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Adherence to Drugs That Prevent Cardiovascular Disease: Meta-analysis on 376,162 Patients

  • Sayed H. Naderi
    Affiliations
    Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine, Queen Mary University of London, Charterhouse Square, London
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  • Jonathan P. Bestwick
    Affiliations
    Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine, Queen Mary University of London, Charterhouse Square, London
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  • David S. Wald
    Correspondence
    Requests for reprints should be addressed to David S. Wald, FRCP, Queen Mary University of London, Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine, Charterhouse Square, London EC1M 6BQ, UK
    Affiliations
    Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine, Queen Mary University of London, Charterhouse Square, London
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      Abstract

      Objective

      Combination therapy, specifically with aspirin, cholesterol and blood pressure-lowering drugs, substantially reduces the risk of coronary heart disease, but the full preventive effect is only realized if treatment continues indefinitely. Our objective was to provide a summary estimate of adherence to drugs that prevent coronary heart disease, according to drug class and use in people who have had a myocardial infarction (secondary prevention) and people who have not (primary prevention).

      Methods

      A meta-analysis of data on 376,162 patients from 20 studies assessing adherence using prescription refill frequency for the following 7 drug classes was performed: aspirin, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, calcium-channel blockers, thiazides, and statins. Meta-regression was used to examine the effects of age, payment, and treatment duration.

      Results

      The summary estimate for adherence across all studies was 57% (95% confidence interval [CI], 50-64) after a median of 24 months. There were statistically significant differences in adherence between primary and secondary prevention: 50% (CI, 45-56) and 66% (CI, 56-75), respectively (P=.012). Adherence was lower for thiazides (42%) than for angiotensin receptor blockers (61%) in primary prevention (P=.02). There were no other statistically significant differences between any of the drug classes in primary or secondary prevention studies. Adherence decreased by 0.15% points/month (P=.07) and was unrelated to age or whether patients paid for their pills.

      Conclusion

      Adherence to preventive treatment is poor and little related to class of drug, suggesting that side effects are not the main cause. General, rather than class-specific, measures at improving adherence are needed.

      Keywords

      SEE RELATED EDITORIAL AND RELATED ARTICLE pp. 841 and 888
      Coronary heart disease is the leading cause of death in both developed and developing countries, accounting for approximately one third of all deaths worldwide.
      World Health Organization
      The top 10 causes of death.
      Combination therapy specifically with aspirin, blood pressure, and serum cholesterol-lowering drugs is effective in prevention, reducing risk by an estimated 80%, with complete adherence to treatment.
      • Wald N.J.
      • Law M.R.
      A strategy to reduce cardiovascular disease by more than 80%.
      • Law M.R.
      • Wald N.J.
      • Morris J.K.
      • Jordan R.E.
      Value of low dose combination treatment with blood pressure lowering drugs: analysis of 354 randomised trials.
      • Law M.R.
      • Wald N.J.
      • Rudnicka A.R.
      Quantifying effect of statins on low density lipoprotein cholesterol, ischaemic heart disease and stroke: systematic review and meta-analysis.
      • Approximately one third of patients with a history of myocardial infarction and approximately one half without do not adhere to effective cardiovascular preventive treatment.
      • Nonadherence is not greatly influenced by the class of drug prescribed (aspirin, blood pressure-lowering drugs, or stat-ins), suggesting that side effects are not the main cause.
      There is evidence that patients stop taking treatment that is intended to be taken lifelong or take it less than prescribed (nonadherence), reducing the potential preventive effect.
      Medicines Adherence: Involving Patients in Decisions About Prescribed Medicines and Supporting Adherence.
      The most widely reported method for studying adherence uses electronic pharmacy data to assess the extent to which patients refill prescriptions over a specified time period.
      • Steiner J.F.
      • Prochazka A.V.
      The assessment of refill compliance using pharmacy records: methods, validity and applications.
      Patients possessing medication more than approximately 75% of the time are judged to be adherent.
      • Kramer J.M.
      • Hammill B.
      • Anstrom K.J.
      • et al.
      National evaluation of adherence to beta-blocker therapy for 1 year after acute myocardial infarction in patients with commercial health insurance.
      Provided that patients obtain their medication from a closed pharmacy system (eg, Health Maintenance Organization), the method provides a reasonably objective measure of adherence that can be simply applied in large studies.
      Studies reporting adherence using pharmacy refill data have yielded conflicting results, with estimates ranging from 30% to 80%.
      • Benner J.S.
      • Glynn R.J.
      • Mogun H.
      • Neumann P.J.
      • Weinstein M.C.
      • Avorn J.
      Long-term persistence in use of statin therapy in elderly patients.
      • Rasmussen J.N.
      • Chong A.
      • Alter D.A.
      Relationship between adherence to evidence based pharmacotherapy and long-term mortality after acute myocardial infarction.
      There is uncertainty over the true prevalence. Differences in the tolerability of specific classes of drug, the motivation of the population studied (eg, patients with or without a history of myocardial infarction), and whether patients pay for their medication are possible explanations for the different estimates. There has been no quantitative summary of the prevalence of adherence across studies.
      This prompted us to carry out a meta-analysis to quantify the prevalence of adherence to cardiovascular preventive medications according to the class of drug, patient group, and method of payment.

      Materials and Methods

      We searched medical databases (PubMed) for studies that assessed the extent to which individuals remained on coronary heart disease preventive drug therapy over time. The search terms used were [adherence, persistence, compliance, or concordance] and [drug treatment, aspirin, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, calcium channel blockers, thiazide diuretics, or statin].
      We included studies of patients with and without a diagnosis of coronary heart disease receiving drugs for the prevention of a coronary heart disease event from the above 7 classes. Studies were included that measured adherence using pharmacy prescription refill data and reported the number of patients who had at least 75% of days covered by a specified drug over a defined time period. We also sought information on the method of payment for medication: self-payment (medication cost borne completely by patient), state payment (cost borne completely by the health care provider), or copayment (cost borne jointly by patient and healthcare provider). If this was not reported in the published articles, the authors were contacted, and in cases where there was no response, the method of payment generally adopted in the countries concerned was applied.
      The primary search generated 2433 citations, which were reduced to 80 on inspection of the titles and review of the abstracts and finally to 17 on review of the published reports. An additional 3 articles were identified through hand-searching the citation lists of relevant studies and review articles, yielding 20 studies for inclusion in the analysis.
      • Kramer J.M.
      • Hammill B.
      • Anstrom K.J.
      • et al.
      National evaluation of adherence to beta-blocker therapy for 1 year after acute myocardial infarction in patients with commercial health insurance.
      • Benner J.S.
      • Glynn R.J.
      • Mogun H.
      • Neumann P.J.
      • Weinstein M.C.
      • Avorn J.
      Long-term persistence in use of statin therapy in elderly patients.
      • Rasmussen J.N.
      • Chong A.
      • Alter D.A.
      Relationship between adherence to evidence based pharmacotherapy and long-term mortality after acute myocardial infarction.
      • Degli Esposti L.
      • Valpiani G.
      • Saragoni S.
      • Capone A.
      A retrospective, population based analysis on persistence with antihypertensive drug therapy in primary care practice in Italy.
      • Van Wijk B.L.G.
      • Klungel O.H.
      • Heerdink E.R.
      • de Boer A.
      Rate and determinants of 10 year persistence with antihypertensive drugs.
      • Simons L.A.
      • Ortiz M.
      • Calcino G.
      Persistence with antihypertensive medication: Australia wide experience, 2004-2006.
      • Marentette M.A.
      • Gerth W.C.
      • Billings D.K.
      • Zarnke K.B.
      Antihypertensive persistence and drug class.
      • Breekveldt-Postma N.S.
      • Penning-van Beest F.J.A.
      • Siiskoven S.J.
      • et al.
      The effect of discontinuation of antihypertensives on the risk of acute myocardial infarction and stroke.
      • Perreault S.
      • Lamarre D.
      • Blais L.
      • et al.
      Persistence with treatment in newly treated middle-aged patients with essential hypertension.
      • Bloom B.S.
      Continuation of initial antihypertensive medication after 1 year of therapy.
      • Elliott W.J.
      • Plauschinat C.A.
      • Skrepnek G.H.
      • Gause D.
      Persistence, adherence, and risk of discontinuation associated with commonly prescribed antihypertensive drug monotherapies.
      • Avorn J.
      • Monette J.
      • Lacour A.
      • et al.
      Persistence of use of lipid lowering medications: a cross national study.
      • Grant R.W.
      • O'Leary K.M.
      • Weilburg J.B.
      • Singer D.E.
      • Meigs J.B.
      Impact of concurrent medication use on statin adherence and refill persistence.
      • Wei L.
      • Flynn R.
      • Murray G.D.
      • MacDonal T.M.
      Use and adherence to beta-blockers for secondary prevention of myocardial infarction: who is not getting the treatment?.
      • Kopjar B.
      • Sales A.E.B.
      • Pineros S.
      • Sun H.
      • Li Y.F.
      • Hedeen A.N.
      Adherence with statin therapy in secondary prevention of coronary heart disease in veterans administration male population.
      • Simpson E.
      • Beck C.
      • Richard H.
      Drug prescriptions after acute myocardial infarction: dosage, compliance and persistence.
      • Roughead E.E.
      • Vitry A.I.
      • Preiss A.K.
      • et al.
      Assessing overall duration of cardiovascular medicines in veterans with established cardiovascular disease.
      • Blackburn D.F.
      • Dobson R.T.
      • Blackburn J.L.
      • et al.
      Adherence to statins, beta blockers and angiotensin converting enzyme inhibitors following a first cardiovascular event: a retrospective cohort study.
      • Gislason G.H.
      • Rasmussen J.N.
      • Abildstrom S.Z.
      • et al.
      Long-term compliance with beta-blockers, angiotensin-converting enzyme inhibitors and statins after acute myocardial infarction.
      • Ho P.M.
      • Magid D.J.
      • Shetterly S.M.
      • et al.
      Medication nonadherence is associated with a broad range of adverse outcomes in patients with coronary artery disease.
      Data were abstracted independently by 2 investigators, and the datasets were cross-checked.
      For each study, an average estimate of adherence was calculated from the average reported adherence to each drug class weighted by the number of patients taking each drug. A random effects meta-analysis
      • DerSimonian R.
      • Laird N.
      Meta-analysis in clinical trials.
      was used to combine data from each study to give a summary estimate of adherence across all studies. Stratified analyses were performed to determine adherence in primary and secondary prevention and for each drug class (aspirin, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blocker, calcium-channel blockers, thiazides, and statins), and according to method of payment.
      Meta-regression was used to examine possible sources of heterogeneity, including age, gender, method of payment, and duration of treatment. All analyses were performed using Stata version 10 (StataCorp LP, College Station, Tex).
      StataCorp
      Stata Statistical Software: Release 10.

      Results

      Table 1 shows details of the studies in the meta-analysis, which included data on 376,162 patients (mean age 64 years, 49% were male). Eleven studies were on patients without a history of coronary heart disease (eg, patients being treated for hypertension) who were receiving drugs for the primary prevention of coronary heart disease, and 9 studies were on patients with a diagnosis of coronary heart disease (eg, after a myocardial infarction) who were receiving drugs for the secondary prevention of recurrent events. Table E1 (available online) shows the prevalence of adherence, according to each drug class in each study.
      Table 1Details of Studies Included in the Meta-Analysis
      First Author, YearPatient Group StudiedLocationMethod of PaymentNo. of SubjectsMean Age (y)Male (%)Follow-up (mo)
      Primary Prevention
       Benner, 2002
      • Benner J.S.
      • Glynn R.J.
      • Mogun H.
      • Neumann P.J.
      • Weinstein M.C.
      • Avorn J.
      Long-term persistence in use of statin therapy in elderly patients.
      High cholesterolUSACopayment2317420120
       Degli Esposti, 2002
      • Degli Esposti L.
      • Valpiani G.
      • Saragoni S.
      • Capone A.
      A retrospective, population based analysis on persistence with antihypertensive drug therapy in primary care practice in Italy.
      HypertensionItalyCopayment16,783564412
       Van Wijk, 2005
      • Van Wijk B.L.G.
      • Klungel O.H.
      • Heerdink E.R.
      • de Boer A.
      Rate and determinants of 10 year persistence with antihypertensive drugs.
      HypertensionNetherlandsCopayment22146036120
       Simons, 2008
      • Simons L.A.
      • Ortiz M.
      • Calcino G.
      Persistence with antihypertensive medication: Australia wide experience, 2004-2006.
      HypertensionAustraliaCopayment48,690684433
       Marentette, 2002
      • Marentette M.A.
      • Gerth W.C.
      • Billings D.K.
      • Zarnke K.B.
      Antihypertensive persistence and drug class.
      HypertensionCanadaCopayment16,413614418
       Breekveldt-Postma, 2008
      • Breekveldt-Postma N.S.
      • Penning-van Beest F.J.A.
      • Siiskoven S.J.
      • et al.
      The effect of discontinuation of antihypertensives on the risk of acute myocardial infarction and stroke.
      HypertensionNetherlandsCopayment81,735554024
       Perreault, 2005
      • Perreault S.
      • Lamarre D.
      • Blais L.
      • et al.
      Persistence with treatment in newly treated middle-aged patients with essential hypertension.
      HypertensionCanadaCopayment19,704583836
       Bloom, 1998
      • Bloom B.S.
      Continuation of initial antihypertensive medication after 1 year of therapy.
      HypertensionUSACopayment21,723564412
       Elliott, 2007
      • Elliott W.J.
      • Plauschinat C.A.
      • Skrepnek G.H.
      • Gause D.
      Persistence, adherence, and risk of discontinuation associated with commonly prescribed antihypertensive drug monotherapies.
      HypertensionUSACopayment60,685584812
       Avorn, 1998
      • Avorn J.
      • Monette J.
      • Lacour A.
      • et al.
      Persistence of use of lipid lowering medications: a cross national study.
      High cholesterolCanada/USACopayment2650751812
       Grant, 2004
      • Grant R.W.
      • O'Leary K.M.
      • Weilburg J.B.
      • Singer D.E.
      • Meigs J.B.
      Impact of concurrent medication use on statin adherence and refill persistence.
      High cholesterolUSACopayment4405536212
      Secondary Prevention
       Kramer, 2006
      • Kramer J.M.
      • Hammill B.
      • Anstrom K.J.
      • et al.
      National evaluation of adherence to beta-blocker therapy for 1 year after acute myocardial infarction in patients with commercial health insurance.
      Myocardial infarctionUSAState payment17,035607112
       Blackburn, 2005
      • Blackburn D.F.
      • Dobson R.T.
      • Blackburn J.L.
      • et al.
      Adherence to statins, beta blockers and angiotensin converting enzyme inhibitors following a first cardiovascular event: a retrospective cohort study.
      Myocardial infarction, angina, PCI, CABGCanadaSelf-payment400587760
       Wei, 2004
      • Wei L.
      • Flynn R.
      • Murray G.D.
      • MacDonal T.M.
      Use and adherence to beta-blockers for secondary prevention of myocardial infarction: who is not getting the treatment?.
      Myocardial infarctionScotlandCopayment386665912
       Gislason, 2006
      • Gislason G.H.
      • Rasmussen J.N.
      • Abildstrom S.Z.
      • et al.
      Long-term compliance with beta-blockers, angiotensin-converting enzyme inhibitors and statins after acute myocardial infarction.
      Myocardial infarctionDenmarkCopayment2976686360
       Kopjar, 2003
      • Kopjar B.
      • Sales A.E.B.
      • Pineros S.
      • Sun H.
      • Li Y.F.
      • Hedeen A.N.
      Adherence with statin therapy in secondary prevention of coronary heart disease in veterans administration male population.
      Myocardial infarction, anginaUSACopayment87686510018
       Simpson, 2003
      • Simpson E.
      • Beck C.
      • Richard H.
      Drug prescriptions after acute myocardial infarction: dosage, compliance and persistence.
      Myocardial infarctionCanadaCopayment14,507745712
       Roughead, 2010
      • Roughead E.E.
      • Vitry A.I.
      • Preiss A.K.
      • et al.
      Assessing overall duration of cardiovascular medicines in veterans with established cardiovascular disease.
      Myocardial infarction, angina or IHDAustraliaCopayment9635787461
       Ho, 2008
      • Ho P.M.
      • Magid D.J.
      • Shetterly S.M.
      • et al.
      Medication nonadherence is associated with a broad range of adverse outcomes in patients with coronary artery disease.
      Myocardial infarction, PCI, CABGUSACopayment15,767667048
       Rasmussen, 2007
      • Rasmussen J.N.
      • Chong A.
      • Alter D.A.
      Relationship between adherence to evidence based pharmacotherapy and long-term mortality after acute myocardial infarction.
      Myocardial infarctionCanadaState payment31,455765512
      PCI=percutaneous coronary intervention; CABG=coronary artery bypass grafting.
      Figure 1 shows a meta-analysis plot of adherence to all classes of drug in each study, stratified according to their use in primary or secondary prevention and ranked in order of increasing effect. The results yield an overall summary adherence of 57% (95% confidence interval [CI], 50-64) over a median treatment period of 24 months. The results were 50% (CI, 45-56) and 66% (CI, 56-75) for primary and secondary prevention studies, respectively (P=.012 for the difference). There was considerable heterogeneity between studies (P<.001).
      Figure thumbnail gr1
      Figure 1Percent adherence to all classes of drug in each study, stratified according to their use in primary or secondary prevention. CI=confidence interval.
      Figure 2 shows adherence on a class-specific basis, separately for primary and secondary prevention studies. In primary prevention, there was a statistically significant lower adherence for thiazides compared with angiotensin receptor blockers (P=.02). There were no statistically significant differences between any of the other drug classes in primary or secondary prevention. Meta-regression analysis showed a 0.15 percentage point decrease in adherence per month of follow-up (P=.07). There was no effect on adherence of gender, age, or method of payment.
      Figure thumbnail gr2
      Figure 2Percent adherence according to drug class and use in primary and secondary prevention. CI=confidence interval; ACE=angiotensin-converting enzyme; ARB=angiotensin receptor blocker; CCB=calcium channel blocker.

      Discussion

      The results of this analysis show that approximately two thirds of patients with a history of coronary heart disease adhere to drugs prescribed to prevent a second coronary heart disease event and approximately half of those without coronary heart disease adhere to drugs prescribed to prevent a first event.
      Previous reviews on adherence to cardiovascular preventive treatments were descriptive and did not combine results within or across studies to provide a quantitative summary of effect.
      • Ho P.M.
      • Bryson C.L.
      • Rumsfeld J.S.
      Medication adherence its importance in cardiovascular outcomes.
      This is the first meta-analysis to do this and shows that after allowing for the 15 percentage point difference in adherence between primary and secondary prevention, there were small differences in adherence between different classes of drug. This suggests that specific drug properties (eg, side effects and frequency of dosing) have a minor influence on whether patients remain on treatment long-term. General factors, such as the frequency and intensity of clinical review by the prescriber,
      • Blackburn D.F.
      • Dobson R.T.
      • Blackburn J.L.
      • et al.
      Adherence to statins, beta blockers and angiotensin converting enzyme inhibitors following a first cardiovascular event: a retrospective cohort study.
      whether prescriptions are initiated in primary or secondary care,
      • Gislason G.H.
      • Rasmussen J.N.
      • Abildstrom S.Z.
      • et al.
      Long-term compliance with beta-blockers, angiotensin-converting enzyme inhibitors and statins after acute myocardial infarction.
      and the level of patient education,
      • Benner J.S.
      • Glynn R.J.
      • Mogun H.
      • Neumann P.J.
      • Weinstein M.C.
      • Avorn J.
      Long-term persistence in use of statin therapy in elderly patients.
      • Ho P.M.
      • Magid D.J.
      • Shetterly S.M.
      • et al.
      Medication nonadherence is associated with a broad range of adverse outcomes in patients with coronary artery disease.
      may be more important determinants of adherence. Heterogeneity between studies was observed and is expected because of such variations in practice, but there was insufficient information on these factors in the study reports for a quantitative assessment across studies.
      We restricted our analysis to studies that measured adherence by prescription refills because this is the most widely used method in the literature and can be simply applied to large populations using a closed pharmacy system. However, the method has certain limitations.
      • Steiner J.F.
      • Prochazka A.V.
      The assessment of refill compliance using pharmacy records: methods, validity and applications.
      • Hamilton R.A.
      • Briceland L.L.
      Use of prescription-refill records to assess patient compliance.
      • Tamblyn R.
      • Lavoie G.
      • Petrella L.
      • et al.
      The use of prescription claims databases in pharmacoepidemiological research: the accuracy and comprehensiveness of the prescription claims databases in Quebec.
      It relies on patients obtaining their medications from a single provider (eg, a single health insurance plan), which may not always be the case. Also, evidence that a prescription has been refilled is not evidence that it has been taken, so estimates are likely to be overestimates.
      Other methods for assessing adherence to medication include electronic medication monitors, pill counts, and measurements of physiologic markers (eg, blood pressure).
      • Osterberg L.
      • Blaschke T.
      Adherence to medication.
      The use of different methods in different studies limits the extent to which results from different studies can be combined. The simplest method is to ask patients whether they are still taking their medication, although this approach is open to bias and possible overestimation. Our PubMed search, for example, identified 7 studies that assessed adherence in this way (all in patients who had experienced a myocardial infarction), including 49,791 patients over a median follow-up of 14 months.
      • Gehi A.K.
      • Ali S.
      • Na B.
      • Whooley M.A.
      Self-reported medication adherence and cardiovascular events in patients with stable coronary heart disease The Heart and Soul Study.
      • Wald D.S.
      • Morton G.
      • Walker K.
      • et al.
      Long-term continuation on cardiovascular drug treatment in patients with coronary heart disease.
      • Melloni C.
      • Alexander K.P.
      • Ou F.
      • et al.
      Predictors of early discontinuation of evidence based medicine after acute coronary syndrome.
      • Eagle K.A.
      • Kline-Rogers E.
      • Goodman S.G.
      • et al.
      Adherence to evidence-based therapies after discharge for acute coronary syndromes: an ongoing prospective, observational study.
      • Sud A.
      • Kline-Rogers E.M.
      • Eagle K.A.
      • et al.
      Adherence to medications by patients after acute coronary syndromes.
      • Newby L.K.
      • La Poiante N.M.A.
      • Chen A.Y.
      • et al.
      Long-term adherence to evidence based secondary prevention therapies in coronary artery disease.
      • Amar J.
      • Ferrieres J.
      • Cambou J.P.
      • et al.
      Persistence of combination of evidence based medical therapy in patients with acute coronary syndromes.
      The summary estimate for adherence in these studies was 90% (95% CI, 87-92). Perhaps the most reliable method for assessing adherence is direct analysis of the drug or drug metabolite. If such tests could be made simple and affordable, they would provide a useful standard method for assessing adherence in both clinical studies and practice.
      There are approximately 400,000 deaths from coronary heart disease in the United States each year.
      • Roger V.L.
      • Go A.S.
      • LIoyd-Jones D.M.
      • et al.
      Heart disease and stroke statistics—2011 update: a report from the American Heart Association.
      Combination therapy reduces the risk of a first or second event by approximately 80%,
      • Wald N.J.
      • Law M.R.
      A strategy to reduce cardiovascular disease by more than 80%.
      • Law M.R.
      • Wald N.J.
      • Morris J.K.
      • Jordan R.E.
      Value of low dose combination treatment with blood pressure lowering drugs: analysis of 354 randomised trials.
      • Law M.R.
      • Wald N.J.
      • Rudnicka A.R.
      Quantifying effect of statins on low density lipoprotein cholesterol, ischaemic heart disease and stroke: systematic review and meta-analysis.
      so with broad coverage of the population at risk (all patients who have a history of cardiovascular disease and all others aged>50 years) and full adherence to treatment, approximately 320,000 deaths could be avoided each year. Applying the overall adherence rates from our study (and assuming an equal proportion of deaths are first and second events) indicates that nonadherence leads to approximately 130,000 (41% of 320,000) avoidable deaths each year in the United States. These estimates are intended to give an approximate indication of the consequences of nonadherence on coronary heart disease death and do not take into account the number of stroke deaths each year (∼130,000) or nonfatal cardiovascular disease events. Even if these estimates were half as great, the cost of nonadherence is substantial.
      Few interventions to improve adherence to cardiovascular drugs have been successfully implemented, and those that have shown a benefit have tended to be complex, costly, and difficult to sustain.
      • Haynes R.B.
      • McDonald H.
      • Garg A.X.
      • Montague P.
      Interventions for helping patients follow prescriptions for medications.
      • Piette J.D.
      Interactive voice response systems in the diagnosis and management of chronic disease.
      • Murray M.D.
      • Young J.
      • Hoke S.
      • et al.
      Pharmacist intervention to improve medication adherence in heart failure: a randomised trial.
      There is a need for a simple and effective method that can be combined with each new prescription. Text messaging has been used successfully to improve the use of sunscreen and other treatments.
      • Armstrong A.W.
      • Watson A.J.
      • Makredes M.
      • et al.
      Text-message reminders to improve sunscreen use: a randomized, controlled study using electronic monitoring.

      Free C, Knight R, Robertson S, et al. Smoking cessation support delivered via mobile phone text messaging (txt2stop): a single blind, randomised trial. Lancet. 378;9785:49-55.

      In a randomized trial of 80 patients, a single text message sent weekly doubled the rate of sunscreen use among those receiving text messages compared with controls.
      • Armstrong A.W.
      • Watson A.J.
      • Makredes M.
      • et al.
      Text-message reminders to improve sunscreen use: a randomized, controlled study using electronic monitoring.
      Mobile phones are widely used, and text messaging may be a useful way of encouraging adherence.

      Conclusions

      Our results show that approximately one third of patients who have had a myocardial infarction and approximately one half of those who have not had a myocardial infarction do not adhere to effective cardiovascular preventive treatment long-term. Adherence is not greatly dependent on the class of drug prescribed, suggesting that interventions to improve adherence need to be broadly applied.

      Supplementary data

      Table E1Number of Subjects Assessed (n) and Percent Adherence (%) According to Specified Drug Class in Each Study
      First AuthorAspirinAngiotensin-Converting Enzyme InhibitorsAngiotensin Receptor BlockersBeta-blockersCalcium Channel BlockersThiazidesStatins
      n (%)n (%)n (%)n (%)n (%)n (%)n (%)
      Primary Prevention
       Benner
      • Benner J.S.
      • Glynn R.J.
      • Mogun H.
      • Neumann P.J.
      • Weinstein M.C.
      • Avorn J.
      Long-term persistence in use of statin therapy in elderly patients.
      231 (32)
       Degli Esposti
      • Degli Esposti L.
      • Valpiani G.
      • Saragoni S.
      • Capone A.
      A retrospective, population based analysis on persistence with antihypertensive drug therapy in primary care practice in Italy.
      4986 (40)317 (58)2459 (38)4680 (31)4341 (30)
       Van Wijk
      • Van Wijk B.L.G.
      • Klungel O.H.
      • Heerdink E.R.
      • de Boer A.
      Rate and determinants of 10 year persistence with antihypertensive drugs.
      342 (62)1152 (32)180 (53)540 (38)
       Simons
      • Simons L.A.
      • Ortiz M.
      • Calcino G.
      Persistence with antihypertensive medication: Australia wide experience, 2004-2006.
      27,266 (45)16,068 (47)9251 (31)
       Marentette
      • Marentette M.A.
      • Gerth W.C.
      • Billings D.K.
      • Zarnke K.B.
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