COMMENTARY ARTICLE | VOLUME 4, ISSUE 2 | OPEN ACCESS DOI: 10.23937/2474-3690/1510034

Hypertension: Drug Adherence and Social Factors

Ana Correia de Oliveira1 and Paulo Santos2,3*

1UCSP Apúlia/Fão, ACeS Cávado III - Barcelos/Esposende, Portugal

2Department of Medicine of Community, Information and Health Decision Sciences (MEDCIDS), Faculty of Medicine of University of Porto, Portugal

3Center for Health Technology and Services Research (CINTESIS), Portugal

*Corresponding author: Paulo Santos, MD, PhD, Department of Medicine of Community, Information and Health Decision Sciences (MEDCIDS), Faculty of Medicine of University of Porto; Center for Health Technology and Services Research, Rua Doutor Plácido Costa, S/N, 4200-450 Porto, Portugal, Tel: (+351)220426600, Fax: (+351)225572583.

Accepted: August 02, 2018 | Published: August 04, 2018

Citation: de Oliveira AC, Santos P (2018) Hypertension: Drug Adherence and Social Factors. J Hypertens Manag 4:034.

Copyright: © 2018 de Oliveira AC, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Hypertension is the most prevalent cardiovascular risk factor in the world, increasing significantly with aging [1]. The treatment of arterial hypertension leads to the reduction of the risk of cardiovascular events, such as stroke and heart disease [2]. In the adult population, the prevalence of hypertension is about 30 to 45%, varying between countries [1]. In 2010, more than 1.3 billion adults age ≥ 20-years-old were hypertensive worldwide, representing an estimated global age-standardized prevalence of hypertension of 31.1%. This figure is increasing with ageing and in the developing countries [3]. In Portugal the prevalence in adults over 18 is estimated in 42.2%, higher in men (44.4% versus 40.2% in women) [2].

The diagnosis of hypertension is primarily based in the office visit's measurements. The value of 140/90 mmHg is the consensual cut-off. Values equal or higher both in systolic or diastolic blood pressure, in patients not previously medicated with antihypertensive medication, define the diagnosis [1]. Last review of the American Heart Association (ACC/AHA) guidelines for hypertension released new targets for the definition of Hypertension, starting on hypertension stage 1 if patient's blood pressure is higher than 130-139 or 80-89 mmHg, and hypertension stage 2 is ≥ 140 or ≥ 90 mmHg [4]. This new definition is based in recent data, showing a significant increase in cardiovascular risk at lower blood pressure values, especially the SPRINT study [5]. However, these guidelines aren't consensual. They significantly increase the prevalence of people living with the diagnosis of hypertension, but not much the recommendation for antihypertensive medication treatment [6]. On the other hand, SPRINT study included high risk hypertensive patients in the enrolment, not allowing the extrapolation for general population in primary prevention. These contradictions lead several societies to reject the rational and the proposal of 2017 American Guidelines. The American Family Physician also asks for the opportunity of making the diagnosis of hypertension based on the out-of-office blood pressure readings instead of an accurate measurement made by a physician, without a clarification of the potential harms versus the net benefit of the treatment intensification [7]. The new guidelines of European Hypertension Society for the Management of Arterial Hypertension will soon be published, and hopefully they will bring some sense to this discussion. Early highlights point the need to improve the treatment of high blood pressure, leading more patients to control the hypertension, which at present is not as good as it should be. Treatment options include naturally the improvement of pharmacological approach, but non-pharmacological interventions and lifestyles modifications are crucial to achieving the targets and should be constantly reinforced. The problem is taking the patients to adhere both to pharmacological and non-pharmacological interventions [8-11].

Therefore, the aim of this article is to review critically the major determinants that interfere with non-adherence and present strategies to improve blood pressure control.

Key Concepts of Adherence to Medications

Adherence is normally accepted as the extent to which a person's behavior corresponds with agreed recommendations from a health care provider, both in taking a medication, following a diet or executing lifestyle changes [12]. It divides in compliance, representing the patient's passive following of provider's orders, and in persistence, as the duration of time patient takes the medication, from initiation to discontinuation of therapy [13]. It has a multidimensional nature due to the different players in the problem: Patients, providers and health care system, and how they interact with each other [11].

Patients have to feel that a negative health condition is a true personal threat and that it can be avoided by the recommended action, if they can successfully take it [14]. However, several problems can interfere like psychological problems, as depression, cognitive deficit, low insight into diagnosis, especially in asymptomatic diseases. On the doctor's side, we point the poor patient-physician relationship, the inadequate follow-up plan and the side effects of treatments. Poor accessibility to care or medicines, the cost of medication, and care and missing appointments are relevant factors related to health systems' organization.

Adherence to Medications in Hypertensive Patients

We accept the concept of drug adherence as the extent to which patients take their medications as prescribed by their healthcare providers [11]. High blood pressure is the main determinant of death worldwide since a long time and we could expect that this threat was well-known by general population as everybody frequently wants to measure their blood pressure [15]. Unfortunately, the reality is far from desired. Adherence to anti-hypertensive medications depends on the patients' behaviour and expectations, the type of medication, the patient-physician relationship, the therapeutic inertia, as providers sometimes don't value properly some deviations to the blood pressure targets, the power of external sources like media, internet and friends' opinions, and several other factors [10]. Ideally, the compliance should be similar to the adherence representing the degree of obedience to the indicated treatments, pharmacological or not, aiming to lower the blood pressure to the target level, and both near 100%, meaning that all the patients respect treatment instructions, following doctors' information and prescription. However, non-adherence is very common and about half, or more, of patients don't take their medications as prescribed [16,17].

Measuring the Adherence to Medications

There is no Gold Standard method to measure drug adherence. The adherence questionnaires are indirect methods. Although frequently inaccurate and biased by patients' behaviour, they remain very valued, providing opportunities to identify patients needing counselling and to educate them according their answers [10]. Pill counting is often used in clinical trials and clinical practice [18,19]. It's more accurate than questionnaires and many times referred as standard for evaluating the adherence to medications [18]. It's based on the number of pills effectively taken, that is, the number of pills dispensed less the number of pills leftover, weighed by number of days of prescription. If the patient has to take a medication twice a day for 30 days, and the prescription has exactly the 60 pills, the number of pills remaining in the box divided by number of daily intakes retrieves the days of non-adherence [19]. However, both patients' questionnaires and pill counting may overestimate adherence to medications because they are dependent of patients report [20]. Electronic counting through a pillbox can overcome the problem, but it's expensive and so not often used. Direct methods, like direct observation of intake, utilization of plasma and urine biomarkers and urine drug detection, are better and more accurate for monitoring, but also more intrusive, and not always easy to apply in clinical practice [10].

Antihypertensive drugs are effective to lower the blood pressure and to prevent cardiovascular, cerebrovascular and renal complications and even death [21]. However, due to the asymptomatic and chronic characteristics of hypertension, non-adherence is highly prevalent, putting patients' health at risk. Attention to the adherence, using a combination of different assessment methods is likely the most effective approach to improve it [10].

Strategies to Improve Adherence to Medications in Hypertensive Patients

Pharmacological treatment is well established in different hypertension guidelines. Antihypertensive drugs proved to be cost-effective, lowering the cardiovascular risk with good security profile and tolerance. The different classes cover the physiopathology pathways of hypertension. They may be combined in single pills with fixed doses, gaining better acceptance and adherence by both patients and doctors [22]. Even since, blood pressure control is far from the ideal, mostly because of low adherence to antihypertensive drugs. The need to use combinations of several medications is an important factor. The unifactorial causality relationship has still a very relevant symbolic presence in most of population: One cause, one disease and one treatment, opposing the current multifactorial approach, that justifies the multiple and different combinations. Another factor in accounting is the drug-related side effects as fatigue, headache, peripheral oedema, cough, allergy, polyuria, erectile and libido dysfunction and metabolic changes, some of them very uncomfortable for patients [23]. The side effects profile justifies that certain medication classes, as beta-blockers and thiazide-diuretics, present lower adherence rates as compared to other classes [10]. Side-effect profile is better evaluated in monotherapy, allowing the establishment of the causal relationship, as the assignment of efficacy. However, most of hypertensive patients will need a combination of two or more drugs, seizing the synergistic effect among the different classes. Using fixed doses in single pill combinations favours higher rates of adherence [24,25]. Nevertheless, evidence shows that 25% of patients do not buy all medications prescribed by the attending physician [26] and 10% of patients often forget to take the prescribed medication on a daily basis. Also, one-third of patients discontinue initial treatment after 6 months and half of patients after one year [16,27]. Recent data suggests that non-adherence occur in 45.2% of all hypertensive patients, and reaches 83.7% in uncontrolled patients [28].

Patient-related factors are relevant determinants for non-adherence. They include lack of understanding their disease, lack of involvement in the treatment decision-making process and, more often, suboptimal health literacy. It's crucial to improve patients' expectations on the effectiveness of the treatment, dealing with previous experiences with pharmacological therapies and lack of motivation. Bad family support and loneliness are also factors that should not be forgotten [19]. The true challenge in medication adherence is to enhance patients' health literacy and to empower them to make good choices for their own health [29].

Males are more likely to show low adherence rates, as the youngers, especially in resistant hypertension [23]. Also, the presence of depression and chronic heart disease are associated to lower drug adherence [30].

Therapeutic adherence is higher in patients with better education and better knowledge about their disease, and also with greater economic income [31-33]. Adherents present better quality of life, both in their physical and their mental status [34]. Health literacy and education should be a priority in these patients and in all people [29]. Moreover, there's a 'healthy adherer effect', where patients who adhere to medications are more likely to engage in other healthy behaviour, like changes in lifestyles, which may influence their health outcomes [10]. Nurses play a very important role in educating the patients towards a better literacy [35].

Providers play an important role in non-adherence. Physician-related factors are very common, when prescribing complex drug regimens, when failing to explain effectively the benefits and harms of the medication, and when disregarding the financial burden to the patient [19]. Doctor-patient communication is crucial and should always be reinforced. The pressure of timing not always enough to make a proper consultation, the waiting time for an appointment and the technology too many times inefficient are problems relevant to medical adherence. Doctors and patients must work together, negotiating the best options in a clinical reasoning pathway towards the achieving of health outcomes, defined and accepted by both. Simplifying the regimen characteristics, imparting knowledge and literacy, modifying patient beliefs and expectations, improving the communication with the patients, leaving the bias and evaluating continuously the process are strategies to enhance adherence which may be applied to patient care settings [36].

Several issues are easy to implement in clinical practice. Lowering the intake frequency is many times possible, putting all medication, or at least the most, at the same time [37]; when we need to intensify the regimen, it's possible to join several drugs in one single pill, with advantages in adherence [22]; providing a good channel for communication with patients, addressing benefits and potential harms of different options both pharmacological and non-pharmacological; and checking regularly the rate of adherence, using the different strategies already focused. Also, an effective interaction between different levels of health care, with exchanging of information in real-time, facilitates the adherence to medications [19].

Adherence to medications is a multifactorial phenomenon, hard to explain in its globality. An intervention that works in one patient may not work in another, leading to the need of combining several strategies, [10] in a personalized way, putting the patient in the center of the system.


Arterial hypertension is the most important risk factor for cardiovascular diseases [1]. Improving blood pressure control is crucial to reduce the cardiovascular morbidity [2], which remains the main cause of death worldwide [38]. In Portugal, we saw a good evolution since the PAP study, in 2001 [39], to the PHYSA study, in 2011 [2], improving the number of patients that are aware of their high blood pressure and the number of patients that had their blood pressure controlled (< 140/90 mmHg). The causes aren't sufficiently established but the improvement of the attention given to blood pressure, especially in primary care, both by doctors and by patients, the vulgarization of single pill associations with 2 or 3 drugs and the reduction in salt consumption in population are certainly relevant factors. Nevertheless, although we have good drugs for controlling of high blood pressure, we still fail in many patients.

Charles Koop once said that no drug is effective if patients don't take it. (C. Everett Koop, MD, US Surgeon General, 1985).

This is crucial to get better results in treatment of arterial hypertension. Patient's responsibility is the way to achieve it and it depends on improving education and literacy, leading to better skills and to higher empowerment [29,40].

More than lowering the targets for blood pressure, it's necessary to look for the determinants of non-adherence and fight them, both in lifestyles and in medication, ensuring the lighten of the burden of hypertension in patients, in health care services and in the health systems.

Sources of Support

This manuscript had no funding.

Statement of Equal Authors' Contribution

All authors contributed equally to the design, writing and discussion of the present manuscript.


  1. Mancia G, Fagard R, Narkiewicz K, Redon J, Zanchetti A, et al. (2013) 2013 ESH/ESC guidelines for the management of arterial hypertension: The task force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). Eur Heart J 34: 2159-2219.

  2. Polonia J, Martins L, Pinto F, Nazare J (2014) Prevalence, awareness, treatment and control of hypertension and salt intake in Portugal: Changes over a decade. The PHYSA study. J Hypertens 32: 1211-1221.

  3. Mills KT, Bundy JD, Kelly TN, Reed JE, Kearney PM, et al. (2016) Global disparities of hypertension prevalence and control: A systematic analysis of population-based studies from 90 countries. Circulation 134: 441-450.

  4. Whelton PK, Carey RM, Aronow WS, Casey DE Jr., Collins KJ, et al. (2018) 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: A report of the american college of cardiology/american heart association task force on clinical practice guidelines. Hypertension 71: e13-e115.

  5. Drawz PE, Pajewski NM, Bates JT, Bello NA, Cushman WC, et al. (2017) Effect of intensive versus standard clinic-based hypertension management on ambulatory blood pressure: Results from the SPRINT (systolic blood pressure intervention trial) ambulatory blood pressure study. Hypertension 69: 42-50.

  6. Muntner P, Carey RM, Gidding S, Jones DW, Taler SJ, et al. (2018) Potential US population impact of the 2017 ACC/AHA high blood pressure guideline. Circulation 137: 109-118.

  7. LeFevre M (2018) ACC/AHA Hypertension Guideline: What is new? What do we do? Am Fam Physician 97: 372-373.

  8. Dickinson HO, Mason JM, Nicolson DJ, Campbell F, Beyer FR, et al. (2006) Lifestyle interventions to reduce raised blood pressure: A systematic review of randomized controlled trials. J Hypertens 2: 215-233.

  9. Elmer PJ, Obarzanek E, Vollmer WM, Simons-Morton D, Stevens VJ, et al. (2006) Effects of comprehensive lifestyle modification on diet, weight, physical fitness, and blood pressure control: 18-month results of a randomized trial. Ann Intern Med 144: 485-495.

  10. Hamdidouche I, Jullien V, Boutouyrie P, Billaud E, Azizi M, et al. (2017) Drug adherence in hypertension: From methodological issues to cardiovascular outcomes. J Hypertens 35: 1133-1144.

  11. Osterberg L, Blaschke T (2005) Adherence to medication. N Engl J Med 353: 487-497.

  12. Sabaté E, World Health Organization (2003) Adherence to long-term therapies: Evidence for action. World Health Organization, Geneva, 198.

  13. Viswanathan M, Golin CE, Jones CD, Ashok M, Blalock S, et al. (2012) Closing the quality gap: revisiting the state of the science (vol. 4: medication adherence interventions: comparative effectiveness). Evidence report/technology assessment.

  14. Glanz K, Rimer BK, Viswanath K (2008) Health behavior and health education: Theory, research, and practice. John Wiley & Sons.

  15. Mendis S, Puska P, Norrving B (2011) Global atlas on cardiovascular disease prevention and control. World Health Organization.

  16. Corrao G, Zambon A, Parodi A, Poluzzi E, Baldi I, et al. (2008) Discontinuation of and changes in drug therapy for hypertension among newly-treated patients: a population-based study in Italy. J Hypertens 26: 819-824.

  17. Brown MT, Bussell JK (2011) Medication adherence: WHO cares? Mayo Clin Proc 86: 304-314.

  18. de Souza WA, Sabha M, de Faveri Favero F, Bergsten-Mendes G, Yugar-Toledo JC, et al. (2009) Intensive monitoring of adherence to treatment helps to identify "true" resistant hypertension. J Clin Hypertens (Greenwich) 11: 183-191.

  19. Lee JK, Grace KA, Foster TG, Crawley MJ, Erowele GI, et al. (2007) How should we measure medication adherence in clinical trials and practice? Ther Clin Risk Manag 3: 685-690.

  20. Cramer JA, Mattson RH, Prevey ML, Scheyer RD, Ouellette VL (1989) How often is medication taken as prescribed? A novel assessment technique. JAMA 261: 3273-3277.

  21. Poulter NR, Prabhakaran D, Caulfield M (2015) Hypertension. Lancet 386: 801-812.

  22. Armario P, Waeber B (2013) Therapeutic strategies to improve control of hypertension. J Hypertens 31: 9-12.

  23. Tedla YG, Bautista LE (2016) Drug Side Effect Symptoms and Adherence to Antihypertensive Medication. American Journal of Hypertension 29: 772-779.

  24. Corrao G, Parodi A, Zambon A, Heiman F, Filippi A, et al. (2010) Reduced discontinuation of antihypertensive treatment by two-drug combination as first step. Evidence from daily life practice. J Hypertens 28: 1584-1590.

  25. Gupta AK, Arshad S, Poulter NR (2010) Compliance, safety, and effectiveness of fixed-dose combinations of antihypertensive agents: A meta-analysis. Hypertension 55: 399-407.

  26. Baroletti S, Dell'Orfano H (2010) Medication adherence in cardiovascular disease. Circulation 121: 1455-1458.

  27. Lee JK, Grace KA, Taylor AJ (2006) Effect of a pharmacy care program on medication adherence and persistence, blood pressure, and low-density lipoprotein cholesterol: A randomized controlled trial. JAMA 296: 2563-2571.

  28. Abegaz TM, Shehab A, Gebreyohannes EA, Bhagavathula AS, Elnour AA (2017) Nonadherence to antihypertensive drugs: A systematic review and meta-analysis. Medicine 96: e5641.

  29. Santos P, Sá L, Couto L, Hespanhol A (2017) Health literacy as a key for effective preventive medicine. Cogent Social Sciences 3.

  30. Irvin MR, Shimbo D, Mann DM, Reynolds K, Krousel-Wood M, et al. (2012) Prevalence and correlates of low medication adherence in apparent treatment-resistant hypertension. J Clin Hypertens (Greenwich) 14: 694-700.

  31. Jankowska-Polanska B, Zameta K, Uchmanowicz I, Szymanska-Chabowska A, Morisky D, et al. (2018) Adherence to pharmacological and non-pharmacological treatment of frail hypertensive patients. J Geriatr Cardiol 15: 153-161.

  32. Park NH, Song MS, Shin SY, Jeong JH, Lee HY (2018) The effects of medication adherence and health literacy on health-related quality of life in older people with hypertension. Int J Older People Nurs 17: e12196.

  33. Jankowska-Polanska B, Blicharska K, Uchmanowicz I, Morisky DE (2016) The influence of illness acceptance on the adherence to pharmacological and non-pharmacological therapy in patients with hypertension. Eur J Cardiovasc Nurs 15: 559-568.

  34. Souza AC, Borges JW, Moreira TM (2016) Quality of life and treatment adherence in hypertensive patients: systematic review with meta-analysis. Rev Saude Publica 50: 71.

  35. Hacihasanoglu R, Gozum S (2011) The effect of patient education and home monitoring on medication compliance, hypertension management, healthy lifestyle behaviours and BMI in a primary health care setting. J Clin Nurs 20: 692-705.

  36. Atreja A, Bellam N, Levy SR (2005) Strategies to enhance patient adherence: Making it simple. MedGenMed 7: 4.

  37. Claxton AJ, Cramer J, Pierce C (2001) A systematic review of the associations between dose regimens and medication compliance. Clin Ther 23: 1296-1310.

  38. Benjamin EJ, Virani SS, Callaway CW, Chamberlain AM, Chang AR, et al. (2018) Heart Disease and Stroke Statistics-2018 Update: A Report from the American Heart Association. Circulation 137: e67-e492.

  39. De Macedo ME, Lima MJ, Silva AO, Alcantara P, Ramalhinho V, et al. (2007) Prevalence, awareness, treatment and control of hypertension in Portugal. The PAP study. Rev Port Cardiol 26: 21-39.

  40. Lee YM, Yu HY, You MA, Son YJ (2017) Impact of health literacy on medication adherence in older people with chronic diseases. Collegian 24: 11-18.