Clinical impact of early clopidogrel discontinuation following acute myocardial infarction hospitalization or stent implantation: analysis in a nationally representative managed-care population

Early Discontinuation of P2Y12 Antagonists and Adverse Clinical Events Post-Percutaneous Coronary Intervention: A Hospital and Primary Care Linked Cohort

Background

Early discontinuation of P2Y₁₂ antagonists post–percutaneous coronary intervention may increase risk of stent thrombosis or nonstent recurrent myocardial infarction. Our aims were to (1) analyze the early discontinuation rate of P2Y₁₂ antagonists post–percutaneous coronary intervention, (2) explore factors associated with early discontinuation, and (3) analyze the risk of major adverse cardiovascular events (death, acute coronary syndrome, revascularization, or stroke) associated with discontinuation from a prespecified prescribing instruction of 1 year.

Method and Results

We studied 2090 patients (2011–2015) who were recommended for clopidogrel for 12 months (+aspirin) post–percutaneous coronary intervention within a retrospective observational population cohort. Relationships between clopidogrel discontinuation and major adverse cardiac events were evaluated over 18‐month follow‐up. Discontinuation of clopidogrel in the first 4 quarters was low at 1.1%, 2.6%, 3.7%, and 6.1%, respectively. Previous revascularization, previous ischemic stroke, and age >80 years were independent predictors of early discontinuation. In a time‐dependent multiple regression model, clopidogrel discontinuation and bleeding (hazard ratio=1.82 [1.01–3.30] and hazard ratio=5.30 [3.14–8.94], respectively) were independent predictors of major adverse cardiac events as were age <49 and ≥70 years (versus those aged 50–59 years), hypertension, chronic kidney disease stage 4+, previous revascularization, ischemic stroke, and thromboembolism. Furthermore, in those with both bleeding and clopidogrel discontinuation, hazard ratio for major adverse cardiac events was 9.34 (3.39–25.70).

Conclusions

Discontinuation of clopidogrel is low in the first year post–percutaneous coronary intervention, where a clear discharge instruction to treat for 1 year is provided. Whereas this is reassuring from the population level, at an individual level discontinuation earlier than the intended duration is associated with an increased rate of adverse events, most notably in those with both bleeding and discontinuation.

Using nationwide ‘big data’ from linked electronic health records to help improve outcomes in cardiovascular diseases: 33 studies using methods from epidemiology, informatics, economics and social science in the ClinicAl disease research using LInked Bespoke studies and Electronic health Records (CALIBER) programme

Background

Electronic health records (EHRs), when linked across primary and secondary care and curated for research use, have the potential to improve our understanding of care quality and outcomes.

Objective

To evaluate new opportunities arising from linked EHRs for improving quality of care and outcomes for patients at risk of or with coronary disease across the patient journey.

Design

Epidemiological cohort, health informatics, health economics and ethnographic approaches were used.

Setting

230 NHS hospitals and 226 general practices in England and Wales.

Participants

Up to 2 million initially healthy adults, 100,000 people with stable coronary artery disease (SCAD) and up to 300,000 patients with acute coronary syndrome.

Main outcome measures

Quality of care, fatal and non-fatal cardiovascular disease (CVD) events.

Data platform and methods

We created a novel research platform [ClinicAl disease research using LInked Bespoke studies and Electronic health Records (CALIBER)] based on linkage of four major sources of EHR data in primary care and national registries. We carried out 33 complementary studies within the CALIBER framework. We developed a web-based clinical decision support system (CDSS) in hospital chest pain clinics. We established a novel consented prognostic clinical cohort of SCAD patients.

Results

CALIBER was successfully established as a valid research platform based on linked EHR data in nearly 2 million adults with > 600 EHR phenotypes implemented on the web portal (seehttps://caliberresearch.org/portal). Despite national guidance, key opportunities for investigation and treatment were missed across the patient journey, resulting in a worse prognosis for patients in the UK compared with patients in health systems in other countries. Our novel, contemporary, high-resolution studies showed heterogeneous associations for CVD risk factors across CVDs. The CDSS did not alter the decision-making behaviour of clinicians in chest pain clinics. Prognostic models using real-world data validly discriminated risk of death and events, and were used in cost-effectiveness decision models.

Conclusions

Emerging ‘big data’ opportunities arising from the linkage of records at different stages of a patient’s journey are vital to the generation of actionable insights into the diagnosis, risk stratification and cost-effective treatment of people at risk of, or with, CVD.

Future work

The vast majority of NHS data remain inaccessible to research and this hampers efforts to improve efficiency and quality of care and to drive innovation. We propose three priority directions for further research. First, there is an urgent need to ‘unlock’ more detailed data within hospitals for the scale of the UK’s 65 million population. Second, there is a need for scaled approaches to using EHRs to design and carry out trials, and interpret the implementation of trial results. Third, large-scale, disease agnostic genetic and biological collections linked to such EHRs are required in order to deliver precision medicine and to innovate discovery.

Study registration

CALIBER studies are registered as follows: study 2 – NCT01569139, study 4 – NCT02176174 and NCT01164371, study 5 – NCT01163513, studies 6 and 7 – NCT01804439, study 8 – NCT02285322, and studies 26–29 – NCT01162187. Optimising the Management of Angina is registered as Current Controlled Trials ISRCTN54381840.

Funding

The National Institute for Health Research (NIHR) Programme Grants for Applied Research programme (RP-PG-0407-10314) (all 33 studies) and additional funding from the Wellcome Trust (study 1), Medical Research Council Partnership grant (study 3), Servier (study 16), NIHR Research Methods Fellowship funding (study 19) and NIHR Research for Patient Benefit (study 33).

Patterns of antiplatelet drug use after a first myocardial infarction during a 10-year period

AIMS

The aims of the present study were to assess antiplatelet drug use patterns after a first myocardial infarction (MI) and to evaluate the determinants of antiplatelet nonpersistence.

METHODS

The present study was conducted in 4690 patients from the Utrecht Cardiovascular Pharmacogenetics cohort with a first MI between 1986 and 2010, who were followed for a maximum of 10 years. Medication use and event diagnosis were obtained from the Dutch PHARMO Record Linkage System. Antiplatelet drug users were classified as persistent users (gap between prescriptions ≤90 days), nonpersistent users (>90-day gap and no refills), and restarters (a new prescription after a >90-day gap). The association between potential determinants and antiplatelet nonpersistence was analysed using Cox regression.

RESULTS

The proportions of persistent users decreased from 84.0% at the 1-year follow-up to 32.8% at 10 years for any antiplatelet drug, and 77.3% to 27.5% for aspirin; and 39.0% to 6.4% for clopidogrel at 6 years. Most nonpersistent users restarted antiplatelet drugs later, leading to 89.3% overall antiplatelet drug users at 10 years after MI. Diabetes (hazard ratio [HR] 0.44; 0.32-0.60), hypertension (HR 0.77; 0.60-0.99), hypercholesterolaemia (HR 0.49; 0.39-0.62) and more recent MI diagnosis period (2003-2007: HR 0.69, 0.61-0.79; 2008-2010: HR 0.38, 0.19-0.77, compared to ≤ 2002 period) lowered the risk of antiplatelet nonpersistence, while vitamin K antagonist (VKA) comedication (HR 18.97; 16.91-21.28) increased this risk.

CONCLUSIONS

A large proportion of patients with a first MI still used antiplatelet drugs after 10 years. The frequent discontinuations during this time frame are expected to reduce the effectiveness of antiplatelet drugs as secondary prevention of cardiovascular diseases. Diabetes, hypertension, hypercholesterolaemia, VKA comedication and MI diagnosis period were determinants of antiplatelet nonpersistence.

Duration of dual antiplatelet therapy following percutaneous coronary intervention on re-hospitalization for acute coronary syndrome

Background

The optimal duration of dual antiplatelet therapy after percutaneous coronary intervention (PCI) remains uncertain. The objective of this study was to examine the association between duration of dual antiplatelet therapy and re-hospitalization for acute coronary syndrome (ACS) in ACS patients who underwent PCI.

Methods

We identified 975 newly diagnosed ACS patients who underwent PCI between July, 2007 and June, 2009, at a medical center in Taiwan. Cox proportional hazard models were used to examine the association between duration of dual antiplatelet therapy (9 months, 12 months and 15 months) and risks of re-hospitalization for ACS.

Results

At a mean follow-up of 2.3 years, we found that use of clopidogrel for ≥ 12 months was associated with a decreased risk of re-hospitalization for ACS (adjusted HR 0.59, 95% CI 0.36-0.95; p = 0.03). However, use of clopidogrel for ≥ 15 months was not associated with a decreased risk of re-hospitalization for ACS (adjusted HR 0.57, 95% CI 0.29-1.13; p = 0.11). Similar results were found in patients who implanted drug-eluting stents (DES), for whom at least 12 months of clopidogrel therapy is especially critical.

Conclusion

The benefit of ≥ 12 months of clopidogrel use in reducing the risk of re-hospitalization for ACS was significant among ACS patients who underwent PCI and was especially critical for those who implanted DES.

Adherence and persistence with prasugrel following acute coronary syndrome with percutaneous coronary intervention

PURPOSE

To measure the adherence and persistence of patients with acute coronary syndrome (ACS) initiating prasugrel after percutaneous coronary intervention (PCI).

METHODS

Using the Thomson Reuters MarketScan Commercial and Medicare Supplemental database, a retrospective cohort study identified patients initiating prasugrel following ACS-PCI hospitalization in 2009-2011. Prasugrel adherence over 12 months was measured using the medication possession ratio (MPR); predictors of adherence were identified using a logistic regression model. Persistence was defined as time on continuous therapy; a Cox model identified predictors of prasugrel discontinuation.

RESULTS

Among 1,340 patients, the mean age was 57 years; 79.5 % were male. Median prasugrel MPR was 93.2 %; 69.0 % of patients had an MPR ≥80 %. Predictors of adherence <80 % included prior PCI [odds ratio (OR) 0.60; 95 % confidence interval (CI) 0.40-0.90], prior depression (OR 0.37; 95 % CI 0.16-0.84), prior bleeding (OR 0.41; 95 % CI 0.19-0.86), and baseline anticoagulant use (OR 0.13; 95 % CI 0.03-0.55). Baseline statin use predicted higher adherence (OR 1.56; 95 % CI 1.21-2.02). The median duration of prasugrel therapy was 259 days. Predictors of discontinuation included prior anemia [hazard ratio (HR) 1.63; 95 % CI 1.21-2.21], prior cardiomyopathy (HR 2.72; 95 % CI 1.44-5.13), and prior ischemic heart disease (HR 1.15; 95 % CI 1.00-1.32); baseline statin use predicted reduced risk of discontinuation (HR 0.85; 95 % CI 0.75-0.97).

CONCLUSIONS

Although adherence to prasugrel was generally high, the duration of therapy was frequently below recommendations. An awareness of risk factors for low adherence or early discontinuation can point to appropriate targets for intervention.

Effect of early clopidogrel discontinuation on rehospitalization in acute coronary syndrome: results from two distinct patient populations

PURPOSE

Results of a study of the association between early discontinuation of clopidogrel therapy and rehospitalization rates among patients with acute coronary syndrome (ACS) are reported.

SUMMARY

In a retrospective observational study, analyses of two nationally representative cohorts of adults hospitalized for acute myocardial infarction (AMI) or coronary stent insertion were conducted to assess risk factors for ACS-related adverse outcomes (rehospitalization for AMI or coronary revascularization) during the 12 months after completion of an initial 28-day course of clopidogrel therapy. Case data were sourced from a commercial insurance claims database, a pharmacy administrative claims database, and a combined dataset that linked hospital discharge and outpatient service data; a time-varying method was used to differentiate adverse events occurring "on" and "off" clopidogrel therapy. One cohort analysis (n = 42,757) indicated that patients who discontinued clopidogrel early (i.e., within 12 months of index discharge) were at significantly increased risk for ACS-related rehospitalization during the 12-month study period (hazard ratio [HR] = 1.11; 95% confidence interval [CI], 1.02-1.20; p < 0.05). In the other cohort analysis (n = 3,171), early clopidogrel discontinuation was associated with an increased risk of rehospitalization or inpatient death (HR = 1.75; 95% CI, 1.59-1.91; p < 0.0001).

CONCLUSION

Observational evidence from analyses of data on two large cohorts of patients with primarily employer-sponsored health insurance suggests that early discontinuation of clopidogrel therapy after hospitalization for AMI or coronary stent insertion is associated with a significant increase in the risk of ACS-related rehospitalization within the 12-month postdischarge period.

Clopidogrel discontinuation after acute coronary syndromes: frequency, predictors and associations with death and myocardial infarction--a hospital registry-primary care linked cohort (MINAP-GPRD)

Aims

Adherence to evidence-based treatments and its consequences after acute myocardial infarction (MI) are poorly defined. We examined the extent to which clopidogrel treatment initiated in hospital is continued in primary care; the factors predictive of clopidogrel discontinuation and the hazard of death or recurrent MI.

Methods and results

We linked the Myocardial Ischaemia National Audit Project registry and the General Practice Research Database to examine adherence to clopidogrel in primary care among patients discharged from hospital after MI (2003–2009). Hospital Episode Statistics and national mortality data were linked, documenting all-cause mortality and non-fatal MI. Of the 7543 linked patients, 4650 were prescribed clopidogrel in primary care within 3 months of discharge. The adjusted odds of still being prescribed clopidogrel at 12 months were similar following non-ST-elevation myocardial infarction (NSTEMI) 53% (95% CI, 51–55) and ST-elevation myocardial infarction (STEMI) 54% (95% CI, 52–56), but contrast with statins: NSTEMI 84% (95% CI, 82–85) and STEMI 89% (95% CI, 87–90). Discontinuation within 12 months was more frequent in older patients [>80 vs. 40–49 years, adjusted hazard ratio (HR) 1.50 (95% CI, 1.15–1.94)] and with bleeding events [HR 1.34 (95% CI, 1.03–1.73)]. 18.15 patients per 100 person-years (95% CI, 16.83–19.58) died or experienced non-fatal MI in the first year following discharge. In patients who discontinued clopidogrel within 12 months, the adjusted HR for death or non-fatal MI was 1.45 (95% CI, 1.22–1.73) compared with untreated patients, and 2.62 (95% CI, 2.17–3.17) compared with patients persisting with clopidogrel treatment.

Conclusion

This is the first study to use linked registries to determine persistence of clopidogrel treatment after MI in primary care. It demonstrates that discontinuation is common and associated with adverse outcomes.

Incidence of death and recurring acute coronary syndrome after stopping clopidogrel therapy in a large commercially-insured population in the US

BACKGROUND/OBJECTIVE

Guidelines support clopidogrel therapy in medically-treated or percutaneous coronary intervention (PCI) patients after hospitalization for acute coronary syndrome (ACS). However, clopidogrel discontinuation has been associated with increased short-term risks. This study evaluated the risk of adverse outcomes (AOs), defined as death or recurrent ACS, after clopidogrel discontinuation in a managed-care population.

METHODS

ACS patients (n = 7625) with ≥1 clopidogrel pharmacy claim from 2001 to 2006 and no AO before discontinuing clopidogrel were identified from administrative claims data. AO occurrences were recorded at 90-day intervals following clopidogrel discontinuation.

RESULTS

The mean (SD) duration of clopidogrel therapy for medically-treated, bare metal stent (BMS) and drug eluting stent (DES) patients was 349.2 (393.1) days, 235.6 (383.0) days, and 280.2 (227.1) days, respectively. Among medically-treated patients, Poisson regression analysis showed a 2.19 times higher AO risk (p < 0.01), a 1.63 times greater risk among BMS patients (p < 0.01), and a 1.56 times greater risk for DES patients (p ≥ 0.05) during days 0-90 versus days 91-180 after clopidogrel discontinuation. Sensitivity analysis showed that medically-treated, BMS and DES patients with ≤90 days of clopidogrel therapy had 2.13, 1.68 and 2.40 times higher AO risk, respectively, during days 0-90 versus 91-180 after discontinuation. No significant elevated AO risk was observed after discontinuation in patients on clopidogrel for 91-270 days. Limitations included those associated with the use of administration claims date, the absence of clinical data and lack of knowledge of aspirin use.

CONCLUSIONS

Patients who discontinued clopidogrel therapy were at high risk of death or recurrent ACS during the first 90 days. AO risks following discontinuation appeared elevated in patients with ≤90 days of clopidogrel therapy versus those with >90 days of treatment.

Medication adherence: WHO cares?

The treatment of chronic illnesses commonly includes the long-term use of pharmacotherapy. Although these medications are effective in combating disease, their full benefits are often not realized because approximately 50% of patients do not take their medications as prescribed. Factors contributing to poor medication adherence are myriad and include those that are related to patients (eg, suboptimal health literacy and lack of involvement in the treatment decision-making process), those that are related to physicians (eg, prescription of complex drug regimens, communication barriers, ineffective communication of information about adverse effects, and provision of care by multiple physicians), and those that are related to health care systems (eg, office visit time limitations, limited access to care, and lack of health information technology). Because barriers to medication adherence are complex and varied, solutions to improve adherence must be multifactorial. To assess general aspects of medication adherence using cardiovascular disease as an example, a MEDLINE-based literature search (January 1, 1990, through March 31, 2010) was conducted using the following search terms: cardiovascular disease, health literacy, medication adherence, and pharmacotherapy. Manual sorting of the 405 retrieved articles to exclude those that did not address cardiovascular disease, medication adherence, or health literacy in the abstract yielded 127 articles for review. Additional references were obtained from citations within the retrieved articles. This review surveys the findings of the identified articles and presents various strategies and resources for improving medication adherence.

Prevalence of stroke/transient ischemic attack among patients with acute coronary syndromes in a real-world setting

BACKGROUND

Atherothrombosis is a systemic disease that may manifest as acute ischemic events in multiple vascular beds. Patients who have experienced an atherothrombosis-related ischemic event in 1 vascular bed are at risk for developing ischemic events in other vascular beds. Antiplatelet therapy demands an understanding of the balance between arterial thrombosis benefit and adverse event risk. Clinical trials indicate that dual antiplatelet therapy with aspirin and the newer thienopyridines increases the risk of bleeding in patients with acute coronary syndromes (ACS) with prior cerebrovascular events. Informed clinical decision making requires a better understanding of the real-world prevalence of cerebrovascular events.

OBJECTIVE AND PURPOSE

To estimate the prevalence of stroke and/or transient ischemic attack (TIA) among patients with ACS within US health plan populations.

METHODS

A retrospective, observational cohort study was conducted of patients with ACS in 5 health care claims databases. The index event was defined as the first documented inpatient health care claim for myocardial infarction or unstable angina. Patients with ≥12 months of pre-index medical care encounter information were included. Stroke/TIA was identified by the first health care claim for these conditions any time prior to or within 90 days following the index ACS event.

RESULTS

Across all databases, between 3.8% and 15.7% of patients with ACS had prior stroke/TIA and between 3.4% and 11.7% of patients with ACS with no history of cerebrovascular events had documented stroke/TIA following the index ACS hospitalization.

CONCLUSION

Despite important differences between the various database populations, there is a high prevalence of documented stroke/TIA in patients with ACS both prior to and following the ACS event. These real-world findings, set within the context of the increased bleeding risk observed with the newer thienopyridines, are important considerations when selecting antiplatelet therapy for patients with ACS.