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ORIGINAL ARTICLE
Year : 2019  |  Volume : 9  |  Issue : 2  |  Page : 80-85

Patterns of Persistence with Antihypertensive Medications Among Newly Diagnosed Hypertensive Patients


1 Department of Pharmacology, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
2 Department of Medicine, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India

Date of Web Publication26-Jun-2019

Correspondence Address:
Nithyananda Chowta
Department of Medicine, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijnpnd.ijnpnd_9_19

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   Abstract 


Persistence and adherence to treatment are essential to reach the treatment goals of hypertension. This study was conducted to investigate the antihypertensive drug persistence in hypertensive patients in the routine clinical settings. Patients above 20 years of age with stage 1 hypertension, who have received the first prescription for hypertension, were included in the study. Patients were followed up for one year. During each follow-up, the parameters noted were systolic and diastolic blood pressure, changes in the prescription by the treating physician, the number of days patient missed the medication and the probable reason for missing the dose, and total doses of anti-hypertensive medications received. Based on patient behavior of persistence with first-line single treatment, they were categorized as continuers, combiners, switchers, discontinuers. A total of 77 patients were included in the study, among them 51(66.2%) were males and 26 (33.8%) were females. Among these, 67 (87.1%) showed 100% adherence to medication schedule. Around 10 (12.99%) patients missed their antihypertensive medication for more than a day (2-24 days, mean 9.89±7.24 days). Amlodipine was the most common antihypertensive used, followed by atenolol and then losartan. There were no significant differences among the types of antihypertensives used among males and females as well as among diabetics and nondiabetics. Around 14 (18.2%) patients needed an add-on antihypertensive after 4-11 months. Most commonly used add on drug was atenolol. The target blood pressure goal (<140/90mmHg) was reached in 70 (90.9%) patients at the end of 1 year.

Keywords: Adherence, hypertension, persistence


How to cite this article:
Chowta MN, Belagali Y, Rai S, Chowta N, Swamy M, Shenoy AK. Patterns of Persistence with Antihypertensive Medications Among Newly Diagnosed Hypertensive Patients. Int J Nutr Pharmacol Neurol Dis 2019;9:80-5

How to cite this URL:
Chowta MN, Belagali Y, Rai S, Chowta N, Swamy M, Shenoy AK. Patterns of Persistence with Antihypertensive Medications Among Newly Diagnosed Hypertensive Patients. Int J Nutr Pharmacol Neurol Dis [serial online] 2019 [cited 2019 Aug 23];9:80-5. Available from: http://www.ijnpnd.com/text.asp?2019/9/2/80/261491




   Introduction Top


Pharmacotherapy of hypertension with effective drugs has shown to reduce the complications associated with uncontrolled hypertension.[1] However, majority of hypertensive patients do not attain target blood pressure goals even with the appropriate prescription of antihypertensive drugs. As per the findings of World Health Organization, an important reason for this is poor adherence to treatment regimens.[2] As in case of any other disease, persistence and adherence to treatment are essential to reach the treatment objectives of hypertension. The treatment recommendations for hypertension are mainly based on the efficacy, safety and cost. As hypertension requires long-term use of medications, compliance is one of the important issues which can affect the treatment outcome. Most patients tend to discontinue treatment even after the proper explanation by the treating physician about the consequences of inadequately controlled blood pressure. Hence, it is important to consider possible compliance of the selected regimens while deciding the treatment guidelines.

It is a well-known fact that adherence to treatment is different in routine practice as compared to a randomized clinical trial. Because of strict monitoring and better attention to patients in the randomized clinical trials, the reported medication adherence and persistence in these trials are much superior to what may be seen in the routine clinical practice.

Methods used to measure adherence include collecting information on pharmacy database about the drug dispensing, refill compliance and persistence.[3] A validated questionnaire was also used to measure the adherence and persistence of medications. Studies have shown that around 50% to 70% of patients adhere to treatment. It has been seen that the initial choice of antihypertensive medication plays a major role in the adherence and persistence of drug therapy. Angiotensin-2-receptor blockers seem to be associated with good adherence, followed by angiotensin converting enzyme inhibitors.[4],[5],[6],[7] Diuretics are associated with poor treatment adherence and persistence.[8] Age, gender, low confidence in the physician, complicated dosage regimen, adverse drug effects, etc. are the factors that affect adherence to antihypertensive treatment. Many patients believe that hypertension is an intermittent condition, and the treatment will make them drug-dependent.[9],[10] Earlier studies have shown a varied level of persistence and adherence with antihypertensive drugs, and the differences that exist between individual drugs with respect to persistence to medications are not addressed in most cases. This study was undertaken to investigate the antihypertensive drug persistence in hypertensive patients in the routine clinical settings and also to identify the factors involved in poor adherence.


   Materials & Methods Top


This prospective, observational study was conducted at a tertiary care hospital attached to a medical college after the approval by the Institutional Ethics Committee. Patients were enrolled into the study after obtaining their written informed consent. All patients were above 20 years of age, were diagnosed with stage 1 hypertension, and had received the first prescription for hypertension.

Patient records were analyzed and all the details, including information on the diagnosis, demographic details, medications prescribed, and frequency of hospital visits were obtained. Patients were asked about the history of missing the doses of antihypertensive medications. Follow up with patients was done at the end of sixth and twelfth months of starting the antihypertensive treatment either by personal interview or by analysis of their records. During each follow up, the parameters assessed included:
  • Blood pressure (Systolic and Diastolic) in sitting position
  • Any changes in the prescription by the treating physician
  • The number of days patient missed the medication
  • Probable reasons for missing the dose
  • Total doses of anti-hypertensive medications received


Persistence with first-line single treatment was categorized as follows: [11]
  • Continuers: Continued the first-line antihypertensive drug for at least 1 year
  • Combiners: Received an additional antihypertensive medication while continuing the initial antihypertensive drug
  • Switchers: Switched over to another class of antihypertensive medication from the first-line and discontinued the initial medication.
  • Discontinuers: Stopped the first-line antihypertensive drug without having another medication till the end of the follow-up.



   Statistical analysis Top


For categorical variables, frequencies and percentages were calculated as appropriate. For continuous variables, descriptive statistics were employed. A paired ‘t’ test was used to compare data between baseline and the end of follow-up; unpaired student ‘t’ test was used to compare between two subgroups. Categorical data were compared using chi-square tests. All tests were performed using a two-tailed test at a significance level of 0.05.


   Results Top


A total of 77 patients were included in the study, among them 51(66.2%) were males and 26 (33.8%) were females. Their baseline parameters are shown in [Table 1]. The mean age of females was significantly higher compared to males (P=0.03).
Table 1 Demographic characteristics

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[Table 2] and [Figure 1] show the types of antihypertensives used. Amlodipine was the most common antihypertensive used followed by atenolol and then losartan. Among 77 patients, seven patients received a combination of two antihypertensives as the initial prescription. There were no significant differences among the types of antihypertensives used among males and females as well as among diabetics and non-diabetics.
Table 2 Comparison of antihypertensives used based on gender and diabetic status

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Figure 1 Antihypertensive used in study population

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Among 77 patients, 67 (87.1%) showed 100% adherence to prescribed medication ([Figure 2]). Around 10 (12.99%) patients missed their antihypertensive medication for more than a day (2–24 days, mean 9.89±7.24 days). Among these patients, five (6.5%) patients gave the reason for nonadherence as ‘forgotten to take’ and another four (5.2%) patients gave the reason as ‘forgotten to carry medication with them’ [[Table 3] and [Figure 2]]. One patient (1.3%) discontinued medication in between because of the adverse effect (edema). Almost all patients continued the treatment until the end of the follow-up period, except one nondiabetic female patient who was on amlodipine and was switched over to hydrochlorothiazide.
Figure 2 Pattern of persistence of initial antihypertensives used

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Table 3 Pattern of persistence of initial antihypertensives used

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Add-on drug was given 4–11 months after the initial prescription of antihypertensive medication (mean 7.2±2.4 months). Most commonly used add-on drug was atenolol.

[Table 4] shows the effect of antihypertensive drugs on blood pressure. There was a significant reduction in blood pressure at the end of the study compared to baseline as well as between visits. The target blood pressure goal (<140/90mmHg) was reached in 70 (90.9%) patients. When a comparison was made between males and females, the target blood pressure goal was reached in all female patients, whereas seven male patients (13.7%) did not achieve the target blood pressure goal. Similarly, when comparison was done between diabetics and non-diabetics, four (17.4%) non-diabetic patients and 3 (5.6%) diabetic patient did not achieve the target blood pressure goal. As monotherapy, the maximum reduction in both systolic and diastolic blood pressure was seen with losartan [Table 5].
Table 4 Effect of drugs on blood pressure

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Table 5 Comparative analysis of antihypertensives effect on blood pressure

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   Discussion Top


Even with the availability of several efficacious classes of antihypertensive drugs, majority of hypertensive patients remain uncontrolled. One of the reason for the same is poor adherence to medication. Thus, poor adherence to antihypertensive medication becomes a public health challenge and hinders in our goal of reaching blood pressure target. The duration of therapy is known to have a major influence on adherence; patients on long-term therapy are less likely to discontinue medication.[12] Poor adherence is more likely during the initial phase of treatment. If the patients have good adherence in the beginning of treatment, they are more likely to stay adherent for long-term. Thus, assessing adherence in the initial phase of treatment is crucial. Hence, we included only new patients who were initiated on antihypertensive therapy.

Persistence with antihypertensive therapy was found to be good in the present study. Except for one patient, all had continued the treatment until the end of the study. As reported by Caro et al. only 78% of patients had persistence with therapy at the end of one year and the persistence with treatment decreased in the first six months after the initiation of treatment and further decline was observed over the next four years.[13] A shorter duration of the follow-up period (1 year) may explain the higher rate of persistence in our study population. Similarly, Perreault et al. also reported that persistence with antihypertensive medication decreased to 75% in the first six months after the initiation of treatment and in the next three years it decreased to 55%.[14] Patients on antihypertensive other than diuretics were found to have higher persistence rate. It was also observed during the study that patients with diabetes or dyslipidaemia had better persistence rate. Our study showed 100% persistence in the diabetic population. Sung et al. showed that 39.2% of the patients had good adherence with continued medication adherence > or =80%.[15] The study has shown higher continued medication adherence (87.1%). Natarajan et al. reported that 77% patients had high adherence.[16] As reported by Lulebo et al., prevalence of non-adherence of antihypertensive therapy is 54.2%. [17] A Comparison of this study to the above mentioned studies may not be appropriate as the number of patients recruited in this study was small. Since this study was a prospective study, done for a period of one year among newly diagnosed cases at a tertiary care hospital, we could not recruit a large number of patients.

Lulebo et al. reported that blood pressure control was achieved in 15.6 % patients.[17] In contrast, in the present study, the blood pressure goal was reached in 90.9% of patients. The higher percentage of the desired outcome in this study could be due to the fact that patients had stage 1 hypertension. Lulebo et al. had found the following reasons for non-adherence: poor knowledge of complications associated with hypertension, unavailability of medications in the healthcare facilities, lack of patient education on hypertension in the healthcare set-ups, prior experience of adverse drug effects, blood pressure being uncontrolled with medication, and use of alternative/non-prescribed medications.[17] The reason given by our patients for missing medication is ‘forgot to take or forgot to carry’.The most frequently used antihypertensive in the present study was amlodipine (54.5%) followed by atenolol (14.5%) and losartan (13%). There was no gender/diabetic status based difference in the pattern of antihypertensive used. Among the three most commonly used antihypertensive as monotherapy, blood pressure lowering efficacy at the end of the study was highest with losartan (10.4/9.4mmHg) and least with amlodipine (8.43/6.91mmHg). Similar to our results, Chen et al. also found calcium channel blockers as the most commonly used antihypertensive as monotherapy. [18] In contrast to our findings, a study done by Shukrala et al. showed hydrochlorothiazide as the most frequently used drug (55%), followed by enalapril (22.3%), methyldopa (11.2%), atenolol (6.9%), and nifedipine (4.6%). [19]

The strength and limitations of the present study must be considered. This was a prospective study where the patients were followed up for one year. Most of the previous studies done to evaluate the persistence and adherence were record-based retrospective studies. Hence, they were invariably associated with the limitations of retrospective design. Sources of bias, as well as confounding factors, were lesser in prospective studies when compared to retrospective studies.

This study was done in a tertiary care setting. Hence, the findings may not reflect the trend in the initial antihypertensive choice in the general population, as the majority of the patients treated by general practitioners are outside the tertiary care centers. The number of patients included was also very small.


   Conclusion Top


The majority of patients were on monotherapy. Amlodipine was the most commonly used antihypertensive as the initial choice. Adherence to antihypertensive therapy was good in a tertiary care setting. Around 18% of patients needed the addition of a second drug.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Gueyffier F, Boutitie F, Boissel JP, Pocock S, Coope J, Cutler J et al. Effect of antihypertensive drug treatment on cardiovascular outcomes in women and men.A meta-analysis of individual patient data from randomized, controlled trials. The INDANA Investigators. Ann Intern Med 1997;126(10):761-7.  Back to cited text no. 1
    
2.
Sabate E. (editor). Adherence to long-term therapies: evidence for action. Geneva, Switzerland: World Health Organization; 2003. (available at http://www.who.int/chronic_conditions/adherencereport/en/)  Back to cited text no. 2
    
3.
Halpern MT, Khan ZM, Schmier JK, Burnier M, Caro JJ, Cramer J et al. Recommendations for evaluating compliance and persistence with hypertension therapy using retrospective data. Hypertension 2006;47(6):1039-48.  Back to cited text no. 3
    
4.
Marentette MA, Gerth WC, Billings DK, Zarnke KB. Antihypertensive persistence and drug class. Can J Cardiol 2002;18(6):649-56.  Back to cited text no. 4
    
5.
Bourgault C, Sénécal M, Brisson M, Marentette MA, Grégoire JP. Persistence and discontinuation patterns of antihypertensive therapy among newly treated patients: a population-based study. J Hum Hypertens. 2005;19(8):607-13.  Back to cited text no. 5
    
6.
Chou CC, Lee MS, Ke CH, Chuang MH. Factors influencing the switch in the use of antihypertensive medications. Int J Clin Pract 2005;59(1):85-91.  Back to cited text no. 6
    
7.
Erkens JA, Panneman MM, Klungel OH, van den Boom G, Prescott MF. Differences in antihypertensive drug persistence associated with drug class and gender: a PHARMO study. Pharmacoepidemiol Drug Saf 2005;14(11):795-803.  Back to cited text no. 7
    
8.
Hasford J, Mimran A, Simons WR. A population-based European cohort study of persistence in newly diagnosed hypertensive patients. J Hum Hypertens 2002;16(8):569-75.  Back to cited text no. 8
    
9.
Breekveldt-Postma NS, Herings RM. Persistence with antihypertensives related to formulation: the case of nifedipine. Ann Pharmacother 2005;39(2):237–42.  Back to cited text no. 9
    
10.
Ross S, Walker A, Macleod MJ. Patient compliance in hypertension: role of illness perceptions and treatment beliefs. J Hum Hypertens 2004;18(9):607-13.  Back to cited text no. 10
    
11.
Mazzaglia G, Mantovani LG, Sturkenboom MC, Filippi A, Trifirò G, Cricelli C et al. Patterns of persistence with antihypertensive medications in newly diagnosed hypertensive patients in Italy: a retrospective cohort study in primary care. J Hypertens 2005;23(11):2093-2100.  Back to cited text no. 11
    
12.
Fitz-Simon N, Bennett K, Feely J. A review of studies of adherence with antihypertensive drugs using prescription databases. Ther Clin Risk Manag 2005;1(2):93-106.  Back to cited text no. 12
    
13.
Caro JJ, Salas M, Speckman JL, Raggio G, Jackson JD. Persistence with treatment for hypertension in actual practice. CMAJ 1999;160(1):31-7.  Back to cited text no. 13
    
14.
Perreault S, Lamarre D, Blais L, Dragomir A, Berbiche D, Lalonde L et al. Persistence with treatment in newly treated middle-aged patients with essential hypertension. Ann Pharmacother 2005; 39(9):1401-8.  Back to cited text no. 14
    
15.
Sung SK, Lee SG, Lee KS, Kim DS, Kim KH, Kim KY. First-year treatment adherence among outpatients initiating antihypertensive medication in Korea: results of a retrospective claims review. Clin Ther 2009;31(6):1309-20.  Back to cited text no. 15
    
16.
Natarajan N, Putnam W, Van Aarsen K, Beverley Lawson K, Burge F. Adherence to antihypertensive medications among family practice patients with diabetes mellitus and hypertension. Can Fam Physician 2013;59(2):e93-e100.  Back to cited text no. 16
    
17.
Lulebo AM, Mutombo PB, Mapatano MA, Mafuta EM, Kayembe PK, Ntumba LT et al. Predictors of non-adherence to antihypertensive medication in Kinshasa,Democratic Republic of Congo: a cross-sectional study. BMC Res Notes 2015; 8: 526.  Back to cited text no. 17
    
18.
Cheng H. Prescribing pattern of antihypertensive drugs in a general hospital in central China.Int J Clin Pharm 2011;33(2):215-20.  Back to cited text no. 18
    
19.
Shukrala F, Gabriel T. Assessment of prescribing, dispensing, and patient use pattern of antihypertensive drugs for patients attending outpatient department of Hiwot Fana Specialized University Hospital, Harar, Eastern Ethiopia. Drug Des Devel Ther 2015;9:519-23.  Back to cited text no. 19
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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