Letters 3 4 We agree that a CAC score of 0 in symptomatic patients may Lyall et al use mendelian randomization, an increasingly not represent low risk. On the other hand, as we showed in popular method to support stronger causal inferences in obser- healthy asymptomatic older people where risk assessment and vational data, but this does not protect against the potential bias drugprescriptionisthemainconsideration,aCACscoreof0most we describe. In the Avon Longitudinal Study of Parents and Chil- likely represents a much lower-risk individual. dren (ALSPAC), a large prospective cohort study in the United Kingdom, both body mass index and smoking predict atten- Philip Greenland, MD dance at subsequent assessment clinics. Genetic antecedents Yuichiro Yano, MD, PhD of factors, such as body mass index and smoking that influence Donald M. Lloyd-Jones, MD, ScM participation, will be subject to a similar bias, which we see in the ALSPAC. Author Affiliations: Department of Preventive Medicine, Northwestern The extent to which bias owing to selection will occur will University Feinberg School of Medicine, Chicago, Illinois (Greenland, Lloyd- depend on the particular association being explored and the op- Jones); Department of Preventive Medicine, University of Mississippi Medical erating selection mechanisms. We suggest that researchers con- Center,
JAMA Cardiology – American Medical Association
Published: Feb 20, 2018
It’s easy to organize your research with our built-in tools.
All the latest content is available, no embargo periods.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud