Optimising case detection within UK electronic health records: use of multiple linked databases for detecting liver injury

OBJECTIVES

We aimed to create a 'multidatabase' algorithm for identification of cholestatic liver injury using multiple linked UK databases, before (1) assessing the improvement in case ascertainment compared to using a single database and (2) developing a new single-database case-definition algorithm, validated against the multidatabase algorithm.

DESIGN

Method development for case ascertainment.

SETTING

Three UK population-based electronic health record databases: the UK Clinical Practice Research Datalink (CPRD), the UK Hospital Episodes Statistics (HES) database and the UK Office of National Statistics (ONS) mortality database.

PARTICIPANTS

16 040 people over the age of 18 years with linked CPRD-HES records indicating potential cholestatic liver injury between 1 January 2000 and 1 January 2013.

PRIMARY OUTCOME MEASURES

(1) The number of cases of cholestatic liver injury detected by the multidatabase algorithm. (2) The relative contribution of each data source to multidatabase case status. (3) The ability of the new single-database algorithm to discriminate multidatabase algorithm case status.

RESULTS

Within the multidatabase case identification algorithm, 4033 of 16 040 potential cases (25%) were identified as definite cases based on CPRD data. HES data allowed possible cases to be discriminated from unlikely cases (947 of 16 040, 6%), but only facilitated identification of 1 definite case. ONS data did not contribute to case definition. The new single-database (CPRD-only) algorithm had a very good ability to discriminate multidatabase case status (area under the receiver operator characteristic curve 0.95).

CONCLUSIONS

CPRD-HES-ONS linkage confers minimal improvement in cholestatic liver injury case ascertainment compared to using CPRD data alone, and a multidatabase algorithm provides little additional information for validation of a CPRD-only algorithm. The availability of laboratory test results within CPRD but not HES means that algorithms based on CPRD-HES-linked data may not always be merited for studies of liver injury, or for other outcomes relying primarily on laboratory test results.

Statins and Risk of Lower Limb Revision Surgery: The Influence of Differences in Study Design Using Electronic Health Records From the United Kingdom and Denmark

Previous observational studies on statins have shown variable results based on the methodology used. Our objective was to study the association between statins and orthopedic implant failure and to explore the influence of methodological differences in study design. Our study base consisted of patients with a primary total joint replacement in Denmark and the United Kingdom (n = 189,286; 1987–2012). We used 4 study designs: 1) case-control (each patient with revision surgery matched to 4 controls), 2) time-dependent cohort (postoperative statin use as a time-varying exposure variable), 3) immortal time cohort (misclassifying the time postoperatively before statin use), and 4) time-exclusion cohort (excluding the time postoperatively before statin use). Cox proportional hazards models and logistic regression were used to estimate incidence rate ratios. In the time-dependent cohort design, statin use was associated with a decreased risk of revision surgery (adjusted incidence rate ratio (IRR) = 0.90, 95% confidence interval (CI): 0.85, 0.96), which was similar to our case-control results (IRR = 0.87, 95% CI: 0.81, 0.93). In contrast, both time-fixed cohort designs yielded substantially lower risk estimates (IRR = 0.36 (95% CI: 0.34, 0.38) and IRR = 0.65 (95% CI: 0.63, 0.68), respectively). We discourage the use of time-fixed cohort studies, which may falsely suggest protective effects. The simple choice of how to classify exposure can substantially change results from biologically plausible to implausible.

Insulin glargine use and breast cancer risk: Associations with cumulative exposure

BACKGROUND

This study was aimed to assess the risk of breast cancer associated with exposure to insulin glargine in women with type 2 diabetes and evaluate whether the pattern of risk concurs with the hypothesized trend of an increase in risk with longer duration of use, taking into account previous cumulative exposure to other types of insulin.

METHODS

We performed a restrospective cohort study (2002-2013) in the Clinical Practice Research Datalink among adult female patients with a first ever insulin prescription (n = 12 468). Time-dependent exposure measures were used to assess associations with duration of use of: (1) other insulin types before glargine was first prescribed (i.e. among switchers); and (2) of glargine during follow-up. Analyses were performed separately for insulin-naïve glargine users and patients switched to glargine. Cox proportional hazards models were used to derive p-trends, hazard ratios (HR) and 95% confidence intervals (CI) for breast cancer associated with glargine use.

RESULTS

During 66 151 person years, 186 breast cancer cases occurred; 76 in glargine users (3.0/1000 years) and 110 in users of other insulins (2.7/1000 years). Among insulin-naïve women, no association with cumulative glargine use was observed (p-trend = 0.91), even after ≥5 years (HR = 1.06, 95% CI 0.48-2.33). Among switchers, a linear trend with years of prior exposure to other insulins was found (p-trend = 0.02). An increased risk was observed in glargine users with extensive (>3 years) past exposure to other insulins (HR = 3.17, 95% CI 1.28-7.84). A non-significant trend with cumulative glargine exposure was found among switchers (p-trend = 0.24).

CONCLUSIONS

Exposure to glargine was not associated with an increased breast cancer risk in insulin-naïve patients. Exposure to other insulins prior to the start of glargine appears to be relevant when studying breast cancer risk associated with glargine use.

Epidemiology of fractures in the United Kingdom 1988-2012: Variation with age, sex, geography, ethnicity and socioeconomic status

Rates of fracture worldwide are changing. Using the Clinical Practice Research Datalink (CPRD), age, and gender, geographical, ethnic and socioeconomic trends in fracture rates across the United Kingdom were studied over a 24-year period 1988-2012. Previously observed patterns in fracture incidence by age and fracture site were evident. New data on the influence of geographic location, ethnic group and socioeconomic status were obtained.

INTRODUCTION

With secular changes in age- and sex-specific fracture incidence observed in many populations, and global shifts towards an elderly demography, it is vital for health care planners to have an accurate understanding of fracture incidence nationally. We aimed to present up to date fracture incidence data in the UK, stratified by age, sex, geographic location, ethnicity and socioeconomic status.

METHODS

The Clinical Practice Research Datalink (CPRD) contains anonymised electronic health records for approximately 6.9% of the UK population. Information comes from General Practitioners, and covers 11.3 million people from 674 practices across the UK, demonstrated to be representative of the national population. The study population consisted of all permanently registered individuals aged ≥18years. Validated data on fracture incidence were obtained from their medical records, as was information on socioeconomic deprivation, ethnicity and geographic location. Age- and sex-specific fracture incidence rates were calculated.

RESULTS

Fracture incidence rates by age and sex were comparable to those documented in previous studies and demonstrated a bimodal distribution. Substantial geographic heterogeneity in age- and sex adjusted fracture incidence was observed, with rates in Scotland almost 50% greater than those in London and South East England. Lowest rates of fracture were observed in black individuals of both sexes; rates of fragility fracture in white women were 4.7 times greater than in black women. Strong associations between deprivation and fracture risk were observed in hip fracture in men, with a relative risk of 1.3 (95% CI 1.21-1.41) in Index of Multiple Deprivation category 5 (representing the most deprived) compared to category 1.

CONCLUSIONS

This study presents robust estimates of fracture incidence across the UK, which will aid decisions regarding allocation of healthcare provision to populations of greatest need. It will also assist the implementation and design of strategies to reduce fracture incidence and its personal and financial impact on individuals and health services.

Predictors and outcomes of increases in creatine phosphokinase concentrations or rhabdomyolysis risk during statin treatment

AIM

The aim was to evaluate clinical risk factors associated with myotoxicity in statin users.

METHODS

This was a cohort study of patients prescribed a statin in UK primary care practices contributing to the Clinical Practice Research Datalink. Outcomes of interest were creatine phosphokinase (CPK) concentrations and clinical records of rhabdomyolysis.

RESULTS

The cohort comprised 641,703 statin users. Simvastatin was most frequently prescribed (66.3%), followed by atorvastatin (24.4%). CPK was measured in 127,209 patients: 81.4% within normal range and 0.7% above <four times the upper limit of normal (ULN). Rhabdomyolysis was recorded in 59 patients. Patients with concomitant prescribing of CYP3A4-interacting drugs had an increased odds ratio (OR) of rhabdomyolysis compared with controls (OR 3.71, 95% CI 1.18, 11.61) and >four times ULN CPK compared with normal CPK (OR 1.28, 95% CI 1.01, 1.60). Rosuvastatin users had higher risk of >four times ULN CPK (OR 1.62, 95% CI 1.22, 2.15) as did patients with larger daily doses of other statin types. A recent clinical record of myalgia was associated with an increased OR of >four times ULN CPK (OR 1.73, 95% CI 1.37, 2.18). In patients who were rechallenged to statins and had repeat CPK measurements after >four times ULN CPK abnormalities, 54.8% of the repeat CPK values were within normal range, 32.1% between one to three times and 13.0% >four times ULN.

CONCLUSIONS

The frequencies of substantive CPK increases and rhabdomyolysis during statin treatment were low, with highest risks seen in those on large daily doses or interacting drugs and on rosuvastatin. CPK measurements appeared to have been done in a haphazard manner and better guidance is needed.

Bridging differences in outcomes of pharmacoepidemiological studies: design and first results of the PROTECT project

Background:

Observational pharmacoepidemiological (PE) studies on drug safety have produced discrepant results that may be due to differences in design, conduct and analysis.

Purpose:

The pharmacoepidemiology work-package (WP2) of the Pharmacoepidemiological Research on Outcomes of Therapeutics by a European ConsorTium (PROTECT) project aims at developing, testing and disseminating methodological standards for design, conduct and analysis of pharmacoepidemiological studies applicable to different safety issues using different databases across European countries. This article describes the selection of the safety issues and the description of the databases to be systematically studied.

Methods:

Based on two consensus meetings and a literature search, we selected five drug-adverse event (AE) pairs to be evaluated in different databases. This selection was done according to pre-defined criteria such as regulatory and public health impact, and the potential to investigate a broad range of methodological issues.

Results:

The selected drug-AE pairs are: 1) inhaled long-acting beta-2 agonists and acute myocardial infarction; 2) antimicrobials and acute liver injury; 3) antidepressants and/or benzodiazepines and hip fracture; 4) anticonvulsants and suicide/suicide attempts; and 5) calcium channel blockers and malignancies. Six European databases, that will be used to evaluate the drug-AE pairs retrospectively, are also described.

Conclusion:

The selected drug-AE pairs will be evaluated in PE studies using common protocols. Based on consistencies and discrepancies of these studies, a framework for guiding methodological choices will be developed. This will increase the usefulness and reliability of PE studies for benefit-risk assessment and decision-making.

Performance of prior event rate ratio adjustment method in pharmacoepidemiology: a simulation study

PURPOSE

Prior event rate ratio (PERR) adjustment method has been proposed to control for unmeasured confounding. We aimed to assess the performance of the PERR method in realistic pharmacoepidemiological settings.

METHODS

Simulation studies were performed with varying effects of prior events on the probability of subsequent exposure and post-events, incidence rates, effects of confounders, and rate of mortality/dropout. Exposure effects were estimated using conventional rate ratio (RR) and PERR adjustment method (i.e. ratio of RR post-exposure initiation and RR prior to initiation of exposure).

RESULTS

In the presence of unmeasured confounding, both conventional and the PERR method may yield biased estimates, but PERR estimates appear generally less biased estimates than the conventional method. However, when prior events strongly influence the probability of subsequent exposure, the exposure effect from the PERR method was more biased than the conventional method. For instance, when the effect of prior events on the exposure was RR = 1.60, the effect estimate from the PERR method was RR = 1.13 and from the conventional method was RR = 2.48 (true exposure effect, RR = 2). In all settings, the variation of the estimates was larger for the PERR method than for the conventional method.

CONCLUSION

The PERR adjustment method can be applied to reduce bias as a result of unmeasured confounding. However, only in particular situations, it can completely remove the bias as a result of unmeasured confounding. When applying this method, theoretical justification using available clinical knowledge for assumptions of the PERR method should be provided.

Benefit-risk assessment in a post-market setting: a case study integrating real-life experience into benefit-risk methodology

PURPOSE

Difficulties may be encountered when undertaking a benefit-risk assessment for an older product with well-established use but with a benefit-risk balance that may have changed over time. This case study investigates this specific situation by applying a formal benefit-risk framework to assess the benefit-risk balance of warfarin for primary prevention of patients with atrial fibrillation.

METHODS

We used the qualitative framework BRAT as the starting point of the benefit-risk analysis, bringing together the relevant available evidence. We explored the use of a quantitative method (stochastic multi-criteria acceptability analysis) to demonstrate how uncertainties and preferences on multiple criteria can be integrated into a single measure to reduce cognitive burden and increase transparency in decision making.

RESULTS

Our benefit-risk model found that warfarin is favourable compared with placebo for the primary prevention of stroke in patients with atrial fibrillation. This favourable benefit-risk balance is fairly robust to differences in preferences. The probability of a favourable benefit-risk for warfarin against placebo is high (0.99) in our model despite the high uncertainty of randomised clinical trial data. In this case study, we identified major challenges related to the identification of relevant benefit-risk criteria and taking into account the diversity and quality of evidence available to inform the benefit-risk assessment.

CONCLUSION

The main challenges in applying formal methods for medical benefit-risk assessment for a marketed drug are related to outcome definitions and data availability. Data exist from many different sources (both randomised clinical trials and observational studies), and the variability in the studies is large.

Cluster randomized trials utilizing primary care electronic health records: methodological issues in design, conduct, and analysis (eCRT Study)

Background

There is growing interest in conducting clinical and cluster randomized trials through electronic health records. This paper reports on the methodological issues identified during the implementation of two cluster randomized trials using the electronic health records of the Clinical Practice Research Datalink (CPRD).

Methods

Two trials were completed in primary care: one aimed to reduce inappropriate antibiotic prescribing for acute respiratory infection; the other aimed to increase physician adherence with secondary prevention interventions after first stroke. The paper draws on documentary records and trial datasets to report on the methodological experience with respect to research ethics and research governance approval, general practice recruitment and allocation, sample size calculation and power, intervention implementation, and trial analysis.

Results

We obtained research governance approvals from more than 150 primary care organizations in England, Wales, and Scotland. There were 104 CPRD general practices recruited to the antibiotic trial and 106 to the stroke trial, with the target number of practices being recruited within six months. Interventions were installed into practice information systems remotely over the internet. The mean number of participants per practice was 5,588 in the antibiotic trial and 110 in the stroke trial, with the coefficient of variation of practice sizes being 0.53 and 0.56 respectively. Outcome measures showed substantial correlations between the 12 months before, and after intervention, with coefficients ranging from 0.42 for diastolic blood pressure to 0.91 for proportion of consultations with antibiotics prescribed, defining practice and participant eligibility for analysis requires careful consideration.

Conclusions

Cluster randomized trials may be performed efficiently in large samples from UK general practices using the electronic health records of a primary care database. The geographical dispersal of trial sites presents a difficulty for research governance approval and intervention implementation. Pretrial data analyses should inform trial design and analysis plans.

Trial registration

Current Controlled Trials ISRCTN 47558792 and ISRCTN 35701810 (both registered on 17 March 2010).

Point-of-care cluster randomized trial in stroke secondary prevention using electronic health records

BACKGROUND AND PURPOSE

The aim of this study was to evaluate whether the remote introduction of electronic decision support tools into family practices improves risk factor control after first stroke. This study also aimed to develop methods to implement cluster randomized trials in stroke using electronic health records.

METHODS

Family practices were recruited from the UK Clinical Practice Research Datalink and allocated to intervention and control trial arms by minimization. Remotely installed, electronic decision support tools promoted intensified secondary prevention for 12 months with last measure of systolic blood pressure as the primary outcome. Outcome data from electronic health records were analyzed using marginal models.

RESULTS

There were 106 Clinical Practice Research Datalink family practices allocated (intervention, 53; control, 53), with 11 391 (control, 5516; intervention, 5875) participants with acute stroke ever diagnosed. Participants at trial practices had similar characteristics as 47,887 patients with stroke at nontrial practices. During the intervention period, blood pressure values were recorded in the electronic health records for 90% and cholesterol values for 84% of participants. After intervention, the latest mean systolic blood pressure was 131.7 (SD, 16.8) mm Hg in the control trial arm and 131.4 (16.7) mm Hg in the intervention trial arm, and adjusted mean difference was -0.56 mm Hg (95% confidence interval, -1.38 to 0.26; P=0.183). The financial cost of the trial was approximately US $22 per participant, or US $2400 per family practice allocated.

CONCLUSIONS

Large pragmatic intervention studies may be implemented at low cost by using electronic health records. The intervention used in this trial was not found to be effective, and further research is needed to develop more effective intervention strategies.

CLINICAL TRIAL REGISTRATION URL

http://www.controlled-trials.com. Current Controlled Trials identifier: ISRCTN35701810.

Population-based cohort study of warfarin-treated patients with atrial fibrillation: incidence of cardiovascular and bleeding outcomes

OBJECTIVES

Atrial fibrillation (AF) is the most common cardiac rhythm disorder with a significant health burden. The aim of this study was to characterise patients with recently diagnosed AF and to estimate the rates of comorbidities and outcome events requiring hospitalisation in routine clinical practice.

DESIGN

Pharmacoepidemiological cohort study using observational data.

METHODS/SETTING

This study included 16 513 patients with a first diagnosis of AF between 1 January 2005 and 28 February 2010 (newly diagnosed patients) using data from the UK Clinical Practice Research Datalink (CPRD) linked to Hospital Episode Statistics (HES) and the Office for National Statistics mortality data. Exposure was stratified by vitamin K antagonist (VKA) exposure (non-use, current, recent and past exposure) based on prescriptions and/or international normalised ratio measurements, and followed for outcome events of interest based on diagnosis codes in the databases, that is, vascular outcomes, bleeding events and others. The main focus of the study was on outcome events requiring hospitalisation using the HES data.

RESULTS

The incidence of vascular outcome hospitalisations (myocardial infarction (MI), stroke or systemic arterial peripheral embolism) was 3.8 (95% CI 3.5 to 4.0)/100 patient-years. The incidence of stroke was 0.9 (0.8 to 1.1) during current VKA exposure, 2.2 (1.6 to 2.9) for recent, 2.4 (1.9 to 2.9) for past and 3.4 (3.1 to 3.7) during non-use. MI incidence was 0.7 (0.6 to 0.9) for current VKA exposure, 0.7 (0.4 to 1.2) for recent, 1.1 (0.8 to 1.5) for past and 1.9 (1.7 to 2.1) during non-use. The incidence of bleeding event hospitalisations was 3.8 (3.4 to 4.2) for current VKA exposure, 4.5 (3.7 to 5.5) for recent, 2.7 (2.2 to 3.3) for past and 2.9 (2.6 to 3.2) during non-use; 38% of intracranial bleeds and 6% of gastrointestinal bleeds were fatal.

CONCLUSIONS

This population-based study from recent years provides a comprehensive characterisation of newly diagnosed patients with AF and incidence estimates of common outcomes with a focus on hospitalised events stratified by VKA exposure. This study will help to place future data on new oral anticoagulants into perspective.

Patterns of risk of cancer in patients with metal-on-metal hip replacements versus other bearing surface types: a record linkage study between a prospective joint registry and general practice electronic health records in England

Background

There are concerns that metal-on-metal hip implants may cause cancer. The objective of this study was to evaluate patterns and timing of risk of cancer in patients with metal-on-metal total hip replacements (THR).

Methods

In a linkage study between the English National Joint Registry (NJR) and the Clinical Practice Research Datalink (CPRD), we selected all THR surgeries (NJR) between 2003 and 2010 (n = 11,540). THR patients were stratified by type of bearing surface. Patients were followed up for cancer and Poisson regression was used to derive adjusted relative rates (RR).

Results

The risk of cancer was similar in patients with hip resurfacing (RR 0.69; 95% Confidence Interval [CI] 0.39–1.22) or other types of bearing surfaces (RR 0.96; 95% CI 0.64–1.43) compared to individuals with stemmed metal-on-metal THR. The pattern of cancer risk over time did not support a detrimental effect of metal hip implants. There was substantial confounding: patients with metal-on-metal THRs used fewer drugs and had less comorbidity.

Conclusions

Metal-on-metal THRs were not associated with an increased risk of cancer. There were substantial baseline differences between the different hip implants, indicating possibility of confounding in the comparisons between different types of THR implants.

Timing of acute myocardial infarction in patients undergoing total hip or knee replacement: a nationwide cohort study

BACKGROUND

Limited evidence suggests that the risk of acute myocardial infarction (AMI) may be increased shortly after total hip replacement (THR) and total knee replacement (TKR) surgery. However, risk of AMI in these patients has not been compared against matched controls who have not undergone surgery. The objective of this study was to evaluate the timing of AMI in patients undergoing THR or TKR surgery compared with matched controls.

METHODS

Retrospective, nationwide cohort study within the Danish national registries. All patients who underwent a primary THR or TKR (n = 95,227) surgery from January 1, 1998, through December 31, 2007, were selected and matched to 3 controls (no THR or TKR) by age, sex, and geographic region. All study participants were followed up for AMI, and disease- and medication history-adjusted hazard ratios (HRs) were calculated.

RESULTS

During the first 2 postoperative weeks, the risk of AMI was substantially increased in THR patients compared with controls (adjusted HR, 25.5; 95% CI, 17.1-37.9). The risk remained elevated for 2 to 6 weeks after surgery (adjusted HR, 5.05; 95% CI, 3.58-7.13) and then decreased to baseline levels. For TKR patients, AMI risk was also increased during the first 2 weeks (adjusted HR, 30.9; 95% CI, 11.1-85.5) but did not differ from controls after the first 2 weeks. The absolute 6-week risk of AMI was 0.51% in THR patients and 0.21% in TKR patients.

CONCLUSIONS

Risk of AMI is substantially increased in the first 2 weeks after THR (25-fold) and TKR (31-fold) surgery compared with controls. Risk assessment of AMI should be considered during the first 6 weeks after THR surgery and during the first 2 weeks after TKR surgery.

Resource utilization and outcomes in patients with atrial fibrillation: a case control study

BACKGROUND

Atrial fibrillation (AF) is the most common sustained disorder of cardiac rhythm. Various new anticoagulation and antiarrythmic treatments are being investigated for the treatment of AF. Before novel treatments can be used widely in actual clinical practice, the cost effectiveness of such novel treatments may need to be determined.

OBJECTIVE

The objectives of the study were to describe resource utilization for AF and control patients, and estimate the incidence of mortality.

METHODS

This case control study evaluated 6 months of primary and secondary care resource utilization and mortality rates for patients within the period 01 April 2001 to 31 March 2006. Cases included 15 373 adults with a record of AF in the General Practice Research Database (GPRD) within the study period. The index date was randomly selected between 6 months after the AF record and end of data collection. Cases were matched to controls by age, gender, general practice and time.

RESULTS

AF patients had significantly higher resource utilization than controls. Resource utilization increased with greater National Institute for Clinical Excellence (NICE) stroke risk strata (graded as low, moderate or high based on associated risk factors). Both current warfarin and aspirin users had higher resource utilization than control patients. Resource utilization remained high amongst AF patients who discontinued therapy. The mortality rate was significantly higher in AF patients than controls, deaths due to circulatory system disease were increased 4-fold and cancer deaths were doubled. All-cause and circulatory mortality rates, as well as rates of clinical outcomes, were related to the NICE stroke risk schema.

CONCLUSIONS

There was large heterogeneity in resource utilization between AF patients, although overall, this was still higher than controls without AF. Higher resource utilization was evident in patients at higher risk of stroke, and remained where antithrombotic therapy was discontinued. The mortality risk in AF was increased substantially, both for cardiovascular and non-cardiovascular causes of death, indicating a large unmet medical need.

Risk of death and cardiovascular outcomes with thiazolidinediones: a study with the general practice research database and secondary care data

Objective

To describe the likely extent of confounding in evaluating the risks of cardiovascular (CV) events and mortality in patients using diabetes medication.

Methods

The General Practice Research Database was used to identify inception cohorts of insulin and different oral antidiabetics. An analysis of bias and incidence of mortality, acute coronary syndrome, stroke and heart failure were analysed in GPRD, Hospital Episode Statistics and death certificates.

Results

206,940 patients were identified. The bias analysis showed that past thiazolidinedione users had a lower mortality risk compared to past metformin users. There were no differences between past users of rosiglitazone and pioglitazone (adjusted RR of 1.04; 95% CI 0.93–1.18). Current rosiglitazone users had an increased risk of death (adjusted RR 1.20; 95% CI 1.08–1.34) and of hospitalisation for heart failure (adjusted RR of 1.73; 95% CI 1.19–2.51) compared to current pioglitazone users. Risk of mortality was increased two-fold shortly after starting rosiglitazone. Excess risk of death over 3 years with rosiglitazone was 0.3 per 100 in those aged 50–64 years, 2.0 aged 65–74, 3.0 aged 75–84, and 7.0 aged 85+. The cause of death with rosiglitazone was more likely to be due to a disease of the circulatory system.

Conclusions

Higher risks for death (overall and due to cardiovascular disease) and heart failure were found for rosiglitazone compared to pioglitazone. These excess risks were largest in patients aged 65 years or older. The European regulatory decision to suspend rosiglitazone is supported by this study.

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.

Use of antidepressant drugs and risk of osteoporotic and non-osteoporotic fractures

AIM

Both tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) have been associated with an increased risk of fractures. The serotonin transporter (5-HTT) has been located in the bone and may play a role in bone physiology. We assessed the association between antidepressant drug use, categorized in a therapeutical-based way and on basis of their affinity for the 5-HTT, and the risk of both osteoporotic and non-osteoporotic fractures.

METHODS

A case-control study was conducted using the PHARMO RLS. Cases were patients with a first hospital admission for a fracture during the study period. Up to four controls were matched to each case on gender, age, geographical area, and index date.

RESULTS

We identified 16,717 cases, of whom 59.5% had an osteoporotic fracture, and 61,517 controls. Compared to no use, current use of SSRIs was associated with a statistically significant increased risk of osteoporotic fractures (OR 1.95, 95% CI 1.69-2.26), as was current use of TCAs and non-SSRI/non-TCA antidepressant drugs (ORs 1.37, 95% CI 1.16-1.63 and 1.40, 95% CI 1.06-1.85, respectively). The risk of an osteoporotic fracture was statistically significantly higher for antidepressants with a high affinity for the 5-HTT (OR 1.86, 95% CI 1.63-2.13) compared to antidepressants with a medium or low affinity (OR 1.43, 95% CI 1.19-1.72 (medium) and OR 1.32 95% CI 0.98-1.79 (low) (p<0.05 for trend). The risk of non-osteoporotic fractures did not show the same trend.

CONCLUSIONS

The extent of affinity for the 5-HTT may contribute to the increased risk of osteoporotic fractures related to antidepressant drug use. The pharmacological mechanism-based classification could to be an appropriate alternative for traditional classification to study the association between the use of antidepressants and the risk of fractures.

Utilization characteristics and treatment persistence in patients prescribed low-dose buprenorphine patches in primary care in the United Kingdom: a retrospective cohort study

BACKGROUND

The 7-day, low-dose buprenorphine patch has been available in the United Kingdom since 2005 for the treatment of chronic nonmalignant pain that is unresponsive to nonopioid analgesics. Osteo-arthritis pain, a significant cause of pain and disability in the elderly, is a common reason for prescribing bu-prenorphine patches.

OBJECTIVES

The goals of this study were to investigate utilization and treatment persistence in patients receiving low-dose buprenorphine patches and the expected patterns of treatment 12 months after the initiation of treatment.

METHODS

This was a retrospective cohort study of patients who were prescribed low-dose buprenorphine patches in general practice in the United Kingdom. Patients in this cohort were matched by age, sex, and practice with comparator cohorts prescribed oral codeine, dihydrocodeine, or tramadol. Data on baseline characteristics, utilization, and adverse events were obtained from the General Practice Research Database, which contains computerized medical records from UK general practice. Treatment persistence was determined based on repeat prescribing within 90 days after the expected end of a prescription; rates of persistence were compared between the buprenorphine and comparator cohorts. Cox proportional hazards regression models were used to compare the incidence of typical opioid adverse effects (constipation, dizziness, and nausea and/or vomiting) between cohorts.

RESULTS

The study cohort included 4968 patients who were prescribed low-dose buprenorphine patches. The majority of patients (64.2%) were aged >65 years, and the most frequently recorded indication for low-dose buprenorphine patches was osteoarthritis (48.7%). Most patients (76.1%) started treatment at the lowest patch strength (5 microg/h). The mean patch strength prescribed over time stabilized at 10 to 12 microg/h. Persistence with low-dose buprenorphine patches over 6 months was significantly higher than with codeine, dihydrocodeine, and tramadol (28.9%, 22.4%, 24.4%, and 23.8%, respectively; P < 0.01). Persistence over 12 months also was significantly higher with low-dose buprenorphine patches compared with the comparators (18.5%, 16.1%, 18.0%, and 17.6%; P < 0.01). After 12 months, the difference in persistence levels between cohorts was not statistically significant. In the Cox proportional hazards regression models, patients using buprenorphine patches had an increased incidence of constipation, dizziness, and nausea and vomiting compared with those who used the comparator opioids (P < 0.05).

CONCLUSIONS

Significantly more patients receiving low-dose buprenorphine patches in this study persisted with treatment at 6 and 12 months compared with those receiving other opioid analgesics. Treatment with low-dose buprenorphine patches was most frequently initiated at the lowest patch strength and stabilized at a mean of 10 to 12 microg/h.