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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 18  |  Issue : 1  |  Page : 9-13

Prescription pattern and blood pressure control among patients on antihypertensive medications attending a tertiary hospital in Lagos: A cross-sectional study


1 Department of Pharmacology, Therapeutics, and Toxicology, Lagos State University College of Medicine, Ikeja, Lagos, Nigeria
2 Department of Medicine, Lagos State University College of Medicine, Ikeja, Lagos, Nigeria

Date of Submission23-Mar-2020
Date of Decision10-Jun-2020
Date of Acceptance02-Jul-2020
Date of Web Publication4-May-2021

Correspondence Address:
Dr. Sunday Oladunjoye Ogundele
Department of Pharmacology, Therapeutics and Toxicology, Lagos State University College of Medicine, Ikeja, 1-5 Oba Akinjobi Street GRA, Ikeja, Lagos
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njbcs.njbcs_12_20

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  Abstract 


Context: Hypertension is a disease of global public health importance affecting an estimated 1 billion people worldwide. Hypertension accounts for about 10.4 million deaths in 2017. Many guidelines are available for the management of hypertension, but despite this, there are wide variations in physicians' choice of antihypertensive medications for blood pressure (BP) control. Aims: We reviewed the prescription pattern of antihypertensive medication and the level of BP control in patients with hypertension. Settings and Design: This is a cross-sectional study among hypertensive patients attending follow-up clinics of a tertiary hospital. Methodology: Structured questionnaires were used to collect information on the antihypertensive medications and clinical profiles of the study participants. Questionnaires were administered to participants during the attendance of the follow-up clinic to capture information relevant to the study. Information retrieved from patients includes details about their baseline demographic characteristics, clinical history, antihypertensive drug history and blood BP recordings. The study protocol was reviewed and approved by the institutional ethics committee. Statistical Analysis: Data were analysed using Microsoft Excel 2003 and the Statistical Package for the Social Sciences version 22.0 software. Results: A total of 489 hypertensive patients took part in the study. The study found that the rate of BP control was 44.6% among the participants. Calcium channel blockers (CCBs) are the most common antihypertensive medication prescribed in our clinics. There was no significant relationship between how long a patient had been attending the follow-up clinic and the level of BP control in patients who have attended the clinic for a minimum period of 3 months. Conclusion: BP control was less than optimal in more than half of the participants, and the most commonly prescribed antihypertensive medication were CCBs.

Keywords: Hypertension medication, Lagos, prescription pattern


How to cite this article:
Ogundele SO, Ajibare AO, Amisu MA, Dada AO. Prescription pattern and blood pressure control among patients on antihypertensive medications attending a tertiary hospital in Lagos: A cross-sectional study. Niger J Basic Clin Sci 2021;18:9-13

How to cite this URL:
Ogundele SO, Ajibare AO, Amisu MA, Dada AO. Prescription pattern and blood pressure control among patients on antihypertensive medications attending a tertiary hospital in Lagos: A cross-sectional study. Niger J Basic Clin Sci [serial online] 2021 [cited 2021 Aug 4];18:9-13. Available from: https://www.njbcs.net/text.asp?2021/18/1/9/315405




  Introduction Top


Hypertension is a disease of global public health importance. The disease affects an estimated one billion people worldwide. Hypertension accounts for about 10.4 million deaths in 2017.[1],[2] This condition is mostly asymptomatic and is best detected through population screening or opportunistic measurement of blood pressure (BP) during an encounter with patients at a hospital visit.[3],[4] Hypertension is more common among Blacks compared to Caucasians.[2],[3] It is also noted that Blacks tend to develop hypertension at an earlier age and develop complications of hypertension more commonly compared to other races.[2],[4] The reason for this is not clear, but racial differences in renal physiology and socio-economic factors have been suggested as possible causes of this difference.

The relationship between BP and cardiovascular and renal complications is continuous, thus making the cut-off values for hypertension arbitrary. The prevalence of hypertension increases with the ageing of individuals.[2] The estimated prevalence of hypertension in urban settings of Nigeria is 30.6%.[5] It is reported by some studies that the reduction of BP when antihypertensive medications are use is associated with a reduction in the rates of cardiovascular diseases (CVDs) among patients with hypertension.[2],[3],[4],[6] The main goal of treating hypertension is to lower the morbidity and mortalities associated with renal and cardiovascular complications of the disease.[2],[6]

In most patients with hypertension, a combination of two or more drugs is required to reach the target BP goal.[2] Medications commonly used in the treatment of hypertension include: calcium channel-blockers (CCBs), beta-blockers, diuretics, angiotensin-converting enzymes inhibitors (ACEI) and angiotensin receptors blockers (ARBs).[2] The renin-angiotensin system (RAS) blockers, ACEIs and ARBs are known to be associated with an increase in serum creatinine levels. An increase of up to 35% from the baseline level is, however, acceptable unless there is associated hyperkalaemia. Antihypertensive medications that are associated with worsening of some co-morbid conditions of hypertension should be avoided in patients with such conditions. Beta-blockers should be avoided in patients with reactive airways or asthma and in patients with heart blocks. The RAS blockers should be avoided in pregnant women or women who are likely to be pregnant while on these medications.[3]

The number of hypertensive patients that do not have their BP at the goal target for control is increasing worldwide.[7] It is, therefore, important to adopt strategies on how to improve control of hypertension to the goal of the treatment target.[7] The justification for this study is that despite the availability of guidelines for the management of hypertension, a wide variation still exists among physicians in the choice of antihypertensive medications for BP control. This study aims to review the prescription pattern of antihypertensive medications among physicians and to also assess the level of BP control among patients attending hypertension follow-up clinics.


  Methodology Top


The study took place at the medical outpatient clinic of a tertiary health facility in Lagos. Hypertensive patients attending the follow-up clinics at any of the units of the Department of Medicine of our hospital that is dedicated to the care of hypertension were invited to take part in the study. The units that manage hypertension in our medical department included in the study were; clinical pharmacology, nephrology, endocrinology and cardiology unit.

Hypertensive patients who are at least 18 years and that have attended the hypertension follow-up clinics for a minimum of 3 months were recruited in our study after consenting to take part. Hypertensive patients who were not on any anti-hypertensive medications were excluded from the study. We defined and classified hypertension according to the WHO/ISH guidelines, BP was taken to be controlled or at goal when it is <140/90 mmHg.[8] The body mass index (BMI) was calculated using weight in kilograms divided by the square of the height in meter. The weight was measured with a standardised weighing scale in kilograms (kg) and height was measured with a Stadiometer in meters (m). We classified BMI using the WHO classification of BMI.[9]

The minimum sample size calculated was 327, using a prevalence of 30.6%[5] for hypertension at 5% precision and standard deviate of 1.96. The study was approved by the hospital health research ethics committee.

The survey reviewed the antihypertensive medications prescribed in the management of the BP of the participants and the rates of their BP control by extracting relevant information from the case notes and by directly asking the participants questions using the structured questionnaire. Information obtained from participants during the survey included the baseline demographic profile of participants, BP recordings at the first visit to the clinic and the BP during index encounters was noted. The details of drug history recorded include the name of antihypertensive medications, duration of use and number of antihypertensive medications.


  Results Top


A total of 489 hypertensive patients participated in the study. The mean age of participants was 60.75 years, with an age range of 20–91 years. More than half, 274 (56%) of the participants were elderly, aged 60 years and above. More women attended the clinics during the survey period compared to men, 350 of the total 489 respondents were women; this represents 71.6% [Table 1].
Table 1: Baseline demographic characteristics of hypertensive patients attending the outpatient follow-up clinics at LASUTH

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Most participants in the study, 211 (43%) were on two antihypertensive medications, whereas only 41 (8.4%) were on 4 or more antihypertensive medications. The most common class of antihypertensive medication prescribed for participants was CCBs, 375 (76.7%) were in this class of drugs. Less than half, 218 (44.6%) of the participants have their BP at goal for control [Table 2].
Table 2: Clinical profiles of hypertensive patients attending the outpatient follow-up clinics at LASUTH

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Among participants who were at targets for BP control, 345 (71%) had their diastolic BP at a target, whereas 231 (47%) had their systolic BP at target. About half, 16/33 (48%) of participants whose systolic BP were at least 180 mmHg were on at least 3 antihypertensive medications [Table 3].
Table 3: Cross-tabulation of the blood pressure measurement of patients attending the follow-up hypertension clinic at LASUTH with the number of antihypertensive medications they are using

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More than half, 282 (58%) of the participants have attended the clinic for at least 12 months. There is no significant correlation between the length of clinic attendant and control of BP in patients who have attended the follow-up clinic for <6 months [Table 4].
Table 4: Cross-tabulation of the duration of the treatment of hypertensive patient attending follow-up clinic at LASUTH with the proportion of patients at blood pressure goal

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  Discussion Top


This study found that the most common antihypertensive medications prescribed for patients attending our follow-up clinic were CCBs and that less than half of the participants had their BP controlled at the target level.

The reported demographic profile of participants in this study showed that more than half of the participants in the study were at least 60 years old. This finding is in keeping with the known demographic pattern of patients with hypertension.[2],[10],[11],[12] The prevalence of hypertension is known to increase with the increasing age of individuals, mostly due to structural changes in the arteries and especially with the stiffness of large artery stiffness. This finding is also confirmed by reports from local Nigerian studies that showed that the prevalence of hypertension is higher among the elderly.[13],[14],[15],[16]

This study showed that the proportion of participants with BP level at goal is less than half; this finding agrees with reports from other studies.[7],[16],[17] Studies have reported that the proportion of hypertensive patients that meet the goal for BP control while on antihypertensive medication is generally low. This finding is particularly common in countries with poor resources.[7],[16],[17] This study also showed that when systolic and the diastolic BP control were independently assessed, systolic BP was shown to be more difficult to control compared to the diastolic BP. It is known that the control of systolic BP is more important and more difficult to achieve in patients older than 50 years compared to the control of the diastolic BP.[2] This because of stiffness and non-compliant nature of the arterial wall in that age group.[2] Systolic BP is a more important CVD risk factor than diastolic BP in patients older than 50 years.[2],[18] Isolated systolic hypertension is more common among older patients compared to the younger ones.[2],[18] The finding from this study that the control of systolic BP is poorer compared to the diastolic BP is consistent with earlier reports in the literature.[2],[18] Most patients with hypertension will reach the diastolic BP goal once systolic BP is at goal.[2],[18] The main aim of hypertension treatment should be on achieving the systolic BP goal. Confounders to the low-level of BP control in this study, however, may include poor adherence and quality of antihypertensive medications. These two were not considered in this study.

The five classes of antihypertensive drugs considered in this study are the major drug classes recommended for the treatment of hypertension.[10] Other classes of drugs have been less widely studied in clinical trials or are known to be associated with a higher risk of adverse effects.[10] The finding that over 80% of our patients are at least on two or more antihypertensive medications are consistent with the recommendation of most guidelines for the management of hypertension.[2],[10],[19] Most patients with hypertension will need 2 or more antihypertensive medications to achieve BP control.[20],[21] Evidence in support of the use of combination drug therapy as opposed to monotherapy shows that a synergistic effect on lowering of BP is achieved.[4] This also reduces the incidence of adverse effects and improved adherence to a drug regimen.[4]

The most commonly prescribed class of antihypertensive medication in this study was CCBs. The preference for CCBs either alone or in combination with other antihypertensive medications is supported by the findings of the CREOLE study, which concluded that CCBs are effective in treating hypertension in blacks.[22] Some studies from other parts of Nigeria reported diuretics as the most commonly prescribed antihypertensive medication.[16],[23] In blacks, diuretics and CCBs have been shown to lower BP more effectively than ACEIs, ARBs, and beta-blockers.[24] Some guidelines recommend diuretics as first-line therapy for patients with hypertension, either alone or in combination with other classes of antihypertensive drugs (ACE inhibitors, ARBs, β-blockers and CCBs).[10],[25] The American Society for Hypertension guidelines recommends either a CCB or a thiazide diuretic as first-line drugs.[26] An Australian study reported a slightly better outcome in white men with a regimen that began with an ACE inhibitor compared with one starting with a diuretic.[27]

The finding that there was no significant difference between the duration of clinic attendance and achievement of the goal of BP target in patients who have attended follow-up clinics for <6 months is in keeping with findings of previous studies.[26] It has been reported that most patients on antihypertensive medications are expected to achieve the full effect of their therapy, whether on one or more medications, within 6–8 weeks of treatment.[26] If control is not achieved, it is probably because of failure to give adequate doses of medications, poor adherence to treatment or poor use of combination therapy, among other factors.[10]

The limitation of the study is that it did not consider complications of hypertension due to CVD and other comorbidities like diabetes in accounting for the choice of antihypertensive medication. It only considers the subspecialty clinics' attendance.


  Conclusion Top


The study found that the rate of BP control with the use of antihypertensive drugs was less than half. CCBs were the most common antihypertensive medication prescribed. No significant relationship was found between the duration of clinic attendance and BP control in patients who have attended the clinic regularly for at least 3 months.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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