Concomitant Use of Oral Anticoagulants with Oral Dipeptidyl Peptidase‐4 Inhibitors and Serious Bleeding Events

In a prior screening study, saxagliptin, a dipeptidyl peptidase‐4 inhibitor (DPP‐4i), was found to have an increased rate of serious bleeding when used concomitantly with several oral anticoagulants (OACs). We aimed to confirm or refute the associations between concomitant use of individual OACs and DPP‐4is and serious bleeding in a large US database, using self‐controlled case series (SCCS) and case‐crossover (CCO) designs. The study population was eligible Medicare beneficiaries co‐exposed to a DPP‐4i (precipitant) and either an OAC (object drug) or lisinopril (negative control object drug) in 2016–2020. For the SCCS, we used conditional Poisson regression to estimate adjusted rate ratios (RRs) between each co‐exposure (vs. not) and serious bleeding and divided the RR by the adjusted RR for the corresponding lisinopril + precipitant pair to obtain ratios of RRs (RRRs). For the CCO, we estimated the adjusted odds ratios (ORs) of exposure to the precipitant in the focal window vs. referent window using multivariable conditional logistic regression and divided the ORs in the object drug‐exposed cases over the ORs in negative object drug‐exposed cases to obtain the ratios of ORs (RORs). The adjusted RRRs for serious bleeding ranged from 0.32 (0.05–1.91) for apixaban/lisinopril + saxagliptin to 3.49 (1.29–9.48) for warfarin/lisinopril + linagliptin. The adjusted RORs ranged from 0.01 (0.00–0.20) for rivaroxaban/lisinopril + saxagliptin to 2.99 (0.74–12.11) for apixaban/lisinopril + linagliptin. While we could not confirm previously identified signals because of statistical imprecision, several numerically elevated estimates still warrant caution in concomitant use and further examination.