Treatment optimisation for blood pressure with single-pill combinations in India (TOPSPIN) - Protocol design and baseline characteristics.

Background: The burden of over 300 million individuals living with hypertension in India is increasing steadily. Most current guidelines recommend initial combination therapy for effective blood pressure (BP) control. However, there is no randomised evidence to inform which combinations to use in the South Asian population, who account for over one-quarter of the world's population.

Methods: This multi-centre, single-blind, randomised, three-arm trial recruited men and women aged 30-79 years with hypertension. The trial compares the efficacy of commonly recommended single pill combinations (SPCs) of three drug classes - calcium channel blocker (amlodipine), ACE inhibitor (perindopril), and a thiazide-like diuretic (indapamide). The primary objective is to determine the most effective two-drug combination, initially at starting doses with forced up-titration at 2 months, in reducing 24-h ambulatory systolic blood pressure (ASBP) at 6 months. The trial has 85 % power to detect a difference of 3 mmHg in 24-h ASBP amongst the groups.Participant recruitment took place from August 2022 to February 2024.

Baseline Results: The 1981 participants (42.0 % women) enrolled had a mean age of 52.1 (SD 11.3) years and a mean body mass index of 26.5 (SD 4.2) kg/m2. 58.1 % of participants had a previous diagnosis of hypertension and 18.6 % of participants were known to diabetes. The mean ASBP was 135.6 (SD 17.0) mmHg, and the mean ambulatory diastolic BP was 84.5 (SD 10.9) mmHg.

Conclusion: The TOPSPIN trial is the first randomised evaluation of commonly used BP-lowering combination therapies in a South Asian population. The results have potentially significant implications for choosing first-line antihypertensive agents among Indians and the South Asian diaspora.