Adherence to statin or aspirin or both in patients with established cardiovascular disease: exploring healthy behaviour vs. drug effects and 10-year follow-up of outcome

Adherence with cardiovascular medications and the outcomes in patients with coronary arterial disease: "Real-world" evidence

BACKGROUND

Cardiovascular medications are vital for the secondary prevention of coronary arterial disease (CAD). However, the effect of cardiovascular medication may depend on the optimal adherence of the patients. This meta-analysis aims to determine the magnitude of adherence to vascular medications that influences the absolute and relative risks (RRs) of mortality in patients with CAD in real-world settings.

METHODS

The Cochrane Library, PubMed, and EMBASE databases were searched through March 1, 2022. Prospective studies reporting association as RR and 95% confidence interval between cardiovascular medication adherence and any cardiovascular events and/or all-cause mortality in patients with CAD were included. A one-stage robust error meta-regression method was used to summarize the dose-specific relationships.

RESULTS

A total of 18 studies were included. There is a significant inverse linear association between cardiovascular medication adherence and cardiovascular events (p_nonlinearity  = .68) or mortality (p_nonlinearity  = .82). The exposure-effect analysis showed that an improvement of 20% cardiovascular medication adherence was associated with 8% or 12% lower risk of any cardiovascular events or mortality, respectively. In subgroup analysis, the benefit was observed in adherence of stain (RR: 0.90, for cardiovascular events, RR: 0.85, for mortality), angiotensin-converting enzyme inhibitors (ACEI)/angiotensin II receptor blockers (ARB)(RR: 0.90, for mortality), and antiplatelet agent (RR: 0.89 for mortality) but not in beta-blocker (RR: 0.90, p = .14, for cardiovascular events, RR: 0.97, p = .32 for mortality). Estimated absolute differences per 1 million individuals per year for mortality associated with 20% improvement were 175 cases for statin, 129 cases for antiplatelet, and 117 cases for ACEI/ARB.

CONCLUSION

Evidence from the real word showed poor adherence to vascular medications contributes to a considerable proportion of all cardiovascular disease events and mortality in patients with CAD.

Long-Term Adherence and Persistence to Low-Dose Aspirin for the Prevention of Cardiovascular Disease: A Population-Based Cohort Study

METHODS

Using information from electronic health records in Germany and the United Kingdom (UK) in a common data model, we followed adults with ≥2 low-dose aspirin prescriptions (75-100 mg) during 2007-2018 for up to 10 years. Included individuals had no low-dose aspirin prescriptions in the year before the follow-up started (date of first low-dose aspirin prescription) and ≥12 months' observation. Adherence was determined using the medication possession ratio (MPR), and persistence was defined as continuous treatment disregarding gaps between prescriptions of <60 days; analyses were undertaken according to indication (primary/secondary CVD prevention).

RESULTS

We identified 144,717 low-dose aspirin users from Germany and 190,907 from the UK. Among patients with 5-10 years' follow-up, median adherence among secondary CVD prevention users was 60% in Germany and 75% in the UK. Among primary prevention users, median adherence was 50% for both countries. Persistence among secondary CVD prevention users was 58.3% at 2 years, 47.0% at 5 years, 35.2% at 10 years (Germany), and 67.5% at 2 years, 58.0% at 5 years, and 46.8% at 10 years (UK). Among primary CVD prevention users, persistence was 52.8% at 2 years, 41.6% at 5 years, 32.1% at 10 years (Germany), 56.3% at 2 years, 45.4% at 5 years, and 33.8% at 10 years (UK).

CONCLUSIONS

Long-term adherence and persistence to low-dose aspirin are suboptimal; efforts for improvement could translate into a lower CVD burden in the general population.

Statin adherence and health outcomes after st-elevation myocardial infarction: 1-year follow-up study

BACKGROUND AND OBJECTIVES

There is deficient control of dyslipidaemia after ST-elevation myocardial infarction (STEMI) despite high rates of statin prescription. The aim of this study was to estimate the rate of statin treatment adherence after a first type 1 STEMI episode, the factors that determine the adherence and its impact on cardiovascular outcomes during the first year of progression.

DESIGN

We conducted an observational retrospective study with a cohort of patients hospitalised between 2008 and 2013, with an active statin prescription during the first year of follow-up.

MATERIAL AND METHODS

We determined the adherence using the proportion of days covered. The relationship between compliance and the rest of the variables was determined with a binary logistic regression analysis. Competing risk analysis assessed the relationship between cardiovascular mortality or new vascular event with adherence.

RESULTS

The study included 552 patients (64.7 ± 13.7; 73.9% men) of the 613 analysed. There was less adherence among foreign nationals, smokers and individuals with hepatic impairment. Compliance was greater starting at 50 years of age, among pensioners and those with dyslipidaemia, obesity and kidney failure and in cases of compliance with the rest of the groups indicated in secondary prevention. Compliance reduced cardiovascular mortality (1.9% vs. 9.1%; HR 0.201; 95% CI 0.075-0.539; p = .001) but not the onset of a new cardiovascular event (5.5% vs. 6.5%; p = .834).

CONCLUSIONS

Statin adherence during the first year after a STEMI is a key factor in mortality, a period in which its assessment is needed beyond the prescription.

Statin adherence and health outcomes after st-elevation myocardial infarction: 1-year follow-up study

BACKGROUND AND OBJECTIVES

There is deficient control of dyslipidaemia after ST-elevation myocardial infarction (STEMI) despite high rates of statin prescription. The aim of this study was to estimate the rate of statin treatment adherence after a first type 1 STEMI episode, the factors that determine the adherence and its impact on cardiovascular outcomes during the first year of progression.

DESIGN

We conducted an observational retrospective study with a cohort of patients hospitalised between 2008 and 2013, with an active statin prescription during the first year of follow-up.

MATERIAL AND METHODS

We determined the adherence using the proportion of days covered. The relationship between compliance and the rest of the variables was determined with a binary logistic regression analysis. Competing risk analysis assessed the relationship between cardiovascular mortality or new vascular event with adherence.

RESULTS

The study included 552 patients (64.7 ± 13.7; 73.9% men) of the 613 analysed. There was less adherence among foreign nationals, smokers and individuals with hepatic impairment. Compliance was greater starting at 50 years of age, among pensioners and those with dyslipidaemia, obesity and kidney failure and in cases of compliance with the rest of the groups indicated in secondary prevention. Compliance reduced cardiovascular mortality (1.9% vs. 9.1%; HR 0.201; 95% CI 0.075-0.539; p = .001) but not the onset of a new cardiovascular event (5.5% vs. 6.5%; p = .834).

CONCLUSIONS

Statin adherence during the first year after a STEMI is a key factor in mortality, a period in which its assessment is needed beyond the prescription.

Effects of different statins application methods on plaques in patients with coronary atherosclerosis

BACKGROUND

Discontinued application of statins may be related to adverse cardiovascular events. However, it is unclear whether different statins administration methods have effects on coronary artery plaques.

AIM

To evaluate the effects of different statins application methods on plaques in patients with coronary atherosclerosis.

METHODS

A total of 100 patients diagnosed with atherosclerotic plaque by coronary artery computed tomography were continuously selected and divided into three groups according to different statins administration methods (discontinued application group, n = 32; intermittent application group, n = 39; sustained application group, n = 29). The effects of the different statins application methods on coronary atherosclerotic plaque were assessed.

RESULTS

The volume change and rate of change of the most severe plaques were significantly reduced in the sustained application group (P ≤ 0.001). The volume change of the most severe plaques correlated positively with low-density lipoprotein (LDL-C) levels only in the sustained application group (R = 0.362, P = 0.013). There were no changes in plaques or LDL-C levels in the intermittent and discontinued application groups.

CONCLUSION

Continuous application of statins is effective for controlling plaque progression, whereas discontinued or intermittent administration of statins is not conducive to controlling plaques. Only with continuous statins administration can a reduction in LDL-C levels result in plaque volume shrinkage.

Efficacy and safety of Shexiang Baoxin pill (MUSKARDIA) in patients with stable coronary artery disease: a multicenter, double-blind, placebo-controlled phase IV randomized clinical trial

BACKGROUND

The Shexiang Baoxin Pill (MUSKARDIA) has been used for treating coronary artery disease (CAD) and angina for more than 30 years in China. Nevertheless, methodologically sound trials on the use of MUSKARDIA in CAD patients are scarce. The aim of the study is to determine the effects of MUSKARDIA as an add-on to optimal medical therapy (OMT) in patients with stable CAD.

METHODS

A total of 2674 participants with stable CAD from 97 hospitals in China were randomized 1:1 to a MUSKARDIA or placebo group for 24 months. Both groups received OMT according to local tertiary hospital protocols. The primary outcome was the occurrence of a major adverse cardiovascular event (MACE), defined as a composite of cardiovascular death, non-fatal myocardial infarction (MI), or non-fatal stroke. Secondary outcomes included all-cause mortality, non-fatal MI, non-fatal stroke, hospitalization for unstable angina or heart failure, peripheral revascularization, angina stability and angina frequency.

RESULTS

In all, 99.7% of the patients were treated with aspirin and 93.0% with statin. After 2 years of treatment, the occurrence of MACEs was reduced by 26.9% in the MUSKARDIA group (MUSKARDIA: 1.9% vs. placebo: 2.6%; odds ratio = 0.80; 95% confidence interval: 0.45-1.07; P  = 0.2869). Angina frequency was significantly reduced in the MUSKARDIA group at 18 months (P = 0.0362). Other secondary endpoints were similar between the two groups. The rates of adverse events were also similar between the two groups (MUSKARDIA: 17.7% vs. placebo: 17.4%, P = 0.8785).

CONCLUSIONS

As an add-on to OMT, MUSKARDIA is safe and significantly reduces angina frequency in patients with stable CAD. Moreover, the use of MUSKARDIA is associated with a trend toward reduced MACEs in patients with stable CAD. The results suggest that MUSKARDIA can be used to manage patients with CAD.

TRIAL REGISTRATION

chictr.org.cn, No. ChiCTR-TRC-12003513.

Designing a Clinical Pharmacy Primary Care Intervention for Myocardial Infarction Patients Using a Patient and Public Involvement Discussion

Objective: to conduct a Patient and Public Involvement (PPI) focus group session. To help inform the design of a clinical pharmacy intervention in primary care for patients after a coronary event. Methods: this study followed a public involvement method. Community members of the public and community engaged research patients who had experienced myocardial infarction where invited to actively take part in a focus group discussion. This is to share past experiences and provide input and advice into the design of a potential research proposal. The session took place at a cardiac rehabilitation centre. Results: four key themes were identified from the focus group these included: experiences with pharmacy and primary care services, medicines knowledge, the pharmacist role and building rapport with healthcare professionals. Nine participants and three researchers attended the PPI discussion session. Seven of the participants were patients who had experienced a cardiac event in the last three months and two were carers. Primary care pharmacy services both clinical and public health were not very familiar to the participants. Different experiences with clinical pharmacy services were reported by participants, while one experience was reported to be helpful others perceived community pharmacists to be to be busy and isolated behind a counter. A general practice GP based specialist nurse was a familiar model of care unlike a specialist clinical pharmacist GP based care role. Participants reported limited time in GP consultations and the need to book double appointments. Participants stressed the need to receive consistent information about their disease and medication from different professionals involved in their care. Different views were expressed regarding the ability to build rapport with a clinical pharmacist when compared to a GP. Input on study outcomes and design was provided by participants. Conclusion: participants in this session mentioned that a clinical pharmacy intervention after hospital discharge would be useful for their continuity of care. Plans are in place to continue to involve patients and the public in the write up, ethics and dissemination of the potential clinical pharmacy proposal.

Cost effectiveness of interventions to improve adherence to statin therapy in ASCVD patients in the United States

INTRODUCTION

Cardiovascular disease (CVD) is the leading cause of death in the United States, and high cholesterol is a leading risk factor for CVD. While statins are effective at reducing cholesterol, they are frequently underused in patients at highest risk of CVD. The objective of this study was to identify interventions which may improve adherence to statins and to assess their cost effectiveness within the US Medicare population.

METHODS

A literature review was undertaken to identify interventions to improve adherence in patients with CVD at highest risk of a recurrent event and to quantify non-adherence and the consequences of non-adherence to statins in this population. A Markov cost-utility model was developed to assess the cost effectiveness of these interventions.

RESULTS

Ten adherence interventions were identified in the literature, with 6 demonstrating statistically significant improvement in adherence. The six interventions were disease management, interactive voice response, nurse counselling, discharge letter, nurse/dietician counselling and electronic pill bottle with feedback. The model found the cost effectiveness of an intervention was highly dependent on its effectiveness and costs. Incremental cost effectiveness ratios ranged from $27,545/QALY for discharge letter with large adherence gain to $130,399/QALY for disease management program with small adherence gain.

CONCLUSION

Some interventions to improve adherence have been shown to be effective, but little attention has been paid to the costs. Further studies on adherence interventions should include economic evaluations.

'Temporary Plasticiser': A novel solution to fabricate 3D printed patient-centred cardiovascular 'Polypill' architectures

Hypertension and dyslipidaemia are modifiable risk factors associated with cardiovascular diseases (CVDs) and often require a complex therapeutic regimen. The administration of several medicines is commonly associated with poor levels of adherence among patients, to which World Health Organisation (WHO) proposed a fixed-dose combination unit (polypill) as a strategy to improve adherence. In this work, we demonstrate the fabrication of patient-specific polypills for the treatment of CVDs by fused deposition modelling (FDM) 3D printing and introduce a novel solution to meet critical quality attributes. The construction of poly(vinyl alcohol) (PVA)-based polypills containing four model drugs (lisinopril dihydrate, indapamide, rosuvastatin calcium and amlodipine besylate) was revealed for the first time. The impact of tablet architecture was explored using multi-layered and unimatrix structures. The novel approach of using distilled water as a 'temporary co-plasticiser' is reported and was found to significantly lower the extruding (90 °C) and 3D printing (150 °C) temperatures from 170 °C and 210 °C respectively, with consequent reduction in thermal stress to the chemicals. XRD indicated that lisinopril dihydrate and amlodipine besylate maintained their crystalline form while indapamide and rosuvastatin calcium were essentially in amorphous form in the PVA tablets. From the multilayer polypills, the release profile of each drug was dependent on its position in the multilayer. In addition to the multilayer architecture offering a higher flexibility in dose titration and a more adaptive solution to meet the expectations of patient-centred therapy, we identify that it also allows orchestrating the release of drugs of different physicochemical characteristics. Adopting such an approach opens up a pathway towards low-cost multidrug delivery systems such as tablets, stents or implants for wider range of globally approved actives.

Factors that contribute to poor adherence to statin therapy in coronary heart disease patients from Chongqing and measures to improve their therapeutic outcomes

To assess the efficacy and short-term outcomes of adherence to statin therapy among coronary heart disease (CHD) patients following their hospital discharge, we enrolled 615 CHD patients who were prescribed statins from The First Affiliated Hospital of Chongqing Medical University in China between February 1st and October 31st of 2013. Statin adherence was evaluated by identifying the proportion of patients who remained adherent or became non-adherent to statin therapy over 4–8 months post-discharge from the hospital. The composite outcomes included all-cause mortality and re-hospitalization with cardiovascular disease. We found that 15.9% patients were non-adherent to their statin therapies and that coronary artery stenosis<75% (OR = 3.433, 95% CI: 2.191–5.380, p < 0.001) and adverse effects (OR = 2.542, 95% CI: 1.327–4.869, p = 0.005) both clearly contributed to poor adherence. The primary self-reported reasons for non-adherence included a lack of knowledge about the benefits of statin therapy (36.7%), the treatment being halted at the advice of their doctor (19.4%), and the difficulty in obtaining statins (12.2%). Non-adherence to statin therapy was significantly associated with an increased risk of cardiovascular events (OR = 1.741, 95% CI: 1.035–2.929, p = 0.037). In conclusion, CHD patients with moderate stenosis or adverse effects tended to have poor statin adherence, and this was significantly associated with increased cardiovascular events. We should strengthen education of the importance of statin therapy for both patients and doctors and facilitate the ability of patients to obtain their statin medication.

Clinical Study Register Code: ChiCTR-EPC-16007839.

Six-month adherence to Statin use and subsequent risk of major adverse cardiovascular events (MACE) in patients discharged with acute coronary syndromes

BACKGROUND

The evidence of adherence to statin decreasing risk of major adverse cardiovascular events (MACEs) is still lack among patients discharged with acute coronary syndrome (ACS). Our objective is to determine the relationship between six-month adherence to statins and subsequent risk of MACEs in patients discharged with ACS.

METHODS

Using two prospective registry cohorts (CPACS-1 and -2), we analyzed data from 12,516 consecutive patients with ACS who were prescribed statin at hospital discharge and survived beyond 6 months without recurrent myocardial infarction (MI) or stroke. Adherence to statin was defined as good (using statin at discharge and 6 months without declined dosage) and poor adherence groups (using statin at discharge but declining dosage or stopping at 6 months). We compared the hazard ratios of all-cause mortality and MACE in subsequent 6 months between groups, using Cox-regression models, adjusting for multiple potential confounders.

RESULTS

Seventy two percent of patients adhered to statin therapy at 6 months. The incident MACE in the poor adherence group was significantly higher than in good adherence group (2.7% vs. 1.8%, p = 0.002). Compared with poor adherence group, the good adherence group showed a 27% lower relative risk of MACE during the 6 month follow up (fully-adjusted hazard ratio (HR) = 0.73; 95%CI: 0.56-0.97). The protective effects of good adherence were similar in groups with different statin dose as well as groups by other baseline clinical characteristics and treatments (p > 0.05 for interaction).

CONCLUSION

Our study highlights the importance of adherence to statin therapy in prevention of MACE and clinicians should aim to achieve higher dosage if tolerable.

CLINICAL TRIAL REGISTRATION

CPACS2 was registered on URL: http://www.anzctr.org.au/default.aspx and unique identifier is ACTRN12609000491268 . CPACS1 was not a clinical trial and thus not registered.

Impact of Bubble Packaging on Adherence to Long-Term Oral Medications Used to Prevent Cardiovascular Disease

Background: Adherence to long-term pharmacotherapy is problematic in the United States. Bubble packaging of medications has been touted to improve patients’ use of medications. Scant research has assessed bubble packaging’s impact on adherence to multiple medications. Objective: To compare medication adherence between patients receiving medications to address cardiovascular disease risk factors in bubble packages to those receiving medications in pill bottles. Methods: This retrospective cohort study utilized prescription dispensing records from an independent pharmacy. Patients receiving statins, β-blockers, angiotensin-converting enzyme inhibitors, or oral hypoglycemic agents were identified and grouped into those who received medications in bubble packages and those received medications in pill bottles. Adherence was assessed with medication possession ratios. Patients were classified as adherent if their medication possession ratio was 80% or more. Results: Receiving medications in bubble packaging was significantly associated with greater adherence compared to pill bottles (P < .001). In adjusted models, greater numbers of medications filled (P = .024) and increasing patient age (P = .018) were significantly associated with low adherence, while bubble packaging was not (P = .13). Stratified analyses revealed that bubble packaging was significantly associated with greater adherence when 4 or fewer medications are filled (P = .012) and for patients between 18 and 44 years of age (P = .023). Conclusion: Bubble packages can improve medication adherence. However, they may not resolve complex issues contributing to the problem of nonadherence, especially for older patients and those prescribed multiple medications.

Does the association between adherence to statin medications and mortality depend on measurement approach? A retrospective cohort study

BACKGROUND

The aim of this study was to examine the relationship between mortality and statin adherence using two different approaches to adherence measurement (summary versus repeated-measures).

METHODS

A retrospective cohort study was conducted using administrative data from Saskatchewan, Canada between 1994 and 2008. Eligible individuals received a prescription for a statin following hospitalization for acute coronary syndrome (ACS). Adherence was measured using proportion of days covered (PDC) expressed either as: 1) a fixed summary measure, or 2) as a repeatedly measured covariate. Multivariable Cox-proportional hazards models were used to estimate the association between adherence and mortality.

RESULTS

Among 9,051 individuals, optimal adherence (≥80%) modeled with a fixed summary measure was not associated with mortality benefits (adjusted HR 0.97, 95% CI 0.86 to 1.09, p = 0.60). In contrast, repeated-measures approach resulted in a significant 25% reduction in the risk of death (adjusted HR 0.75, 95% CI 0.67 to 0.85, p < 0.01).

CONCLUSIONS

Unlike the summary measure, the repeated measures approach produces a significant reduction of all-cause mortality with optimal adherence. This effect may be a result of the repeated measures approach being more sensitive, or more prone to survival bias. Our findings clearly demonstrate the need to undertake (and report) multiple approaches when assessing the benefits of medication adherence.

A systematic review to assess adherence and persistence with statins

OBJECTIVE

To identify and assess studies published over a 10 year period up to February 2016 which measure adherence or persistence with statins, to summarize their methods, strengths and weaknesses and to summarize evidence linking statin adherence/persistence with risk of cardiovascular events.

METHODS

Electronic databases and abstracts from four major cardiovascular disease conferences were searched from January 2005 to February 2016. The study selection process was performed by two reviewers working independently. Studies were included if they reported data regarding patient adherence or persistence with statins in adults with primary hypercholesterolemia, using any type of study design or length of follow-up. One reviewer extracted the study data and assessed study quality, which was checked by a second reviewer independently. Given the heterogeneity between the included studies a narrative critique and summary is presented.

RESULTS

We report on 84 real world studies which aimed to assess adherence or persistence with statins. The majority of studies concluded that good adherence/persistence was associated with reduction in cardiovascular events and mortality. In two studies high intensity statin regimens were associated with poorer patient adherence when compared to low intensity statins. Adherence and persistence with statin therapy also has an impact on hospitalization costs and other cardiovascular disease (CVD) related costs.

CONCLUSIONS

Adherence and persistence are associated with a reduction in CVD events and mortality. There was limited evidence to suggest that high intensity statin regimens are associated with poorer treatment adherence when compared to lower intensity regimens. Hence, more robust studies are required to establish this association. As recommended by the 2013 ACC/AHA, 2016 ESC and several other clinical guidelines, clinicians and pharmacy managers should regularly monitor statin therapy adherence.

Investigating the prevalence, predictors, and prognosis of suboptimal statin use early after a non-ST elevation acute coronary syndrome

Background

High-potency statin therapy is recommended in the secondary prevention of cardiovascular disease but discontinuation, dose reduction, statin switching, and/or nonadherence occur in practice.

Objectives

To determine the prevalence and predictors of deviation from high-potency statin use early after a non-ST elevation acute coronary syndrome (NSTE-ACS) and its association with subsequent major adverse cardiovascular events (MACE) and all-cause mortality (ACM).

Methods

A total of 1005 patients from a UK-based prospective NSTE-ACS cohort study discharged on high-potency statin therapy (atorvastatin 80 mg, rosuvastatin 20 mg, or 40 mg daily) were included. At 1 month, patients were divided into constant high-potency statin users, and suboptimal users incorporating statin discontinuation, dose reduction, switching statin to a lower equivalent potency, and/or statin nonadherence. Follow-up was a median of 16 months.

Results

There were 156 suboptimal (∼15.5%) and 849 constant statin users. Factors associated in multivariable analysis with suboptimal statin occurrence included female sex (odds ratio 1.75, 95% confidence interval [CI] 1.14–2.68) and muscular symptoms (odds ratio 4.28, 95% CI 1.30–14.08). Suboptimal statin use was associated with increased adjusted risks of time to MACE (hazard ratio 2.10, 95% CI 1.25–3.53, P = .005) and ACM (hazard ratio 2.46, 95% CI 1.38–4.39, P = .003). Subgroup analysis confirmed that the increased MACE/ACM risks were principally attributable to statin discontinuation or nonadherence.

Conclusions

Conversion to suboptimal statin use is common early after NSTE-ACS and is partly related to muscular symptoms. Statin discontinuation or non-adherence carries an adverse prognosis. Interventions that preserve and enhance statin utilization could improve post NSTE-ACS outcomes.

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Deviation from high-potency statin therapy is common early in secondary prevention.

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Deviation can be by discontinuation, dose reduction, switching, or nonadherence.

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Muscular symptoms are associated with suboptimal statin use.

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Statin discontinuation/nonadherence is associated with increased adverse outcomes.

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Interventions to enhance statin use could improve secondary prevention outcomes.

Getting less of what you want: reductions in statistical power and increased bias when categorizing medication adherence data

Medication adherence is thought to be the principal clinical predictor of positive clinical outcomes, not only for serious mental illnesses such as schizophrenia, bipolar disorder, or depression, but also for physical conditions such as diabetes. Consequently, research on medication often looks not only at medication condition (e.g., placebo, standard medication, investigative medication), but also at adherence in taking those medications within each medication condition. The percentage (or proportion) scale is one of the more frequently employed and easily interpretable measures. Patients can be 0 % adherent, 100 % adherent, or somewhere in between. For simplicity, many reported adherence analyses dichotomize or trichotomize the adherence predictor when estimating its effect on outcomes of interest. However, the methodological literature shows that the practice of categorizing continuously distributed predictors reduces statistical power at best and, at worst, can severely bias parameter estimates. This can result in inflated Type I errors (false positive acceptance of null adherence effects) or Type II errors (false negative rejection of true adherence effects). We extend the methodological literature on categorization to the construct of adherence. The measurement scale of adherence leads to a diverse family of potential distributions including uniform, n-shaped, u-shaped (i.e., bimodal), positively skewed, and negatively skewed. Using a simulation study, we generated negative, null, and positive "true" effects of adherence on simulated continuous and binary outcomes. We then estimated the adherence effect with and without categorizing the adherence variable. We show how parameter estimates and standard errors can be severely biased when categorizing adherence. The categorization of adherence is shown to cause null effects to become positive or negative depending on the distribution of the simulated adherence variable, inflating Type I errors. When the adherence effect was significantly different from zero, categorization can render the effect null, inflating Type II errors. We recommend that adherence be measured continuously and analyzed without categorization when using it as a predictor in regression models.

Impact of statin adherence on cardiovascular disease and mortality outcomes: a systematic review

AIMS

While suboptimal adherence to statin medication has been quantified in real-world patient settings, a better understanding of its impact is needed, particularly with respect to distinct problems of medication taking. Our aim was to synthesize current evidence on the impacts of statin adherence, discontinuation and persistence on cardiovascular disease and mortality outcomes.

METHODS

We conducted a systematic review of peer-reviewed studies using a mapped search of Medline, Embase and International Pharmaceutical Abstracts databases. Observational studies that met the following criteria were included: defined patient population;statin adherence exposure; defined study outcome [i.e. cardiovascular disease (CVD), mortality]; and reporting of statin-specific results.

RESULTS

Overall, 28 studies were included, with 19 studies evaluating outcomes associated with statin adherence, six with statin discontinuation and three with statin persistence. Among adherence studies, the proportion of days covered was the most widely used measure, with the majority of studies reporting increased risk of CVD (statistically significant risk estimates ranging from 1.22 to 5.26)and mortality (statistically significant risk estimates ranging from 1.25 to 2.54) among non-adherent individuals. There was greater methodological variability in discontinuation and persistence studies. However, findings of increased CVD (statistically significant risk estimates ranging from 1.22 to 1.67) and mortality (statistically significant risk estimates ranging from 1.79 to 5.00) among nonpersistent individuals were also consistently reported.

CONCLUSIONS

Observational studies consistently report an increased risk of adverse outcomes associated with poor statin adherence. These findings have important implications for patients and physicians and emphasize the importance of monitoring and encouraging adherence to statin therapy.

Cost-effectiveness and public health benefit of secondary cardiovascular disease prevention from improved adherence using a polypill in the UK

OBJECTIVE

To evaluate the public health and economic benefits of adherence to a fixed-dose combination polypill for the secondary prevention of cardiovascular (CV) events in adults with a history of myocardial infarction (MI) in the UK.

DESIGN

Markov-model-based cost-effectiveness analysis, informed by systematic reviews, which identified efficacy, utilities and adherence data inputs.

SETTING

General practice in the UK.

PARTICIPANTS

Patients with a mean age of 64.7 years, most of whom are men with a recent or non-recent diagnosis of MI and for whom secondary preventive medication is indicated and well tolerated.

INTERVENTION

Fixed-dose combination polypill (100 mg aspirin, 20 mg atorvastatin and 2.5, 5, or 10 mg ramipril) compared with multiple monotherapy.

PRIMARY AND SECONDARY OUTCOME MEASURES

CV events prevented per 1000 patients; cost per life-year gained; and cost per quality-adjusted life-year (QALY) gained.

RESULTS

The model estimates that for each 10% increase in adherence, an additional 6.7% fatal and non-fatal CV events can be prevented. In the base case, over 10 years, the polypill would improve adherence by ∼20% and thereby prevent 47 of 323 (15%) fatal and non-fatal CV events per 1000 patients compared with multiple monotherapy, with an incremental cost-effectiveness ratio (ICER) of £8200 per QALY gained. Probabilistic sensitivity analyses for the base-case assumptions showed an 81.5% chance of the polypill being cost-effective at a willingness-to-pay threshold of £20,000 per QALY gained compared with multiple monotherapy. In scenario analyses that varied structural assumptions, ICERs ranged between cost saving and £21,430 per QALY gained.

CONCLUSIONS

Assuming that some 450,000 adults are at risk of MI, a 10 percentage point uptake of the polypill could prevent 3260 CV events and 590 CV deaths over a decade.The polypill appears to be a cost-effective strategy to prevent fatal and non-fatal CV events in the UK.

Association of Medicare Part D low-income cost subsidy program enrollment with increased fill adherence to clopidogrel after coronary stent placement

STUDY OBJECTIVE

To determine the association between enrollment in the Medicare Part D low-income subsidy (LIS) program, which reduces out-of-pocket medication costs, and fill adherence to the antiplatelet drug clopidogrel after coronary stent placement.

DESIGN

Retrospective cohort study.

DATA SOURCE

Pharmacy claims database of a large national Medicare Part D insurer.

PATIENTS

We selected a total of 2967 beneficiaries of a national Medicare Part D plan who had a coronary stent placed between April and December 2006 and were prescribed clopidogrel but were not preexisting users of clopidogrel. Of these patients, 504 were enrolled in the LIS program and 2463 were not.

MEASUREMENTS AND MAIN RESULTS

We defined LIS status as enrollment in the LIS program at any point during the 12 months after the procedure. We examined the association between LIS status and good medication fill adherence to clopidogrel, defined as proportion of days covered of 80% or more, or discontinuation of clopidogrel over the 12-month window starting from the date of their stent placement. We also identified patients with claims-based diagnoses of major bleeding events while taking clopidogrel. For those patients, we calculated fill adherence only for the period between medication initiation and the onset of major bleeding and/or did not classify them as having inappropriately discontinued the medication. We created a propensity score predicting the propensity of being eligible for the LIS benefit and used inverse propensity score weighting with regression adjustment to generate estimates of the effect parameters. LIS enrollment was associated with a higher predicted likelihood of good clopidogrel fill adherence after stent placement (54.8% for LIS enrollees vs 47.6% for non enrollees; p=0.008). No significant difference was noted between the two groups in predicted risk of discontinuing clopidogrel after stent placement (18.3% for LIS enrollees vs 21.0% for non enrollees; p=0.21).

CONCLUSION

The LIS benefit was associated with better clopidogrel fill adherence after stent placement. Although clopidogrel is now available in generic form, our work underscores the need for efforts to identify and enroll patients in the LIS benefit who require costly antiplatelet medications for coronary heart disease.

Prevalence of dyslipidaemia in statin-treated patients in South Africa: results of the DYSlipidaemia International Study (DYSIS)

INTRODUCTION AND OBJECTIVES

Cardiovascular disease (CVD) is the leading cause of mortality worldwide and increased levels of low-density lipoprotein cholesterol (LDL-C) are an important modifiable risk factor. Statins lower LDL-C levels and have been shown to reduce CVD risk. Despite the widespread availability of statins, many patients do not reach the lipid targets recommended by guidelines. We evaluated lipid goal attainment in statin-treated patients in South Africa and analysed variables contributing to poor goal attainment as part of the DYSlipidaemia International Study (DYSIS).

METHODS

This cross-sectional, observational study enrolled 1 029 consecutive South African patients consulting officebased physicians. Patients were at least 45 years old, had to be treated with a stable dose of statins for at least three months and had been fasting for 12 hours. We evaluated lipid goal attainment and examined variables associated with residual dyslipidaemia [abnormal levels of LDL-C, highdensity lipoprotein cholesterol (HDL-C) and/or triglycerides (TG)].

RESULTS

We found that 50.3% of the patients overall did not achieve target LDL-C levels and 73.5% of patients were at very high cardiovascular risk. In addition, 33.7% had low levels of HDL-C, while 45.3% had elevated TG levels despite statin therapy. Asian and mixed-ancestry patients but not black (vs Caucasian thnicity), as well as obese individuals in South Africa were more likely to still have dyslipidaemia involving all three lipid fractions.

CONCLUSIONS

We observed that many patients in South Africa experienced persistent dyslipidaemia despite statin treatment, supporting the concept that there is a need for more intensive statin therapy or the development of novel treatment strategies. Measures aimed at combating obesity and other lifestyle-related risk factors are also vital for effectively controlling dyslipidaemia and reducing the burden of CVD.

Statin use after first myocardial infarction in UK men and women from 1997 to 2006: Who started and who continued treatment?

BACKGROUND AND AIMS

To examine trends in initiation and continuation of statin treatment after myocardial infarction (MI) and their determinants, during a period of increasing usage.

METHODS AND RESULTS

9367 patients aged 30-84 with a first Myocardial Infarction (MI) in 1997-2006 were identified in DIN-LINK, an anonymised, UK primary care database. We assessed statin initiation (prescription within 6 months of MI) and continued therapy (% covered by a prescription on a given day of those prescribed a statin within 6 months). The influences of co-morbidities and socio-economic deprivation (Index of Multiple Deprivation) were examined. Statin initiation increased from 37% for MIs in 1997 to 92% in 2006. Continuation at 1 year remained stable over successive cohorts at approximately 80%, settling to about 76% in patients with 5-10 years follow up. Younger age, affluence, revascularisation in 6 months after MI, and absence of congestive heart failure, predicted higher initiation and continuation; a diagnosis of hypertension or diabetes predicted higher initiation, while smoking was associated with poorer continuation. Men had higher initiation and continued therapy, but these effects were largely explained by their younger age. Type of statin initially prescribed did not influence continued usage.

CONCLUSION

Statin use after MI increased markedly between 1997 and 2006, whilst continued therapy remained high and stable. Importantly, first choice of statin had no effect on continuation. Whilst the high current levels of initiation may have reached a ceiling, increasing continuation rates among smokers, older patients and those from lower socio-economic groups, should remain a priority.

Derivation and preliminary validation of an administrative claims-based algorithm for the effectiveness of medications for rheumatoid arthritis

INTRODUCTION

Administrative claims data have not commonly been used to study the clinical effectiveness of medications for rheumatoid arthritis (RA) because of the lack of a validated algorithm for this outcome. We created and tested a claims-based algorithm to serve as a proxy for the clinical effectiveness of RA medications.

METHODS

We linked Veterans Health Administration (VHA) medical and pharmacy claims for RA patients participating in the longitudinal Department of Veterans Affairs (VA) RA registry (VARA). Among individuals for whom treatment with a new biologic agent or nonbiologic disease-modifying agent in rheumatic disease (DMARD) was being initiated and with registry follow-up at 1 year, VARA and administrative data were used to create a gold standard for the claims-based effectiveness algorithm. The gold standard outcome was low disease activity (LDA) (Disease Activity Score using 28 joint counts (DAS28) ≤ 3.2) or improvement in DAS28 by > 1.2 units at 12 ± 2 months, with high adherence to therapy. The claims-based effectiveness algorithm incorporated biologic dose escalation or switching, addition of new disease-modifying agents, increase in oral glucocorticoid use and dose as well as parenteral glucocorticoid injections.

RESULTS

Among 1,397 patients, we identified 305 eligible biologic or DMARD treatment episodes in 269 unique individuals. The patients were primarily men (94%) with a mean (± SD) age of 62 ± 10 years. At 1 year, 27% of treatment episodes achieved the effectiveness gold standard. The performance characteristics of the effectiveness algorithm were as follows: positive predictive value, 76% (95% confidence interval (95% CI) = 71% to 81%); negative predictive value, 90% (95% CI = 88% to 92%); sensitivity, 72% (95% CI = 67% to 77%); and specificity, 91% (95% CI = 89% to 93%).

CONCLUSIONS

Administrative claims data may be useful in evaluating the effectiveness of medications for RA. Further validation of this effectiveness algorithm will be useful in assessing its generalizability and performance in other populations.

Cost-effectiveness analysis: cardiovascular benefits of proton pump inhibitor co-therapy in patients using aspirin for secondary prevention

BACKGROUND

Many patients with cardiovascular (CV) disease will stop aspirin (ASA) because of ASA-related dyspepsia. Proton pump inhibitor (PPI) co-therapy may reduce ASA-related dyspepsia, enhancing ASA adherence and improving CV outcomes.

AIM

To explore the impact of PPI co-therapy on CV outcomes in long-term, low-dose ASA users.

METHODS

We modified a previously published Markov model to assess the long-term impact of PPI co-therapy on CV and upper gastrointestinal bleeding (UGIB) outcomes among patients using ASA for secondary CV prevention. UGIB events, recurrent myocardial infarctions (MIs) and incremental cost-effectiveness ratios (ICERs) were measured. The perspective taken was that of a long-term payer.

RESULTS

Compared with ASA alone, ASA plus PPI resulted in fewer lifetime UGIB events (3.4% vs. 7.2%) and increased ASA adherence (74% vs. 71%). Increased ASA adherence resulted in fewer recurrent MIs (26 fewer events per 10000 patients). On average, the ASA plus PPI strategy resulted in 38 additional days of life per patient, with the majority of this benefit (61%) because of a reduction in CV mortality (rather than UGIB-related mortality). ASA plus PPI was also more costly than ASA alone, with an ICER of $19000 per life-year saved. Results were sensitive to cost of PPI and impact of PPI on ASA adherence.

CONCLUSIONS

Proton pump inhibitor co-therapy has the potential to impact not only GI, but also CV outcomes in patients with CV disease using ASA and such co-therapy is likely to be cost-effective. Future studies should better quantify the CV benefits of PPI co-therapy.

A competing risks prescription refill model of compliance and persistence

OBJECTIVES

There is evidence to suggest that noncompliant and nonpersistent behaviors have differing risk factors, clinical consequences, and responses to intervention. This has led to calls for these behaviors to be defined and measured separately to characterize medication-taking behavior comprehensively. Current prescription refill models of compliance are, however, unable to appropriately distinguish between noncompliant and nonpersistent behaviors. To address this limitation, a prescription refill model of medication-taking behavior in which noncompliance and nonpersistence are treated as competing risks is presented.

METHODS

The proposed competing risks model of compliance and persistence is compared with a selection of widely applied prescription refill models of compliance and persistence using a common cohort of patients prescribed statin therapy.

RESULTS

The competing risks model allows the simultaneous measurement of noncompliance and nonpersistence, the partitioning of their individual contributions to medication-taking behavior, and the estimation of noncompliance risk for patients with varying treatment persistence. The results from this model provide information about the relative and overall contributions of noncompliant and nonpersistent behaviors to medication-taking behavior. The methodology also allows an assessment of the differential influence of various risk factors on these behaviors.

CONCLUSIONS

The proposed competing risks model differentiates between noncompliant and nonpersistent behaviors using prescription refill data. Results from the model provide insights into the dynamics of noncompliant and nonpersistent behaviors that have not been possible with current prescription refill methodologies.