Table 4.

Summary of findings from prespecified secondary analyses

Analysis		Relevant results*,†
Minimizing the role of chance, bias, and/or confounding
Exclusion of persons with baseline history of GIB/ICH		Excluded N = 7,259 users (3.1% of cohort) gemfibrozil: aHR within 30 days of cohort entry = 1.76, 1.31 to 2.37 gemfibrozil: aHR within 180 days of cohort entry = 1.51, 1.20 to 1.91 fenofibrate: aHR within 180 days of cohort entry = 1.32, 1.06 to 1.63
Exclusion of persons with baseline enrollment in Medicaid managed care		Excluded N = 77,251 users (32.6% of cohort) gemfibrozil: aHR within 30 days of cohort entry = 1.37, 0.95 to 1.97 Excluded N = 80,923 users (34.2% of cohort) gemfibrozil: aHR within 180 days of cohort entry = 1.25, 0.94 to 1.66 fenofibrate: aHR within 180 days of cohort entry = 1.25, 0.97 to 1.59
Exclusion of ICH outcomes with a co-occurring intracranial injury diagnosis		Excluded N = 21 users (<0.01% of cohort) gemfibrozil: aHR within 30 days of cohort entry = 1.81, 1.37 to 2.37 Excluded N = 54 users (0.02% of cohort) gemfibrozil: aHR within 180 days of cohort entry = 1.55, 1.25 to 1.93 fenofibrate: aHR within 180 days of cohort entry = 1.27, 1.04 to 1.56
Exclusion of empirical covariates from the PS thought to be strong correlates of exposure but not associated with the outcome		Excluded N = 149 covariates (22.0% of covariates included in final model) gemfibrozil: aHR within 30 days of cohort entry = 1.78, 1.36 to 2.34 gemfibrozil: aHR within 180 days of cohort entry = 1.51, 1.21 to 1.87 fenofibrate: aHR within 180 days of cohort entry = 1.24, 1.01 to 1.52
Exclusion of persons with a pre-cohort entry to on-or-after cohort entry increase in warfarin dose		Excluded N = 13,709 users (5.8% of cohort) gemfibrozil: aHR within 30 days of cohort entry = 1.82, 1.38 to 2.41 gemfibrozil: aHR within 180 days of cohort entry = 1.57, 1.26 to 1.97 fenofibrate: aHR within 180 days of cohort entry = 1.23, 1.00 to 1.53‡
Further elucidating the association between exposure and outcome
Increasing maximum follow-up time to 180 days, including examining the following discreet time windows: 1–29 days; 30–59 days; 60–119 days; and 120–180 days		See Figure 3 and Appendix Table 4
Examining effect modification by presumed indication for warfarin	atrial fibrillation/flutter	P-value for interaction term (antihyperlipidemic × atrial fibrillation/flutter) = 0.026 Among users with atrial fibrillation/flutter: gemfibrozil: aHR within 30 days of cohort entry = 2.29, 1.61 to 3.25 Among users without atrial fibrillation flutter: gemfibrozil: aHR within 30 days of cohort entry = 1.32, 0.86 to 2.03
	valvular heart disease	As the p-value for the interaction term (antihyperlipidemic × valvular heart disease) was non-significant (p = 0.211), stratified results are not presented
	venous thromboembolism	As the p-value for the interaction term (antihyperlipidemic × venous thromboembolism) was non-significant (p = 0.681), stratified results are not presented
	other indication	As the p-value for the interaction term (antihyperlipidemic × other indication) was non-significant (p = 0.560), stratified results are not presented
Examining effect modification by laboratory monitoring for level of anticoagulation		As the p-value for the interaction term (antihyperlipidemic × laboratory monitoring) was non-significant (p = 0.921), stratified results are not presented
Examining effect modification by duration of prior warfarin use		As the p-value for the interaction term (antihyperlipidemic × duration of prior warfarin use) was non-significant (p = 0.964), stratified results are not presented

aHR = propensity score-adjusted hazard ratio; GIB = gastrointestinal bleeding; ICH = intracranial hemorrhage; PS = propensity score

^*most non-significant findings not shown; data available from the authors

^†comparison vs. pravastatin

^‡p = 0.053