IJCRR - Vol 06 Issue 10, May
Date of Publication: 30-Nov--0001
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FACTORS ASSOCIATED WITH ADHERENCE TO ANTIHYPERTENSIVE TREATMENT AMONG PATIENTS ATTENDING A TERTIARY CARE HOSPITAL IN MANGALORE, SOUTH INDIA
Author: Nithin Kumar, Bhaskaran Unnikrishnan, Rekha Thapar, Prasanna Mithra, Vaman Kulkarni, Ramesh Holla, Darshan Bhagawan, Ishita Mehta
Abstract:Background: Adherence to antihypertensive medication is very important in preventing complications. Objectives: To assess the level of adherence of hypertensive patients to their anti-hypertensive medications and to study the various factors influencing the adherence among these patients. Methodology: 120 hypertensive patients were interviewed using a pre-tested semi-structured questionnaire. The Morisky 8-Item Medication Adherence scale was used. Univariate and multivariate analysis was done to determine the factors associated with good adherence. Results: The mean age of study participants was 58.41 +/- 14.4 years. 45.8% of the participants had low level of adherence. On Univariate analysis, not experiencing any side-effects, provision of free medication and regular checkups were found to be significantly associated good adherence. None of the factors were found to be statistically associated with adherence on multivariate analysis. Conclusion: The level of adherence to treatment among the participants can be achieved through better health promotion and education strategies.
Keywords: Adherence, Antihypertensive medications, Morisky scale, Patient related factors, Health system related factors, Mangalore
Hypertension or high blood pressure is defined as having persistent, elevated systolic blood pressure of 140 mmHg or above and/or diastolic blood pressure of 90 mmHg or above. It is rapidly emerging asa global public health challenge because of its high prevalence, especially in middle and low income countries. The risk for cardiovascular diseases including coronary artery disease, congestive heart failure, stroke (ischemic and haemorrhagic), renal failure and peripheral arterial disease increases two-fold in the presence of hypertension.. Itis oneamong the leading risk factors for cardiovascular mortalityand accounts for 9.4 million deaths globally and 7 per cent of disability adjusted life years (DALYs) in 2010. The prevalence of hypertension in India is estimated to be around 20% - 40% in urban and 12% -17% in rural areas. It is also alarming to notice that more and more young adults are being diagnosed with hypertension. According to a World Health Organization (WHO) report, the prevalence of hypertension in India among men and women aged 25 years or more was 23.1% and 22.6% respectively.
Regular blood pressure monitoring and continuous treatment for control of hypertension can improve this scenario.Adherence to medication is very important to keep high blood pressure under check and prevent complications. The available evidence shows that reduction of blood pressure is associated with significant decrease in the incidence of stroke, ischemic heart disease, congestive heart failure, and renal failure, irrespective of age, gender, race or ethnicity, type of antihypertensive used, or severity of hypertension. However adherence to antihypertensive medication is an issue of concern and poses a serious challenge to clinicians, and healthcare systems because of the mounting evidence that non adherence is prevalent. Non adherence to long term medication for chronic diseases is a complex process and a complicated issue affecting patients? health, health expenditure, and resources? utilization. Non- adherence to antihypertensive medication is one of the main reason for failure to control blood pressure among those on treatment and is generally associated with bad outcomes of the disease.  Adherence has been often used interchangeably with the term „compliance?. However, the term adherence is preferred over compliance because the former implies an interactive, collaborative relationship between the patient and the care-giver.  Complianceis defined as the extent to which a person?s medication-taking behaviour coincides with the healthcare providers? medical advice and relies on patient obedience.[8,9] WHO defines adherence as ''the extent to which aperson's behaviour in taking medication, following a diet , and /or executing lifestylechanges corresponds with agreed recommendations from a health care provider.It is observed that patient adherence to treatment can be influenced by socioeconomic factors, health system and health care related factors, medication and disease related factors and finally, patient related factors. The problem of non-adherence may not be limited to developing countries only, but its impact in developing countries like India is higher given the paucity of health resources and inequities in access to health care. Due to poor adherence it is inevitable that patient lands up with medical complications resulting, in himspending large amount of money on hospitalization and chronic illness care [6, 10] Even though adherence to medication can be measured using indirect methods like pill counts, pharmacy refill rates and electronic medication monitors it is rarely practiced in clinical care.  Self-reporting questionnaires with high validity and reliability have also been developed to measure the level of adherence to antihypertensive medication. [11, 12, 13]. However, ensuring patient adherence to therapy still remains a challenge for practitioners. Hence medication adherence has been called “The next frontier in quality improvement”and is anintegral part of cardiovascular outcomes research.[6,14] The present cross-sectional study was conducted to assess the level of adherence and the factors influencing adherence among hypertensive patientsin Coastal South India.
This cross-sectional study was conducted among the hypertensive patients attending the peripheral outreach clinics belonging to the Department of Community Medicine, and the Medicine OPD at the hospital attached to Kasturba Medical College, Mangalore.The study participants were above 18 years of age and on anti-hypertensive treatment for more than 6 months. The sample size of 119 was calculated taking the level of adherence to antihypertensive medication as 60%. [15, 16, 17] with a relative precision of 15% and 95% confidence interval. Adding a non-response error of 10%, the sample size to be studied was 131.The data was collected using a pretested semi-structured questionnaire consisting of 4 sections: Section AParticipant?s general information, Section BDiagnosis and treatment details of hypertension, Section C - Health System related details and Section D -The Morisky 8-Item Medication
Adherence Questionnaireto assess the level of adherence to the anti-hypertensive medication. The questionnaire consists of a set of 8 questions with a yes or no answer. 1 point was awarded for every yes response and a zero for every no. A total score of >2 meant low adherence, 1 or 2 is medium adherence and a 0 shows high adherence. Ethics Committee approval was obtained from the Institutional Ethics Committee of Kasturba Medical College, Mangalore (affiliated to Manipal University), India prior to the commencement of the study. After obtaining the required permission from the hospital/Medical college, the study participants were briefed about the nature and the purpose of the study, and were included in the study after taking a written informed consent. The socioeconomic status was assessed using the Kuppuswamy Scale. 
The collected data was entered in, and analyzed using SPSS (Statistical Package for Social Sciences) version 11.5 (SPSS, Inc., Chicago, IL, USA). The data was analyzed in terms of descriptive statistics (Mean, Standard deviation and IQR) and the results were expressed in proportions. We undertook both unadjusted and adjusted logistic regression to assess the various (Patient related, Medication related and Health system related) factors favoring adherence to anti-hypertensive medication among patients. The fit of the logistic model was assessed with the Hosmer and Lemeshow goodness-of-fit test; P < 0.05 was considered evidence of a statistically significant difference between predictive and outcome variables. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) are reported
A total of 120 hypertensive patients were assessed about their level of adherence towards antihypertensive medication giving a response rate of 100%. The mean age of study participants was 58.4 +/- 14.4 years. Majority (n =76, 63.3%) of the participants were males and a higher proportion (n=66, 55.0%) were above 55 years of age. The family history of hypertension was present in 33.3% (n=40) of study participants. Comorbidities were present among 50.8% (n=61) of the participants of which Diabetes Mellitus (n=44, 72.1%) was the most common comorbid illness. The baseline characteristics of the study participants are shown in Table1. The mean duration of hypertension among the patients was 5 years (IQR 3-12) More than half (n=76, 63.3%) of the participants were diagnosed to be hypertensive in a private clinic. By self-report 116 (96.7%) of 120 patients were adherent to their anti-hypertensive medications. However on assessing the adherence level using Morisky scale it was observed that 54.2% of the participants had a medium level of adherence and 45.8% had poor level of adherence to their medication. There were no participants with high level of adherence to antihypertensive medication in our study. For the purpose of comparison, participants with medium level of adherence were considered to have a good adherence and those with low level of adherence were considered to be having poor adherence to medication. Table 2 shows the patient factors determininggood adherence to anti-hypertensive medication as measured by Morisky adherence scale.Adherence rate towards anti-hypertensive medications was better among participants above 60 years of age (57.4%)compared to those below 60 years (51.5%), (OR =0.8, CI= 0.4 – 1.6, p=0.520), but was not found to be statistically significant. Even though adherence rates were found to be better among married participants, those with positive family history of hypertension and among those who understood the doctor?s advice, none were found to be statistically significant in determining good adherence behaviour. Table 3 shows the medication related factors determining adherence to antihypertensive medications. Not experiencing any side-effects due to medicationwas found to be associated with good adherence and the association was found to be
statistically significant. (OR=0.1, 0.03-0.52, p=0.003) Table 4 shows the health system related factors determining good adherence to antihypertensive medications. Participants who were taking free medication were found to have better adherence towards their hypertensive medications and it was statistically significant. (OR=0.4,0.2-0.9,p=0.030) Even though on Univariate analysis, not experiencing any side-effects, provision of free medication and regular checkups were found to be significantly associated good adherence, on multivariate analysis none of the factors were found to be statistically associated with adherence. (Table-5)
Non-adherence to chronic disease medication is a major public health problem that has been called an "invisibleepidemic”. Reviews from developed countries such as the United States have shown that only 51% of the patients treated for hypertension adhere to the prescribed treatment where as in developing countries like China, Gambia and the Seychelles, only 43%, 27% and 26%, respectively, of patients adhere to their antihypertensive medication regimen.The present study was conducted to assess the level of adherence to antihypertensive medication among the hypertensive patients in Mangalore, a Coastal city in South India. In our study by self-report 96.7% of the participants felt they were adherent to their prescribed medications. However on assessment using the Morisky scale 54.2% were found to have a moderate level of adherence to their hypertensive medication and 45.8% had a poor level of adherence.Our study findings are similar to studies from China  and Malaysia  where overall 52% and 53.4% of the participants were found to be adherent to their anti-hypertensive medication respectively. Similar studies from other parts of the globe have reported the prevalence of adherence to hypertensive medications to be ranging from 60% to 77%. [15, 16, 20-25].In a study in Birmingham, UK  only 44.8% of the participants were adherent to their hypertensive medication.The wide range inprevalence of adherence to antihypertensive medication across various studies may be due to the use of different scales to assess adherence. However there is no denying the fact that non-adherence to medication is a matter of huge concern. It is evident from our study as well as from others mentioned above; the problem of non-adherence is universal and not just limited to developed or developing countries.But its impact may be more onthose countries with limited resources since poor adherence poses a huge challengefor improving health in poor populations, and also results in underutilization of already limited treatment resources. Various studies across countries have identified different factors influencing adherence to antihypertensive medication. In a study from Malaysia  females were found to be more adherent towards their medication compared to males, where as in UK males were found to be more adherent towards medication which was similar to our study finding. Instudies from China  and Pakistan  age seemed to be an important factor influencing adherence with older patients being more adherent compared to younger patients. Similar observations were made in our study. The latter study also reported better awareness about the disease as an important factor for adherence towards medication which was also reported by study in Northwestern Ethiopia.  To add to this finding, in a study in Bangladesh lack of information about the disease was an important factor for non-adherence to medication. The adherence was seen to be higher among patients on more medications. [16, 25].In a study in Greece , fear of complications of hypertension, personal relationship with the treating physician favored adherence.In the health system related factors the people who live closer to the hospital and those who get free drugs were seen to be more adherent to their medications than those who had to
come from a distance and had to pay for their drugs. Distance to the hospital as a factor which caused non adherence was also reported by other studies. [16, 24] Absence of any side effects to the medications, availability of free antihypertensive drugs and regular checkup of blood pressure were found to be associated with good adherence to antihypertensive medication in our study which were not found to be significant after multivariate analysis. On stratifying the factors, as well as those reported from other studies, the multifactorial nature of the problem of non-adherence is evident. Not one factor can be solely held responsible for influencing non-adherence among patients.The interventions planned to combat the problem should be targeted towards social, economic, medical, behavioral and health system related factors. The limitation of our study would be that the Morisky adherence questionnaire used in this study has not been validated in the Indian population. Also the sample size of our study is small to generalize the findings to a large extent. However there is a paucity of literature on adherenceto antihypertensive medications in the Indian subcontinent. We would like to recommend further studies in the region as well as across the country to assess the adherence level as well as the various factors influencing it. The clinicians should spend quality time with their patients and make them aware of the risk of complications arising from poor adherence to treatment. Health education plays an important role as well in creating awareness about the complications of hypertension among patients in general, with display of posters and flipcharts which can have an added effect. Patient self-help groups need to be formed and promoted where in the patients can discuss their reasons for non-adherence and try to solve it.The health system needs to be strengthened to make sure lack of medication is never a cause for non-adherence. The proposed National Programme on Prevention and Control of Diabetes, Cardiovascular diseases and Stroke (NPDCS) should address the issue of Non
adherence to medication and recognize it as one of modifiable risk factor for complications of hypertension. By preventing this risk factor, the qualities of life for individuals with hypertension can be improvedand will reduce the overall cardiovascular morbidity and mortality.
From our study, as well as those reported from other studies, the multifactorial nature of the problem of non-adherence is evident. Not one factor can be solely held responsible for influencing non-adherence among patients.The interventions planned to combat the problem should be targeted towards social, economic, medical, behavioral and health system related factors. The limitation of our study would be that theMorisky adherence questionnaire used in this study has not been validated in the Indian population. Also the sample size of our study is small to generalize the findings to a large extent. However there is a paucity of literature on adherence to antihypertensive medications in the Indian subcontinent. We would like to recommend further studies in the region as well as across the country to assess the adherence level as well as the various factors influencing it. The clinicians should spend quality time with their patients and make them aware of the risk of complications arising from poor adherence to treatment. Health education plays an important role as well in creating awareness about the complications of hypertension among patients in general, with display of posters and flipcharts which can have an added effect. Patient self-help groups need to be formed and promoted where in the patients can discuss their reasons for nonadherence and try to solve it. The health system needs to be strengthened to make sure lack of medication is never a cause for non-adherence. The proposed National Programme on Prevention and Control of Diabetes, Cardiovascular diseases and Stroke (NPDCS) should address the issue of Nonadherence to medication and recognize it as one of modifiable risk factor for complications of
hypertension. By preventing this risk factor, the qualities of life for individuals with hypertension can be improved and will reduce the overall cardiovascular morbidity and mortality.ACKNOWLEDGEMENTS The authors are grateful to the study participants who voluntarily took part in the study. We wish to acknowledge the support provided by the Department of Community Medicine, Kasturba Medical College, Mangalore and Manipal University for encouraging research and its publication in international journals of repute. Authors also acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.
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