Validity and completeness of colorectal cancer diagnoses in a primary care database in the United Kingdom

Development and Validation of Case-Finding Algorithms for Digestive Cancer in the Spanish Healthcare Database BIFAP

BACKGROUND

electronic health records (EHRs) are helpful tools in epidemiology despite not being primarily collected for research. In Spain, primary care physicians play a central role and manage patients even in specialized care. All of this introduces variability that may lead to diagnostic inconsistencies. Therefore, data validation studies are crucial, so we aimed to develop and validate case-finding algorithms for digestive cancer in the primary care database BIFAP.

METHODS

from 2001 to 2019, subjects aged 40-89 without a cancer history were included. Case-finding algorithms using diagnostic codes and text-mining were built. We randomly sampled, clustered, and manually reviewed 816 EHRs. Then, positive predictive values (PPVs) and 95% confidence intervals (95% CIs) for each cancer were computed. Age and sex standardized incidence rates (SIRs) were compared with those reported by the National Cancer Registry (REDECAN).

RESULTS

we identified 95,672 potential cases. After validation, the PPV (95% CI) for hepato-biliary cancer was 87.6% (81.8-93.4), for esophageal cancer, it was 96.2% (93.1-99.2), for pancreatic cancer, it was 89.4% (84.5-94.3), for gastric cancer, it was 92.5% (88.3-96.6), and for colorectal cancer, it was 95.2% (92.1-98.4). The SIRs were comparable to those reported by the REDECAN.

CONCLUSIONS

the case-finding algorithms demonstrated high performance, supporting BIFAP as a suitable source of information to conduct epidemiologic studies of digestive cancer.

Public health impact of low-dose aspirin on colorectal cancer, cardiovascular disease and safety in the UK - Results from micro-simulation model

Background

Low-dose aspirin therapy reduces the risk of cardiovascular disease and may have a positive effect on the prevention of colorectal cancer. We evaluated the population-level expected effect of regular low-dose aspirin use on cardiovascular disease (CVD), colorectal cancer (CRC), gastrointestinal bleeding, symptomatic peptic ulcers, and intracranial hemorrhage, using a microsimulation study design.

Methods

We used individual-level state transition modeling to assess the impact of aspirin in populations aged 50–59 or 60–69 years old indicated for low-dose aspirin usage for primary or secondary CVD prevention. Model parameters were based on data from governmental agencies from the UK or recent publications.

Results

In the 50–59 years cohort, a decrease in incidence rates (IRs per 100 000 person years) of non-fatal CVD (-203 and −794) and fatal CVD (-97 and-381) was reported in the primary and secondary CVD prevention setting, respectively. The IR reduction of CRC (-96 and −93) was similar for primary and secondary CVD prevention. The IR increase of non-fatal (116 and 119) and fatal safety events (6 and 6) was similar for primary and secondary CVD prevention. Similar results were obtained for the 60–69 years cohort.

Conclusions

The decrease in fatal CVD and CRC events was larger than the increase in fatal safety events and this difference was more pronounced when low-dose aspirin was used for secondary compared to primary CVD prevention. These results provide a comprehensive image of the expected effect of regular low-dose aspirin therapy in a UK population indicated to use aspirin for CVD prevention.

The validity of the claims-based definition of rheumatoid arthritis evaluated in 64 hospitals in Japan

BACKGROUND

An administrative database covering a whole population such as the national database in Japan may be used to estimate the nationwide prevalence of diseases including rheumatoid arthritis (RA) when a well-validated definition of the disease is available. In Japan, the record linkage between the administrative database and medical charts in hospitals is strictly prohibited. A "hospital-based" validation study is one of few possible validation studies where claims kept inside the study hospital are rearranged into the database structure.

METHODS

We selected random samples of 19,734 patients from approximately 1.6 million patients who received medical care between February 2018 and January 2019 in one of the 64 hospitals of the Tokushukai Medical Group. We excluded patients whose observation period was less than 365 days and identified 334 patients who met the definition of "possible cases of RA" whose medical charts were then independently evaluated by two rheumatologists. In a sensitivity analysis, we assessed bias due to misclassifying some patients with RA who did not meet the definition of "possible cases of RA" as a patient with no RA.

RESULTS

The kappa coefficient between the two rheumatologists was 0.80. The prevalence of RA in the study population was estimated to be 0.56%. We found that [condition code of RA] and ([any disease-modifying antirheumatic drug] or [oral corticosteroid with no systemic autoimmune diseases (other than RA) and no polymyalgia rheumatica]) had a relatively high sensitivity (approximately 73%) and a high positive predictive value (approximately 80%). In a sensitivity analysis, we found that when some patients with RA who did not meet the definition of "possible cases of RA" were misclassified as a patient with no RA, then this would lead to underestimation of the prevalence of the definition-positive patients and the adjusted prevalence.

CONCLUSIONS

We recommend using the claims-based definition of RA (found in the current validation study) to estimate the prevalence of RA in Japan. We also suggest estimating the adjusted prevalence using the quantitative bias analysis method, since the prevalence of the disease in the "hospital-based" validation study is different from that in the administrative database.

TRIAL REGISTRATION

The current study is not a clinical trial and hence not subject to trial registration.

Digoxin use is associated with pancreatic cancer risk but does not affect survival

PURPOSE

Digoxin affects several cellular pathways involved in tumorigenesis. We sought to determine the association between digoxin use and pancreatic cancer risk and survival.

METHODS

A nested case-control study using The Health Improvement Network (THIN), a population-representative database from the United Kingdom (UK). Cases included all individuals with incident diagnosis of pancreatic cancer. Each case was matched to up to four controls using incidence density sampling based on age, sex, practice site, calendar time, and duration of follow-up. Exposure of interest was digoxin therapy before cancer diagnosis. Odds ratios (ORs) and 95% confidence intervals (CIs) for the association between digoxin use and pancreatic cancer risk were estimated using conditional logistic regression. We further conducted a retrospective cohort study among pancreatic cancer cases using Cox regression model in order to evaluate the association between digoxin use and overall survival.

RESULTS

We identified 4,113 cases with incident pancreatic cancer and 16,072 matched controls. The adjusted OR for diagnosis of pancreatic cancer among active digoxin users was 1.41 (95% CI 1.16-1.72). The risk did not change among active users with duration of therapy of more than 1 year (adjusted OR of 1.39, 95% CI 1.11-1.76). Digoxin was not associated with change in overall survival with an adjusted hazard ratio of 0.97 (95% CI 0.81-1.18).

CONCLUSIONS

Digoxin use was associated with modestly increased pancreatic cancer risk but did not affect overall survival.

Feasibility study to identify women of childbearing age at risk of pregnancy not using any contraception in The Health Improvement Network (THIN) database

Background

Worldwide the rate of unplanned pregnancies is more than 40%. Identifying women at risk of pregnancy can help prevent negative outcomes and also reduce healthcare costs of potential complications. It can also allow the investigation of the natural history of pregnancy outcomes, such as ectopic pregnancies or miscarriages. The use of medical records databases has been a crucial development in the field of pharmacoepidemiology – e.g. The Health Improvement Network (THIN) database is a validated database representative of the UK population. This project aimed to test the feasibility of identifying a population of women of childbearing age who are at risk of pregnancy not using any contraception in THIN database.

Methods

First a cohort of women of childbearing age (15-45yo) was identified. By applying a computer-based algorithm, containing codes for contraception methods or other suggestion of contraception, the risk of pregnancy was then ascertained. Next, two validation steps were implemented: 1) Revision of medical records/free text and 2) Questionnaires were sent to primary care practitioners (PCP) of women whose medical records had been reviewed. Positive predicted values (PPV) were calculated.

Results

A total of 266,433 women were identified in THIN. For the first validation step, 123 records were reviewed, with a PPV of 99.2% (95%CI: 95.5–99.9). For the questionnaires step, the PPV was of 82.3% (95%CI: 70–91.1). Information on sexual behaviour and attitudes towards conception was not captured by THIN.

Conclusion

This study shows that by applying a comprehensive computer-based algorithm, THIN can be used to identify women at risk of pregnancy.

Toward the Development of Data Governance Standards for Using Clinical Free-Text Data in Health Research: Position Paper

BACKGROUND

Clinical free-text data (eg, outpatient letters or nursing notes) represent a vast, untapped source of rich information that, if more accessible for research, would clarify and supplement information coded in structured data fields. Data usually need to be deidentified or anonymized before they can be reused for research, but there is a lack of established guidelines to govern effective deidentification and use of free-text information and avoid damaging data utility as a by-product.

OBJECTIVE

This study aimed to develop recommendations for the creation of data governance standards to integrate with existing frameworks for personal data use, to enable free-text data to be used safely for research for patient and public benefit.

METHODS

We outlined data protection legislation and regulations relating to the United Kingdom for context and conducted a rapid literature review and UK-based case studies to explore data governance models used in working with free-text data. We also engaged with stakeholders, including text-mining researchers and the general public, to explore perceived barriers and solutions in working with clinical free-text.

RESULTS

We proposed a set of recommendations, including the need for authoritative guidance on data governance for the reuse of free-text data, to ensure public transparency in data flows and uses, to treat deidentified free-text data as potentially identifiable with use limited to accredited data safe havens, and to commit to a culture of continuous improvement to understand the relationships between the efficacy of deidentification and reidentification risks, so this can be communicated to all stakeholders.

CONCLUSIONS

By drawing together the findings of a combination of activities, we present a position paper to contribute to the development of data governance standards for the reuse of clinical free-text data for secondary purposes. While working in accordance with existing data governance frameworks, there is a need for further work to take forward the recommendations we have proposed, with commitment and investment, to assure and expand the safe reuse of clinical free-text data for public benefit.

No association between use of phosphodiesterase 5 inhibitors and colorectal cancer in men with erectile dysfunction

PURPOSE

There is an increase interest on the potential chemoprotective effect of selective phosphodiesterase 5 (PDE5) inhibitors. Several authors have shown in vivo the immune-mediated anti-tumor effect of these inhibitors on tumors arising from the digestive tract.

OBJECTIVES

To test the potential effect of selective PDE5 inhibitors against colorectal cancer (CRC) onset previously observed.

METHODS

We used data from The Health Improvement Network database and identified an established cohort of 200 000 new users of low-dose aspirin and a matched comparison cohort aged 40-84 years between 1 January 2000 and 31 December 2011. A follow-up to identify CRC cases was performed within an extensive validation exercise. Nested case-control analyses compared PDE5 inhibitors vs non-use on CRC risk were performed.

RESULTS

Restricting to males (59.3% controls and 59.5% cases), no association was observed among current users of PDE5 inhibitors (1.05 [95% CI: 0.69-1.60]) and neither among recent (1.36 [95% CI: 0.81-2.28]) or past users (1.06 [95% CI: 0.72-1.58]). No duration response effect was found.

CONCLUSIONS

Our results do not support an increased risk of CRC associated with the use of PDE5 inhibitors among men with erectile dysfunction.

Identification of validated case definitions for medical conditions used in primary care electronic medical record databases: a systematic review

Objectives

Data derived from primary care electronic medical records (EMRs) are being used for research and surveillance. Case definitions are required to identify patients with specific conditions in EMR data with a degree of accuracy. The purpose of this study is to identify and provide a summary of case definitions that have been validated in primary care EMR data.

Materials and Methods

We searched MEDLINE and Embase (from inception to June 2016) to identify studies that describe case definitions for clinical conditions in EMR data and report on the performance metrics of these definitions.

Results

We identified 40 studies reporting on case definitions for 47 unique clinical conditions. The studies used combinations of International Classification of Disease version 9 (ICD-9) codes, Read codes, laboratory values, and medications in their algorithms. The most common validation metric reported was positive predictive value, with inconsistent reporting of sensitivity and specificity.

Discussion

This review describes validated case definitions derived in primary care EMR data, which can be used to understand disease patterns and prevalence among primary care populations. Limitations include incomplete reporting of performance metrics and uncertainty regarding performance of case definitions across different EMR databases and countries.

Conclusion

Our review found a significant number of validated case definitions with good performance for use in primary care EMR data. These could be applied to other EMR databases in similar contexts and may enable better disease surveillance when using clinical EMR data. Consistent reporting across validation studies using EMR data would facilitate comparison across studies.

Systematic review registration

PROSPERO CRD42016040020 (submitted June 8, 2016, and last revised June 14, 2016).

Aromatase inhibitors and the risk of colorectal cancer in postmenopausal women with breast cancer

Background

A large trial of postmenopausal women with breast cancer reported an imbalance in colorectal cancer events with aromatase inhibitors (AIs), compared with tamoxifen in the adjuvant setting. This unexpected signal was observed within 3 years of randomization. To date, no observational studies have examined this important safety question in the natural setting of clinical practice. Thus, the objective of this study was to determine whether AIs, when compared with tamoxifen, are associated with increased risk of colorectal cancer in postmenopausal women with breast cancer.

Patients and methods

Using the UK Clinical Practice Research Datalink, we identified women, at least 55 years of age, with breast cancer newly treated with either AIs or tamoxifen between 1 January 1996 and 30 September 2015, with follow-up until 30 September 2016. High-dimensional propensity score-adjusted Cox proportional hazards models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) of incident colorectal cancer associated with AIs when compared with tamoxifen overall, by cumulative duration of use, and time since initiation. All exposures were lagged by 1 year for latency considerations.

Results

A total of 9701 and 8893 patients initiated AIs and tamoxifen as first-line hormonal therapy (median follow-up of 2.4 and 2.9 years, respectively). Compared with tamoxifen, AIs were not associated with an increased risk of colorectal cancer (incidence rates of 150 per 100 000 person-years in both groups; adjusted HR: 0.90, 95% CI: 0.53-1.52). Similarly, there was no evidence of an association with cumulative duration of use (P-heterogeneity = 0.54), and time since initiation (P-heterogeneity = 0.66).

Conclusions

In this first population-based study, the use of AIs was not associated with an increased risk of colorectal cancer. These findings should provide reassurance to the concerned stakeholders.

Elevated Vitamin B12 Levels and Cancer Risk in UK Primary Care: A THIN Database Cohort Study

BACKGROUND

Elevated vitamin B12 levels (B12) are associated with increased short-term cancer risk. However, the implications for early cancer detection in primary care have not been assessed.

METHODS

Individuals with plasma B12 measurements were sampled from The Health Improvement Network primary care database, UK. Persons with low B12 levels were excluded together with persons with cancer or B12 treatment before date of B12 measurement. Incident cancer was the outcome of interest and was identified through Read codes. Individuals were disaggregated according to plasma B12 levels (unit: pmol/L): 150-600 (reference range values), 601-800, 801-1,000, and >1,000.

RESULTS

Among the 757,185 persons who met the inclusion criteria, we identified 33,367 incident cancers during 2,874,059 years of follow-up. We found a higher 1-year cancer risk among the 25,783 (3.4%) persons with elevated B12 levels compared with those with normal B12 levels. After multivariable adjustment for lifestyle factors and social deprivation, persons with B12 >1,000 pmol/L had a 1-year incidence rate ratio of 4.72 (95% confidence interval: 3.99-5.58). The association showed a nonlinear dose-response pattern, and it remained robust in stratified analyses, including when reducing the risk of confounding by indication in subanalyses. The risks were particularly elevated for liver cancer, pancreas cancer, and myeloid malignancies among persons with elevated B12 levels.

CONCLUSIONS

Elevated plasma B12 levels were associated with a higher 1-year cancer risk than normal B12 levels among persons seen in UK primary care, suggesting that some cancers may affect B12 metabolism.

IMPACT

Elevated B12 may mark occult cancer.

Cancer recording in patients with and without type 2 diabetes in the Clinical Practice Research Datalink primary care data and linked hospital admission data: a cohort study

OBJECTIVES AND SETTING

Conflicting results from studies using electronic health records to evaluate the associations between type 2 diabetes and cancer fuel concerns regarding potential biases. This study aimed to describe completeness of cancer recording in UK primary care data linked to hospital admissions records.

DESIGN

Patients aged 40+ years with insulin or oral antidiabetic prescriptions in Clinical Practice Research Datalink (CPRD) primary care without type 1 diabetes were matched by age, sex and general practitioner practice to non-diabetics. Those eligible for linkage to Hospital Episode Statistics Admitted Patient Care (HES APC), and with follow-up during April 1997-December 2006 were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Cancer recording and date of first record of cancer were compared. Characteristics of patients with cancer most likely to have the diagnosis recorded only in a single data source were assessed. Relative rates of cancer estimated from the two datasets were compared.

PARTICIPANTS

53 585 patients with type 2 diabetes matched to 47 435 patients without diabetes were included.

RESULTS

Of all cancers (excluding non-melanoma skin cancer) recorded in CPRD, 83% were recorded in HES APC. 94% of cases in HES APC were recorded in CPRD. Concordance was lower when restricted to same-site cancer records, and was negatively associated with increasing age. Relative rates for cancer were similar in both datasets.

CONCLUSIONS

Good concordance in cancer recording was found between CPRD and HES APC among type 2 diabetics and matched controls. Linked data may reduce misclassification and increase case ascertainment when analysis focuses on site-specific cancers.

Trends in the contemporary incidence of colorectal cancer and patient characteristics in the United Kingdom: a population-based cohort study using The Health Improvement Network

Background

Cancer registry data show that survival of colorectal cancer (CRC) in the United Kingdom is poor compared with other European countries and the United States, yet these data sources lack information on patient comorbidities and medication use, which could help explain these differences.

Methods

Among individuals aged 40–89 years in The Health Improvement Network (2000–2014), we identified first ever cases of CRC and calculated incidence rates with 95% confidence intervals (CIs). For CRC cases and non-cases in two separate calendar years (2002 and 2014), we evaluated patient demographics, lifestyle factors, comorbidities and medication use and bowel screening.

Results

The incidence of CRC remained relatively constant across the study period; incidence rates per 10,000 person-years (95% CIs) were 9.27 (8.59–1.01) in 2000, 10.65 (10.15–11.18) in 2007 and 8.37 (7.93–8.83) in 2014. Incidence rates per 10,000 person-years were higher in men than women at 11.44 (95% CI: 10.35-12.66) vs. 7.40 (95% CI: 6.59–8.32) in 2000, and 9.39 (95% CI: 8.74–10.10) vs. 7.38 (95% CI: 6.81–8.00) in 2014. An increase was seen in the proportion of CRC cases diagnosed at age < 60 years. In 2002, 3.5% of CRC cases were diagnosed at age 40–49 compared with 5.1% in 2014 (p = 0.064). Similarly, in 2002, 12.5% were diagnosed at age 50–59 years compared with 16.2% in 2014 (p = 0.002). Between 2002 and 2014, previous bowel screening increased in both CRC cases (+ 10.6%) and non-cases (+ 9.7%)(p < 0.001 for both groups). Greater rises in the following were seen among CRC cases compared with non-cases: diabetes (+ 9.3% vs. + 3.3%; p < 0.001 for both), obesity (+ 14.5% vs. + 10.1%; p < 0.001 for both), hypertension (+ 8.3% vs. + 3.6%; p < 0.001 for both), atrial fibrillation (+ 2.6% [p < 0.01] vs. + 0.3% [p < 0.001]), and use of proton pump inhibitors (+ 11.5% vs. + 9.0%), anti-hypertensives (+ 9.9% vs. + 1.4%) and warfarin (+ 3.2% vs. + 0.4%); p < 0.001 for CRC cases and non-cases with respect to each medication.

Conclusions

CRC incidence has remained relatively stable in the UK over the last decade. The increased prevalence of some comorbidities and medications among CRC cases should be considered when evaluating patterns in CRC survival.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4265-1) contains supplementary material, which is available to authorized users.

Incidence of colorectal cancer in new users and non-users of low-dose aspirin without existing cardiovascular disease: A cohort study using The Health Improvement Network

BACKGROUND

Evidence regarding the chemo-protective effects of aspirin has influenced expert opinion in favour of low-dose aspirin use in certain patient populations without cardiovascular disease (CVD). The effects of aspirin in reducing the incidence of colorectal cancer (CRC) may be a large contributor to this favourable risk-benefit profile of low-dose aspirin in primary CVD prevention.

METHODS

Using The Health Improvement Network, we estimated the incidence of CRC in individuals free of CVD and either prescribed or not prescribed prophylactic low-dose aspirin. Two cohorts - new-users of low-dose aspirin (N=109,426) and a comparator cohort of non-users (N=154,056) at start of follow-up - were followed (maximum 13years) to identify incident CRC cases. Individuals with a record of CVD, cancer or low-dose aspirin prescription before start of follow-up were excluded.

RESULTS

2330 incident cases of CRC occurred; 885 in the aspirin cohort and 1445 in the comparator cohort, after mean follow-ups of 5.43years and 5.17years, respectively. Incidence rates of CRC per 10,000 person-years (95% confidence interval) were 14.90 (13.95-15.92) in the aspirin cohort and 18.15 (17.24-19.12) in the comparator cohort; incidence rate ratio 0.82 (0.76-0.89) adjusted for age, sex and primary care practitioner (PCP) visits in the previous year. Lower incidence rates were seen in the aspirin cohort for all strata evaluated (gender, age group and number of PCP visits in the previous year) except those aged ≥80years.

CONCLUSION

Among most individuals without established CVD, initiation of low-dose aspirin is associated with a reduced incidence of CRC.

New use of low-dose aspirin and risk of colorectal cancer by stage at diagnosis: a nested case-control study in UK general practice

Background

Evidence from clinical trial populations suggests low-dose aspirin reduces the risk of colorectal cancer (CRC). Part of this reduction in risk might be due to protection against metastatic disease.

Methods

We investigated the risk of CRC among new-users of low-dose aspirin (75–300 mg), including risk by stage at diagnosis. Using The Health Improvement Network, we conducted a cohort study with nested case–control analysis. Two cohorts (N = 170,336 each) aged 40–89 years from 2000 to 2009 and free of cancer were identified: i) new-users of low-dose aspirin, ii) non-users of low-dose aspirin, at start of follow-up, matched by age, sex and previous primary care practitioner visits. Patients were followed for up to 12 years to identify incident CRC. 10,000 frequency-matched controls were selected by incidence density sampling where the odds ratio is an unbiased estimator of the incidence rate ratio (RR). RRs with 95% confidence intervals were calculated. Low-dose aspirin use was classified ‘as-treated’ independent from baseline exposure status to account for changes in exposure during follow-up.

Results

Current users of low-dose aspirin (use on the index date or in the previous 90 days) had a significantly reduced risk of CRC, RR 0.66 (95% CI 0.60–0.74). The reduction in risk was apparent across all age groups, and was unrelated to dose, indication, gender, CRC location or case-fatality status. Reduced risks occurred throughout treatment duration and with all low-dose aspirin doses. RRs by aspirin indication were 0.71 (0·63–0·79) and 0.60 (0.53–0.68) for primary and secondary cardiovascular protection, respectively. Among cases with staging information (n = 1421), RRs for current use of low-dose aspirin were 0.94 (0.66–1.33) for Dukes Stage A CRC, 0.54 (0.42–0.68) for Dukes B, 0.71 (0.56–0.91) for Dukes C, and 0.60 (0.48–0.74) for Dukes D. After 5 years’ therapy, the RR for Dukes Stage A CRC was 0.53 (0.24–1.19).

Conclusions

Patients starting low-dose aspirin therapy have a reduced risk of Stages B–D CRC, suggesting a role for low-dose aspirin in the progression of established CRC; a substantial reduction in the risk of Dukes A CRC may occur after 5 years’ therapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3594-9) contains supplementary material, which is available to authorized users.

A Clinical Prediction Model to Assess Risk for Pancreatic Cancer Among Patients With New-Onset Diabetes

BACKGROUND & AIMS

Approximately 50% of all patients with pancreatic ductal adenocarcinoma (PDA) develop diabetes mellitus before their cancer diagnosis. Screening individuals with new-onset diabetes might allow earlier diagnosis of PDA. We sought to develop and validate a PDA risk prediction model to identify high-risk individuals among those with new-onset diabetes.

METHODS

We conducted a retrospective cohort study in a population representative database from the United Kingdom. Individuals with incident diabetes after the age of 35 years and 3 or more years of follow-up after diagnosis of diabetes were eligible for inclusion. Candidate predictors consisted of epidemiologic and clinical characteristics available at the time of diabetes diagnosis. Variables with P values <.25 in the univariable analyses were evaluated using backward stepwise approach. Model discrimination was assessed using receiver operating characteristic curve analysis. Calibration was evaluated using the Hosmer-Lemeshow test. Results were internally validated using a bootstrapping procedure.

RESULTS

We analyzed data from 109,385 patients with new-onset diabetes. Among them, 390 (0.4%) were diagnosed with PDA within 3 years. The final model (area under the curve, 0.82; 95% confidence interval, 0.75-0.89) included age, body mass index, change in body mass index, smoking, use of proton pump inhibitors, and anti-diabetic medications, as well as levels of hemoglobin A1C, cholesterol, hemoglobin, creatinine, and alkaline phosphatase. Bootstrapping validation showed negligible optimism. If the predicted risk threshold for definitive PDA screening was set at 1% over 3 years, only 6.19% of the new-onset diabetes population would undergo definitive screening, which would identify patients with PDA with 44.7% sensitivity, 94.0% specificity, and a positive predictive value of 2.6%.

CONCLUSIONS

We developed a risk model based on widely available clinical parameters to help identify patients with new-onset diabetes who might benefit from PDA screening.

Prescribing of cyproterone acetate/ethinylestradiol in UK general practice: a retrospective descriptive study using The Health Improvement Network

OBJECTIVE

To investigate prescribing patterns of cyproterone acetate/ethinylestradiol (CPA/EE) in the United Kingdom before and after the 2013 prescribing guidance.

STUDY DESIGN

We conducted a retrospective descriptive study in UK general practice. The study population included women with a first prescription (index date) for CPA/EE in The Health Improvement Network in 2011 (N=2760), 2012 (N=2923) and 2014 (N=2341). We evaluated the proportion of new CPA/EE users with (i) a diagnosis of a hyperandrogenic condition, menstrual problem, consultation for contraception management, and other acne treatment, in the year before the index date; and (ii) proportion of new CPA/EE users with concomitant use of another hormonal contraceptive (HC).

RESULTS

The percentage of CPA/EE new users with a record of a hyperandrogenic condition was 61% in 2011, 62% in 2012 and 63% in 2014. Corresponding percentages for acne were 51%, 54% and 55%, respectively. When manually reviewing patient records for a sample of CPA/EE new users (n=200), the acne was recorded in 77% of women, hirsutism in 9.5% and polycystic ovary syndrome in 9.5%. Majority of CPA/EE users had a prior acne diagnosis and/or treatment, 76% (n=2091) in 2011, 79% (n=2296) in 2012 and 78% (n=1834) in 2014. Concomitant use of CPA/EE and another HC was rare, 1% of CPA/EE users in 2011 and fewer than 0.5% of CPA/EE users in both 2012 and 2014.

CONCLUSIONS

Before and after 2013, the majority of UK women starting treatment with CPA/EE had a condition in line with its approved indication and had received prior acne treatment as per guidance.

The Protective Effect of Low-Dose Aspirin against Colorectal Cancer Is Unlikely Explained by Selection Bias: Results from Three Different Study Designs in Clinical Practice

BACKGROUND

We conducted three differently designed nested case-control studies to evaluate whether the protective effect of low-dose aspirin against colorectal cancer (CRC) is explained by selection bias.

METHODS

Using a large validated UK primary care database, we followed different cohorts of patients, who varied in their demographic and clinical characteristics, to identify first ever cases of CRC. In Studies 1 and 2, two cohorts were followed, i) new users of low-dose aspirin at start of follow-up (N = 170,336 in Study 1, N = 171,527 in Study 2) and either ii) non-users of low-dose aspirin (Study 1, N = 170,336) or new users of paracetamol (Study 2, N = 149,597) at start of follow-up. In Study 3 a single cohort of individuals näive to low-dose aspirin at the start of observation was followed. Controls were selected using incidence sampling and logistic regression used to obtain an unbiased estimate of the incidence rate ratio (RR) with 95% confidence intervals (CIs). Low-dose aspirin exposure was analyzed 'as-treated' before the index date (CRC date for cases, random date for controls).

RESULTS

In the three studies, median (maximum) follow-up was 5.1 (12), 5.8 (12) and 7.5 (13) years, respectively. 3033 incident CRC cases were identified in Study 1, 3174 in Study 2, and 12,333 in Study 3. Current use of low-dose aspirin was associated with a significantly reduced risk of 34%, 29% and 31% in the three studies, respectively; corresponding RRs (95% CIs) were 0.66 (0.60-0.73), 0.71 (0.63-0.80) and 0.69 (0.64-0.74). In each study, significantly reduced risks of CRC were seen when low-dose aspirin was used for primary or secondary cardiovascular disease prevention, in both sexes, and across all age groups evaluated.

CONCLUSION

Low-dose aspirin is associated with a significantly reduced risk of CRC. The consistency of our findings across different studies makes selection bias an unlikely explanation.

Validity and completeness of colorectal cancer diagnoses in a primary care database in the United Kingdom

Purpose

To validate the recorded diagnoses of colorectal cancer (CRC) and identify false negatives in The Health Improvement Network (THIN) primary care database.

Methods

We conducted a validation study of incident CRC cases in THIN among patients aged 40–89 years from 2000–2011. CRC Read code entries (N = 3805) were verified by manual review of patients' electronic medical records (EMRs) including free‐text comments. Incident CRC cases in THIN ascertained following manual review were validated against two data sources deemed gold standards: (i) questionnaires sent to primary care practitioners (PCPs; for a random sample of 100 potential CRC cases), and (ii) Hospital Episode Statistics (HES) among linked practices. False negatives in THIN were identified by searching for International Classification of Diseases‐10 codes related to CRC in HES.

Results

Of 3805 CRC cases identified in THIN via Read codes, 3033 patients (80.0%) were considered definite cases after manual review of EMRs. The positive predictive value (PPV) of CRC Read codes was 86.0% after removing patients identified from THIN via a Read code for ‘fast track referral for suspected CRC’. The response rate from PCPs was 87.0% (n = 87), and the PPV of CRC in THIN was 100% based on PCP questionnaires. Using HES, the PPV for CRC in THIN was 97.9% (556/568), and false negative rate was 6.1% (36/592).

Conclusions

CRC diagnostic Read codes in THIN have a high PPV, which is increased further following manual review of free‐text comments. The false negative rate of CRC diagnoses in THIN is low. © 2015 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.