Factors influencing participation and long-term commitment to self-monitoring of blood pressure in a large remote clinical trial: The treatment in morning versus evening (TIME) study

This study investigates factors associated with active participation, and long-term commitment, to home blood pressure monitoring (HBPM) in the TIME study, a remote clinical trial assessing the effectiveness of morning vs. evening dosing of antihypertensive medications on cardiovascular outcomes in adults with hypertension. Participants reporting HBPM ownership were invited to submit blood pressure (BP) measurements three-monthly. Factors associated with active participation (submitting at least one set of BP measurements), and longer-term commitment (at least six sets of BP measurements), were analysed using multivariable logistic regression. 11,059 participants agreed to provide BP measurements, of whom 7646 submitted. Active participation was associated with age (adjusted odds ratio (AOR) per decade, 1.29; 95% CI 1.23–1.36), positive family history of hypertension (AOR 1.11; 95% CI 1.01–1.21), number of antihypertensive medications (AOR, 1.10; 95% CI 1.04–1.16), and lower deprivation (AOR per decile, 1.03; 95% CI 1.01–1.05). People with higher body mass index (BMI) and smokers were less likely to participate (AOR, 0.91 (per increase of 5.0 kg/m2) and 0.63 respectively; all p < 0.001). 3,655 participants (47.8%) submitted measurements beyond one year. Non-modifiable risk factors – age (AOR per decade, 1.29; 95% CI 1.21–1.37) and positive family history of hypertension (AOR, 1.15; 95% CI 1.03–1.27) – were positively associated with longer-term commitment. Higher BMI (AOR per 5.0 kg/m2, 0.89; 95% CI 0.85–0.93), smoking (AOR 0.60, 95% CI 0.44–0.82) and higher baseline systolic blood pressure (AOR per mmHg, 0.99; 95% CI 0.98–0.99) were negatively associated. This study provides insight into factors that influence HBPM use.