Utility of a Systolic Blood Pressure Polygenic Risk Score With Chlorthalidone Response

Importance: The clinical utility of polygenic risk scores (PRS) for blood pressure (BP) response to antihypertensive treatment (AHT) has not been elucidated. Objective: To investigate the ability of a systolic BP (SBP) PRS to predict AHT response and apparent treatment-resistant hypertension (aTRH). Design, Setting, and Participants: The Genetics of Hypertension Associated Treatments (GenHAT) study was an ancillary pharmacogenomic study to the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). ALLHAT, which enrolled participants aged 55 years or older with hypertension (HTN) starting in February 1994, completed follow-up in March 2002. The current study was conducted from a subset of Black GenHAT participants randomized to the treatment groups of either chlorthalidone (n = 3745) or lisinopril (n = 2294), with genetic data available from a prior genetic association study. The current study's objective was to examine the association of the SBP PRS to AHT response over 6 months, as well as to examine the predictive accuracy of the SBP PRS with aTRH. The current analysis took place in February 2023, with additional analyses conducted in July 2024. Exposure: An SBP PRS (comprising 1 084 157 genetic variants) stratified as quintiles and per SD. Main Outcomes and Measures: The primary outcome was change in SBP (ΔSBP) and diastolic BP (ΔDBP) over 6 months. aTRH was defined as the use of 3 AHTs with uncontrolled HTN at year 3 of follow-up or taking 4 or more AHTs at year 3 of follow-up, regardless of BP. Baseline demographics were compared across PRS quintiles using Kruskal-Wallis or χ2 tests as appropriate. The least-square means of BP response were calculated through multivariable adjusted linear regression, and multivariable adjusted logistic regression was used to calculate the odds ratios and 95% confidence intervals for aTRH. Results: Among 3745 Black GenHAT participants randomized to chlorthalidone treatment, median (IQR) participant age was 65 (60-71) years, and 2064 participants (55.1%) were female. Each increasing quintile of the SBP PRS from 1 to 5 was associated with a reduced BP response to treatment over 6 months. Participants in the lowest quintile experienced a mean ΔSBP of -10.01 mm Hg (95% CI, -11.11 to -8.90) compared to -6.57 mm Hg (95% CI, -7.67 to -5.48) for participants in the median quintile. No associations were observed between the SBP PRS and BP response to lisinopril. Participants in the highest PRS quintile had 67% higher odds of aTRH compared to those in the median quintile (odds ratio, 1.67; 95% CI, 1.19-2.36). These associations were independently validated. Conclusions and Relevance: In this genetic association study, Black individuals with HTN at a lower genetic risk of elevated BP experienced an approximately 3.5 mm Hg-greater response to chlorthalidone compared with those at an intermediate genetic risk of elevated BP. SBP PRS may also identify individuals with HTN harboring a higher risk of treatment-resistant HTN. Overall, SBP PRS demonstrates potential to identify those who may have greater benefit from chlorthalidone, but future research is needed to determine if PRS can inform initiation and choice of treatment among individuals with HTN.