Cancer recording and mortality in the General Practice Research Database and linked cancer registries.

PURPOSE: Large electronic datasets are increasingly being used to evaluate healthcare delivery. The aim of this study was to compare information held by cancer registries with that of the General Practice Research Database (GPRD). METHODS: A convenience sample of 101 020 patients aged 40+ years drawn from GPRD formed the primary data source. This cohort was derived from a larger sample originally established for a cohort study of diabetes. GPRD records were linked with those from cancer registries in the National Cancer Data Repository (NCDR). Concordance between the two datasets was then evaluated. For cases recorded only on one dataset, validation was sought from other datasets (Hospital Episode Statistics and death registration) and by detailed analysis of a subset of GPRD records. RESULTS: A total of 5797 cancers (excluding non-melanomatous skin cancer) were recorded on GPRD. Of these cases, 4830 were also recorded on NCDR (concordance rate of 83.3%). Of the 976 cases recorded on GPRD but not on NCDR, 528 were present also in the hospital records or death certificates. Of the 341 cases recorded on NCDR but not on GPRD, 307 were recorded in these other two datasets. Rates of concordance varied by cancer type. Cancer registries recorded larger numbers of patients with lung, colorectal, and pancreatic cancers, whereas GPRD recorded more haematological cancers and melanomas. As expected, GPRD recorded significantly more non-melanomatous skin cancer. Concordance decreased with increasing age. CONCLUSION: Although concordance levels were reasonably high, the findings from this study can be used to direct efforts for better recording in both datasets.

Variability of antibiotic prescribing in patients with chronic obstructive pulmonary disease exacerbations: a cohort study.

BACKGROUND: The role of antibiotics in treating mild or moderate exacerbations in patients with acute chronic obstructive pulmonary disease (COPD) is unclear. The aims were to: (i) describe patient characteristics associated with acute exacerbations amongst a representative COPD population, (ii) explore the relationship between COPD severity and outcomes amongst patients with exacerbations, and (iii) quantify variability by general practice in prescribing of antibiotics for COPD exacerbations. METHOD: A cohort of 62,747 patients with COPD was identified from primary care general practices (GP) in England, and linked to hospital admission and death certificate data. Exacerbation cases were matched to three controls and characteristics compared using conditional logistic regression. Outcomes were compared using incidence rates and Cox regression, stratified by disease severity. Variability of prescribing at the GP level was evaluated graphically and by using multilevel models. RESULTS: COPD severity was found to be associated with exacerbation and subsequent mortality (very severe vs. mild, odds ratio for exacerbation 2.12 [95%CI 19.5-2.32]), hazard ratio for mortality 2.14 [95%CI 1.59-2.88]). Whilst 61% of exacerbation cases were prescribed antibiotics, this proportion varied considerably between GP practices (interquartile range, 48-73%). This variation is greater than can be explained by patient characteristics alone. CONCLUSIONS: There is significant variability between GP practices in the prescribing of antibiotics to COPD patients experiencing exacerbations. Combined with a lack of evidence on the effects of treatment, this supports the need and opportunity for a large scale pragmatic randomised trial of the prescribing of antibiotics for COPD patients with exacerbations, in order to clarify their effectiveness and long term outcomes whilst ensuring the representativeness of subjects.

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.

Risk of new onset autoimmune disease in 9- to 25-year-old women exposed to human papillomavirus-16/18 AS04-adjuvanted vaccine in the United Kingdom.

To assess the risk of autoimmune disease (AD) in 9-25 year-old women within 1 year after the first AS04-HPV-16/18vaccine dose, a retrospective, observational database cohort study was conducted using CPRD GOLD. From CPRD GOLD 4 cohorts (65,000 subjects each) were retrieved: 1 exposed female cohort (received ≥1 AS04-HPV-16/18 vaccine dose between Sep2008-Aug2010) and 3 unexposed cohorts: historical female (Sep2005-Aug2007), concurrent male, and historical male. Co-primary endpoints were confirmed neuroinflammatory/ophthalmic AD and other AD, secondary endpoints were confirmed individual AD. Risk of new onset of AD was compared between cohorts (reference: historical cohort) using Poisson regression. The main analysis using confirmed cases showed no neuroinflammatory/ophthalmic AD cases in the female exposed cohort. Incidence rate ratio (IRR) (95% CI) of other AD was 1.41 (0.86 to 2.31) in female and 1.77 (0.94 to 3.35) in male cohorts when compared to the female and male historical cohort, respectively. Secondary endpoints were evaluated for diseases with >10 cases, which were Crohn's disease (IRR: 1.21 [0.37 to 3.95] for female and 4.22 [0.47 to 38.02] for male cohorts), autoimmune thyroiditis (IRR: 3.75 [1.25 to 11.31] for female and no confirmed cases for male cohorts) and type 1 diabetes (IRR: 0.30 [0.11 to 0.83] for female and 2.46 [1.08 to 5.60] for male cohorts). Analysis using confirmed and non-confirmed cases showed similar results, except for autoimmune thyroiditis in females, IRR: 1.45 (0.79 to 2.64). There was no evidence of an increased risk of AD in women aged 9 to 25 years after AS04-HPV-16/18 vaccination.

Risk of spontaneous abortion and other pregnancy outcomes in 15-25 year old women exposed to human papillomavirus-16/18 AS04-adjuvanted vaccine in the United Kingdom.

BACKGROUND: We assessed the risk of spontaneous abortion (SA) after inadvertent exposure to HPV-16/18-vaccine during pregnancy using an observational cohort design. METHODS: The study population included women aged 15-25 years registered with the Clinical Practice Research Datalink General Practice OnLine Database in the United Kingdom (UK), who received at least one HPV-16/18-vaccine dose between 1st September 2008 and 30th June 2011. Exposed women had the first day of gestation between 30 days before and 45 days (90 days for the extended exposure period) after any HPV-16/18-vaccine dose. Non-exposed women had the first day of gestation 120 days-18 months after the last dose. SA defined as foetal loss between weeks 1 and 23 of gestation (UK definition). RESULTS: The frequency of SA was 11.6% (among 207 exposed) and 9.0% (632 non-exposed), women: hazard ratio (HR) adjusted for age at first day of gestation 1.30 (95% confidence interval: 0.79-2.12). Sensitivity analysis per number of doses administered (-30 to +45-day risk period) showed a HR for SA of 1.11 (0.64-1.91) for 18/178 women with one dose during the risk period versus 2.55 (1.09-5.93) in 6/29 women with two doses within a 4-5 weeks period. The proportion of pre-term/full-term/postterm deliveries, small/large for gestational age infants, and birth defects was not significantly different between exposed and non-exposed women. Results were consistent using a (United States) SA definition of foetal loss between weeks 1-19 and/or the extended risk period. CONCLUSION: There was no evidence of an increased risk of SA and other adverse pregnancy outcomes in young women inadvertently HPV-16/18-vaccinated around gestation. Nevertheless, women who are pregnant or trying to become pregnant are advised to postpone vaccination until completion of pregnancy.

Smoking cessation interventions following acute coronary syndrome: a missed opportunity?

BACKGROUND: It is recommended that general practitioners (GPs) offer cessation advice and pharmacological interventions to smokers with acute coronary syndrome (ACS). The study objective was to describe the extent to which this is done, and to describe outcomes by smoking status. DESIGN: Patients aged 30+ hospitalised for troponin-positive ACS from 2002 to 2009, discharged home alive, were identified in the Myocardial Ischaemia National Audit Project registry. Patient data were linked to the General Practice Research Database, Hospital Episode Statistics, and Office of National Statistics mortality data, enabling a unique perspective of longitudinal smoking data. Patients who smoked prior to the hospitalisation had GP interventions and quitting status established in the 3 months following discharge, and were followed up for major clinical outcomes. METHODS: The outcomes evaluated included death, repeat ACS, stroke, heart failure, and major adverse cardiac events (MACE). RESULTS: Of the 4834 patients included, 965 (20%) were smokers at the time of their ACS. After the ACS event, only 225 (24%) received any GP smoking intervention within 3 months, with 82 (9%) receiving advice only, and 143 (15%) receiving a pharmacological intervention. Patients who quit (320; 33%) were at a decreased risk of mortality (relative risk (RR) 0.49; 95% confidence interval (CI) 0.35-0.69) and MACE (RR 0.61; 0.46-0.80) compared with patients who did not. CONCLUSIONS: Whilst a high proportion of patients with ACS are smokers, there is a low level of GP cessation intervention following hospital discharge. This missed opportunity of patient care is important given the decreased risk of mortality and MACE found amongst those who quit.

Completeness and diagnostic validity of recording acute myocardial infarction events in primary care, hospital care, disease registry, and national mortality records: cohort study.

OBJECTIVE: To determine the completeness and diagnostic validity of myocardial infarction recording across four national health record sources in primary care, hospital care, a disease registry, and mortality register. DESIGN: Cohort study. PARTICIPANTS: 21 482 patients with acute myocardial infarction in England between January 2003 and March 2009, identified in four prospectively collected, linked electronic health record sources: Clinical Practice Research Datalink (primary care data), Hospital Episode Statistics (hospital admissions), the disease registry MINAP (Myocardial Ischaemia National Audit Project), and the Office for National Statistics mortality register (cause specific mortality data). SETTING: One country (England) with one health system (the National Health Service). MAIN OUTCOME MEASURES: Recording of acute myocardial infarction, incidence, all cause mortality within one year of acute myocardial infarction, and diagnostic validity of acute myocardial infarction compared with electrocardiographic and troponin findings in the disease registry (gold standard). RESULTS: Risk factors and non-cardiovascular coexisting conditions were similar across patients identified in primary care, hospital admission, and registry sources. Immediate all cause mortality was highest among patients with acute myocardial infarction recorded in primary care, which (unlike hospital admission and disease registry sources) included patients who did not reach hospital, but at one year mortality rates in cohorts from each source were similar. 5561 (31.0%) patients with non-fatal acute myocardial infarction were recorded in all three sources and 11 482 (63.9%) in at least two sources. The crude incidence of acute myocardial infarction was underestimated by 25-50% using one source compared with using all three sources. Compared with acute myocardial infarction defined in the disease registry, the positive predictive value of acute myocardial infarction recorded in primary care was 92.2% (95% confidence interval 91.6% to 92.8%) and in hospital admissions was 91.5% (90.8% to 92.1%). CONCLUSION: Each data source missed a substantial proportion (25-50%) of myocardial infarction events. Failure to use linked electronic health records from primary care, hospital care, disease registry, and death certificates may lead to biased estimates of the incidence and outcome of myocardial infarction. TRIAL REGISTRATION: NCT01569139 clinicaltrials.gov.

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.