s opposed to a prevalence of 28.7% and control of around 31% being reported from US[9, 10]. Hence there is sharp contrast in the control of hypertension in between the two countries. Several studies have been conducted to identify these factors and they have been broadly classified into patient-related and physician related factors. Physician related factors responsible for control of hypertension include practice patterns of the physicians, their knowledge base and perceptions about the care delivered by them.
The NHSP showed that 70% of all hypertensive in Pakistan are unaware if their condition. Knowledge regarding control of hypertension including preventive mechanisms, factors affecting control of hypertension like diet, physical activity and insight into measures which can prevent complications of hypertension, have not been studied in depth in our population. There are studies done on medical students and physicians on their knowledge about hypertension but there is limited data from patients. Some studies have been done on awareness in hypertensive patients in Pakistan, however these have mainly focused on risk factor identification for hypertension and not primarily on control of hypertension[13, 14]. We therefore designed this study to elucidate the knowledge about hypertension in hypertensive patients at three tertiary care centers in Karachi. Secondly we sought to compare the knowledge of patients with uncontrolled hypertension and controlled hypertension.
Study design and population
It was a crossectional study conducted at three tertiary care hospitals in Karachi; Aga Khan Hospital, Ziauddin Hospital and Civil Hospital Karachi. The Aga Khan Hospital is a 577 bedded facility, which provides high quality of patient care in a broad range of secondary and tertiary services to over 50,000 hospitalised patients and to approximately 600,000 outpatients annually. It is located in the center of Karachi. The Ziauddin hospital is a 300 bedded hospital and is located in north of Karachi. The Civil hospital is a 1900 bedded public sector hospital located in center of Karachi. Population of different socioeconomic strata caters to these hospitals. The study was conducted in 2009–2010. All hypertensive patients (an average BP of ≥140/90 mm Hg or if the participant is taking antihypertensive medications) > 18 years of age presenting to the outpatient clinics were included. Diagnosis of hypertension was confirmed by history, medical file or last prescription of any antihypertensive. Those who visited a doctor for the first time with hypertension were excluded. Patients were consecutively recruited from the outpatient setting of each hospital. Ethical approval was taken from the ethical review committee Aga Khan University (1193-Med/ERC-09). Ethical approval was also taken from Institutional Review board, Dow University of Health Sciences (IRB/DUHS/2010/40) and Ethics committee of Ziauddin University (letter 08-04-2010) Medical specialists conducting the clinic were informed about the conduct of the study. Patients fulfilling the inclusion criteria were approached and recruited by the trained research staff. Informed consent was taken from all patients before recruitment.
Study variables and measurement
Primary outcome was knowledge score which was based on 15 item questions. Knowledge was also computed as a composite measure of sum of all the 15 item questions. These questions were developed by brainstorming with experts managing hypertension and who suggested that correct response of these questions can be counted towards having sound knowledge on hypertension (in patients). Questions regarding knowledge were asked and were marked on a scale of 1–5. (Additional file1). Higher scores on a scale of 1–5 denoted more affirmative (positive) response and alluded to a better knowledge of hypertension There were some item questions which had multiple responses also. Each correct response is given a score of 1, and incorrect response is given score of 0, where there are multiple correct responses for one item question, score of 1 i