The eloquent Invited Commentary by Kaul and Diamond illustrates the great care that must be taken before concluding that an association described in an observational study truly represents a cause-effect relationship. In our discussion of the article by Liew and colleagues, the editors believed that it provided useful incremental data about an important condition. However, as with many good studies, the data are not definitive enough to suggest changes in clinical practice. Rather, we hope the study galvanizes more research on the relationship between aspirin and macular degeneration. For example, ASPREE (Aspirin in Reducing Events in the Elderly), a large international, randomized controlled trial on the effect of aspirin on cardiovascular outcomes and dementia in elderly persons, hopefully will consider rigorously assessing for macular degeneration.
After the editors decided to accept this article, we discussed the risk that press reports would fall into the trap of reporting this study as definitive. This study provides an opportunity to educate the public about the subtleties and incremental nature of medical research. Our understanding of disease etiology advances as evidence accumulates from multiple good studies.
Covinsky KE. The Incremental Nature of Clinical ResearchComment on “The Association of Aspirin Use With Age-Related Macular Degeneration”. JAMA Intern Med. 2013;173(4):266. doi:10.1001/jamainternmed.2013.2790