COVID-19 infection and risk of incident hypertension: a case-control time-to-event study

Most previous studies of increased hypertension (HTN) incidence following COVID-19 infection lack longitudinal testing and diagnostic information and under-represent minorities. We examined this relationship using a case-control time-to-event-study of 39,746 individuals continuously incarcerated from January 1, 2019 to March 1, 2020 (pandemic start), followed until March 1, 2023 in 31 California state prisons. Those included had no pre-pandemic HTN diagnosis and no blood pressure-altering medication prescriptions; had BMI and blood pressure measurements before and during the pandemic; and were tested for COVID-19. Exposure began 31 days after COVID-19 positivity. Clinical diagnosis established incident HTN. Multivariate Cox proportional hazards models adjusted for age, sex, race/ethnicity, BMI, baseline blood pressure, and frequency of healthcare contacts and COVID-19 testing. We assessed confounding from changes in HTN testing post-COVID. 21,480 individuals tested COVID-19 positive prior to HTN diagnosis (or censoring). The subsequent crude HTN incidence rate was 32.5 per 1,000 person-years (exposed) [95%CI: 30.5-34.6] versus 27.1 (unexposed) [25.8-28.5]. COVID-19 infection was associated with significantly increased HTN incidence (main effects HRR: 1.44 [1.32-1.57]; including interactions: HRR: 2.05 [1.50-2.79]), with stronger association for higher BMI, higher pre-pandemic blood pressure, and older age. Potential confounding from post-COVID increases in HTN diagnostic testing cannot explain these results.