A READERS GUIDE TO THE EVALUATION OF CAUSATION

In this article, we review the criteria used to establish a causal ass ociation. A literature search strategy will be outlined. We present a clinical scenario that was formulated to examine the evidence for nons teroidal anti-inflammatory drugs as a possible cause of gastrointestin al ulceration and bleeding. Several of the studies identified in the l iterature search were critically appraised and the criteria needed to confirm a causal link were then applied. These guidelines may be emplo yed to not only demonstrate the aetiology of a disease but have wider applicability in terms of determining whether a medication may be caus ing certain adverse events.