Long-term use of antiplatelet drugs by stroke patients: a follow-up study based on prescription register data

Disability Status and Secondary Prevention Among Survivors of Stroke: A Cross-Sectional Analysis of the 2011 to 2018 National Health and Nutrition Examination Survey

BACKGROUND

Among survivors of stroke, adherence to secondary prevention care is associated with decreased risk of recurrent stroke. However, not all survivors of stroke use secondary stroke prevention treatment. We examined the association between the disability status of survivors of stroke and their treatment and control of diabetes, hyperlipidemia, and hypertension.

METHODS AND RESULTS

In a cross-sectional analysis of the 2011 to 2018 National Health and Nutrition Examination Survey, we compared diabetes, hyperlipidemia, and hypertension treatment and control rates among self-reported survivors of stroke age ≥20 years with and without disability. Disability was defined as self-reporting any of 5 physical or 4 functional domains assessed using a structured questionnaire. Logistic regression models adjusted for age, sex, race and ethnicity, and history of medical conditions were used to estimate associations between disability status and risk factor treatment and control. The mean age of survivors of stroke was 65.1 years, and 55.5% were female; 76% (95% CI, 72.7%-79.3%) self-reported at least 1 disability. Age-standardized treatment rates for diabetes, hyperlipidemia, and hypertension were 33.1% (95% CI, 26.9%-39.2%), 67.5% (95% CI, 62.6%-72.3%), and 78.4% (95% CI, 74.6%-82.2%), respectively. Age-standardized control rates for diabetes, hyperlipidemia, and hypertension were 86.8% (95% CI, 83.8%-89.8%), 20.5% (95% CI, 15.0%-25.9%), and 47.1% (95% CI, 42.6%-51.7%), respectively. In adjusted models, those with and without disabilities had similar odds of risk factor treatment and control.

CONCLUSIONS

In the United States, three-quarters of survivors of stroke self-reported a disability, and these patients had similar odds of diabetes, hyperlipidemia, and hypertension treatment and control compared with those without disability.

Antiplatelet Treatment Patterns and Outcomes for Secondary Stroke Prevention in the United Kingdom

INTRODUCTION

Stroke is a leading cause of death and disability worldwide. Antiplatelet therapies are recommended to reduce the risk of recurrent stroke in patients with ischemic stroke/transient ischemic attack (IS/TIA). This study evaluated outpatient antiplatelet treatment patterns and outcomes for secondary stroke prevention (SSP) among UK adults without atrial fibrillation who were hospitalized for IS/TIA.

METHODS

This retrospective observational study utilized data from the UK Clinical Practice Research Datalink linked with Hospital Episode Statistics data (01/01/2011-30/06/2019). Treatment patterns included type and duration of treatments. Treatment outcomes included IS, myocardial infarction, major bleeding, and cardiovascular-related and all-cause mortality. Descriptive statistics were reported.

RESULTS

Of 9270 patients, 13.9% (1292) might not receive antithrombotic therapy within 90 days of hospital discharge. Of 7978 patients who received antiplatelet therapies, most used clopidogrel (74.8%) or aspirin (16.7%) single antiplatelet therapy and clopidogrel + aspirin dual antiplatelet therapy (DAPT, 5.9%). At 1-year post-hospitalization, 36.9, 43.3, and 35.1% of those receiving these treatments discontinued them, respectively, and of the patients initiating DAPT, 62.3% switched to single antiplatelet therapy. At 1-year post-discharge, the incidence rate (per 100 person-years) of IS, myocardial infarction, major bleeding, cardiovascular-related mortality, and all-cause mortality among the treated were 6.5, 0.7, 4.1, 5.0, and 7.3, respectively, and among the untreated were 14.9, 0.7, 8.6, 28.1, and 39.8, respectively.

CONCLUSIONS

In the United Kingdom, 13.9% of patients hospitalized for stroke might not have any antiplatelet treatment to prevent secondary stroke; among the treated, clopidogrel, aspirin, and DAPT were commonly used. These study findings suggest that improved anti-thrombotic therapies for long-term SSP treatment are needed, which may lead to higher treatment and persistence rates and, therefore, improved outcomes in this population.

Association of Statin Use With Risk of Stroke Recurrence After Intracerebral Hemorrhage

BACKGROUND AND OBJECTIVES

Survivors of spontaneous intracerebral hemorrhage (ICH) may have indications for statin therapy. The effect of statins on the risk of subsequent hemorrhagic and ischemic stroke (IS) in this setting is uncertain. We sought to determine the risk of any stroke (ischemic stroke, IS or recurrent ICH), IS, and recurrent ICH associated with statin use among ICH survivors.

METHODS

Using the Danish Stroke Registry, we identified all patients admitted to a hospital in Denmark (population 5.8 million) with a first-ever ICH between January 2003 and December 2021 who were aged 50 years or older and survived >30 days. Patients were followed up until August 2022. Within this cohort, we conducted 3 nested case-control analyses for any stroke, IS, and recurrent ICH. We matched controls for age, sex, time since first-ever ICH, and history of prior IS. The primary exposure was statin use before or on the date of subsequent stroke or the equivalent date in matched controls. Using conditional logistic regression, we calculated adjusted odds ratios (aORs) and corresponding 95% confidence intervals (CIs) for any stroke, IS, and recurrent ICH associated with statin exposure.

RESULTS

We identified 1,959 patients with any stroke (women 45.3%; mean [SD] age, 72.6 [9.7] years) who were matched to 7,400 controls; 1,073 patients with IS (women 42.0%; mean [SD] age, 72.4 [10.0] years) who were matched to 4,035 controls and 984 patients with recurrent ICH (women 48.7%; mean [SD] age, 72.7 [9.2] years) who were matched to 3,755 controls. Statin exposure was associated with a lower risk of both any stroke (cases 38.6%, controls 41.1%; aOR 0.88; 95% CI 0.78-0.99) and IS (cases 39.8%, controls 41.8%, aOR 0.79; 95% CI 0.67-0.92), but was not associated with recurrent ICH risk (cases 39.1%, controls 40.8%, aOR 1.05; 95% CI 0.88-1.24).

DISCUSSION

Exposure to statins was not associated with an increased risk of recurrent ICH but was associated with a lower risk of any stroke, largely due to a lower risk of IS. Confirmation of these findings in randomized trials is needed.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that statin use in patients with ICH is associated with a lower risk of any stroke and IS and not with increased risk of recurrent ICH.

Large-vessel-occlusion in patients with previous ischemic stroke: an analysis of adherence to secondary preventive medication for different etiologies

BACKGROUND

Large vessel occlusion (LVO) is a severe condition that carries a high risk of morbidity and mortality, underscoring the importance of effective prevention strategies. This retrospective study aimed to analyze the intake of preventive medication at the time of hospitalization in a cohort of recurrent stroke patients presenting with acute LVO.

METHODS

The study assessed the intake of either platelet aggregation inhibitors (PAI), oral anticoagulants (OAC) or statins at admission in patients with recurrent stroke and correlated it with the final classification of LVO. The frequency of those secondary preventive medication in recurrent stroke patients was defined as primary endpoint. The Modified Rankin Scale (mRS) at discharge was used as a functional outcome and defined as a secondary outcome measure.

RESULTS

This study included 866 patients who were treated for LVO between 2016 and 2020, of whom 160 (18.5%) had a recurrent ischemic stroke. OAC (25.6% vs. 14.1%, p < 0.01), PAI (50.0% vs. 26.0%, p < 0.01), or statin therapy (50.6% vs. 20.8%, p < 0.01) at admission were significantly more frequent in recurrent stroke patients compared to patients with a first-time stroke. Concerning LVO etiology in recurrent stroke patients, OAC at admission was taken in 46.8% of cardioembolic LVO, whereas PAI and statin at admission in macroangiopathic LVO were administered to 40.0%; neither PAI nor OAC was taken in 26.0%, 28.3%, and 31.6% of cardioembolic, macroangiopathic, or cryptogenic strokes, respectively. Regardless of stroke recurrence or etiology, there was an increase in mRS at discharge.

CONCLUSIONS

Despite high-quality healthcare, this study suggested a significant proportion of patients with recurrent stroke who were either non-adherent or insufficiently adherent to secondary preventive medication. Given the disability associated with LVO, improving patients' medication adherence and identifying unknown stroke causes are crucial for effective prevention strategies.

A data-informed approach using individualised dispensing patterns to estimate medicine exposure periods and dose from pharmaceutical claims data

Pharmaceutical claims data are often used as the primary information source to define medicine exposure periods in pharmacoepidemiological studies. However, often critical information on directions for use and the intended duration of medicine supply are not available. In the absence of this information, alternative approaches are needed to support the assignment of exposure periods. This study summarises the key methods commonly used to estimate medicine exposure periods and dose from pharmaceutical claims data; and describes a method using individualised dispensing patterns to define time-dependent estimates of medicine exposure and dose. This method extends on important features of existing methods and also accounts for recent changes in an individual's medicine use. Specifically, this method constructs medicine exposure periods and estimates the dose used by considering characteristics from an individual's prior dispensings, accounting for the time between prior dispensings and the amount supplied at prior dispensings. Guidance on the practical applications of this method is also provided. Although developed primarily for application to databases, which do not contain duration of supply or dose information, use of this method may also facilitate investigations when such information is available and there is a need to consider individualised and/or changing dosing regimens. By shifting the reliance on prescribed duration and dose to determine exposure and dose estimates, individualised dispensing information is used to estimate patterns of exposure and dose for an individual. Reflecting real-world individualised use of medicines with complex and variable dosing regimens, this method offers a pragmatic approach that can be applied to all medicine classes.

Antidepressant Fill and Dose Trajectories in Pregnant Women with Depression and/or Anxiety: A Norwegian Registry Linkage Study

Background

Few studies investigated longitudinal antidepressant exposure during pregnancy and included dosage in the assessment.

Methods

We conducted a nationwide, registry-linkage study in Norway using data on antidepressant prescription fills in pregnancies lasting ≥32 weeks in women with a delivery between 2009 and 2018 who had a depression/anxiety diagnosis and antidepressant fills prior to pregnancy. Information on antidepressant exposure by week (measured by filled prescriptions) and prescribed average daily dose was used in longitudinal k-means trajectory modelling for a 108-week time window from six months prior to pregnancy to one year after delivery. Factors associated with trajectory group membership were examined using multinomial logistic regression models.

Results

We included 8,460 pregnancies in 8,092 women. Four antidepressant fill trajectories were identified based on filled antidepressant prescriptions: two distinct discontinuing patterns, one at around the start of pregnancy (30.4%) and one around the end of pregnancy (33.8%); one continuing pattern (20.6%); and one interrupting pattern (15.2%). Using average usual daily dose, we identified low dose discontinuing (60.3%), medium dose reducing (20.6%) and high dose continuing (15.2%) patterns. The multinomial logistic regressions showed that the fill trajectory group membership was strongly associated with: antidepressant type and dose prior to pregnancy and co-medication prior to pregnancy, maternal age, marital status, parity, previous pregnancy loss, and pregnancy planning.

Conclusion

Longitudinal trajectory modelling revealed distinct antidepressant fill and dosage patterns in the period around pregnancy. Knowledge about factors associated with utilization trajectories might be useful for health-care personnel counselling women about antidepressant use in pregnancy.

Use of Complementary and Alternative Medicine and Adherence to Medication Therapy Among Stroke Patients: A Meta-analysis and Systematic Review

Purpose: To identify the use patterns of complementary and alternative medicine (CAM) and its impact on medication adherence among patients with stroke.

Method: A systematic search through Science Direct, Google Scholar, and PubMed was performed to identify potential studies up to June 2021.The primary outcome was CAM use, and the secondary outcome was medication adherence among patients with stroke. Articles included in the review met the following criteria: 1) patients with stroke ≥18 years old on prescribed medications, and 2) medication adherence reported status. Meta-analyses were conducted to estimate the pooled prevalence of complementary and alternative medicine and adherence in stroke patients using a random-effects model.

Results: A total of 1,330 studies were screened, of which 22 were included in the final analysis. The type of studies included were cross-sectional surveys, cohort studies, retrospective studies and prospective survey. The pooled prevalence of CAM usage was at 38% (29–48% CI) and medication non-adherence among stroke patients was at 29% (20–48% CI). The most common reason for inadequate stroke therapy and higher dependence on CAM was the patients’ lack of knowledge and the regimen complexity of the medication. Other factors for medication non-adherence were forgetfulness, side effects, cost, and lack of doctor-patient communication.

Conclusion: A low prevalence of CAM usage and non-adherence to medications was observed among patients with stroke. Studies investigating the association between CAM usage and medication adherence among patients with stroke are scarce and future researches are needed to explore the influence of CAM use on stroke medication adherence.

Factors associated with medication persistence among ischemic stroke patients: a systematic review

OBJECTIVE

An investigation of the prevalence of medication persistence and associated factors in order to inform effective strategies for improving medication persistence.

METHODS

A systematic review of the literature from 2010 to the present was performed, using the PRISMA protocol. Primary and empirical observational studies of adult ischemic stroke or transient ischemic attack patients were included. PubMed, CINAHL, Web of Science, Cochrane Library, and PsycInfo databases were searched using the key terms stroke, ischemic stroke, medication persistence, medication adherence, and patient compliance.

RESULTS

Of four hundred twenty-eight journal articles retrieved, a final 18 articles were included. Short-term medication persistence was 46.2-96.7%, and long-term medication persistence was 41.7-93.0%. Identified hospital-related factors for medication persistence were stroke unit care, in-hospital medical complications, and early follow-up visit. Demographic factors for medication persistence were older age, and high/adequate financial status; disease-related factors were disease history, stroke subtype, and symptom severity. Age less than 75, female sex, comorbidity, antiplatelet medication switch, and polypharmacy were identified as factors of medication nonpersistence.

CONCLUSIONS

Stroke patients' medication persistence decreases over time, and persistence on antiplatelets, anticoagulants, and statin was poor. Several factors were associated with medication persistence, and these factors should be considered in future secondary preventative strategies.

Post-stroke medication adherence and persistence rates: a meta-analysis of observational studies

BACKGROUND

Following a doctor's prescribed medication regimen is the key to prevent recurrent stroke and adverse outcomes. Many studies have investigated post-stroke drug adherence and persistence in patients. However, a comprehensive analysis of the data is lacking.

OBJECTIVES

A meta-analysis of published literature was conducted to summarize the ratio of medication adherence and persistence in patients after stroke.

METHODS

Relevant studies were identified by conducting a literature search using PubMed, EMBASE and Web of Science up to April 2019. We also reviewed the reference list of the retrieved articles to identify additional studies. We included observational studies that reported data on patients' medication adherence or persistence status, or the rate of medication adherence or persistence among patients with stroke could be calculated based on the information provided.

RESULTS

The overall high medication adherence rate of patients with stroke was 64.1% (95% CI: 57.4%-70.8%), and the persistence rate of patients with stroke was 72.2% (95% CI: 69.1%-75.3%). The highest persistence rate was observed in cohort studies which was 80.1% (95% CI: 76.7%-83.4%). The medication adherence rate was the highest in cases where the rates were assessed through interviews or self-reports (77.7% (95% CI: 71.3%-84.1%)).

CONCLUSIONS

Medication adherence and persistence rates are low in patients after suffering a stroke. Patient medication adherence or persistence and their influencing factors should be considered for the treatment of stroke patients. More detailed disease prevention and management strategies need to be developed for stroke patients with different comorbidities.

Development of a tool to support person-centred medicine-focused consultations with stroke survivors

OBJECTIVE

To develop a tool to support medicine-focused person-centred consultations between community pharmacists and stroke survivors.

METHOD

Semi-structured interviews with 15 stroke survivors and 16 community pharmacists were conducted. Thematic analysis of the data was performed and emerging themes examined to determine their relevance to the principles of delivering person-centred care. Findings were used to generate a framework from which a consultation tool was created. Face validity and the feasibility of using the tool in practice were explored with participating pharmacists.

RESULTS

Three major themes were identified; personal, process and environmental factors. A tool, in two parts, was developed, A 'Getting to know me' form which would help the pharmacist to appreciate the individual needs of the stroke survivor and a consultation guide to facilitate the consultation process. Pharmacists considered that both were useful and would support a person-centred medicine-focussed consultation.

CONCLUSION

A consultation tool, reflecting the needs of stroke survivors, has been developed and is feasible for use within community pharmacy practice.

PRACTICE IMPLICATIONS

Pharmacists must recognise the individual needs of stroke survivors to ensure that they provide consultations which are truly person-centred. The tool developed could support medicine-related consultations with patients with other long term conditions.

Using the "proportion of patients covered" and the Kaplan-Meier survival analysis to describe treatment persistence

PURPOSE

Standard Kaplan-Meier (KM) survival analysis is often used to study treatment persistence estimating the proportion of patients who have not yet experienced a treatment break by a given day after treatment initiation. This method only allows patients to be studied until their first treatment break. The "proportion of patients covered" (PPC) method is another approach to study treatment persistence. It measures the proportion of live patients currently covered by treatment. We aimed to describe the PPC method, show how the KM survival analysis and the PPC method can describe treatment persistence, and discuss the interpretation/application of the methods.

METHODS

We identified new users of statins, selective serotonin reuptake inhibitors, hormone replacement therapy, and ibuprofen. We used KM estimates and the PPC to describe persistence in the 3 years post treatment initiation, using a grace period of 90 days to define a treatment break.

RESULTS

Three years after statin initiation, approximately 40% of patients were still in continuous treatment (KM survival) and 60% of patients still alive were in current treatment (PPC). Corresponding numbers were 12% and 25% for selective serotonin reuptake inhibitors and 9% and 29% for hormone replacement therapy. At 1 year, numbers were 5% and 10% for ibuprofen. The PPC showed markedly less variability than the KM survival analysis with different choices of grace periods.

CONCLUSIONS

The KM survival analysis and the PPC method can be used to study different aspects of treatment persistence. Together, they provide a more complete picture of treatment persistence and drug use patterns.

Non-persistence with antiplatelet therapy in elderly patients after a transient ischemic attack

BACKGROUND

Antiplatelet therapy following a transient ischemic attack (TIA) constitutes an important secondary prevention measure.

AIMS

The study was aimed at evaluating the development of non-persistence with antiplatelet therapy in elderly patients after a TIA and identifying patient-related characteristics associated with the probability of non-persistence during the follow-up period.

METHODS

The study cohort (n = 854) was selected from the database of the largest health insurance provider of the Slovak Republic. It included patients aged ≥65 years, in whom antiplatelet medication was initiated following a TIA diagnosis during the period between 1 January 2010 and 31 December 2010. Each patient was followed for a period of 3 years from the date of the first antiplatelet medication prescription associated with TIA diagnosis. Patients in whom there was a treatment gap of at least 6 months without antiplatelet medication prescription were defined as "non-persistent". The factors predicting non-persistence were identified in the Cox proportional hazards model.

RESULTS

At the end of the follow-up period, 345 (40.4%) patients were non-persistent with antiplatelet medication. Protective factors decreasing a patient´s likelihood of becoming non-persistent were age ≥75 years [hazard ratio (HR) = 0.75], polypharmacy (concurrent use of ≥6 drugs) (HR = 0.79), arterial hypertension (HR = 0.68), diabetes mellitus (HR = 0.74), hypercholesterolemia (HR = 0.75), and antiplatelet medication switching during the follow-up period (HR = 0.73).

CONCLUSIONS

It is concluded that following a TIA, elderly patients aged <75 years or those with normal serum cholesterol levels, without certain comorbid conditions and polypharmacy may benefit from special counselling to encourage persistence with secondary preventive medication.

Drug exposure in register-based research-An expert-opinion based evaluation of methods

Background

In register-based pharmacoepidemiological studies, construction of drug exposure periods from drug purchases is a major methodological challenge. Various methods have been applied but their validity is rarely evaluated. Our objective was to conduct an expert-opinion based evaluation of the correctness of drug use periods produced by different methods.

Methods

Drug use periods were calculated with three fixed methods: time windows, assumption of one Defined Daily Dose (DDD) per day and one tablet per day, and with PRE2DUP that is based on modelling of individual drug purchasing behavior. Expert-opinion based evaluation was conducted with 200 randomly selected purchase histories of warfarin, bisoprolol, simvastatin, risperidone and mirtazapine in the MEDALZ-2005 cohort (28,093 persons with Alzheimer’s disease). Two experts reviewed purchase histories and judged which methods had joined correct purchases and gave correct duration for each of 1000 drug exposure periods.

Results

The evaluated correctness of drug use periods was 70–94% for PRE2DUP, and depending on grace periods and time window lengths 0–73% for tablet methods, 0–41% for DDD methods and 0–11% for time window methods. The highest rate of evaluated correct solutions for each method class were observed for 1 tablet per day with 180 days grace period (TAB_1_180, 43–73%), and 1 DDD per day with 180 days grace period (1–41%). Time window methods produced at maximum only 11% correct solutions. The best performing fixed method TAB_1_180 reached highest correctness for simvastatin 73% (95% CI 65–81%) whereas 89% (95% CI 84–94%) of PRE2DUP periods were judged as correct.

Conclusions

This study shows inaccuracy of fixed methods and the urgent need for new data-driven methods. In the expert-opinion based evaluation, the lowest error rates were observed with data-driven method PRE2DUP.

Predictive factors of non-adherence to secondary preventative medication after stroke or transient ischaemic attack: A systematic review and meta-analyses

Purpose

Non-adherence to secondary preventative medications after stroke is relatively common and associated with poorer outcomes. Non-adherence can be due to a number of patient, disease, medication or institutional factors. The aim of this review was to identify factors associated with non-adherence after stroke.

Method

We performed a systematic review and meta-analysis of studies reporting factors associated with medication adherence after stroke. We searched MEDLINE, EMBASE, CINAHL, PsycINFO, CENTRAL and Web of Knowledge. We followed PRISMA guidance. We assessed risk of bias of included studies using a pre-specified tool based on Cochrane guidance and the Newcastle–Ottawa scales. Where data allowed, we evaluated summary prevalence of non-adherence and association of factors commonly reported with medication adherence in included studies using random-effects model meta-analysis.

Findings

From 12,237 titles, we included 29 studies in our review. These included 69,137 patients. The majority of included studies (27/29) were considered to be at high risk of bias mainly due to performance bias. Non-adherence rate to secondary preventative medication reported by included studies was 30.9% (95% CI 26.8%–35.3%). Although many factors were reported as related to adherence in individual studies, on meta-analysis, absent history of atrial fibrillation (OR 1.02, 95% CI 0.72–1.5), disability (OR 1.27, 95% CI 0.93–1.72), polypharmacy (OR 1.29, 95% CI 0.9–1.9) and age (OR 1.04, 95% CI 0.96–1.14) were not associated with adherence.

Discussion

This review identified many factors related to adherence to preventative medications after stroke of which many are modifiable. Commonly reported factors included concerns about treatment, lack of support with medication intake, polypharmacy, increased disability and having more severe stroke.

Conclusion

Understanding factors associated with medication taking could inform strategies to improve adherence. Further research should assess whether interventions to promote adherence also improve outcomes.

From prescription drug purchases to drug use periods – a second generation method (PRE2DUP)

BACKGROUND

Databases of prescription drug purchases are now widely used in pharmacoepidemiologic studies. Several methods have been used to generate drug use periods from drug purchases to investigate various aspects; e.g., to study associations between exposure and outcome. Typically, such methods have been fairly simplistic, with fixed assumptions of drug use pattern and or dose (for example, the assumed usage of 1 tablet per day). This paper describes a novel PRE2DUP method that constructs drug use periods from purchase histories, and verified by a validation based on an expert evaluation of the drug use periods generated by the method.

METHODS

The PRE2DUP method is a novel approach based on mathematical modelling of personal drug purchasing behaviors. The method uses a decision procedure that includes each person's purchase history for each ATC code, processed in a chronological order. The method constructs exposure time periods and estimates the dose used during the period by considering the purchased amount in Defined Daily Doses (DDDs), which is recorded in the prescription register database. This method takes account of stockpiling of drugs, personal purchasing pattern; i.e., regularity of the purchases, and periods of hospital or nursing home care where drug use is not recorded in the prescription register. The method can be applied to a variety of drug classes with different doses and use patterns by controlling restriction parameters for each ATC class, or even each drug package. In the presented example, the PRE2DUP method was applied to a register-based MEDALZ-2005 study cohort. All drug purchases (3,793,085) recorded in the Finnish prescription register between 2002 and 2009 for persons with Alzheimer's disease (28,093) were included.

RESULTS

Results of the expert-opinion based validation indicate that PRE2DUP method creates drug use periods with a relatively high correctness. Drugs with varying patterns of use and drugs used on a short-term basis only require more precise parameters.

CONCLUSIONS

PRE2DUP method gives highly accurate drug use periods for most drug classes, especially those meant for long-term use.

Generic switching and non-persistence among medicine users: a combined population-based questionnaire and register study

BACKGROUND

Generic substitution means that one medicinal product is replaced by another product containing the same active substance. It is strictly regulated with respect to its bioequivalence, and all products must have undergone appropriate studies. Although generic substitution is widely implemented, it still remains to be answered how generic switch influences persistence to long-term treatment, and if it is modified by patients' concerns about medicine and views on generic medicine. This study focuses on users of antidepressants and antiepileptics, and their experience of generic switching.

METHODS

The study was an observational cohort study. By use of a prescription database, we identified patients who had redeemed prescriptions on generically substitutable drugs, and a questionnaire was mailed to them. We analyzed predictors of discontinuation in relation to generic switch and patients' attitudes towards generic medicines and concerns about their medicine.

RESULTS

Patients who experience their first-time switch of a specific drug were at higher risk of non-persistence, Hazard Ratio 2.98, 95% CI (1.81;4.89) versus those who have never switched, and 35.7% became non-persistent during the first year of follow-up. Generic switching did not influence persistence considerably in those having previous experience with generic switching of the specific drug. Stratified analyses on users of antidepressants and antiepileptics underpin the results, showing higher risk of non-persistence for first-time switchers for both drug categories.

CONCLUSION

In conclusion, patients who are first-time switchers of a specific drug were at higher risk of non-persistence compared to never switchers and those having experienced previous generic switching.

Discontinuation of antiplatelet treatment and risk of recurrent stroke and all-cause death: a cohort study

BACKGROUND

We wished to examine the impact of antiplatelet drug discontinuation on recurrent stroke and all-cause mortality.

METHODS

We identified a cohort of incident ischaemic stroke patients in a Danish stroke registry, 2007-2011. Using population-based registries we assessed subjects' drug use and followed them up for stroke recurrence, or all-cause death. Person-time was classified by antiplatelet drug use into current use, recent use (≤150 days after last use), and non-use (>150 days after last use). Lipid-lowering drug (LLD) use was classified by the same rules. We used Cox proportional hazard models to calculate the adjusted hazard ratio (HR) and corresponding 95% confidence intervals (CIs) for the risk of recurrent stroke or death associated with discontinuation of antiplatelet or LLD drugs.

RESULTS

Among 4,670 stroke patients followed up for up a median of 1.5 years, 237 experienced a second stroke and 600 died. Compared with current antiplatelet drug use, both recent use (1.3 (0.8-2.0)), and non-use (1.3 (0.8-1.9)) were associated with increased recurrent stroke risk. The corresponding HRs of death were 1.9 (1.4-2.5) for recent and 1.8 (1.4-2.3) for non-use of antiplatelet drugs. Recent statin use was associated with markedly increased risk of death (2.1 (1.7-2.6)), and only marginally with recurrent stroke (1.2 (0.9-1.6)).

CONCLUSIONS

Antiplatelet drug discontinuation may be associated with an increased recurrent stroke risk. Our results on death risk indicate that non-pharmacological biases, such as 'sick stopper', may threaten the validity of this risk estimate.

Long-term use of antiplatelet drugs by patients with transient ischaemic attack

PURPOSE

To determine the degree of long-term non-persistence to antiplatelet drugs in patients with transient ischaemic attack (TIA) and identify determinants of this drug-use pattern.

METHODS

We used community-based prescription registry data to determine antiplatelet drug use in TIA patients presenting to a Danish neurology department in the period 2006-2010. Non-persistence was defined as failure to present a prescription for antiplatelet drugs within 180 days after the dosage of a previous prescription had run out. We used Cox regression to calculate the hazard ratio (HR) for non-persistence and the corresponding 95 % confidence interval (CI) by potential determinants, including a stroke risk score (ABCD2 score). Adherence during follow-up [80 % medication possession ratio (MPR80)] was calculated for antiplatelets, statins and antihypertensive drugs.

RESULTS

The cohort comprised 594 (84 % evaluated as in-patients) TIA patients. During follow-up (median 1.7 years, interquartile range 0.9-3.0 years), 140 (23.6 %) patients became non-persistent. Non-persistence was associated with younger age (<55 years: HR 1.9, 95 % CI 1.3-2.8) and delay between TIA onset and neurological evaluation (7+ days: HR 2.0, 95 % CI 1.0-4.1). Among admitted patients, a higher ABCD2 score (4+: HR 1.3, 95 % CI 0.8-2.1) was also indicative of non-persistence. Non-persistent users were less adherent to other preventive medication (MPR80: statins 31.8 vs. 75.3 %, p value < 0.001; antihypertensives 64.3 vs. 79.5 %, p value: 0.02) than persistent users.

CONCLUSION

Long-term antiplatelet non-persistence was most pronounced in patients of younger age, those with delayed evaluation of symptoms and those at greater risk of stroke. It was also associated with a lower adherence to preventive medication in general.