecessary, as there is no conflict to...