Fig 1.
Overview of the study design to compare the gastrointestinal bleeding risk between 1 of 4 statins concomitantly administered with warfarin.
All patients who were administered warfarin or a statin between January 1996 and August 2013 in a Korean university hospital were enrolled. Patients were divided into four groups based on the prescribed statin. Within-class comparisons were conducted after 1:1 propensity score (PS) matching. *The propensity scores were calculated using age; sex; Charlson comorbidity index; antithrombotic, nonsteroidal anti-inflammatory drug, steroid, or fibrate use for >30 days during the observation period; underlying liver cirrhosis; and underlying coagulation disorders. GI, gastrointestinal; PDC, proportion of days covered.
Fig 2.
Definition of continuous administration, co-administration, and observation period for statins and warfarin.
(A) Continuous administration was defined as repeated prescriptions of the same medication with a <30-day interval between the end of the previous prescription and start of the following prescription. The co-administration period was defined as overlapping continuous administration of both a statin and warfarin. (B) The observation period lasted up to 2 years from the start of the statin and warfarin co-administration and ended when a gastrointestinal (GI) bleeding event occurred or observation was censored.
Table 1.
Baseline characteristics and laboratory results at baseline and during the observation period for the four statin groups.
Fig 3.
Kaplan Meier curves for the gastrointestinal bleeding-free survival rate according to exposure to four different statins concomitantly administered with warfarin.
(A) Pravastatin vs. the other statins, (B) Simvastatin vs. the other statins, (C) Atorvastatin vs. the other statins, (D) Rosuvastatin vs. the other statins.
Table 2.
Incidence of gastrointestinal bleeding in patients administered both warfarin and a statin, based on the 3 steps of identification.
Table 3.
Cox proportional hazards regression analysis of gastrointestinal bleeding for each statin group during the observation period.