Table 1.

Characteristics of the UK Biobank cohort participants.

Variable	GWAS discovery set (N=39,986)	PRS testing set (N=424,411)
Enrollment age	55.6 (7.6)	57.1 (8.1)
ECG age	64.0 (7.7)	Not applicable
Female	20,809 (52.0%)	232,654 (54.8%)
Race (White British)	38,617 (96.6%)	370,121 (87.2%)
Height (cm)	169.1 (9.2)	168.3 (9.3)
Weight (kg)	76.0 (15.2)	78.0 (16.0)
Systolic blood pressure	138.3 (18.6)	138.1 (18.7)
Diastolic blood pressure	79.1 (10.1)	82.4 (10.2)
Smoking (current)	1,446 (3.6%)	46,433 (11.0%)
Antihypertensive medication use (Yes)	4,275 (10.7%)	88,887 (18.6%)
Diabetes (Yes)	1,546 (3.9%)	11,089 (2.6%)
Heart failure (Yes)	186 (0.5%)	1,701 (0.4%)
Myocardial infarction (Yes)	916 (2.3%)	9,657 (2.3%)

Clinical variables were ascertained at baselines. For the genome-wide association studies (GWAS) discovery set, baseline refers to the time of electrocardiogram (ECG) visit. For the polygenic risk scores (PRS) testing set, baseline refers to the time of study enrollment. Descriptive statistics of enrollment age, female, race, and history of diabetes, heart failure and myocardial infarction for the PRS testing set were calculated using the complete sample (N=424,411). Height, weight, systolic blood pressure and diastolic blood pressure were summarized in a subset with the data available (N=423,044). The sample size for participants who self-reported their smoking status and medication use were 423,919 and 477,644, respectively.