|Year : 2018 | Volume
| Issue : 3 | Page : 128-136
Medication use practices and inspection of returned pills during follow-up attendance at a tertiary care hypertension clinic in Nigeria
Abimbola O Olowofela, Ambrose O Isah
Department of Medicine, University of Benin, University of Benin Teaching Hospital, Benin, Nigeria
|Date of Web Publication||4-Oct-2018|
Dr. Abimbola O Olowofela
Department of Medicine, University of Benin, University of Benin Teaching Hospital, Benin City, PMB 1111
Background: Medication use practices in the treatment of hypertension (HTN) have been shown to determine outcomes. This study characterizes the profile of medication practices by hypertensive patients attending a tertiary health-care facility in Nigeria. Materials and Methods: This was a cross-sectional study in the outpatient HTN clinic of a tertiary hospital in southern Nigeria. Hypertensive patients seen during routine clinic visits were given the usual clinic instructions and requested to come with all medicines including herbal medications in their possession at their subsequent visits. A semi-structured observer-administered questionnaire was used to document all information sought and on medicines inspected. Data collected were analyzed and presented descriptively. Results: A total of 509 patients were recruited into the study (M:F ratio 1:2.2) aged 22–97 years. The mean(SD) number of all medicines used by the patients was 5.5 ± 2.While the mean(SD) number of antihypertensive medicines was 2.9 ± 1.3 with 75 patients (14.8%), 135 (26.6%), 144 (28.3%) and 154 (30.3%) on 1, 2, 3, and 4 or more antihypertensive medicines respectively. Calcium channel blocker was the most used antihypertensive medicine, 350 (68.8%). Of interest, was the use in 68 (13.4%) patients of unprescribed herbal medicines. A number of patients, i.e., 205 (40.2%) had discrepancy between their prescribed medicines and that presented to the clinic. This included the use of nonprescribed medicines, including analgesics (35%), vitamins (28.1%), nonsteroidal anti-inflammatory drugs (17.1%), and food supplements (6.8%). Conclusion: This study highlights the profile of antihypertensive medication use, revealing the significant use of nonprescribed medicines and factors likely to influence outcomes of therapy. It further underscores the importance of careful inspection during clinic attendance of all medication being taken by the patient.
Keywords: Ambulatory care, antihypertensive agents, drug utilization, Nigeria, nonprescription drugs
|How to cite this article:|
Olowofela AO, Isah AO. Medication use practices and inspection of returned pills during follow-up attendance at a tertiary care hypertension clinic in Nigeria. Sahel Med J 2018;21:128-36
|How to cite this URL:|
Olowofela AO, Isah AO. Medication use practices and inspection of returned pills during follow-up attendance at a tertiary care hypertension clinic in Nigeria. Sahel Med J [serial online] 2018 [cited 2019 May 25];21:128-36. Available from: http://www.smjonline.org/text.asp?2018/21/3/128/242742
| Introduction|| |
Hypertension (HTN) is a chronic disease that requires lifelong therapy and clinic follow-up. The HTN clinic is a specialized clinic where a holistic view of the hypertensive patient is carried out, and different facets of care are administered to the hypertensive patient. The treatment of HTN is both nonpharmacologic and pharmacologic. Drug therapy in HTN is most times lifelong and this needs to be reiterated in many instances to patients attending follow-up. It is expected that with appropriate treatment and optimal clinic attendance, patients attain good blood pressure control.
There are many factors that contribute to inadequate blood pressure control in the hypertensive patient and to medication practices to a large extent. These medication factors range from patients' understanding of their prescriptions during the interaction with the physician, determining how the patients use their medicines at home, examining the possible irrational drug use habits as well as measuring the level of adherence. Other medication practices that have been shown to affect blood pressure control indirectly include the development of adverse drug reactions (ADRs) dosing frequency complexity of regimen, costs as well as duration of therapy and polypharmacy.,,, Fewer daily dosing, monotherapies, and fewer changes in the medications have been associated with better adherence. Other major predictors of poor medication practices that have also been identified are cognitive impairment, missed appointments among others.
Most patients also misuse their medicines by not keeping to the prescription given. Bedell et al., in assessing discrepancies between what was prescribed and that used by the patient, found 75% having discrepancies in their medications attributable mostly to additional use of over-the-counter (OTC) drugs, vitamins, and herbal supplements.
In Nigeria, the contributory factors to nonadherence in the management of HTN have not been fully explored; however, there have been suggestions of inappropriate use of medicines in Nigeria. Proprietary medicines sold as OTC medicines and herbal medicines use may be high in Nigeria. This may be due to the ready availability of such medicines, and this poses a great risk to the patient due to the potential drug-drug or herb-drug interactions that may result from their use in hypertensive patients; this may also be an important consideration in blood pressure control.
The significance of comedication in antihypertensive therapy is often overlooked more so when the medicines used are not prescribed. The consequences of drug-drug interaction adversely affecting the blood pressure control or the occurrence of drug-induced untoward effects are erroneously attributed to prescribed antihypertensive medicines and distract from the management plan. The availability of all categories of medicines OTC, their use by patients, and the nondisclosure of their use to supervising clinicians presents an important and overlooked clinical problem.
This study is intended to examine the occurrence of this problem with a view to determining its magnitude, profile, and management in the Nigerian setting.
| Methodology|| |
This cross-sectional study was carried out at the consultant medical outpatient department (COPD) of a 730-bed tertiary health-care facility in Southern Nigeria. The consenting patients were recruited sequentially from the HTN clinic of the COPD. A minimum sample size of 382 participants was calculated with a confidence level of 95% and a power of 80%, a prevalence of 46% from a previous study, and a formula for simple proportions. A total number of 510 participants were, however, recruited into the study.
Ethical approval was granted by the ethics and research committee of the hospital for the study, participating patients signed the informed consent form, and data from the study were anonymized.
A semi-structured interviewer-administered questionnaire was used to collect data. The questionnaire collected demographic information such as age, sex, religion, educational status, occupation, marital status, and average monthly income. Other information sought included duration of therapy, comorbidities, any known complication of HTN, as well as that documented in the patient's medical record, the average cost of buying medicines monthly, as well as if they were seeing other physicians or attending other clinics. The classification of occupations was done using the International Standard Classification of Occupations 2008 (ISCO 08).
Patients were requested to come along with all their medicines including herbal medicines and OTC using a medicine bag [Figure 1] earlier given to them and were asked about details of all the medication presented.
|Figure 1: The medicine bag distributed to patients to encourage them bring their medicines to clinic for inspection|
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All information were based on self-report and compared with the medicines which they brought to clinic and the clinic records. Information sought included number of prescribed antihypertensive medicines, doses in milligrams, frequency per day, duration of intake in months, time of intake of the medicine (morning, afternoon, and evening), and any adverse reactions associated with the medicine.
Prescriptions and case notes, available at the time of the interview, were also used in getting reliable data, particularly from illiterate patients. They also presented all other medicines used, including nonprescribed medications, and herbal supplements when applicable. Discrepancies in the medicines used and that prescribed were also noted in the data collection form.
A standard medicine formulary (British National Formulary) and ethical medicines index (A commercial medicine booklet) were used to identify some products. The active agents in combination or coformulated medicines were counted as individual medicines.
Measurement of blood pressure
HTN was defined according to the WHO/International Society of HTN (ISH) classification using a blood pressure cutoff point of ≥140/90 mmHg. The patients were seated for 5 min and had their blood pressure taken with mercury sphygmomanometers (Accuson®, Kris-Alloy, England) and stethoscopes using the auscultatory method. Blood pressure was taken using the first Korotkoff sound as systolic blood pressure and the fifth Korotkoff sound as diastolic blood pressure in the sitting position. An appropriate-sized cuff (cuff bladder encircling at least 80% of the arm) was used to ensure accuracy.
Blood pressure control was determined in patients with uncomplicated HTN as <140/90 mmHg and <130/80 mmHg in diabetics and CKD patients according to the Nigeria HTN Guidelines which is based on the WHO/ISH guidelines.
Data analysis and statistical consideration
The data were analyzed using SPSS version 16 for Windows (SPSS Inc., Chicago, IL, USA). The mean (± two standard deviations [SD]) was computed for all continuous data. Frequencies were calculated for categorical variables.
In univariate analyses, means were compared using Student's t-test. Categorical variables were compared using Chi-square and Fisher's exact tests, as applicable. Tests of proportions and odds ratios (with 95% confidence intervals) were calculated from the 2 × 2 tables. Nonparametric tests (Mann–Whitney) were also used. P < 0.05 was considered to be statistically significant for all analyses.
| Results|| |
Five hundred and ten patients were recruited for the study. However, a patient was unable to complete the questionnaire, leaving 509 patients and giving a response rate of 99.9%.
Sociodemographic characteristics of participants
The sociodemographic characteristics of the patients (ages ranged 22–97 years) recruited into the study are as shown in [Table 1]. Diabetes mellitus (DM) was the most commonly associated co-morbid state (27.9%) others include osteoarthritis 36 (7.1%), gastrointestinal disorders including peptic ulcer disease, cholelithiasis 22 (4.3%, respiratory diseases-11 (2.2%) Neurological diseases 11 (2.2%), and others 12 (2.4%) as stated in the case records following earlier clinical examination and investigations.
|Table 1: Sociodemographic and other characteristics of hypertensive patients|
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Those who were seeing other internal medicine physicians were 77 (15.1%), of which 35/77 (45.5%) were seeing endocrinologists. Patients who attended other clinics were 73 (14.3%) and these included: ophthalmology clinics; 22/73 (30.1%), surgical clinics; 19/73 (26.0%), private clinics (general practice and specialist clinics); 17/73 (20.5%), other government clinics or health facilities; 12/73 (16.4%), and psychiatry; 3/73 (4.1%).
The duration of last clinic visit ranged from 2 days to 116 weeks (mean 10.5 ± 10.2 weeks and median of 10 weeks). Only 15 (2.9%) had not attended clinic in 6 months.
The average monthly cost of medicines ranged from N10 to N40,000 (US$0.06–265), with a median value of N3,500 (US$23.2) in 476 (93.5%) of the patients. Thirty-three patients (6.5%) did not know the monthly cost of their medicines. Most patients paid for their medicines (51.5%) or were helped by family members, 51.6%; national health insurance, 7.7%; employer, 0.2%; and other sources, 0.6% (multiple responses were accepted).
The number of pills prescribed ranged from 1 to 10 with a mean ± SD (4.1 ± 1.5); however, the number of pills returned as used ranged from 1 to 12 with a mean ± SD (4.8 ± 1.9). The mean number of medicines used by the patients was 5.5 ± 2.1 with a range 1–16 (the active ingredients in combination medicines were counted individually).
An average of 2.9 ± 1.3 (range 1–7) antihypertensive medicines were used with seventy-five patients (14.8%) on monotherapy while 135 (26.6%), 144 (28.3%), and 154 (30.3%) patients were on 2, 3, and 4 or more antihypertensive medicines, respectively. They used all the classes of antihypertensive medicines with calcium channel blocker (CCB) being the most commonly used in 350 (68.8%) and alpha-blockers being the least used class in 19 (3.7%). Other medicines used by the patients included antidiabetic agents, 223 (43.8%), vitamins, antiplatelet agents, herbal supplements, food supplements, antimalarials, and antibiotics [Table 2].
A total of 205 (40.3%) patients had some discrepancies in the prescribed medicines and that presented to the clinic, of this number the discrepancy ranged from not using any of the prescribed medications in 10/205 (4.9%) of the patients to using nonprescribed medicines in 195/205 (95.1%) patients including herbal medicines [Table 3].
|Table 3: Categories of discrepancies observed in the hypertensive patients|
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Most of the patients, i.e., 131/205 (64%) were at risk of possible clinical effects from the additional nonprescribed medicines; they were using ranging from possible risks of drug-drug, drug-herb interactions 62/205 (30%), risks of overdose (5), as well as therapeutic failure in 1 patient. Seven patients had an ADR to their nonprescribed medicines while eight patients self-initiated the switch to nonprescribed medications due to suspected ADRs that occurred with the use of their prescribed medications.
Eighteen patients (6.8%) were found to have a discrepancy regarding their antihypertensive medications which ranged from substitutions with another antihypertensive. Four patients used two antihypertensive medicines from the same class (different nondihydropyridine CCBs), two patients used different brands of the same medicine, and two patients had drugs with antihypertensive effects from the surgeons while an additional two (2) patients were underdosing themselves. Notable in this study was the use of a China made blood pressure lowering device by a patient [Figure 2]; the said patient had stopped antihypertensive medicines since commencing the use of the device.
|Figure 2: An example of blood pressure lowering device (China made) used by a patient|
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The prolonged use of nonprescribed nonsteroidal anti-inflammatory drugs (NSAIDs) as well as the benzodiazepines daily for up to 12 months for complaints such as osteoarthritis and insomnia, respectively, was equally noted in this study. It was also seen that combinations of prednisolone and NSAIDs as well as multiple NSAIDs were used simultaneously in the treatment of these arthritic pains.
Notable also in this study was the use of chloroquine and artesunate monotherapy by some of the patients in the treatment of malaria and the use of different brands of artemether-lumefantrine by a patient due to perceived treatment failure of initial therapy. We note that very few patients returned with nonprescribed antibiotics in the study.
Food and herbal supplements were also presented by 21 patients (4.1%), and these classes of medicines were not prescribed at all as earlier shown in [Table 2]. They were used by patients to supplement their diet and general well-being. In three patients, the supplements were used to support the effectiveness of either their antihypertensive or antidiabetic medications. The use of herbal medicines was seen in 68 (13.4%) patients who used them for treating HTN and other medical conditions. Thirty-four (50%) of those using herbal medicines were not aware of the constituents. Some patients volunteered some suspected constituents such as bark of trees, roots, leaves of fruits (mango, cashew, bitter leaf, dogonyaro Azadirachta indica), and alcohol-based preparations. (An inappropriately bottled herbal medicine was presented by a patient) [Figure 3]. More females, i.e., 39 (57.4%) used herbal medicines than men, 29 (42.6%), and this was statistically significant (χ2 = 5.587, P = 0.03).
|Figure 3: An example of herbal medicine (inappropriately bottled) used by a patient|
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Notable in this study was the presence of “gift medicines” from relatives abroad in 5 patients (0.9%); this resulted in a high pill burden that ranged from 8 to 12 pills returned by the 5 patients. Most of the medicines sent were NSAIDS, food and herbal supplements, antidiabetic and antihypertensive medicines. [Figure 4] shows a picture of medicines presented by a patient.
|Figure 4: Multiple nonprescribed medicines brought by a patient sent by relatives abroad|
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A total of 177 (34.8%) patients had controlled blood pressure in this study with majority 109/177 (61.6%) having no discrepancy in their prescribed medicines although there was no statistically significant association between blood pressure control and medication discrepancy (χ2 = 0.389, P = 0.533).
We also evaluated possible factors that may have contributed to the discrepancies seen in the return of pills, and we found that patients who had suffered an ADR, visiting other clinics, patients using herbal medications, and those who had not visited clinic in >6 months had a higher risk of having some discrepancy in their medication, and these were statistically significant [Table 4]. However, there appeared to be no difference in the educational status, presence of comorbid conditions as well as the age of the patients.
|Table 4: Factors associated with discrepancies to prescribed medicines following univariate analysis|
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In view of the proportion of hypertensive patients with Diabetes Mellitus (HTN/DM) - 142 (27.9%) in this study, we also evaluated their medication practices and discovered that they had more pills prescribed (mean + SD = 5.1 ± 1.6) than hypertensive patients without diabetes (mean ± SD = 4.5 ± 1.3), and this was statistically significant (t = 9.67, P < 0.001). They (HTN/DM) also used more pills (mean ± SD = 5.6 ± 1.9) than those without DM (mean ± SD = 4.5 ± 1.8). This was also statistically significant (t = 5.89, P < 0.001). However, a fewer proportion, i.e., 45/142 (31.7%) of those who had diabetes and HTN had discrepancies with their medications compared with those who did not have diabetes, 160/367 (43.6%), and this was statistically significant (χ2 = 6.034, P = 0.014). The level of blood pressure control was poor in the patients who had diabetes and HTN as a major proportion of them were uncontrolled, 128/142 (90.1%), and there was a statistically significant association between the level of blood pressure control and presence of DM (χ2 = 53.899, P = <0.001).
| Discussion|| |
This in-depth study on the medication practices and medicines in patient's possession at home has revealed a lot of irrational drug use as well as some potentially dangerous use of medicines by hypertensive patients at home some of which are likely to impact on blood pressure control.
Population studies have revealed that adherence to medications by patients who have chronic diseases is about 50%, and this is said to be worse in developing countries, where there are inadequate health facilities, illiteracy and poverty preventing them from adhering to their treatments. The asymptomatic nature of the disease and need for lifelong therapy are perhaps the most important contributing factors to nonadherence in HTN.
The pill burden the patients placed on themselves by adding nonprescribed medicines and potentially increasing the cost of their medicines has also been highlighted in this study. This was similar to a study conducted earlier in this area that revealed the drug use profile of patients. This study has shown that hypertensive patients indulge in various medication practices relating to their antihypertensive therapy, ranging from herbal supplements and food supplements to antihypertensive medicines which were not prescribed; this observation was made in an earlier study.
The use of unprescribed antihypertensive medicine may be ascribed to lack of understanding by some patients who persist in using medicines already discontinued. It may also have been the result of gifts sent from relatives purportedly to help the patients' blood pressure control and general well-being, and this may have impacted negatively on prescription adherence as patients tend to believe medicines sent from overseas would be good and effective. These medicines in most instances may not have been shown to their doctors, creating potentials for serious and maybe fatal drug-drug interactions, as were buttressed in the study that recommended that a complete medication review should be carried out on all patients' medications which they should present to the clinic.
The duration of use of all medicines should also be done as it was seen in the study that some patients used NSAIDS, benzodiazepines as well as steroids for up to 12 months.
The use of food supplements, vitamins, and herbal supplements and herbal medicine in addition to antihypertensive medicines was similar to findings in earlier studies that revealed that these classes of medicines also had the highest usage among the sampled population in those studies., This may be due to cultural beliefs and perception about the effectiveness of complementary and alternative medicine (CAM) and possible adverse reaction that may arise from allopathic medicine and possibility of weight reduction in some patients.
Herbal medicines used by the patients were for treating HTN as well as other medical conditions. A majority of those who used herbal medicines were not aware of the constituents. It was also shown that more females used herbal medicines than men; this may be because women may have stronger beliefs about the effectiveness of herbal medicines and increased health-seeking behavior than men; it may also be attributed to the presence of gynecological disorders that exists in women as demonstrated in study on the use of traditional and complementary medicines in Taiwan. A slightly higher proportion of herbal medicine use was found in a community-based study that reviewed the prevalence of CAM use in urban Nigeria, and another study had indicated that herbal medicines were the most used CAM, and herb-drug interactions may occur with the use of herbs, herbal products, and medicines. Herbs are believed to be safer, more effective than conventional allopathic medicine.
Other medicines used include NSAIDS which were largely nonprescribed although only 7.1% of the population was noted to have arthritis. The use of NSAIDS in HTN is not recommended due to the fluid-retaining properties and worsening of blood pressure control. Glucocorticoids though not commonly prescribed were used by a proportion of patients. They are known to worsen blood pressure control due to their ability to induce sodium and fluid retention. These medicines were used to treat arthritis in combination with NSAIDS (unconfirmed anecdotal reports). The complications and potential risks associated with long-term use of this combination portend doom to subsequent blood pressure control of these patients and development of target organ damage. It also further buttresses the need to identify and monitor comorbid conditions in the hypertensive patient as major factor seen in this study was the attendance of multiple clinics by the patients resulting in multiple medicines being used by the patient but hitherto unknown by the doctor. Even though the patient may be seeing the doctors in the same facility, record keeping processes make it difficult to access patients' other prescribed medications. Electronic health record system may reduce the incidence of this negative trend.
One of the factors which was significant on univariate analysis was adverse reaction to medicines as more persons who had adverse reactions to their medicines had more discrepancies. This has been identified as a major deterrent to adherence as different studies, saw patients discontinuing or modifying their therapy due to adverse reactions. A similar pattern was also seen in this study as some of those who did not use their medicines regularly were due to the development of adverse reaction.,
The study also showed that patients who had a higher rate of discrepancies in their medications had one of the following reasons: multiple clinics, presence of an adverse reaction, use of herbal medicines, and time since the last attendance at the clinic. This was similar to what was found in another study where older age, increased number of medicines as well multiple clinic attendances were found to be associated with discrepancies in medication use. These factors serve as reminders that patients do not always disclose all practices that may adversely affect their medication-taking behavior and as such the physician needs to be alert to them. The duration of their last clinic visit also adversely affected adherence, and intervention directed at reminding patients about clinic appointments may be useful subsequently in practice.
Furthermore, this study highlighted the existence of some devices that are purported to lower blood pressure through some unknown mechanism. This does not augur well for patient management as the patient may tend to believe the device which has no scientific basis actually works. It was equally obvious from this study that actual sighting of the returned pills served to improve the quality of the consultation between the doctors and the patients and helped patients who had difficulty in understanding the difference in brand and use of the same class of medicines.
There was no association between blood pressure control and discrepancies in medications prescribed in the whole population of this study; this may be due to the fact that many factors such as age, gender, and comorbidity contribute to blood pressure control which has also been shown to be poor in other settings.,, It is, however, notable that hypertensive patients with diabetes had poorer control of their blood pressure; this was also seen in another study, where the presence of diabetes increased the odds of poor blood pressure control. The reasons for this may also be multifactorial and implies a greater level of care for patients with diabetes. The study also revealed that diabetics used more medicines but had fewer discrepancies with their medications; this may indicate that an increased number of prescribed medicines may again not be the only factor that may result in medication discrepancy as seen in another study.
| Conclusion|| |
This study highlights the profile of antihypertensive medication use revealing the significant use of nonprescribed medicines. The inspection of the medicines revealed that the unprescribed medicines may detract from good medication practices at home. This is an unrecognized problem in the clinic and addressing them with proper counseling may improve blood pressure control and obviate harmful effects from unprescribed medicines. The study also highlighted the emerging practice of the use of “gift” medicines. The practice of inspecting medicines during routine clinic attendance should be comprehensively integrated into the standard of care of hypertensive patients since this may determine the outcome of clinical care of these patients.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL, et al
. Seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure. Hypertens Am Heart Assoc 2003;42:1206-52.
1999 World Health Organization-international society of hypertension guidelines for the management of hypertension. Guidelines subcommittee. J Hypertens 1999;17:151-83.
Hugtenburg JG, Timmers L, Elders PJ, Vervloet M, van Dijk L. Definitions, variants, and causes of nonadherence with medication: A challenge for tailored interventions. Patient Prefer Adherence 2013;7:675-82.
Monane M, Bohn R, Gurwitz J, Glynn R, Levin R, Avorn J. A population-based study of compliance with antihypertensive therapy: Role of Age, Gender and Race. Am J Public Health 1996;86:1805-9.
Isah A, Isah E, Shah D, Obasohan A. An assessment of patient's knowledge and experience in a Nigerian Teaching Hospital Hypertension Clinic. Niger Postgrad Med J 1998;5:173-5.
Munger MA, Van Tassell BW, LaFleur J. Medication nonadherence: An unrecognized cardiovascular risk factor. MedGenMed 2007;9:58.
Kang CD, Tsang PP, Li WT, Wang HH, Liu KQ, Griffiths SM, et al
. Determinants of medication adherence and blood pressure control among hypertensive patients in hong kong: A cross-sectional study. Int J Cardiol 2015;182:250-7.
Eisen SA, Miller DK, Woodward RS, Spitznagel E, Przybeck TR. The effect of prescribed daily dose frequency on patient medication compliance. Arch Intern Med 1990;150:1881-4.
Osterberg L, Blaschke T. Adherence to medication. N Engl J Med 2005;353:487-97.
Bedell SE, Jabbour S, Goldberg R, Glaser H, Gobble S, Young-Xu Y, et al
. Discrepancies in the use of medications: Their extent and predictors in an outpatient practice. Arch Intern Med 2000;160:2129-34.
Isah AO, Ohaju-Obodo J, Isah EC, Ozemoya O. Drug use profile in a Nigerian city hospital. Pharmacoepidemiol Drug Saf 1997;6:319-24.
Amira CO, Okubadejo NU. Factors influencing non-compliance with anti-hypertensive drug therapy in Nigerians. Niger Postgrad Med J 2007;14:325-9. [Full text]
Bland J, Butland B, Peacock J, Poloniecki J, Reid F, Sedgwick P. Sample size calculation. Statistical Guide for Research Grant Application. London: St. George's University of London; 2012. p. 37-44.
ILO. International Standard Classification of Occupations: ISCO-08. Structure, Group Definitions and Correspondence Tables. Geneva: International Labour Office; 2012. p. 420.
Sabate E. Adherence to Long-term Therapies: Evidence for Action. Geneva, Switzerland: World Health Organization; 2003.
Amira OC, Okubadejo NU. Frequency of complementary and alternative medicine utilization in hypertensive patients attending an urban tertiary care centre in Nigeria. BMC Complement Altern Med 2007;7:30.
Gohar F, Greenfield SM, Beevers DG, Lip GY, Jolly K. Self-care and adherence to medication: A survey in the hypertension outpatient clinic. BMC Complement Altern Med 2008;8:4.
Kaptchuk TJ, Eisenberg DM. The persuasive appeal of alternative medicine. Ann Intern Med 1998;129:1061-5.
Upchurch DM, Burke A, Dye C, Chyu L, Kusunoki Y, Greendale GA, et al
. A sociobehavioral model of acupuncture use, patterns, and satisfaction among women in the United States, 2002. Womens Health Issues 2008;18:62-71.
Shih CC, Liao CC, Su YC, Tsai CC, Lin JG. Gender differences in traditional chinese medicine use among adults in Taiwan. PLoS One 2012;7:e32540.
Osamor PE, Owumi BE. Complementary and alternative medicine in the management of hypertension in an urban Nigerian community. BMC Complement Altern Med 2010;10:36.
Johnson AG, Nguyen TV, Day RO. Do nonsteroidal anti-inflammatory drugs affect blood pressure? A meta-analysis. Ann Intern Med 1994;121:289-300.
Wallenius SH, Vainio KK, Korhonen MJ, Hartzema AG, Enlund HK. Self-initiated modification of hypertension treatment in response to perceived problems. Ann Pharmacother 1995;29:1213-17.
Mutua EM, Gitonga MM, Mbuthia B, Muiruri N, Cheptum JJ, Maingi T, et al
. Level of blood pressure control among hypertensive patients on follow-up in a regional referral hospital in central Kenya. Pan Afr Med J 2014;18:278.
Lloyd-Sherlock P, Beard J, Minicuci N, Ebrahim S, Chatterji S. Hypertension among older adults in low- and middle-income countries: Prevalence, awareness and control. Int J Epidemiol 2014;43:116-28.
Ojo OS, Malomo SO, Sogunle PT, Ige AM. An appraisal of blood pressure control and its determinants among patients with primary hypertension seen in a primary care setting in Western Nigeria. S Afr Fam Pract Taylor Francis 2016;58:192-201.
Fox CS, Golden SH, Anderson C, Bray GA, Burke LE, de Boer IH, et al
. Update on prevention of cardiovascular disease in adults with type 2 diabetes mellitus in light of recent evidence: A Scientific statement from the American Heart Association and the American Diabetes Association. Diabetes Care 2015;38:1777-803.
Grant RW, Devita NG, Singer DE, Meigs JB. Polypharmacy and medication adherence in patients with type 2 diabetes. Diabetes Care 2003;26:1408-12.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]