Where p1 represents the proportion of patients with controlled HTN at the HC level (15.6%) ; p2 represents the proportion of patients with controlled HTN in the GRH level (we assumed that the proportion would be twice that in HCs (31.2%); z is the value of the standard normal distribution corresponding to a significance level of alpha of 0.05 (1.96); and β is power (80%), z1-β = 0.84.