%0 Journal Article
%T Performance of the disease risk score in a cohort study with policy-induced selection bias.
%A Tadrous M
%A Mamdani MM
%A Juurlink DN
%A Krahn MD
%A Lévesque LE
%A Cadarette SM
%J J Comp Eff Res
%V 4
%N 6
%D Nov 2015
%M 26529307
%F 2.04
%R 10.2217/cer.15.40
%X <B>OBJECTIVE: </B>To examine the performance of the disease risk score (DRS) in a cohort study with evidence of policy-induced selection bias.<BR><B>METHODS: </B>We examined two cohorts of new users of bisphosphonates. Estimates for 1-year hip fracture rates between agents using DRS, exposure propensity scores and traditional multivariable analysis were compared.<BR><B>RESULTS: </B>The results for the cohort with no evidence of policy-induced selection bias showed little variation across analyses (-4.1-2.0%). Analysis of the cohort with evidence of policy-induced selection bias showed greater variation (-13.5-8.1%), with the greatest difference seen with DRS analyses.<BR><B>CONCLUSIONS: </B>Our findings suggest that caution may be warranted when using DRS methods in cohort studies with policy-induced selection bias, further research is needed.