The general practice research database: role in pharmacovigilance

CPRD GOLD and linked ONS mortality records: Reconciling guidelines

BACKGROUND

The Clinical Practice Research Datalink (CPRD) GOLD is an extremely influential U.K. primary care dataset for epidemiological research having a number of published papers based on its data much bigger than any other U.K. primary care dataset. The Office for National Statistics (ONS) death data for England can be linked to GOLD at the patient level and are considered the gold standard on mortality. GOLD, which also holds death data, has been recently assessed against ONS linked dataset and the accuracy of its dates of death has been deemed sufficient for the majority of observational studies. However, there is a lack of guidance on how to manage the challenges existing when ONS mortality and GOLD datasets are linked, including linkage coverage period, linkage correctness likelihood, linkage regional limitations and data discrepancy.

OBJECTIVES

Provide reconciling guidelines on how to make maximum and at the same time trustworthy use of mortality information coming from both GOLD and ONS linked datasets with the aim of improving the quality, reproducibility, transparency and comparison of clinical research.

METHOD AND RESULTS

We have developed recommendations on how to manage mortality data coming from both GOLD and linked ONS, taking into account linkage coverage period, linkage correctness likelihood, linkage regional limitations and data discrepancies between these two datasets. We have also implemented these guidelines in an SQL algorithm for researchers to use.

CONCLUSION

We have provided detailed guidelines on the reconciliation of mortality data between GOLD and ONS linked death datasets, taking into account both their strengths and limitations. The consistent application of these guidelines made practical by an SQL algorithm, has the potential to improve clinical research quality, reproducibility, transparency and comparison.

Cardiovascular and Cerebrovascular Safety of Testosterone Replacement Therapy Among Aging Men with Low Testosterone Levels: A Cohort Study

PURPOSE

We assessed the risk of ischemic stroke, transient ischemic attack, and myocardial infarction associated with testosterone replacement therapy (TRT) among aging men with low testosterone levels.

METHODS

Using the UK Clinical Practice Research Datalink, we formed a cohort of men aged 45 years or older with low testosterone levels and no evidence of hypogonadotropic or testicular disease, between 1995 and 2017. Hazard ratios (HRs) and 95% confidence intervals (CIs) of a composite of ischemic stroke/transient ischemic attack and myocardial infarction were estimated using time-dependent Cox proportional hazards models, comparing current use of TRT with nonuse.

RESULTS

The cohort included 15,401 men. During 71,541 person-years of follow-up, 850 patients experienced an ischemic stroke/transient ischemic attack/myocardial infarction (crude incidence rate 1.19 [95% confidence interval (CI), 1.11-1.27] per 100 persons per year). Compared with nonuse, current use of TRT was associated with an increased risk of the composite outcome (HR 1.21; 95% CI, 1.00-1.46). This risk was highest in the first 6 months to 2 years of continuous TRT use (HR 1.35; 95% CI, 1.01-1.79), as well as among men aged 45-59 years (HR 1.44; 95% CI, 1.07-1.92).

CONCLUSIONS

TRT may increase the risk of cardiovascular events in aging men with low testosterone levels, particularly in the first 2 years of use. In the absence of identifiable causes of hypogonadism, TRT should be initiated with caution among aging men with low testosterone levels.

Colorectal cancer and markers of anemia

Unexplained iron-deficiency anemia is an important marker for colorectal cancer (CRC). Our objectives were as follows: (a) to assess whether the association between anemia and CRC can be detected on the 'Clinical Practice Research Datalink', (b) to evaluate the timing between laboratory changes and CRC detection, and (c) to analyze its association with survival. We conducted a case-control study on patients with an incident CRC diagnosis during 2008-2012 and a 1 : 1-matched control group. We compared anemia markers serum ferritin (SF), hemoglobin (Hb), mean corpuscular volume (MCV), and red blood cell count between cases and controls using conditional logistic regression. We assessed survival in CRC cases. SF values up to 20 ng/ml were associated with an odds ratio [OR (95% confidence interval)] of 10.66 (6.88-16.51) compared with SF values of 101-300 ng/ml when restricted to measurements up to 180 days before the CRC diagnosis. For measurements taken at 1 year or earlier before the diagnosis, the OR was 2.02 (1.57-2.61). For Hb values less than 9 g/dl compared with Hb values of 13.0-15.9 g/dl the corresponding ORs were 74.25 (34.69-158.91) and 2.19 (1.31-3.67), respectively. The corresponding ORs for MCV values up to 80 fl compared with MCV values of 86-95 fl were 13.94 (10.31-18.85) and 1.89 (1.51-2.36), respectively. Low levels of these markers were only weakly associated with survival. Hb, MCV, and SF levels substantially dropped only shortly before the CRC diagnosis. Although slightly more cases had anemia markers compared with controls at 1 year or earlier before the diagnosis, most cases still had normal values. The Clinical Practice Research Datalink is well-suited to detect associations between low Hb, MCV, and SF levels and CRC.

Comparative effectiveness of novel oral anticoagulants in UK patients with non-valvular atrial fibrillation and chronic kidney disease: a matched cohort study

OBJECTIVES

To evaluate the effectiveness and safety of novel oral anticoagulants (NOACs) compared with vitamin K antagonists (VKAs) among patients with non-valvular atrial fibrillation (NVAF), particularly those with chronic kidney disease (CKD).

DESIGN

Population-based matched cohort study.

SETTING

Over 670 primary care practices in the UK, contributing to the Clinical Practice Research Datalink.

PARTICIPANTS

Up to 6818 adult patients newly treated with NOACs between 2011 and 2016, matched 1:1 to new users of VKAs on age, sex and high-dimensional propensity score.

INTERVENTIONS

Current exposure to NOACs compared with current exposure to VKAs.

MAIN OUTCOME MEASURES

HRs of ischaemic stroke and systemic embolism (SE), major bleeding, gastrointestinal (GI) bleeding, intracranial bleeding, myocardial infarction and all-cause mortality.

RESULTS

In as-treated analyses, the rates of ischaemic stroke/SE were similar between NOACs and VKAs (HR 0.94; 95% CI 0.62 to 1.42), as were the rates of major bleeding (HR 0.86; 95% CI 0.56 to 1.33). NOACs also significantly increased the risk of GI bleeding (HR 1.78; 95% CI 1.27 to 2.48). In patients with NVAF and CKD, NOACs and VKAs remained comparable with respect to the risk of ischaemic stroke/SE (HR 0.79; 95% CI 0.40 to 1.58) and major bleeding (HR 0.88; 95% CI 0.47 to 1.62), with no difference in the risk of GI bleeding (HR 0.99; 95% CI 0.63 to 1.55). Similar results were obtained in on-treatment analyses using a time-dependent exposure definition.

CONCLUSIONS

Our results suggest that in the UK primary care, NOACs are overall effective and safe alternatives to VKAs, among patients with NVAF altogether, as well as in patients with NVAF and CKD.

Treatment choice, medication adherence and glycemic efficacy in people with type 2 diabetes: a UK clinical practice database study

OBJECTIVE

Using primary care data obtained from the UK Clinical Practice Research Datalink, this retrospective cohort study examined the relationships between medication adherence and clinical outcomes in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Data were extracted for patients treated between 2008 and 2016, and stratified by oral antihyperglycemic agent (OHA) line of therapy (mono, dual or triple therapy). Patients were monitored for up to 365 days; associations between medication possession ratio (MPR) and outcomes at 1 year (glycated hemoglobin A1c (HbA1c), weight and hypoglycemia incidence) were assessed using linear regression modeling and descriptive analyses.

RESULTS

In total, 33 849 patients were included in the study (n=23 925 OHA monotherapy; n=8406 OHA dual therapy; n=1518 OHA triple therapy). One-year change in HbA1c was greater among adherent (-0.90 to -1.14%; -9.8 to -12.5 mmol/mol) compared with non-adherent patients (-0.49 to -0.69%; -5.4 to -7.5 mmol/mol). On average, adherent patients had higher hypoglycemia event rates than non-adherent patients (rate ratios of 1.24, 1.10 and 2.06 for OHA mono, dual and triple therapy cohorts, respectively) and experienced greater weight change from baseline. A 10% improvement in MPR was associated with -0.09% (-1.0 mmol/mol), -0.09% (-1.0 mmol/mol) and -0.21% (-2.3 mmol/mol) changes in HbA1c for OHA mono, dual and triple therapy cohorts, respectively.

CONCLUSIONS

For patients with type 2 diabetes, increasing medication adherence can bring about meaningful improvements in HbA1c control as the requirement for treatment escalation increases. Regimens associated with weight loss and the avoidance of hypoglycemia were generally associated with better medication adherence and improved glycemic control.

The limitations of some European healthcare databases for monitoring the effectiveness of pregnancy prevention programmes as risk minimisation measures

PURPOSE

Pregnancy prevention programmes (PPPs) exist for some medicines known to be highly teratogenic. It is increasingly recognised that the impact of these risk minimisation measures requires periodic evaluation. This study aimed to assess the extent to which some of the data needed to monitor the effectiveness of PPPs may be present in European healthcare databases.

METHODS

An inventory was completed for databases contributing to EUROmediCAT capturing pregnancy and prescription data in Denmark, Norway, the Netherlands, Italy (Tuscany/Emilia Romagna), Wales and the rest of the UK, to determine the extent of data collected that could be used to evaluate the impact of PPPs.

RESULTS

Data availability varied between databases. All databases could be used to identify the frequency and duration of prescriptions to women of childbearing age from primary care, but there were specific issues with availability of data from secondary care and private care. To estimate the frequency of exposed pregnancies, all databases could be linked to pregnancy data, but the accuracy of timing of the start of pregnancy was variable, and data on pregnancies ending in induced abortions were often not available. Data availability on contraception to estimate compliance with contraception requirements was variable and no data were available on pregnancy tests.

CONCLUSION

Current electronic healthcare databases do not contain all the data necessary to fully monitor the effectiveness of PPP implementation, and thus, special data collection measures need to be instituted.

The Risk of Achilles or Biceps Tendon Rupture in New Statin Users: A Propensity Score-Matched Sequential Cohort Study

INTRODUCTION

Case reports and pharmacovigilance data reported cases of tendon ruptures in statin users, but evidence from observational studies is scarce and inconclusive. We aimed to assess the association between new statin use and tendon rupture.

METHODS

We performed a propensity score (PS)-matched sequential cohort study, using data from the Clinical Practice Research Datalink. Patients aged ≥45 years with at least one new statin prescription between 1995 and 2014 were PS-matched within 2-year entry blocks to patients without a statin prescription during the block. We followed patients until they had a recorded Achilles or biceps tendon rupture, completed 5 years of follow-up, or were censored for change in exposure status or another censoring criterion. We calculated hazard ratios (HRs) with 95 % confidence intervals (CIs), applying Cox proportional hazard analyses in the overall cohort (crude and multivariable) and in the PS-matched cohort. We performed subgroup analyses by sex, age, treatment duration, and statin dose.

RESULTS

We observed a crude HR of 1.32 (95 % CI 1.21-1.44) in the overall cohort, which attenuated after multivariable adjustment (HR 1.02, 95 % CI 0.92-1.12) and after PS-matching (HR 0.95, 95 % CI 0.84-1.08). Crude HRs were higher in women than in men, but remained around null in both sexes after multivariable adjustment and PS-matching. Subgroup analyses by age, treatment duration, and statin dose revealed null results across all subgroups.

CONCLUSION

The results of this cohort study suggest that statin use does not increase the risk of tendon rupture, irrespective of gender, age, statin dose, or treatment duration.

Association of Hypoglycemia With Subsequent Dementia in Older Patients With Type 2 Diabetes Mellitus

Background

Studies have found conflicting evidence regarding the association of hypoglycemia with dementia. We evaluated an association of hypoglycemia with subsequent dementia in patients with type 2 diabetes.

Methods

This retrospective longitudinal cohort study used the Clinical Practice Research Datalink, an electronic medical records data from the United Kingdom, from 2003 to 2012. We included patients aged >65 years diagnosed with type 2 diabetes, with no prior diagnosis of dementia. Dementia was defined using diagnosis codes from medical records. All patients were followed from the date of initial diabetes diagnosis. To account for competing risk of death, we used Fine and Gray's competing risk model to determine the association of hypoglycemia with dementia while adjusting for potential confounders. Hypoglycemia was modeled as a time-dependent covariate.

Results

Of 53,055 patients, 5.7% (n = 3,018) had at least one hypoglycemia episodes. The overall incidence rate of dementia was 12.7 per 1,000 person-years. In the fully adjusted model that controlled for all confounders, the occurrence of at least one hypoglycemia episode was associated with 27% higher odds of subsequent dementia (hazard ratio = 1.27; 95% confidence interval = 1.06-1.51). The risk increased with the number of hypoglycemia episodes: one episode (hazard ratio = 1.26; 95% confidence interval = 1.03-1.54); two or more episodes (hazard ratio = 1.50; 95% confidence interval = 1.09-2.08).

Conclusions

Hypoglycemia is associated with a higher risk of dementia and may be responsible in part for the higher risk of dementia in patients with diabetes. Alternatively, hypoglycemia may be a marker for undiagnosed cognitive impairment, and we cannot rule out the possibility of reverse causation between hypoglycemia and dementia.

A comparison of methods for estimating the temporal change in a continuous variable: Example of HbA1c in patients with diabetes

Purpose

To compare the more complex technique, functional principal component analysis (FPCA), to simpler methods of estimating values of sparse and irregularly spaced continuous variables at given time points in longitudinal data using a diabetic patient cohort from UK primary care.

Methods

The setting for this study is the Clinical Practice Research Datalink (CPRD), a UK general practice research database. For 16,034 diabetic patients identified in CPRD, with at least 2 measures in a 30‐month period, HbA1c was estimated after temporarily omitting (i) the final and (ii) middle known values using linear interpolation, simple linear regression, arithmetic mean, random effects, and FPCA. Performance of each method was assessed using mean prediction error. The influence on predictive accuracy of (1) more homogeneous populations and (2) number and range of known HbA1c values was explored.

Results

When estimating the last observation, the predictive accuracy of FPCA was highest with over half of predicted values within 0.4 units, equivalent to laboratory measurement error. Predictive accuracy improved when estimating the middle observation with almost 60% predicted values within 0.4 units for FPCA. These results were marginally better than that achieved by simpler approaches, such as last‐occurrence‐carried‐forward linear interpolation. This pattern persisted with more homogeneous populations as well as when variability in HbA1c measures coupled with frequency of data points were considered.

Conclusions

When estimating change from baseline to prespecified time points in electronic medical records data, a marginal benefit to using the more complex modelling approach of FPCA exists over more traditional methods.

Trends in the prescription of novel oral anticoagulants in UK primary care

AIMS

Novel oral anticoagulants (NOACs) are alternatives to vitamin-K antagonists (VKAs) for the prevention of thromboembolism. It is unclear how NOACs have been adopted in the UK since first introduced in 2008. The present study was conducted to describe the trends in the prescription of NOACs in the UK, including dabigatran, rivaroxaban and apixaban.

METHODS

Using the UK's Clinical Practice Research Datalink, the rates of new use of NOACs and VKAs from 2009 to 2015 were calculated using Poisson regression. Patient characteristics associated with NOAC initiation were identified using multivariate logistic regression.

RESULTS

The overall rate of oral anticoagulant initiation increased by 58% over the study period [rate ratio (RR) 1.58; 95% confidence interval (CI) 1.23, 2.03], even as the rate of new VKA use decreased by 31% (RR 0.69; 95% CI 0.52, 0.93). By contrast, the rate of initiation of NOAC increased, particularly from 2012 onwards, with a 17-fold increase from 2012 to 2015 (RR 17.68; 95% CI 12.16, 25.71). In 2015, NOACs accounted for 56.5% of oral anticoagulant prescriptions, with rivaroxaban prescribed most frequently, followed by apixaban and then dabigatran. Compared to VKAs, new NOAC users were less likely to have congestive heart failure, coronary artery disease and peripheral vascular disease, and more likely to have a history of ischaemic stroke.

CONCLUSIONS

In the UK, the rate of initiation of NOACs has increased substantially since 2009, and these agents have now surpassed VKAs as the anticoagulant of choice. Moreover, the characteristics of patients initiated on NOACs have changed over time, and this should be accounted for in future studies comparing NOACs and VKAs.

Managing glycaemia in older people with type 2 diabetes: A retrospective, primary care-based cohort study, with economic assessment of patient outcomes

AIMS

To describe the relative health and economic outcomes associated with different second-line therapeutic approaches to manage glycaemia in older type 2 diabetes patients requiring escalation from metformin monotherapy.

MATERIALS AND METHODS

The Clinical Practice Research Datalink database was used to inform a retrospective observational cohort study of patients with type 2 diabetes treated with metformin monotherapy requiring escalation (addition or switch) to a second-line oral regimen from January 1, 2008 to December 31, 2014. Primary outcomes included time to first event (any event, myocardial infarction [MI], stroke, or composite of MI/stroke [major adverse cardiovascular event; MACE]) and total event rate. The health economic consequences associated with the choice of second-line treatment in older patients were assessed using the CORE Diabetes Model.

RESULTS

A total of 10 484 patients were included; the majority escalated to second-line treatment with metformin + sulphonylurea (SU; 42%) or switched to SU monotherapy (28%). In multivariate adjusted analyses, total event rates for MACE with metformin + dipeptidyl peptidase-4 (DPP-4) inhibitor were significantly lower than with metformin + SU (0.61, 95% confidence interval [CI] 0.39-0.98), driven by a lower MI rate in the metformin + DPP-4 inhibitor group (0.52, 95% CI 0.27-0.99). Economic analyses estimated that metformin + DPP-4 inhibitor treatment was associated with the largest gain in health benefit, and cost-effectiveness ratios were favourable (<£30 000 per quality-adjusted life-year) for all second-line treatment scenarios.

CONCLUSIONS

With respect to treatment choice, data from the present study support the notion of prescribing beyond metformin + SU, as alternative regimens have been shown to be associated with reduced outcomes risk and value for money.

Influenza infections and risk of Alzheimer's disease

Influenza may cause neuropsychiatric disorders, including confusion, delirium, convulsions, and encephalopathy. We conducted a case-control study to evaluate the association between diagnosed influenza and the risk of developing Alzheimer's disease (AD) using the UK-based Clinical Practice Research Datalink (CPRD). We identified 19,463 patients who developed an incident AD diagnosis between 1998 and 2013 and matched them 1:1 to dementia-free controls on age, sex, general practice, calendar time and number of years of recorded history. We calculated adjusted odds ratios (aORs) with 95% confidence intervals (CIs) of developing AD in association with previous influenza infections and stratified by number of infections prior to the AD diagnosis date. Patients with a previous influenza infection were not at an increased risk of developing AD as compared to those with no previous infection (aOR, 95% CI 0.94, 0.87-1.02) overall. Nor was increasing number of infections related to an increased risk of developing AD; the aOR (95% CI) for those with 1, 2, or ⩾3 episodes was 0.98 (0.90-1.07), 0.70 (0.56-0.88), and 0.92 (0.63-1.34), respectively. Presence of an underlying chronic inflammatory disease in those with an influenza infection did not increase the risk of developing AD (aOR, 95% CI 0.83, 0.71-0.96), either, and there was no association between the severity of influenza infections (based on recorded neurological or bacterial complications) and the risk of AD. In conclusion, considering the limitations of this large observational study, we found no association between influenza infections and the risk of developing AD.

Latest trends in ADHD drug prescribing patterns in children in the UK: prevalence, incidence and persistence

OBJECTIVES

To investigate attention deficit and hyperactivity disorder (ADHD) drug prescribing in children under 16 years old in the UK between 1992 and 2013.

METHODS

All patients under 16 registered in the Clinical Practice Research Datalink (CPRD) with a minimum of 1 year of observation time and who received at least one prescription of any ADHD drug between 1 January 1992 and 31 December 2013.Trends in prevalence and incidence of use of ADHD drugs in children were calculated between 1995 and 2013 and persistence in new users was estimated.

RESULTS

The prevalence of ADHD drug use in children under 16 increased 34-fold overall, rising from 1.5 95% CI (1.1 to 2.0) per 10 000 children in 1995 to 50.7 95% CI (49.2 to 52.1) per 10 000 children in 2008 then stabilising to 51.1 95% CI (49.7 to 52.6) per 10 000 children in 2013. The rate of new users increased eightfold reaching 10.2 95% CI (9.5 to 10.9) per 10 000 children in 2007 then decreasing to 9.1 95% CI (8.5 to 9.7) per 10 000 children in 2013. Although prevalence and incidence increased rather steeply after 1995, this trend seems to halt from 2008 onwards. We identified that 77%, 95% CI (76% to 78%) of children were still under treatment after 1 year and 60% 95% CI (59% to 61%) after 2 years.

CONCLUSIONS

There was a marked increase in ADHD drug use among children in the UK from 1992 until around 2008, with stable levels of use since then. UK children show relatively long persistence of treatment with ADHD medications compared to other countries.

Doubling of serum creatinine and the risk of cardiovascular outcomes in patients with chronic kidney disease and type 2 diabetes mellitus: a cohort study

BACKGROUND

Doubling of serum creatinine is often used as a marker for worsening kidney function in nephrology trials. Most people with chronic kidney disease die of other causes before reaching end-stage renal disease. We were interested in the association between doubling of serum creatinine and the risk of a first-time diagnosis of angina pectoris, congestive heart failure (CHF), myocardial infarction (MI), stroke, or transient ischemic attack in patients with chronic kidney disease and with diagnosed type 2 diabetes mellitus.

METHODS

We identified all adult patients registered in the "Clinical Practice Research Datalink" between 2002 and 2011 with incident chronic kidney disease and type 2 diabetes mellitus and did a cohort study with a Cox proportional hazard analysis.

RESULTS

We identified in total 27,811 patients, 693 developed angina pectoris, 1,069 CHF, 508 MI, 970 stroke, and 578 transient ischemic attacks. Patients whose serum creatinine doubled during follow-up had increased risks of CHF (hazard ratio [HR] 2.98, 95% confidence interval [CI] 2.27-3.89), MI (HR 2.53, 95% CI 1.62-3.96), and stroke (HR 1.93, 95% CI 1.38-2.69), as compared with patients whose serum creatinine did not double. The relative risks of angina pectoris (HR 1.18, 95% CI 0.66-2.10) or a transient ischemic attack (HR 1.32, 95% CI 0.78-2.22) were similar in both groups.

CONCLUSION

Diabetic patients with a doubling of serum creatinine were at an increased risk of CHF, MI, or stroke, compared with diabetic patients whose serum creatinine did not double during follow-up.

Prescribing of Antidiabetic Medicines before, during and after Pregnancy: A Study in Seven European Regions

AIM

To explore antidiabetic medicine prescribing to women before, during and after pregnancy in different regions of Europe.

METHODS

A common protocol was implemented across seven databases in Denmark, Norway, The Netherlands, Italy (Emilia Romagna/Tuscany), Wales and the rest of the UK. Women with a pregnancy starting and ending between 2004 and 2010, (Denmark, 2004-2009; Norway, 2005-2010; Emilia Romagna, 2008-2010), which ended in a live or stillbirth, were identified. Prescriptions for antidiabetic medicines issued (UK) or dispensed (non-UK) during pregnancy and/or the year before or year after pregnancy were identified. Prescribing patterns were compared across databases and over calendar time.

RESULTS

1,082,673 live/stillbirths were identified. Pregestational insulin prescribing during the year before pregnancy ranged from 0.27% (CI95 0.25-0.30) in Tuscany to 0.45% (CI95 0.43-0.47) in Norway, and increased between 2004 and 2009 in all countries. During pregnancy, insulin prescribing peaked during the third trimester and increased over time; third trimester prescribing was highest in Tuscany (2.2%) and lowest in Denmark (0.5%). Of those prescribed an insulin during pregnancy, between 50.5% in Denmark and 88.8% in the Netherlands received an insulin analogue alone or in combination with human insulin, this proportion increasing over time. Oral products were mainly metformin and prescribing was highest in the 3 months before pregnancy. Metformin use during pregnancy increased in some countries.

CONCLUSION

Pregestational diabetes is increasing in many areas of Europe. There is considerable variation between and within countries in the choice of medication for treating pregestational diabetes in pregnancy, including choice of insulin analogues and oral antidiabetics, and very large variation in the treatment of gestational diabetes despite international guidelines.

Clobazam and clonazepam use in epilepsy: Results from a UK database incident user cohort study

OBJECTIVE

To compare patient characteristics and treatment patterns among clobazam (CLB) and clonazepam (CZP)-treated patients with epilepsy in a longitudinal primary care database.

METHODS

In this pharmacoepidemiological study, real-life usage data from the Clinical Practice Research Database (CPRD) were evaluated. The CPRD collects data from approximately 690 primary care practices throughout the UK. Data included were from patients with ≥1 incident CLB or CZP prescription from 1995 to 2011 and were present in the database for ≥182 days prior to the index date (date patient was first prescribed CLB or CZP within the study period).

RESULTS

Of 21,099 patients who met inclusion criteria, 18.4% were receiving CLB and 81.6% were receiving CZP. More patients used CLB for epilepsy than CZP (76.1% vs 8.7%). CLB-treated adults (≤18years) were younger than those treated with CZP (41.0 vs 48.2 years; p<0.001), while CLB-treated children (≤18 years) were older than those treated with CZP (8.8 vs 7.3 years, p<0.001). The median CLB dosage did not change from baseline to last follow-up, while median CZP dosage increased 25% in adults and 50% in children. Median treatment duration, as well as retention rate up to 10 years, was similar between CLB and CZP in each age group.

CONCLUSIONS

Among adult and pediatric patients in the UK, CLB is more often prescribed for epilepsy than CZP. The median CLB dosage used by both adults and children remained stable over the 16-year study period, while the median CZP dosage increased in both adults and children.

Rosacea in Patients with Ulcerative Colitis and Crohn's Disease: A Population-based Case-control Study

BACKGROUND

Cutaneous manifestations are common in patients with inflammatory bowel diseases (IBDs) (ulcerative colitis [UC] and Crohn's disease [CD]). Previous case reports described patients with IBD who developed rosacea. IBD and rosacea are inflammatory epithelial diseases, presumably associated with changes in the innate immune system. We explored the association between IBD and incident rosacea.

METHODS

We conducted a population-based matched (1:1) case-control analysis on the association between IBD and rosacea, stratified by IBD disease duration and severity. We used data from the UK-based Clinical Practice Research Datalink. Cases had an incident diagnosis of rosacea recorded between 1995 and 2013.

RESULTS

Among 80,957 rosacea cases and the same number of controls, a history of UC was associated with an increased risk of rosacea (odds ratio [OR] 1.65, 95% confidence interval [CI], 1.43-1.90), with the highest OR in those with short UC duration (OR 2.85, 95% confidence interval, 1.80-4.50 for patients with <2 years of disease history). A history of CD yielded an overall OR of 1.49 (95% CI, 1.25-1.77), which did not correlate with disease duration. Additional analyses on IBD disease severity yielded evidence for a higher risk of rosacea in those with higher UC and CD activity.

CONCLUSIONS

Our findings provide evidence that patients with IBD may be at increased risk of rosacea (higher in UC), particularly during phases of increased IBD-associated gastrointestinal tract inflammation.

Morbidity and medication in a large population of individuals with Down syndrome compared to the general population

AIM

The aim of this study was to describe the incidence of morbidities and the prevalence of medical prescriptions in a large Down syndrome population.

METHOD

A retrospective cohort study was carried out using the UK Clinical Practice Research Datalink from 1 January 2004 to 31 December 2013. We matched individuals with Down syndrome to randomly selected control participants by practice site, sex, birth year, and recording period.

RESULTS

A total of 6430 individuals with Down syndrome (3009 females, 3421 males) and 19 176 controls (8966 females, 10,210 males) were included in the study. The incidence of cardiovascular disorders, gastrointestinal diseases (incidence rate ratio [IRR] 7.9 at 3 to <6y: yearly prevalence ratio [YPR] for laxatives 4.7), and sleeping disorders (IRR 4.8 in 3 to <6y) was increased in children with Down syndrome versus control participants. New onset of congenital heart malformation, ear diseases, eye disorders, autism, hypothyroidism, diabetes, and obesity were more frequent in childhood and remained elevated in adulthood (overall IRR 35.5, 1.7, 3.1, 4.4, 13.1, 1.3, and 2.6 respectively), whereas the gap widened in adulthood for epilepsy and intellectual disability (IRR 15.2 and 158 respectively, in participants older than 30y). At ≥ 30 years, the incidence of hypotension and dementia was raised (IRR 3.0 and 92.1 respectively; YPR for dementia drugs: 76.3); and that of hypertension, depression and anxiety was lowered (IRR 0.2, 0.5, and 0.4 respectively).

INTERPRETATION

The profile of newly occurring morbidities in Down syndrome varies across the developmental lifespan.

Asthma medication prescribing before, during and after pregnancy: a study in seven European regions

OBJECTIVES

To explore utilisation patterns of asthma medication before, during and after pregnancy as recorded in seven European population-based databases.

DESIGN

A descriptive drug utilisation study.

SETTING

7 electronic healthcare databases in Denmark, Norway, the Netherlands, Italy (Emilia Romagna and Tuscany), Wales, and the Clinical Practice Research Datalink representing the rest of the UK.

PARTICIPANTS

All women with a pregnancy ending in a delivery that started and ended between 2004 and 2010, who had been present in the database for the year before, throughout and the year following pregnancy.

MAIN OUTCOME MEASURES

The percentage of deliveries where the woman received an asthma medicine prescription, based on prescriptions issued (UK) or dispensed (non-UK), during the year before, throughout or during the year following pregnancy. Asthma medicine prescribing patterns were described for 3-month time periods and the choice of asthma medicine and changes in prescribing over the study period were evaluated in each database.

RESULTS

In total, 1,165,435 deliveries were identified. The prevalence of asthma medication prescribing during pregnancy was highest in the UK and Wales databases (9.4% (CI95 9.3% to 9.6%) and 9.4% (CI95 9.1% to 9.6%), respectively) and lowest in the Norwegian database (3.7% (CI95 3.7% to 3.8%)). In the year before pregnancy, the prevalence of asthma medication prescribing remained constant in all regions. Prescribing levels peaked during the second trimester of pregnancy and were at their lowest during the 3-month period following delivery. A decline was observed, in all regions except the UK, in the prescribing of long-acting β-2-agonists during pregnancy. During the 7-year study period, there were only small changes in prescribing patterns.

CONCLUSIONS

Differences were found in the prevalence of prescribing of asthma medications during and surrounding pregnancy in Europe. Inhaled β-2 agonists and inhaled corticosteroids were, however, the most popular therapeutic regimens in all databases.

Molluscum contagiosum and associations with atopic eczema in children: a retrospective longitudinal study in primary care

BACKGROUND

Molluscum contagiosum (MC) is a common skin condition in children. Consultation rates and current management in primary care, and how these have changed over time, are poorly described. An association between the presence of atopic eczema (AE) and MC has been shown, but the subsequent risk of developing MC in children with a diagnosis of AE is not known.

AIM

To describe the consultation rate and management of MC in general practice in the UK over time, and test the hypothesis that a history of AE increases the risk of developing MC in childhood.

DESIGN AND SETTING

Two studies are reported: a retrospective longitudinal study of MC cases and an age-sex matched case-cohort study of AE cases, both datasets being held in the UK Clinical Practice Research Datalink from 2004 to 2013.

METHOD

Data of all recorded MC and AE primary care consultations for children aged 0 to 14 years were collected and two main analyses were conducted using these data: a retrospective longitudinal analysis and an age-sex matched case-cohort analysis.

RESULTS

The rate of MC consultations in primary care for children aged 0 to 14 years is 9.5 per 1000 (95% CI = 9.4 to 9.6). The greatest rate of consultations for both sexes is in children aged 1-4 years and 5-9 years (13.1 to 13.0 (males) and 13.0 to 13.9 (females) per 1000 respectively). Consultation rates for MC have declined by 50% from 2004 to 2013. Children were found to be more likely to have an MC consultation if they had previously consulted a GP with AE (OR 1.13; 95% CI = 1.11 to 1.16; P<0.005).

CONCLUSION

Consultations for MC in primary care are common, especially in 1-9-year-olds, but they declined significantly during the decade under study. A primary care diagnosis of AE is associated with an increased risk of a subsequent primary care diagnosis of MC.

No evidence for a decreased risk of thyroid cancer in association with use of metformin or other antidiabetic drugs: a case-control study

Background

Use of metformin has been associated with a decreased cancer risk. We aimed to explore whether use of metformin or other antidiabetic drugs is associated with a decreased risk for thyroid cancer.

Methods

We conducted a case-control analysis (1995 to 2014) using the U.K.-based Clinical Practice Research Datalink (CPRD). Cases had a first-time diagnosis of thyroid cancer, six controls per case were matched on age, sex, calendar time, general practice, and number of years of active history in the database prior to the index date. We assessed odds ratios (ORs) with 95 % confidence intervals (95 % CI), adjusted for body mass index (BMI), smoking, and diabetes mellitus.

Results

In 1229 cases and 7374 matched controls, the risk of thyroid cancer associated with ever use of metformin yielded an adjusted OR of 1.48, 95 % CI 0.86–2.54. The relative risk estimate was highest in long-term (≥30 prescriptions) users of metformin (adjusted OR 1.83, 95 % CI 0.92–3.65), based on a limited number of 26 exposed cases. No such association was found in users of sulfonylurea, insulin, or thiazolidinediones (TZD). Neither a diabetes diagnosis (adjusted OR 1.17, 95 % CI 0.89–1.54), nor diabetes duration >8 years (adjusted OR 1.22, 95 % CI 0.60–2.51) altered the risk of thyroid cancer.

Conclusion

In our observational study with limited statistical power, neither use of metformin nor of other antidiabetic drugs were associated with a decreased risk of thyroid cancer.

Smoke-free legislation and the incidence of paediatric respiratory infections and wheezing/asthma: interrupted time series analyses in the four UK nations

We investigated the association between introduction of smoke-free legislation in the UK (March 2006 for Scotland, April 2007 for Wales and Northern Ireland, and July 2007 for England) and the incidence of respiratory diseases among children. We extracted monthly counts of new diagnoses of wheezing/asthma and RTIs among children aged 0–12 years from all general practices in the Clinical Practice Research Datalink during 1997–2012. Interrupted time series analyses were performed using generalised additive mixed models, adjusting for underlying incidence trends, population size changes, seasonal factors, and pandemic influenza, as appropriate. 366,642 new wheezing/asthma diagnoses and 4,324,789 RTIs were observed over 9,536,003 patient-years. There was no statistically significant change in the incidence of wheezing/asthma after introduction of smoke-free legislation in England (incidence rate ratio (IRR) 0.94, 95% CI 0.81–1.09) or any other UK country (Scotland: IRR 0.99, 95% CI 0.83–1.19; Wales: IRR 1.09, 95% CI 0.89–1.35; Northern Ireland: IRR 0.96, 95% CI 0.76–1.22). Similarly no statistically significant changes in RTI incidence were demonstrated (England: IRR 0.95, 95% CI 0.86–1.06; Scotland: IRR 0.96, 95% CI 0.83–1.11; Wales: IRR 0.97, 95% CI 0.86–1.09; Northern Ireland: IRR 0.90, 95% CI 0.79–1.03). There were no demonstrable reductions in the incidence of paediatric wheezing/asthma or RTIs following introduction of smoke-free legislation in the UK.

Benzodiazepines and risk of death: Results from two large cohort studies in France and UK

Benzodiazepines are widely prescribed for the treatment of anxiety or insomnia, but their impact on mortality is still debated. This study investigated the impact of benzodiazepine use on short term mortality. Exposed-unexposed cohorts were constructed with the Clinical Practice Research Datalink (CPRD) in the UK and with the General Sample of Beneficiaries (EGB) in France. Benzodiazepine incident users were matched to incident users of antidepressants/non-benzodiazepine sedatives and to controls (non-users of antidepressants or anxiolytics/hypnotics) according to age and gender in both sources (and practice for the CPRD only). Survival at one year was studied using Cox regression model. In the CPRD, the final population comprised 94 123 patients per group (57 287 in the EGB). In the CPRD, adjusted HR was 3.73 in benzodiazepine users (95% CI, 3.43-4.06), and 1.61 (1.47-1.76) in antidepressant/non-benzodiazepine users compared to controls. When considering benzodiazepine use as a time-dependent covariate, adjusted HR for current use at 12 months was 1.70 (1.36-2.12). In the EGB, adjusted HR was 1.26 in benzodiazepine users (95% CI, 1.08-1.48), and 1.07 (95% CI, 0.91-1.27) in antidepressant/non-benzodiazepine users. When considering benzodiazepine use as a time-dependent covariate, adjusted HR for current use at 12 months was 1.03 (0.74-1.44). Using two nationally representative databases, we found a significant while moderate increase in all-cause mortality in relation to benzodiazepines, in a population of incident and mostly occasional users. This issue need to be monitored given the extensive use of these drugs.

Antiepileptic drug prescribing before, during and after pregnancy: a study in seven European regions

PURPOSE

The aim of this study was to explore antiepileptic drug (AED) prescribing before, during and after pregnancy as recorded in seven population-based electronic healthcare databases.

METHODS

Databases in Denmark, Norway, the Netherlands, Italy (Emilia Romagna/Tuscany), Wales and the Clinical Practice Research Datalink, representing the rest of the UK, were accessed for the study. Women with a pregnancy starting and ending between 2004 and 2010, which ended in a delivery, were identified. AED prescriptions issued (UK) or dispensed (non-UK) at any time during pregnancy and the 6 months before and after pregnancy were identified in each of the databases. AED prescribing patterns were analysed, and the choice of AEDs and co-prescribing of folic acid were evaluated.

RESULTS

In total, 978 957 women with 1 248 713 deliveries were identified. In all regions, AED prescribing declined during pregnancy and was lowest during the third trimester, before returning to pre-pregnancy levels by 6 months following delivery. For all deliveries, the prevalence of AED prescribing during pregnancy was 51 per 10 000 pregnancies (CI95 49-52%) and was lowest in the Netherlands (43/10 000; CI95 33-54%) and highest in Wales (60/10 000; CI95 54-66%). In Denmark, Norway and the two UK databases lamotrigine was the most commonly prescribed AED; whereas in the Italian and Dutch databases, carbamazepine, valproate and phenobarbital were most frequently prescribed. Few women prescribed with AEDs in the 3 months before pregnancy were co-prescribed with high-dose folic acid: ranging from 1.0% (CI95 0.3-1.8%) in Emilia Romagna to 33.5% (CI95 28.7-38.4%) in Wales.

CONCLUSION

The country's differences in prescribing patterns may suggest different use, knowledge or interpretation of the scientific evidence base. The low co-prescribing of folic acid indicates that more needs to be done to better inform clinicians and women of childbearing age taking AEDs about the need to offer and receive complete preconception care.

Antiepileptic drugs and the risk of ischaemic stroke and myocardial infarction: a population-based cohort study

OBJECTIVES

Hepatic enzyme-inducing antiepileptic drugs (AEDs) increase serum lipid levels and other atherogenic markers via the induction of cytochrome P450 and may therefore increase the risk of vascular events. We sought to assess the risk of ischaemic stroke and myocardial infarction (MI) according to AED enzymatic properties.

DESIGN

Population-based cohort study with nested case-control analysis.

SETTING

650 general practices in the UK contributing to the Clinical Practice Research Datalink.

PARTICIPANTS

A cohort of 252,407 incident AED users aged 18 or older between January 1990 and April 2013. For each case of ischaemic stroke or MI, up to 10 controls were randomly selected among the cohort members in the risk sets defined by the case and matched on age, sex, indication for AED, calendar time and duration of follow-up.

INTERVENTIONS

Current use of enzyme-inducing and enzyme-inhibiting AEDs compared with non-inducing AEDs.

PRIMARY OUTCOME MEASURES

Incidence rate ratios (RRs) of ischaemic stroke and MI.

RESULTS

5069 strokes and 3636 MIs were identified during follow-up. Inducing AEDs use was associated with a small increased risk of ischaemic stroke (RR=1.16, 95% CI 1.02 to 1.33) relative to non-inducing AEDs, most likely due to residual confounding. However, current use of inducing AEDs for ≥ 24 months was associated with a 46% increased risk of MI (RR=1.46, 95% CI 1.15 to 1.85) compared with the same duration of non-inducing AED, corresponding to a risk difference of 1.39/1000 (95% CI 0.33 to 2.45) persons per year. Current use of inhibiting AED was associated with a decreased risk of MI (RR=0.81, 95% CI 0.66 to 1.00).

CONCLUSIONS

The use of enzyme-inducing AEDs was not associated with an increased risk of ischaemic stroke; a small increase of MI with prolonged use was observed. In contrast, use of inhibiting AEDs was associated with a decreased risk of MI.

Antipsychotic drug use and the risk of seizures: follow-up study with a nested case-control analysis

OBJECTIVE

To investigate the association between antipsychotic drug use and the development of first-time seizures in patients with schizophrenia, affective disorders, or dementia.

METHODS

We used data from the UK-based Clinical Practice Research Datalink database to conduct a follow-up study with a nested case-control analysis between 1998 and 2013. We identified patients with schizophrenia, affective disorders, or dementia, and estimated incidence rates of seizures among users of four antipsychotic drug subclasses, defined according to existing hypotheses on their seizure-inducing potential (1, olanzapine or quetiapine; 2, amisulpride, aripiprazole, risperidone, or sulpiride; 3, low-to-medium potency first-generation antipsychotic drugs [chlorpromazine, zuclopenthixol, flupenthixol, pericyazine, promazine, thioridazine]; 4, medium-to-high potency first-generation antipsychotic drugs [haloperidol, prochlorperazine, trifluoperazine]), and among those who did not use antipsychotic drugs. To adjust for confounding, we estimated odds ratios for seizures separately among patients with affective disorders or dementia, stratified by antipsychotic drug use and timing of use.

RESULTS

In the total cohort of 60,121 patients (who had schizophrenia, affective disorders, or dementia), the incidence rate of seizures per 10,000 person-years was 32.6 (95 % confidence interval [CI] 22.6-42.6) in users of olanzapine or quetiapine, 24.1 (95 % CI 13.2-34.9) in users of amisulpride, aripiprazole, risperidone, or sulpiride, 49.4 (95 % CI 27.7-71.0) in users of low-to-medium potency antipsychotic drugs, 59.1 (95 % CI 40.1-78.2) in users of medium-to-high potency antipsychotic drugs, and 11.7 (95 % CI 10.0-13.4) in non-users of antipsychotic drugs. Patients with dementia had significantly higher incidence rates of first-time seizures compared with patients with affective disorders, irrespective of antipsychotic drug use. In patients with affective disorders, current use of medium-to-high potency first-generation antipsychotic drugs was associated with an increased risk of seizures (adjusted odds ratio 2.51 [95 % CI 1.51-4.18]) compared with non-use, while use of other antipsychotic drugs was not associated with seizures. In patients with dementia, current use of olanzapine or quetiapine (adjusted odds ratio 2.37 [95 % CI 1.35-4.15]), low-to-medium potency first-generation antipsychotic drugs (adjusted odds ratio 3.08 [95 % CI 1.34-7.08]), and medium-to-high potency first-generation antipsychotic drugs (adjusted odds ratio 2.24 [95 % CI 1.05-4.81]) was associated with an increased risk of seizures compared with non-use, but current use of amisulpride, aripiprazole, risperidone, or sulpiride (adjusted odds ratio 0.92 [95 % CI 0.48-1.75]) was not. Use of antipsychotic drugs in patients with schizophrenia could not be investigated because of small numbers.

CONCLUSIONS

Current use of medium-to-high potency first-generation antipsychotic drugs was associated with a 2.5-fold increased risk of seizures compared with non-use of antipsychotic drugs in patients with affective disorders. In these patients, current use of all other antipsychotic drug subclasses was not associated with seizures. In patients with dementia, current and past use of all antipsychotic drug subclasses, except amisulpride, aripiprazole, risperidone, or sulpiride, was associated with an increased risk of seizures.

Small-particle Inhaled Corticosteroid as First-line or Step-up Controller Therapy in Childhood Asthma

BACKGROUND

Because randomized controlled trials of established pediatric asthma therapies are expensive and difficult to perform, observational studies may fill gaps in the evidence base.

OBJECTIVES

To compare the effectiveness of representative small-particle inhaled corticosteroid (ICS) with that of standard size-particle ICS for children initiating or stepping up ICS therapy for asthma (analysis 1) and to compare the effectiveness of ICS dose step-up using small-particle ICS with adding long-acting β2-agonist (LABA) to the ICS (analysis 2).

METHODS

These historical matched cohort analyses drew on electronic medical records of children with asthma aged 5 to 11 years. Variables measured during 2 consecutive years (1 baseline year for confounder definition and 1 outcome year) included risk-domain asthma control (no hospital attendance for asthma, acute oral corticosteroids, or lower respiratory tract infection requiring antibiotics) and rate of severe exacerbations (asthma-related emergency, hospitalization, or oral corticosteroids).

RESULTS

In the initiation population (n = 797 in each cohort), children prescribed small-particle ICS versus standard size-particle ICS experienced greater odds of asthma control (adjusted odds ratio, 1.49; 95% CI, 1.10-2.02) and lower severe exacerbation rate (adjusted rate ratio, 0.56; 95% CI, 0.35-0.88). Step-up outcomes (n = 206 in each cohort) were also significantly better for small-particle ICS, with asthma control adjusted odds ratio of 2.22 (95% CI, 1.23-4.03) and exacerbations adjusted rate ratio of 0.49 (95% CI, 0.27-0.89). The number needed to treat with small-particle ICS to achieve 1 additional child with asthma control was 17 (95% CI, 9-107) for the initiation population and 5 (95% CI, 3-78) for the step-up population. Outcomes were not significantly different for stepped-up small-particle ICS dose versus ICS/LABA combination (n = 185 in each cohort).

CONCLUSIONS

Initiating or stepping up the ICS dose with small-particle ICS rather than with standard size-particle ICS is more effective and shows similar effectiveness to add-on LABA in childhood asthma.

The association between psychiatric diseases, psychotropic drugs and the risk of incident rosacea

BACKGROUND

Psychological conditions, such as traumatic events or stress, have been discussed controversially as aetiological factors for rosacea.

OBJECTIVES

To assess the association between diagnosed depression, other affective disorders or schizophrenia and subsequent incident rosacea. We further aimed at evaluating the possible role of various psychotropic drugs within this association.

METHODS

We conducted a matched case-control study of psychiatric diseases and incident rosacea, stratified by exposure to various psychotropic drugs, using the UK-based General Practice Research Database. Cases had a first diagnosis of rosacea recorded between 1995 and 2009. Each case was matched to one control on age, sex, general practice and years of history on the database.

RESULTS

A history of depression or other affective disorders was not associated with an increased risk of developing rosacea; lithium was the only antidepressant drug that significantly altered this association. Current long-term use of lithium was associated with a decreased odds ratio (OR) of 0·58 [95% confidence interval (CI) 0·38-0·88] among people without a schizophrenia diagnosis (with or without affective disorders), compared with people not exposed to lithium. Patients with diagnosed schizophrenia revealed a decreased rosacea risk (OR 0·71, 95% CI 0·60-0·91), independent of antipsychotic drug use.

CONCLUSIONS

Depression or other affective disorders were not associated with incident rosacea, whereas patients with schizophrenia were at a decreased risk of this skin disease in our study population. The materially decreased risk of rosacea among people with chronic lithium exposure may lead to new insights into the pathomechanism of rosacea.

Application of multicategory exposure marginal structural models to investigate the association between long-acting beta-agonists and prescribing of oral corticosteroids for asthma exacerbations in the Clinical Practice Research Datalink

OBJECTIVE

To examine the comparative effectiveness of inhaled long-acting beta-agonist (LABA), inhaled corticosteroid (ICS), and ICS/LABA combinations.

METHODS

We used a retrospective cohort design of patients older than 12 years with asthma diagnosis in the Clinical Practice Research Datalink to evaluate asthma-related morbidity measured by oral corticosteroid (OCS) initiation within 12 months of initiating LABAs, ICSs, or ICSs/LABAs. Asthma severity 12 months before drug initiation (use of OCSs, asthma-related hospital or emergency department visits, and number of short-acting beta-agonist prescriptions) and during follow-up (short-acting beta-agonist prescriptions and total number of asthma drug classes) was adjusted as a time-varying variable via marginal structural models.

RESULTS

A total of 51,103 patients with asthma were followed for 12 months after receiving first prescription for study drugs from 1993 to 2010. About 92% initiated ICSs, 1% initiated LABAs, and 7% initiated ICSs/LABAs. Compared with ICSs, LABAs were associated with a 10% increased risk of asthma exacerbations requiring short courses of OCSs (hazard ratio [HR] 1.10; 95% confidence interval [CI] 1.07-1.18). ICS/LABA initiators were 62% less likely than ICS initiators (HR 0.38; 95% CI 0.12-0.66) and 50% less likely than LABA initiators to receive OCS prescriptions for asthma exacerbations (HR 0.50; 95% CI 0.14-0.78).

CONCLUSIONS

In concordance with current asthma management guidelines, inhaled LABAs should not be prescribed as monotherapy to patients with asthma. The findings suggest the presence of time-dependent confounding by asthma severity, which was accounted for by the marginal structural model.

Risk factors for acute exacerbations of COPD in a primary care population: a retrospective observational cohort study

OBJECTIVES

To evaluate risk factors associated with exacerbation frequency in primary care. Information on exacerbations of chronic obstructive pulmonary disease (COPD) has mainly been generated by secondary care-based clinical cohorts.

DESIGN

Retrospective observational cohort study.

SETTING

Electronic medical records database (England and Wales).

PARTICIPANTS

58,589 patients with COPD aged ≥40 years with COPD diagnosis recorded between 1 April 2009 and 30 September 2012, and with at least 365 days of follow-up before and after the COPD diagnosis, were identified in the Clinical Practice Research Datalink. Mean age: 69 years; 47% female; mean forced expiratory volume in 1s 60% predicted.

OUTCOME MEASURES

Data on moderate or severe exacerbation episodes defined by diagnosis and/or medication codes 12 months following cohort entry were retrieved, together with demographic and clinical characteristics. Associations between patient characteristics and odds of having none versus one, none versus frequent (≥2) and one versus frequent exacerbations over 12 months follow-up were evaluated using multivariate logistic regression models.

RESULTS

During follow-up, 23% of patients had evidence of frequent moderate-to-severe COPD exacerbations (24% one; 53% none). Independent predictors of increased odds of having exacerbations during the follow-up, either frequent episodes or one episode, included prior exacerbations, increasing dyspnoea score, increasing grade of airflow limitation, females and prior or current history of several comorbidities (eg, asthma, depression, anxiety, heart failure and cancer).

CONCLUSIONS

Primary care-managed patients with COPD at the highest risk of exacerbations can be identified by exploring medical history for the presence of prior exacerbations, greater COPD disease severity and co-occurrence of other medical conditions.

Nonsteroidal anti-inflammatory drugs and the risk of nonmelanoma skin cancer

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been assigned a promising role in the chemoprevention of various malignancies. However, epidemiological data on the association between NSAID use and nonmelanoma skin cancer (NMSC) are limited. To explore whether patients regularly exposed to systemic NSAIDs are at a reduced risk of basal cell carcinoma (BCC) or squamous cell carcinoma (SCC), we conducted a population-based case-control analysis using the Clinical Practice Research Datalink, a United Kingdom primary care database. We identified 65,398 patients with incident BCC and 7,864 patients with incident SCC diagnosed between 1995 and 2013 and matched 1 and 4 NMSC-free controls to each BCC and SCC case, respectively, on age, sex, general practice, calendar time and years of history in the database. We compared prior NSAID exposure between cases and controls using multivariate conditional logistic regression analyses controlling for several potential confounders. Overall, we found no association between NSAID use and BCC, but when looking exclusively at users of single NSAID substances there was a suggestion of a reduced BCC risk in regular users of aspirin and ibuprofen (adjusted odds ratio [adj. OR]: 0.92, 95% confidence interval [CI]: 0.85-0.99 and adj. OR: 0.61, 95% CI: 0.48-0.78, respectively). The risk of SCC was slightly decreased in regular users of any NSAIDs (adj. OR: 0.89, 95% CI: 0.82-0.97), with the strongest risk reduction observed in current users of coxibs (adj. OR: 0.77, 95% CI: 0.62-0.95). These findings provide evidence that patients predisposed to NMSC might benefit from chemoprevention with NSAIDs.

Allopurinol Initiation and Change in Blood Pressure in Older Adults With Hypertension

Hypertension is a key risk factor for cardiovascular disease, and new treatments are needed. Uric acid reduction lowers blood pressure (BP) in adolescents, suggesting a direct pathophysiological role in the development of hypertension. Whether the same relationship is present in older adults is unknown. We explored change in BP after allopurinol initiation using data from the UK Clinical Practice Research Datalink. Data were extracted for patients with hypertension aged >65 years who were prescribed allopurinol with pretreatment and during treatment BP readings. Data from comparable controls were extracted. The change in BP in patients with stable BP medication was the primary outcome and was compared between groups. Regression analysis was used to adjust for potential confounding factors, and a propensity-matched sample was generated. Three hundred sixty-five patients who received allopurinol and 6678 controls were included. BP fell in the allopurinol group compared with controls (between-group difference in systolic and diastolic BP: 2.1 mm Hg; 95% confidence interval, −0.6 to 4.8; and 1.7 mm Hg; 95% confidence interval, 0.4–3.1, respectively). Allopurinol use was independently associated with a fall in both systolic and diastolic BP on regression analysis ( P <0.001). Results were consistent in the propensity-matched sample. There was a trend toward greater fall in BP in the high-dose allopurinol group, but change in BP was not related to baseline uric acid level. Allopurinol use is associated with a small fall in BP in adults. Further studies of the effect of high-dose allopurinol in adults with hypertension are needed.

Metformin and the risk of head and neck cancer: a case-control analysis

AIMS

Metformin use has been associated with a decreased risk of some cancers, although data on head and neck cancer (HNC) are scarce. We explored the relation between the use of antidiabetic drugs and the risk of HNC.

METHODS

We conducted a case-control analysis in the UK-based Clinical Practice Research Datalink (CPRD) of people with incident HNC between 1995 and 2013 below the age of 90 years. Six controls per case were matched on age, sex, calendar time, general practice and number of years of active history in the CPRD prior to the index date. Other potential confounders including body mass index (BMI), smoking, alcohol consumption and comorbidities were also evaluated. The final analyses were adjusted for BMI, smoking and diabetes mellitus (or diabetes duration in a sensitivity analysis). Results are presented as odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Use of metformin was neither associated with a statistically significant altered risk of HNC overall (1-29 prescriptions: adjusted OR 0.87, 95% CI 0.61-1.24 and ≥ 30 prescriptions adjusted OR 0.80, 95% CI 0.53-1.22), nor was long-term use of sulphonylureas (adjusted OR 0.87, 95% CI 0.59-1.30), or any insulin use (adjusted OR 0.92, 95% CI 0.63-1.35). However, we found a (statistically non-significant) decreased risk of laryngeal cancer associated with long-term metformin use (adjusted OR 0.41, 95% CI 0.17-1.03).

CONCLUSIONS

In this population-based study, the use of antidiabetic drugs was not associated with a materially altered risk of HNC. Our data suggest a protective effect of long-term metformin use for laryngeal cancer.

Comparing the effectiveness of small-particle versus large-particle inhaled corticosteroid in COPD

Purpose

Small airway changes and dysfunction contribute importantly to airway obstruction in chronic obstructive pulmonary disease (COPD), which is currently treated with inhaled corticosteroids (ICS) and long-acting bronchodilators at Global initiative for Obstructive Lung Disease (GOLD) grades 2–4. This retrospective matched cohort analysis compared effectiveness of a representative small-particle ICS (extrafine beclomethasone) and larger-particle ICS (fluticasone) in primary care patients with COPD.

Patients and methods

Smokers and ex-smokers with COPD ≥40 years old initiating or stepping-up their dose of extrafine beclomethasone or fluticasone were matched 1:1 for demographic characteristics, index prescription year, concomitant therapies, and disease severity during 1 baseline year. During 2 subsequent years, we evaluated treatment change and COPD exacerbations, defined as emergency care/hospitalization for COPD, acute oral corticosteroids, or antibiotics for lower respiratory tract infection.

Results

Mean patient age was 67 years, 57%–60% being male. For both initiation (n=334:334) and step-up (n=189:189) patients, exacerbation rates were comparable between extrafine beclomethasone and fluticasone cohorts during the 2 year outcome period. Odds of treatment stability (no exacerbation or treatment change) were significantly greater for patients initiating extrafine beclomethasone compared with fluticasone (adjusted odds ratio 2.50; 95% confidence interval, 1.32–4.73). Median ICS dose exposure during 2 outcome years was significantly lower (P<0.001) for extrafine beclomethasone than fluticasone cohorts (315 μg/day versus 436 μg/day for initiation, 438 μg/day versus 534 μg/day for step-up patients).

Conclusion

We observed that small-particle ICS at significantly lower doses had comparable effects on exacerbation rates as larger-particle ICS at higher doses, whereas initiation of small-particle ICS was associated with better odds of treatment stability during 2-years’ follow-up.

Incidence of and risk factors for severe hypoglycaemia in treated type 2 diabetes mellitus patients in the UK--a nested case-control analysis

AIMS

To assess incidence rates (IRs) of and identify risk factors for incident severe hypoglycaemia in patients with type 2 diabetes newly treated with antidiabetic drugs.

METHODS

Using the UK-based General Practice Research Database, we performed a retrospective cohort study between 1994 and 2011 and a nested case-control analysis. Ten controls from the population at risk were matched to each case with a recorded severe hypoglycaemia during follow-up on general practice, years of history in the database and calendar time. Using multivariate conditional logistic regression analyses, we adjusted for potential confounders.

RESULTS

Of 130,761 patients with newly treated type 2 diabetes (mean age 61.7 ± 13.0 years), 690 (0.5%) had an incident episode of severe hypoglycaemia recorded [estimated IR 11.97 (95% confidence interval, CI, 11.11-12.90) per 10,000 person-years (PYs)]. The IR was markedly higher in insulin users [49.64 (95% CI, 44.08-55.89) per 10,000 PYs] than in patients not using insulin [8.03 (95% CI, 7.30-8.84) per 10,000 PYs]. Based on results of the nested case-control analysis increasing age [≥ 75 vs. 20-59 years; adjusted odds ratio (OR), 2.27; 95% CI, 1.65-3.12], cognitive impairment/dementia (adjusted OR, 2.00; 95% CI, 1.37-2.91), renal failure (adjusted OR, 1.34; 95% CI, 1.04-1.71), current use of sulphonylureas (adjusted OR, 4.45; 95% CI, 3.53-5.60) and current insulin use (adjusted OR, 11.83; 95% CI, 9.00-15.54) were all associated with an increased risk of severe hypoglycaemia.

CONCLUSIONS

Severe hypoglycaemia was recorded in 12 cases per 10,000 PYs. Risk factors for severe hypoglycaemia included increasing age, renal failure, cognitive impairment/dementia, and current use of insulin or sulphonylureas.

The association between Parkinson's disease and anti-epilepsy drug carbamazepine: a case-control study using the UK General Practice Research Database

AIMS

To investigate whether the use of carbamazepine is associated with reduced risk of Parkinson's disease.

METHODS

We conducted a population-based, matched case-control study of patients randomly selected from the UK General Research Practice Database. We identified 8549 patients with Parkinson's disease using diagnosis criteria with a positive predictive value of 90%. These patients were compared with 42, 160 control subjects matched for age, sex and general practice.

RESULTS

Overall, 3.0% of cases (257 of 8549) had at least one recorded prescription for carbamazepine compared with 2.5% (1050 of 42, 160) of controls. The crude odds ratio for the association between Parkinson's disease and carbamazepine was 1.22 (95% confidence interval 1.06-1.40), but this reduced to 0.93 (95% confidence interval 0.81-1.08, P = 0.34) after adjusting for annual consultation rate. Further adjustment for body mass index, smoking status, alcohol consumption or use of calcium channel blockers did not affect results. There was no evidence that risk decreased with higher doses or longer duration of carbamazepine use.

CONCLUSIONS

There was little to no evidence that use of carbamazepine is associated with reduced risk of Parkinson's disease. Although the study was underpowered, it does indicate that any effect of carbamazepine is likely to be small.

Recent advances in the utility and use of the General Practice Research Database as an example of a UK Primary Care Data resource

Since its inception in the mid-1980s, the General Practice Research Database (GPRD) has undergone many changes but remains the largest validated and most utilised primary care database in the UK. Its use in pharmacoepidemiology stretches back many years with now over 800 original research papers. Administered by the Medicines and Healthcare products Regulatory Agency since 2001, the last 5 years have seen a rebuild of the database processing system enhancing access to the data, and a concomitant push towards broadening the applications of the database. New methodologies including real-world harm-benefit assessment, pharmacogenetic studies and pragmatic randomised controlled trials within the database are being implemented. A substantive and unique linkage program (using a trusted third party) has enabled access to secondary care data and disease-specific registry data as well as socio-economic data and death registration data. The utility of anonymised free text accessed in a safe and appropriate manner is being explored using simple and more complex techniques such as natural language processing.

Bone fractures in children with autistic spectrum disorder

BACKGROUND

Bone fractures in children represent a source of significant disability and morbidity. Are children with autistic spectrum disorder (ASD) at an altered risk of fractures compared with typically developing children?

METHODS

Using the General Practice Research Database, the authors assessed the prevalence of fractures in boys with ASD diagnosed between 2 and 8 years. A cross-sectional design was used to compare the prevalence of fractures among children with ASD and age-matched controls, conditional logistic regression to explore the relative risk of having a fracture in association with diagnosed ASD.

RESULTS

The study population comprised 3,219 boys with a first-time diagnosis of ASD and 12,265 matched controls. ASD was associated with a significantly decreased risk of developing a fracture at any time in childhood (odds ratio [OR], 0.68, 95% confidence interval [CI], 0.59-0.77, p < .0001). The relative risk estimates were lower for the time period after ASD diagnosis (OR, 0.56, 95% CI, 0.48-0.66, p < .0001) but were not different for the time period before ASD diagnosis (OR, 0.96, 95% CI, 0.78-1.18, p = .6866). Adjusting for use of different drugs did not change the estimates.

CONCLUSION

The relative risk of experiencing a fracture at any time in childhood is lower for boys with ASD compared with healthy boys.