Author Affiliations: Vattikuti Urology Institute, Henry Ford Health System, Detroit Michigan.
In the Research Letter titled “Declines in Prostate Cancer Incidence After Changes in Screening Recommendations,”1 Howard demonstrates an immediate decline in the incidence of early-stage prostate cancer among men 75 years or older, following the US Preventive Services Task Force (USPSTF) recommendations against screening men in this age group. This finding is of particular interest given recent data that demonstrate stable rates of self-reported screening in men 75 years or older between 2005 and 2010.2 There is face validity to Howard's assertion, and the temporality of screening recommendations and incidence merits further investigation; nonetheless, the implicit limitations of observational data caution against apportionment of causality. Observational data often demonstrate the influence of secular trends that require complex statistical methodology to control for measured and unmeasured confounding.
Sammon JD, Sukumar S, Trinh Q. Prostate Cancer Screening and Incidence: A Question of Causality. JAMA Intern Med. 2013;173(5):392-393. doi:10.1001/jamainternmed.2013.2164