Incidence and prevalence of antiphospholipid syndrome (APS) in the USA (2016-2019): a retrospective database study.

OBJECTIVE

Few epidemiological studies are reported in the published literature on the incidence or prevalence of antiphospholipid syndrome (APS), and available results are heterogeneous. This study aimed to estimate the incidence and prevalence of APS in the USA, overall and by APS subtype.

DESIGN

A retrospective analysis of APS disease incidence and a cross-sectional analysis of disease prevalence.

SETTING

Merative MarketScan Commercial Claims and Encounters Database, and the Medicare Supplemental and Coordination of Benefits Database.

PARTICIPANTS

All individuals with claims for at least two antiphospholipid antibody tests undertaken at least 12 weeks apart and a diagnosis claim for APS as a primary or secondary diagnosis on or after the second antibody test, during the period 1 January 2016 to 31 December 2019.

MAIN OUTCOME MEASURES

Annual incidence and prevalence of APS and APS subtypes.

RESULTS

In total, 1708 cases of APS were identified during the study period (2016-2019), of which 83% were women. The overall annual standardised incidence rate of APS per 100 000 person-years increased slightly over the study period, from 2.31 in 2016 to 2.71 in 2019. In 2019, the estimated annual prevalence of APS per 100 000 persons was 10.42 per 100 000 persons (95% CI 9.96-10.90). Based on this and US census data, we have estimated that 34 000 persons in the USA were affected by APS in 2019.

CONCLUSIONS

These data add to the estimates of prevalence and incidence of APS in the literature, all of which have different strengths and limitations of the different data sources and case ascertainment methods.