Author Affiliations: Johns Hopkins Medical Institutions, Baltimore, Maryland (firstname.lastname@example.org).
To the Editor: Clinical research relying on readily available, inexpensive data originally collected for administrative or billing purposes or both has increased exponentially. Yet the inherent limitations of these administrative databases are frequently ignored. Drs Vaughan Sarrazin and Rosenthal1 provided a summary of these important limitations, including some potential pitfalls in examining diagnostic procedures. A major and often overlooked pitfall is surveillance bias—the phenomenon of “the more you look, the more you find.”2
Haut ER, Pronovost PJ, Schneider EB. Limitations of Administrative Databases. JAMA. 2012;307(24):2589–2590. doi:10.1001/jama.2012.6626