Scientific
publications

OBJECTIVES: To investigate the extent to which variation exists in the initiation rate of statin therapy for the primary prevention of cardiovascular disease between countries of the UK and between different regions within England. DESIGN: Cohort study using data from a large UK primary care database. SETTING UK PARTICIPANTS: 4,820,885 individuals from 554 general practices during the period 2004-2012. MAIN OUTCOME MEASURES: Rate of statin therapy initiation per 1000 person-years. RESULTS: Relative to a fixed English rate of 1 initiation per 1000 person-years and accounting for gender, age and social deprivation level, the rate was similar for Scotland at 0.92 (95% CI 0.84 to 1.00) and rates for Northern Ireland and Wales were higher at 1.40 (95% CI 1.20 to 1.62) and 1.18 (95% CI 1.05 to 1.32), respectively. Within England, the regions could be classified into three groups with respect to statin therapy initiation rates (relative to a rate of 1 initiation per 1000 person-years for London): the South Central 0.73 (95% CI 0.64 to 0.83), South West 0.80 (95% CI 0.71 to 0.91), East of England 0.81 (95% CI 0.71 to 0.94) and South East Coast 0.83 (95% CI 0.73 to 0.95); strategic health authorities had similar low rates followed by the East Midlands 0.88 (95% CI 0.73 to 1.05), West Midlands 0.96 (95% CI 0.84 to 1.09), North East 0.96 (95% CI 0.79 to 1.16), Yorkshire and Humber 0.97 (95% CI 0.81 to 1.17) and London strategic health authorities. North West England exhibited the highest rate of statin therapy initiation of 1.16 (95% CI 1.02 to 1.31). CONCLUSIONS: Considerable variation in the rate of statin therapy initiation was observed between the four countries of the UK and between different geographical regions within England.

BACKGROUND: Between 19%-44% pregnant women are prescribed antibiotics during pregnancy. A single, large randomised-controlled-trial (ORACLE Childhood Study II) found an increased risk of childhood cerebral palsy and possibly epilepsy following prophylactic antibiotic use in pregnant women with spontaneous preterm labour. We ascertained whether this outcome could be reproduced across the population of babies delivered at term and prospectively followed in primary-care using data from The Health Improvement Network. METHODS: We determined the risk of cerebral palsy or epilepsy in children whose mothers were prescribed antibiotics during pregnancy using a cohort of 195,909 women linked to their live, term-born, singleton children. We compared the effect of antibiotic class, number of courses and timing of prescribing in pregnancy. Analyses were adjusted for maternal risk factors (e.g. recorded infection, age, chronic conditions, social deprivation, smoking status). Children were followed until age seven years or cessation of registration with the primary-care practitioner. RESULTS: In total, 64,623 (33.0%) women were prescribed antibiotics in pregnancy and 1,170 (0.60%) children had records indicating cerebral palsy or epilepsy. Adjusted analyses showed no association between prescribing of any antibiotic and cerebral palsy or epilepsy (adj.HR 1.04, 95%CI 0.91-1.19). However, compared with penicillins, macrolides were associated with an increased risk of cerebral palsy or epilepsy (adj.HR 1.78, 95%CI 1.18-2.69; number needed to harm 153, 95%CI 71-671). CONCLUSIONS: We found no overall association between antibiotic prescribing in pregnancy and cerebral palsy and/or epilepsy in childhood. However, our finding of an increased risk of cerebral palsy or epilepsy associated with macrolide prescribing in pregnancy adds to evidence that macrolide use is associated with serious harm.

PURPOSE: Cervical dystonia (CD) is a hypertonic condition caused by damage to the central nervous system. Very few studies have assessed the overall economic burden of the disease. The objective of this study was to describe the utilization of health care resources of patients with CD in the UK primary care setting, using a large population-based database. PATIENTS AND METHODS: Adults with a first diagnosis of CD between January 1, 2007 and January 31, 2011, who were registered to a general practitioner (GP) practice contributing to The Health Improvement Network (THIN), were included. Sociodemographic and clinical characteristics were assessed at the time of diagnosis. Health care resource utilization and pharmacological treatment were investigated at the end of the first and second year after diagnosis. RESULTS: Overall, 4,024 newly diagnosed patients with CD were identified, with average age at diagnosis of 45 years old; 65.3% were female. Depression in the year prior to diagnosis was the most common comorbidity. Primary care utilization was high in the first year, with 99.2% of patients visiting their GP (on average 6.2 times), and 43% visiting a nurse (on average 2.5 times). Patients were most commonly referred to an orthopedic surgeon, and 15.9% reported at least one physiotherapy visit. In the second year, utilization was similar. Prescriptions of at least one of the investigated treatments were found in 82.0% and 45.3%, in the first and second year, respectively. CONCLUSION: Findings suggest a high number of new CD cases are being identified in primary care, but not all will be referred to secondary care. Health care resource utilization was compared with that of all patients registered in THIN, which is representative of the UK, and the adjusted usage of primary care resources was found to be similar to that of the THIN population.

BACKGROUND: The UK has poor lung cancer survival rates and high early mortality, compared to other countries. We aimed to identify factors associated with early death, and features of primary care that might contribute to late diagnosis. METHODS: All cases of lung cancer diagnosed between 2000 and 2013 were extracted from The Health Improvement Network database. Patients who died within 90 days of diagnosis were compared with those who survived longer. Standardised chest X-ray (CXR) and lung cancer rates were calculated for each practice. RESULTS: Of 20,142 people with lung cancer, those who died early consulted with primary care more frequently prediagnosis. Individual factors associated with early death were male sex (OR 1.17; 95% CI 1.10 to 1.24), current smoking (OR 1.43; 95% CI 1.28 to 1.61), increasing age (OR 1.80; 95% CI 1.62 to 1.99 for age ≥80 years compared to 65-69 years), social deprivation (OR 1.16; 95% CI 1.04 to 1.30 for Townsend quintile 5 vs 1) and rural versus urban residence (OR 1.22; 95% CI 1.06 to 1.41). CXR rates varied widely, and the odds of early death were highest in the practices which requested more CXRs. Lung cancer incidence at practice level did not affect early deaths. CONCLUSIONS: Patients who die early from lung cancer are interacting with primary care prediagnosis, suggesting potentially missed opportunities to identify them earlier. A general increase in CXR requests may not improve survival; rather, a more timely and appropriate targeting of this investigation using risk assessment tools needs further assessment.

BACKGROUND: Inhaled, long-acting beta-2-adrenoceptor agonists (LABA) have well-established roles in asthma and/or COPD treatment. Drug utilisation patterns for LABA have been described, but few studies have directly compared LABA use in different countries. We aimed to compare the prevalence of LABA-containing prescriptions in five European countries using a standardised methodology. METHODS: A common study protocol was applied to seven European healthcare record databases (Denmark, Germany, Spain, the Netherlands (2), and the UK (2)) to calculate crude and age- and sex-standardised annual period prevalence rates (PPRs) of LABA-containing prescriptions from 2002-2009. Annual PPRs were stratified by sex, age, and indication (asthma, COPD, asthma and COPD). RESULTS: From 2002-2009, age- and sex-standardised PPRs of patients with LABA-containing medications increased in all databases (58.2%-185.1%). Highest PPRs were found in men ≥ 80 years old and women 70-79 years old. Regarding the three indications, the highest age- and sex-standardised PPRs in all databases were found in patients with "asthma and COPD" but with large inter-country variation. In those with asthma or COPD, lower PPRs and smaller inter-country variations were found. For all three indications, PPRs for LABA-containing prescriptions increased with age. CONCLUSIONS: Using a standardised protocol that allowed direct inter-country comparisons, we found highest rates of LABA-containing prescriptions in elderly patients and distinct differences in the increased utilisation of LABA-containing prescriptions within the study period throughout the five European countries.

OBJECTIVES: We aimed to quantify the risk of major adverse cardiovascular events (MACE) among patients with psoriatic arthritis (PsA), rheumatoid arthritis (RA) and psoriasis without known PsA compared with the general population after adjusting for traditional cardiovascular risk factors. METHODS: A population-based longitudinal cohort study from 1994 to 2010 was performed in The Health Improvement Network (THIN), a primary care medical record database in the UK. Patients aged 18-89 years of age with PsA, RA or psoriasis were included. Up to 10 unexposed controls matched on practice and index date were selected for each patient with PsA. Outcomes included cardiovascular death, myocardial infarction, cerebrovascular accidents and the composite outcome (MACE). Cox proportional hazards models were used to calculate the HRs for each outcome adjusted for traditional risk factors. A priori, we hypothesised an interaction between disease status and disease-modifying antirheumatic drug (DMARD) use. RESULTS: Patients with PsA (N=8706), RA (N=41 752), psoriasis (N=138 424) and unexposed controls (N=81 573) were identified. After adjustment for traditional risk factors, the risk of MACE was higher in patients with PsA not prescribed a DMARD (HR 1.24, 95% CI 1.03 to 1.49), patients with RA (No DMARD: HR 1.39, 95% CI 1.28 to 1.50, DMARD: HR 1.58, 95% CI 1.46 to 1.70), patients with psoriasis not prescribed a DMARD (HR 1.08, 95% CI 1.02 to 1.15) and patients with severe psoriasis (DMARD users: HR 1.42, 95% CI 1.17 to 1.73). CONCLUSIONS: Cardiovascular risk should be addressed with all patients affected by psoriasis, PsA or RA.

AIMS: The aim of this study was to identify risk factors for hyperkalaemia in a cohort of patients with newly diagnosed heart failure in the UK. METHODS AND RESULTS: A nested case-control study was conducted using data from The Health Improvement Network primary care database. A cohort of 19 194 patients aged 1-89 years between January 2000 and December 2005 with newly diagnosed heart failure was followed up and cases of hyperkalaemia identified. Cases were frequency matched to controls by age, sex, and calendar year, and information on demographics, co-morbidities, co-medications, and lifestyle factors was extracted from the database. Using unconditional logistic regression models, odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to identify potential risk factors. In total, 2176 hyperkalaemia cases were identified over a mean follow-up of 3.9 years. Significant risk factors for hyperkalaemia were: renal failure (OR 3.81; 95% CI 3.29-4.42), type II diabetes (OR 1.52; 95% CI 1.31-1.75), valvular heart disease (OR 1.28; 95% CI 1.06-1.54), and current use of potassium-sparing diuretics (OR 3.01; 95% CI 2.61-3.48), ACE inhibitors (OR 1.70; 95% CI 1.41-2.04), trimethoprim (OR 2.82; 95% CI 1.88-4.23), non-steroidal anti-inflammatory drugs (OR 1.41; 95% CI 1.11-1.79), and several drug combinations. The risk was highest within the first month of medication use and decreased thereafter. CONCLUSION: Our findings may help to better identify patients with heart failure most likely to benefit from careful monitoring of serum potassium levels. Particular vigilance is needed during the start of treatment with certain medications.

AIMS: In order to exert its pharmacodynamic effect, the diabetes drug metformin needs to be taken up into hepatocytes by the organic cation transporter (OCT) system. A recent in vitro study found that proton pump inhibitors (PPIs) inhibit OCT1, OCT2 and OCT3, suggesting that PPIs might reduce metformin's effectiveness. This pharmacoepidemiologic study looked for evidence of a clinical effect of such an interaction. METHODS: This was an observational cohort study examining changes in glycosylated haemoglobin (HbA1c) with exposure to metformin and to PPIs as single agents and in combination. The aim was to assess evidence of a deleterious drug-drug interaction. RESULTS: PPIs did not reduce the effectiveness of metformin, and indeed were associated with a minimally better glycaemic response by - 0.06 HbA1c percentage points (95% confidence interval, -0.10, -0.01) in metformin initiators. CONCLUSIONS: Despite a mechanistic basis for a potential drug-drug interaction, we found no evidence of a deleterious interaction between PPIs and metformin.

OBJECTIVES: To investigate the optimal systolic blood pressure goal above which new antihypertensive medications should be added or doses of existing medications increased ("systolic intensification threshold") and to determine the relation between delays in medication intensification and follow-up and the risk of cardiovascular events or death. DESIGN: Retrospective cohort study. SETTING: Primary care practices in the United Kingdom, 1986-2010. PARTICIPANTS: 88 756 adults with hypertension from The Health Improvement Network nationwide primary care research database. MAIN OUTCOME MEASURES: Rates of acute cardiovascular events or death from any cause for patients with different hypertension treatment strategies (defined by systolic intensification threshold, time to intensification, and time to follow-up over the course of a 10 year treatment strategy assessment period) after adjustment for age, sex, smoking status, socioeconomic deprivation, history of diabetes, cardiovascular disease or chronic kidney disease, Charlson comorbidity index, body mass index, medication possession ratio, and baseline blood pressure. RESULTS: During a median follow-up of 37.4 months after the treatment strategy assessment period, 9985 (11.3%) participants had an acute cardiovascular event or died. No difference in risk of the outcome was seen between systolic intensification thresholds of 130-150 mm Hg, whereas systolic intensification thresholds greater than 150 mm Hg were associated with progressively greater risk (hazard ratio 1.21, 95% confidence interval 1.13 to 1.30; P<0.001 for intensification threshold of 160 mm Hg). Outcome risk increased progressively from the lowest (0-1.4 months) to the highest fifth of time to medication intensification (hazard ratio 1.12, 1.05 to 1.20; P=0.009 for intensification between 1.4 and 4.7 months after detection of elevated blood pressure). The highest fifth of time to follow-up (>2.7 months) was also associated with increased outcome risk (hazard ratio 1.18, 1.11 to 1.25; P<0.001). CONCLUSIONS: Systolic intensification thresholds higher than 150 mm Hg, delays of greater than 1.4 months before medication intensification after systolic blood pressure elevation, and delays of greater than 2.7 months before blood pressure follow-up after antihypertensive medication intensification were associated with increased risk of an acute cardiovascular event or death. These findings support the importance of timely medical management and follow-up in the treatment of patients with hypertension.

IMPORTANCE: Hypertension is prevalent among patients with psoriasis. The effect of psoriasis and its severity on hypertension control is unknown. OBJECTIVE: To determine the association between uncontrolled blood pressure and psoriasis, both overall and according to objectively measured psoriasis severity, among patients with diagnosed hypertension. DESIGN, SETTING, AND PARTICIPANTS: Population-based cross-sectional study nested in a prospective cohort drawn from The Health Improvement Network (THIN), an electronic medical records database broadly representative of the general population in the United Kingdom. The study population included a random sample of patients with psoriasis (n = 1322) between the ages of 25 and 64 years in THIN who were included in the Incident Health Outcomes and Psoriasis Events prospective cohort and their age- and practice-matched controls without psoriasis (n = 11,977). All included patients had a diagnosis of hypertension; their psoriasis diagnosis was confirmed and disease severity was classified by their general practitioners. MAIN OUTCOMES AND MEASURES: Uncontrolled hypertension was defined as a systolic blood pressure of 140 mm Hg or higher or a diastolic blood pressure of 90 mm Hg or higher based on the blood pressure recorded closest in time to the assessment of psoriasis severity. RESULTS: There was a significant positive dose-response relationship between uncontrolled hypertension and psoriasis severity as objectively determined by the affected body surface area in both unadjusted and adjusted analyses that controlled for age, sex, body mass index, smoking and alcohol use status, presence of comorbid conditions, and current use of antihypertensive medications and nonsteroidal anti-inflammatory drugs (adjusted odds ratio [aOR], 0.97; 95% CI, 0.82-1.14 for mild psoriasis; aOR, 1.20; 95% CI, 0.99-1.45 for moderate psoriasis; and aOR, 1.48; 95% CI, 1.08-2.04 for severe psoriasis; P = .01 for trend). The likelihood of uncontrolled hypertension among psoriasis overall was also increased, although not statistically significantly so (aOR, 1.10; 95% CI, 0.98-1.24). CONCLUSIONS AND RELEVANCE: Among patients with hypertension, psoriasis was associated with a greater likelihood of uncontrolled hypertension in a dose-dependent manner, with the greatest likelihood observed among those with moderate to severe psoriasis defined by 3% or more of the body surface area affected. Our data suggest a need for more effective blood pressure management, particularly among patients with more severe psoriasis.

PURPOSE: Age-related macular degeneration (AMD) is the most common cause of legal blindness in Western patients over 65 years of age. We aimed to establish the incidence of AMD, and the association of diabetes, and cardiovascular and eye diseases with the risk of AMD, in a large cohort of primary care patients in the United Kingdom. METHODS: Using data from The Health Improvement Network database in the United Kingdom, all individuals with a first recorded diagnosis of AMD from 2004 to 2010 were identified (N = 10,516) and frequency-matched to 19,389 AMD-free individuals by age, sex, and calendar year of AMD occurrence. Logistic regression was used to examine comorbidities and risk factors for AMD. RESULTS: The incidence of AMD was 18.08 (95% confidence interval [CI], 17.74-18.43) per 10,000 person-years. A positive association with AMD was observed for smoking, a high frequency of primary care visits, and referrals. Diabetes and use of antidiabetic drugs were associated with an increased risk of AMD. Prevalence of cardiovascular diseases among AMD patients was slightly higher than in controls, with a small increased risk of AMD among patients with myocardial infarction, heart failure, or hyperlipidemia. Positive associations were observed between prior eye diseases and risk of AMD, in particular for chorioretinal disorders. CONCLUSIONS: The incidence of AMD in the United Kingdom is in line with previously reported incidence rates from population-based studies. The study suggests an association between diabetes, prior eye diseases, cardiovascular comorbidities and AMD risk, and a link between AMD and higher healthcare utilization.

IMPORTANCE: People with severe mental illness (SMI), including schizophrenia and bipolar disorder, have excess rates of cardiovascular disease (CVD). Risk prediction models validated for the general population may not accurately estimate cardiovascular risk in this group. OBJECTIVE: To develop and validate a risk model exclusive to predicting CVD events in people with SMI incorporating established cardiovascular risk factors and additional variables. DESIGN, SETTING, AND PARTICIPANTS: We used anonymous/deidentified data collected between January 1, 1995, and December 31, 2010, from the Health Improvement Network (THIN) to conduct a primary care, prospective cohort and risk score development study in the United Kingdom. Participants included 38,824 people with a diagnosis of SMI (schizophrenia, bipolar disorder, or other nonorganic psychosis) aged 30 to 90 years. During a median follow-up of 5.6 years, 2324 CVD events (6.0%) occurred. MAIN OUTCOMES AND MEASURES: Ten-year risk of the first cardiovascular event (myocardial infarction, angina pectoris, cerebrovascular accidents, or major coronary surgery). Predictors included age, sex, height, weight, systolic blood pressure, diabetes mellitus, smoking, body mass index (BMI), lipid profile, social deprivation, SMI diagnosis, prescriptions for antidepressants and antipsychotics, and reports of heavy alcohol use. RESULTS: We developed 2 CVD risk prediction models for people with SMI: the PRIMROSE BMI model and the PRIMROSE lipid model. These models mutually excluded lipids and BMI. In terms of discrimination, from cross-validations for men, the PRIMROSE lipid model D statistic was 1.92 (95% CI, 1.80-2.03) and C statistic was 0.80 (95% CI, 0.76-0.83) compared with 1.74 (95% CI, 1.63-1.86) and 0.78 (95% CI, 0.75-0.82) for published Cox Framingham risk scores. The corresponding results in women were 1.87 (95% CI, 1.76-1.98) and 0.79 (95% CI, 0.76-0.82) for the PRIMROSE lipid model and 1.58 (95% CI, 1.48-1.68) and 0.77 (95% CI, 0.73-0.81) for the Cox Framingham model. Discrimination statistics for the PRIMROSE BMI model were comparable to those for the PRIMROSE lipid model. Calibration plots suggested that both PRIMROSE models were superior to the Cox Framingham models. CONCLUSIONS AND RELEVANCE: The PRIMROSE BMI and lipid CVD risk prediction models performed better in SMI compared with models that include only established CVD risk factors. Further work on the clinical effectiveness and cost-effectiveness of the PRIMROSE models is needed to ascertain the best thresholds for offering CVD interventions.

OBJECTIVE: Economic evaluations of new diabetes therapies rely heavily upon the UK Prospective Diabetes Study (UKPDS) equations for prediction of cardiovascular events; however, concerns persist regarding their relevance to current clinical practice and appropriate use in populations other than newly diagnosed patients. This study refits the UKPDS 68 event equations, using contemporary data describing low- and intermediate-risk patients. RESEARCH DESIGN AND METHODS: Anonymized patient data describing demographics, risk factors and incidence of cardiovascular and microvascular events were extracted from The Health Improvement Network (THIN) database over the 10-year period from 1 January 2000 to 31 December 2009. Following multiple imputation of missing values, accelerated failure-time Weibull regression equations were refitted to produce new coefficients for each risk group. Discriminatory performance was assessed and compared with both UKPDS 68 and UKPDS 82 risk equations, and the implication of coefficient choice within an economic evaluation was assessed using the Cardiff type 2 diabetes model. RESULTS: When applied to patient-level data, the three sets of coefficients (UKPDS, THIN low-risk and intermediate-risk) lead to fairly consistent predictions of the 5-year risk of events. Exceptions include lower predicted rates of myocardial infarction and higher rates of ischaemic heart disease, congestive heart failure and end-stage renal disease with both sets of revised THIN coefficients compared with UKPDS. Over a modelled lifetime, the coefficients derived from the low-risk data predict fewer total cardiovascular events compared with UKPDS, while those from the intermediate-risk data predict a greater number. The areas under the receiver-operating characteristic curves demonstrated a marginal improvement in the discriminatory performance of the refitted equations. The incremental cost-effectiveness ratio associated with dapagliflozin versus sulphonylurea in addition to metformin changed from £7,708 to £7,519 and £6,906 per QALY gained, using the THIN intermediate- and low-risk coefficients, respectively. CONCLUSION: The results suggest that while the UKPDS equations perform best in newly diagnosed patients, they may overpredict the lifetime risk in this group and underpredict it in patients with more advanced diabetes. Implementation of the revised coefficients will result in different absolute numbers of predicted diabetes-related events; however, they are not expected to significantly affect the conclusions of economic modelling.

PURPOSE: UK primary care databases are frequently used in observational studies with cancer outcomes. We aimed to systematically review methods used by such studies to identify and validate incident cancers of the breast, colorectum, and prostate. METHODS: Medline and Embase (1980-2013) were searched for UK primary care database studies with incident breast, colorectal, or prostate cancer outcomes. Data on the methods used for case ascertainment were extracted and summarised. Questionnaires were sent to corresponding authors to obtain details about case ascertainment. RESULTS: Eighty-four studies of breast (n = 51), colorectal (n = 54), and prostate cancer (n = 31) were identified; 30 examined >1 cancer type. Among the 84 studies, 57 defined cancers using only diagnosis codes, while 27 required further evidence such as chemotherapy. Few studies described methods used to create cancer code lists (n = 5); or made lists available directly (n = 5). Twenty-eight code lists were received on request from study authors. All included malignant neoplasm diagnosis codes, but there was considerable variation in the specific codes included which was not explained by coding dictionary changes. Code lists also varied in terms of other types of codes included, such as in-situ, cancer morphology, history of cancer, and secondary/suspected/borderline cancer codes. CONCLUSIONS: In UK primary care database studies, methods for identifying breast, colorectal, and prostate cancers were often unclear. Code lists were often unavailable, and where provided, we observed variation in the individual codes and types of codes included. Clearer reporting of methods and publication of code lists would improve transparency and reproducibility of studies.

Studies on outcomes in bladder cancer rely on accurate methods to identify patients with bladder cancer and differentiate bladder cancer stage. Medical record and administrative databases are increasingly used to study cancer incidence, but few have distinguished cancer stage, and none have focused on bladder cancer. In this study, we used data from The UK Health Improvement Network (THIN) to identify patients with bladder cancer using at least one diagnostic code for bladder cancer, and distinguish muscle-invasive from non-invasive disease using a subsequent code for cystectomy. Algorithms were validated against a gold standard of physician-completed questionnaires, pathology reports, and consultant letters. Algorithm performance was evaluated by measuring positive predictive value (PPV) and corresponding 95% confidence interval (CI). Among all patients coded with bladder cancer (n = 194), PPV for any bladder cancer was 99.5% (95% CI, 97.2-99.9). PPV for incident bladder cancer was 93.8% (95% CI, 89.4-96.7). PPV for muscle-invasive bladder cancer was 70.1% (95% CI, 59.4-79.5) in patients with cystectomy (n = 95) and 83.9% (95% CI, 66.3-94.5) in those with cystectomy plus additional codes for metastases and death (n = 31). Using our codes for bladder cancer, the age- and sex-standardized incidence rate (SIR) of bladder cancer in THIN approximated that measured by cancer registries (SIR within 20%), suggesting that sensitivity was high as well. THIN is a valid and novel database for the study of bladder cancer. Our algorithm can be used to examine the epidemiology of muscle-invasive bladder cancer or outcomes following cystectomy for patients with muscle invasion.

PURPOSE: The purpose of this study was to determine the continuation rates of new users of long-acting reversible contraceptive (LARC) methods in the UK, using data from general practice. METHODS: We conducted an observational study using a general practitioner (GP) database, The Health Improvement Network (THIN). The methods studied were copper intrauterine devices (Cu-IUDs), levonorgestrel-releasing intrauterine system (LNG-IUS), progestogen-only implants and progestogen-only injections. The study population comprised women in THIN aged 18-44 years during the period 2004-2009 who had been registered with their GP for at least 5 years, with a computerized prescription history of at least 1 year. Using computer algorithms, the database was searched for the Read and Multilex codes for each LARC method. New LARC users were identified and followed until there was a record indicating termination of use or the study period ended. RESULTS: The proportion of women who discontinued use during the same year of administration was 7.5% for Cu-IUDs, 10.6% for LNG-IUS, 13.2% for progestogen-only implants and 54.4% for progestogen-only injections. By the end of the study, a higher proportion of Cu-IUD and LNG-IUS users (21.1 and 18.6%, respectively) undertook consecutive use of the same method than progestogen-only implant users (10.7%). Manual review of computerized profiles demonstrated the validity of this approach. CONCLUSIONS: In the UK, the continuation rates of LARCs are high, and approximately one fifth of women chose to have a second intrauterine device fitted after expiry of the first device. A validation step demonstrated the reliability of the methodology and computer algorithms used.