Incidence of venous thrombotic events and events of special interest in a retrospective cohort of commercially insured US patients

Objective To estimate the US incidence of thrombotic events and related rare diagnoses. Design Claims-based retrospective cohort study of incidence. Setting US commercial health insurance administrative claims database. Participants Adults 25-64 years of age between 2015 and 2019 with a minimum of 12 consecutive thrombosis-free months of continuous enrolment beginning 2014 were selected. Main outcomes Age (10-year intervals) and sex stratum-specific incidence rates per 100 000 person-years were determined for venous thromboembolism (VTE), cerebral venous thrombosis (CVT) and other major venous thrombotic events, and events of special interest, including immune thrombocytopenic purpura (ITP), haemolytic-uremic syndrome (HUS) and heparin-induced thrombocytopenia (HIT). Results Of 13 249 229 enrollees (half female/male), incidence of venous thromboembolic events (deep vein thrombosis (DVT), pulmonary embolism (PE), CVT or other major venous thrombotic conditions) was 247.89 per 100 000 person-years (95% CI: 245.96 to 249.84). Incidence of VTE was 213.79 with ICD codes alone (95% CI: 211.99 to 215.59) and 129.34 (95% CI: 127.95 to 130.75) when also requiring a filled anticoagulation prescription or an inferior vena cava (IVC) filter. Incidence was 6.37 for CVT (95% CI: 6.07 to 6.69), 26.06 for ITP (95% CI: 25.44 to 26.78), 0.94 for HUS (95% CI: 0.82 to 1.06) and 4.82 for HIT (95% CI: 4.56 to 5.10). The co-occurrence of CVT with either ITP or HIT (diagnoses within 14 days of one another) was 0.090 (95% CI: 0.06 to 0.13). Incidence tended to increase with age and was higher for women under 55. Incidence for CVT, HUS and CVT with ITP or HIT was higher for women in all age groups. Incidence of PE and CVT increased significantly over the 5-year period, while DVT rates decreased. Conclusions These results are the first US estimates for the incidence of thrombotic and rare events of interest in a large, commercially insured US population. Findings provide a critically important reference for determining excess morbidity associated with COVID-19 and more generally for vaccine pharmacovigilance.