Impact of special GP training on adherence to antihypertensive medication : a cluster randomized controlled trial

Date of Award


Document Type


Degree Name

Master of Science in Epidemiology & Biostatistics (MSc Epidemiology & Biostats)


Community Health Sciences


Hypertension is a major public health challenge and a modifiable risk factor for many chronic diseases. Non-adherence to antihypertensive treatment is an important reason for uncontrolled levels of blood pressure. The importance of physician related interventions on adherence to such treatment has not yet been explored. The objective of this study was to determine the impact of special general practitioner (GP) training in management of hypertension (special care) on adherence to antihypertensive medication versus usual care provided by GPs in the community. We hypothesized that medication adherence of individuals seeking special care is higher compared to those seeking usual care from GPs. This study was a sub-study built into a cluster randomized controlled trial conducted in 6 urban clusters of Karachi. Clusters were randomized to special care vs. usual care. In special care intervention clusters, GPs were trained intensively over one day in the management of hypertension, including use of non-pharmacological interventions and low cost generic drug. Eligible subjects were hypertensive individuals taking antihypertensive medication, aged 40 years or above and visiting GPs in the selected clusters. Subjects were blinded to intervention assignment. Adherence was measured using the Medication Event Monitoring System (MEMS), an electronic bottle that records the date and time of cap opening and pill intake. Data were downloaded on the computer using an electronic "communicator". Primary adherence outcome was correct dosing, defined as percentage of prescribed doses taken. Secondary adherence outcome was timing compliance, defined as the percentage of prescribed number of doses taken within a correct interval. A linear regression analysis was conducted and multivariable models were built to study factors associated with the primary and secondary outcomes. A total of 217 eligible individuals were approached in selected clusters and 200 (92.1%) consented to participate. 178 (89%) successfully completed six weeks of follow-up. The mean age (SD) of study participants in both the randomized groups was 55 years (+ 11). Correct dosing of medication (SD) was seen in 43.6% (16.9) of subjects in special care group as opposed to 38.3% (19.0) in the usual care group (p=0.05). Timing compliance to medicine was seen in 42.6% (20.6) of subjects in special care group as opposed to 36.4% (16.8) in usual care (p=0.03). For subjects seeking special care there was a relative improvement of 13% (95% CI: 9.0-17.9) and 17% (95% CI: 12.0- 22.0) for dosing and timing compliance, respectively. In the multivariable model, special GP care (% adherence=6.0, 95% CI: 1.1-10.9) and family encouragement was associated with both adherence outcomes. GP factors independently associated with correct dosing were explaining medication purpose to patient (% adherence=19.0, 95% CI: 13.7-24.3) and self reported consultation time of >10 minutes compared to <=10 minutes (% adherence=6.5, 95% CI: 1.9-11.1). GP factors associated with timing compliance were explaining medication purpose (% adherence=10.8, 95% CI: 4.5-17.1) and prescribing once compared to twice or over daily dose of medication (% adherence=6.4, 95% CI: 0.9-11.8). A supplementary analysis done on a subset of study population reveals hypertension control rates were 49% in special care and 29% in the usual care group (p=0.04). In conclusion, special care by GPs had a positive impact on improving patients' medication adherence. Based on our findings, we recommend that rigorous training of GPs in management of hypertension should be incorporated in hypertension control programs in urban Pakistan. Our results need further confirmation in long term studies.

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