Pattern of Medication Prescribing and Factors Associated with Meeting of Target Blood Pressure among Persons with Hypertension in Federal Police Referral Hospital, Ethiopia

Study Setting

This study was conducted in FPRH which is located in Addis Ababa, the capital of Ethiopia. The hospital has a total of 310 beds and is engaged in providing various services including; preventive, diagnostic and medical treatment services to in-patients and out-patients.

**Study Design**

An institution based cross sectional study was conducted from 15th October 2016 to 15th January 2017 for a period of three months.

**Source Population**

The source population of this study was all outpatients who have been attending to the chronic care clinic of FPRH during the study period and the study population was the persons with hypertension that fulfilled the specified inclusion criteria.

**Inclusion and Exclusion Criteria**

The inclusion criteria for the study comprised; persons who had uninterrupted follow up to the clinic since of at least one year back, those aged of 18 years or above, patients who could speak and hear Amharic language and gave verbal informed consent to participate in the interview. On the other hand, those patients with incomplete medical records about their last visit measurement (for persons who were either unable to recall or doubted last visit measures), those with no medication or disease history either in the chronic care clinic or chronic care pharmacy data base and those patients who were not able to attend appointments of the chronic care clinic and pharmacy during the study period were excluded from the study.

**Sample Size**

The sample size was calculated based on a population proportion formula and the prevalence of hypertension in the city of Addis Ababa [9].

$$n = \frac{(Z\alpha/2)^2 P(1-P)}{E^2}$$

Where;
n= desired sample size
$\alpha = 0.05$ or $Z\alpha/2=1.96$ for level of confidence
P = 0.3, (from a population based survey conducted in Addis Ababa, Ethiopia) [9].
E = 0.05 for margin of error

$$n = \frac{(1.96)^2 0.3(1-0.3)}{(0.05)^2} = 323$$

After having made an adjustment to the above figure using a reduction formula for the total population of hypertensive outpatients who were on follow up to the chronic care clinic, and adding 10% non-response rate or incomplete records, we have finally came up with a sample size of 330 participants.

**Sampling Technique**

A systematic random sampling technique was employed in selecting the study participants. Initially, the total number of study subjects was identified based on their chronic care clinic visit and medication refill appointment dates in the chronic care pharmacy unit database. As refills were done every three months, the sampling interval was determined by dividing the total number of persons with type 2 diabetes mellitus (DM) to the required sample size. Accordingly, a random integer between 0 and the sampling interval was selected, and selection was continued till the end based on the subject’s appointment date to refill the medications.

**Data Collection Procedure and Quality**

Data was collected using a semi-structured interview of study participants by a trained pharmacist. Interview was scheduled based on the participants’ refill date to the chronic care pharmacy unit. After obtaining their consent, participants were briefed about the purpose of the study, and invited whether they would want to participate in the study. They were also assured to withdraw from the interview at any moment if they are uncomfortable. Sociodemographic characteristics, disease history, and adherence issues were recorded by interviewing the participants. Last visit outcome results were taken from medication charts based on the medication record numbers (MRNs). Classes of drugs prescribed, type of therapy and number of drugs were identified from prescription papers and database records.

For ensuring consistency and data quality, interview was conducted in Amharic (a national working language which all participants speak). The data collector was trained for two days on the relevance of the study, data collection techniques, informed consent and confidentiality of the data collected. Prior to the start of the data collection period, a pilot of 30 subjects’ medication records, obtained from the chronic care clinic, was evaluated against the required variables in the study. Completeness of data collected was checked every day by the principal investigators (PIs).

**Operational Definitions**

Blood pressure target meeting: was measured based on either the systolic or diastolic pressure reports of the participant. Consequently, in subjects aged 60 or above, BP target was considered met if systolic measure was <150 mmHg and diastolic measure <90 mmHg. In the subjects below the age of 60, BP target was considered met if systolic measure was <140 and diastolic measure was <90mmHg irrespective of chronic kidney disease or diabetes mellitus presence. Dietary adherence: Was measured based on vegetable, fiber, salt, fat and alcohol intake levels. It was considered good if the participant reports to take at least 2 servings of vegetables/fruits for ≥3 days/week , whole grains, fiber or fish at least 2 servings for ≥3days/week, small amount of fat or sugar, less than 2.3g salt (<1TSF) intake per day, and less than 600ml alcoholic intake per day. Exercise adherence: Was considered active if participant reported to exercise for at least 30 minutes in >=4 days of the week. Medication adherence: Was measured based on a participant’s reported daily missed doses of the prescribed anti-diabetic medications. If participant has not missed more than 80 percent of the doses in a month, it was assumed good adherence.

Ethics Approval and Consent

The study was approved by the School of Pharmacy Research and Ethics committee, College of Health Sciences, Addis Ababa University. Before the start of actual data collection, permission was obtained from Federal Police Health Service Directorate. The study was conducted with an informed consent acquired from each participant, and the data collection was conducted confidentially. Personal identifiers such as; MRN, Name, Address, or telephone number were not included in the personal information interview.

Data Analysis

After coded and checked manually for completeness, data was entered into statistical package for social sciences (SPSS) version 20 and cleaned before analysis. Frequency distributions and percentage tables were used to present socio-demographic variables and participants’ characteristics. A binary logistics regression was carried out for determining factors associated with target meeting of the outcome measure. Target meeting of each outcome variable was tested individually and in combination. Because a national hypertension management guideline is not available in Ethiopia, target levels used in this study were set based on the recommendations in the Eighth Joint National Committee (JNC8) and Ethiopian standard treatment guidelines [17, 18].

Characteristics of Study Participants

Of the 330 subjects required to be included in the study, 318 (96.4%) fulfilled the inclusion criteria and were considered for further analysis. The mean age was 56.6 years with median (standard deviation (SD)) of 55.5 (12.4) years ranging from 26 to 89.

Majority of the study participants were in the age group 46 to 60 years (39.3%). One hundred eighty nine (59.4%) were males, and 300 (94.3%) of the participants are married. More than a two third (72.6%) of the subjects were military. Close to half (49.1%) had at least one type of comorbidity. Frequent comorbid conditions included; dyslipidemia in 87(27.4%), diabetes mellitus in 69 (21.7%), congestive heart failure in 25(7.9%), arthritis in 10(3.1%) and, dyspepsia in 6 (1.95) subjects. One hundred seventy two (54.1%) of the subjects were taking two individual or combined drug formulations during the study period (Table 1).

Pattern of Prescribing Antihypertensive Drugs to the Study Participants

Diuretics were the top prescribed class of antihypertensive agents accounted by 201(63.2%) of the subjects. Hydrochlorothiazide, a thiazide diuretic, was the most frequent. Next highly utilized classes of drugs included; calcium channel blockers among 172 (54.1%) subjects followed by angiotensin converting enzyme inhibitors prescribed for 153 (48.1%) participants. Drugs

that act on both Alpha and beta receptors were the least prescribed (0.6%) (Table2).

Common Antihypertensive Drugs taken by Patients

Table 3 below shows the top ten antihypertensive drugs prescribed to the patients during the study period.

Accordingly; hydrochlorothiazide, a thiazide diuretic agent, was the most frequently prescribed drug among 169 (53.1%) subjects followed by Enalapril by 140 (44.0%) and nefidipine by 121(38.1%) subjects.

The median of last visit systolic blood pressure in the present study was 140 mmHg with mean (SD) of 138.7(17.25) and range of 100 to 180 mmHg. Similarly, two variables was attained by 103(32.4%) of the participants. As presented in the table below, blood pressure was considered in terms of the combined outcome of the systolic and diastolic measures for determining possible factors associated with treatment target meeting.

Male gender was associated with a close to half chance of treatment target meeting as compared to being a female (AOR: 0.51, 95% CI: 0.28-0.93). This study has also shown that patients who have been on antihypertensive therapy for more than 5 years were less likely to attain treatment target compared to those who took therapy for 5 years or less (AOR: 0.51, 95% CI: 0.27-0.95). On the other hand, good dietary adherence has shown a positive association with target meeting of antihypertensive therapy (AOR: 5.52, 95% CI: 2.74-11.11) (Table 4).

Availability of Data

The datasets during and/or analyzed during the current study are available from the corresponding author.

Competing Interests

The authors declare that they have no competing interests.

Funding

There is no source of funding.

Authors’ Contributions

TS and AI designed the proposal while TT and MA were involved in the supervision of the data collection. TS did the data entry while AI and ST completed the analysis. All of the authors have been involved in the write up and approval of the final manuscript.

Acknowledgements

We would like to thank the staff members of the chronic care clinic and chronic care pharmacy unit of federal police referral hospital for their unreserved support during the conduct of this study. We, also, forward our heartily gratitude to persons with chronic illnesses and who have given informed consent to participate in this study.