Rosie Cornish

Risk of death during and after opiate substitution treatment in primary care: prospective observational study in UK General Practice Research Database

Objective To investigate the effect of opiate substitution treatment at the beginning and end of treatment and according to duration of treatment. Design Prospective cohort study. Setting UK General Practice Research Database Participants Primary care patients with a diagnosis of substance misuse prescribed methadone or buprenorphine during 1990-2005. 5577 patients with 267 003 prescriptions for opiate substitution treatment followed-up (17 732 years) until one year after the expiry of their last prescription, the date of death before this time had elapsed, or the date of transfer away from the practice. Main outcome measures Mortality rates and rate ratios comparing periods in and out of treatment adjusted for sex, age, calendar year, and comorbidity; standardised mortality ratios comparing opiate users’ mortality with general population mortality rates. Results Crude mortality rates were 0.7 per 100 person years on opiate substitution treatment and 1.3 per 100 person years off treatment; standardised mortality ratios were 5.3 (95% confidence interval 4.0 to 6.8) on treatment and 10.9 (9.0 to 13.1) off treatment. Men using opiates had approximately twice the risk of death of women (morality rate ratio 2.0, 1.4 to 2.9). In the first two weeks of opiate substitution treatment the crude mortality rate was 1.7 per 100 person years: 3.1 (1.5 to 6.6) times higher (after adjustment for sex, age group, calendar period, and comorbidity) than the rate during the rest of time on treatment. The crude mortality rate was 4.8 per 100 person years in weeks 1-2 after treatment stopped, 4.3 in weeks 3-4, and 0.95 during the rest of time off treatment: 9 (5.4 to 14.9), 8 (4.7 to 13.7), and 1.9 (1.3 to 2.8) times higher than the baseline risk of mortality during treatment. Opiate substitution treatment has a greater than 85% chance of reducing overall mortality among opiate users if the average duration approaches or exceeds 12 months. Conclusions Clinicians and patients should be aware of the increased mortality risk at the start of opiate substitution treatment and immediately after stopping treatment. Further research is needed to investigate the effect of average duration of opiate substitution treatment on drug related mortality.

Using Data Linkage to Investigate Inconsistent Reporting of Self-Harm and Questionnaire Non-Response.

The objective of this study was to examine agreement between self-reported and medically recorded self-harm, and investigate whether the prevalence of self-harm differs in questionnaire responders vs. non-responders. A total of 4,810 participants from the Avon Longitudinal Study of Parents and Children (ALSPAC) completed a self-harm questionnaire at age 16 years. Data from consenting participants were linked to medical records (number available for analyses ranges from 205–3,027). The prevalence of self-harm leading to hospital admission was somewhat higher in questionnaire non-responders than responders (2.0 vs. 1.2%). Hospital attendance with self-harm was under-reported on the questionnaire. One third reported self-harm inconsistently over time; inconsistent reporters were less likely to have depression and fewer had self-harmed with suicidal intent. Self-harm prevalence estimates derived from self-report may be underestimated; more accurate figures may come from combining data from multiple sources.

Using linked educational attainment data to reduce bias due to missing outcome data in estimates of the association between the duration of breastfeeding and IQ at 15 years

Background: Most epidemiological studies have missing information, leading to reduced power and potential bias. Estimates of exposure-outcome associations will generally be biased if the outcome variable is missing not at random (MNAR). Linkage to administrative data containing a proxy for the missing study outcome allows assessment of whether this outcome is MNAR and the evaluation of bias. We examined this in relation to the association between infant breastfeeding and IQ at 15 years, where a proxy for IQ was available through linkage to school attainment data. Methods: Subjects were those who enrolled in the Avon Longitudinal Study of Parents and Children in 1990–91 (n = 13 795), of whom 5023 had IQ measured at age 15. For those with missing IQ, 7030 (79%) had information on educational attainment at age 16 obtained through linkage to the National Pupil Database. The association between duration of breastfeeding and IQ was estimated using a complete case analysis, multiple imputation and inverse probability-of-missingness weighting; these estimates were then compared with those derived from analyses informed by the linkage. Results: IQ at 15 was MNAR—individuals with higher attainment were less likely to have missing IQ data, even after adjusting for socio-demographic factors. All the approaches underestimated the association between breastfeeding and IQ compared with analyses informed by linkage. Conclusions: Linkage to administrative data containing a proxy for the outcome variable allows the MNAR assumption to be tested and more efficient analyses to be performed. Under certain circumstances, this may produce unbiased results.

Using Linkage to Electronic Primary Care Records to Evaluate Recruitment and Nonresponse Bias in The Avon Longitudinal Study of Parents and Children

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An evaluation of the impact of 'Lifeskills' training on road safety, substance use and hospital attendance in adolescence

Highlights • Lifeskills training is for 10–11 year olds and covers many safety domains.• Evaluated using longitudinal cohort data linked to hospital attendance data.• Attendance at A&E common but hospital admissions coded as due to an accident rare.• Lifeskills attendance associated with some reported safer behaviours in adolescence.• Use of cycle helmets and reflective/fluorescent clothing low overall.

Defining adolescent common mental disorders using electronic primary care data: a comparison with outcomes measured using the CIS-R

Objective To compare the prevalence of common mental disorders (CMDs) derived from data held in primary care records with that measured using the revised Clinical Interview Schedule (CIS-R) in order to assess the potential robustness of findings based only on routinely collected data. Design and setting Comparison study using linkage between the Avon Longitudinal Study of Parents and Children (ALSPAC) and electronic primary care records. Participants We studied 1562 adolescents who had completed the CIS-R in ALSPAC at age 17–18 years and had linkage established to their primary care records. Outcome measures Outcome measures from ALSPAC were whether or not an individual met International Classification of Diseases-10 criteria for a diagnosis of (1) a CMD or, specifically, (2) depression. Lists of Read codes corresponding to diagnoses, symptoms and treatments were used to create 12 definitions of CMD and depression alone using the primary care data. We calculated sensitivities and specificities of these, using CIS-R definitions as the reference standard. Results Sensitivities ranged from 5.2% to 24.3% for depression and from 3.8% to 19.2% for CMD. The specificities of all definitions were above 98% for depression and above 96% for CMD. For both outcomes, the definition that included current diagnosis, treatment or symptoms identified the highest proportion of CIS-R cases. Conclusions Most individuals meeting case definitions for CMD based on primary care data also met CIS-R case definitions. Conversely many individuals identified as cases using the CIS-R had no evidence of CMD in their clinical records. This suggests that clinical databases are likely to yield underestimates of the burden of CMD in the population. However, clinical records appear to yield valid diagnoses which may be useful for studying risk factors and consequences of CMD. The greatest epidemiological value may be obtained when information is available from survey and clinical records.

P115 Case definitions for common mental health disorders among adolescents using electronic primary care data: a comparison with self-reported data from the Avon Longitudinal Study of Parents and Children

Background Rates of common mental disorders may be increasing among children and adolescents, though evidence of this is mixed. Symptom questionnaires in population surveys may overestimate clinical disease. Conversely, lower participation of individuals with mental disorders may lead to underestimates in surveys. Clinical databases may have greater population coverage and contain information of more obvious clinical validity; however, several factors, including the help-seeking behaviour of individuals and the recording practices of clinicians, may influence burden-of-disease estimates based on these databases. The aim of the current investigation was to compare case definitions of common mental disorders (CMD) using linked electronic primary care data to definitions derived from self-reported data obtained in an observational study. Methods We studied 1,562 adolescents who had completed the Revised Clinical Interview Schedule (CIS-R) in the Avon Longitudinal Study of Parents and Children (ALSPAC) at age 17–18 years and had linkage established to their electronic primary care records for at least 6 months after the time they completed the CIS-R. We used lists of Read codes corresponding to diagnoses, symptoms and treatment to create twelve definitions of CMD and also of depression alone. We calculated sensitivities and specificities of these, using CIS-R case definitions as the reference standard. All analyses were carried in Stata 13.0. Results Sensitivities ranged from 5.2% to 24.3% for depression and from 3.8% to 19.2% for CMD. The specificities of all definitions were above 98% for depression and above 96% for CMD. For both depression and CMD, the definition that included current diagnosis, treatment or symptoms identified the highest proportion of cases. Discussion Most individuals meeting case definitions for CMD based on information in clinical records also met CMD case definitions based on symptoms reported in a contemporaneous survey. Conversely, many individuals identified as CMD cases based on reported symptoms had no evidence of CMD in their clinical records. A small number of individuals with CMD recorded in their clinical records had not reported symptoms of this in the survey. Overall, these data suggest that clinical databases are likely to yield underestimates of the burden of CMD in the population. Clinical records appear to yield highly valid diagnoses of common mental disorders which may be useful for studying risk factors and outcomes of these conditions. The greatest epidemiological value is likely to be obtained when the combination of information from both survey data and clinical records is possible.

P11 The impact of cycle proficiency training on cycle-related behaviours and accidents in adolescence: findings from ALSPAC, a UK longitudinal cohort

Background In the UK, some children undertake National Cycle Proficiency Scheme [NCPS] training (now known as Bikeability) in their final years of primary school. It aims to promote cycling and safe cycling behaviours but there has been little scientific evaluation of its effectiveness. Our aim was to examine the impact of cycle training on cycle-related behaviours and accidents in adolescence. Methods The sample (n = 5415) were participants in the Avon Longitudinal Study of Parents and Children who reported whether or not they had received NCPS training. Outcomes were self-reported at 14 and 16 years: cycling to school, ownership of cycle helmet, use of cycle helmet and high-visibility clothing on last cycle, and involvement in a cycle accident. An additional outcome, hospital admittance due to a cycle accident from 11–16 years, was also included for a subsample (n = 2222) who have been linked to Hospital Episodes Statistics (HES) data. The association between cycle proficiency training and each of the outcomes was analysed using multilevel logistic regression (individual level 1, school level 2), adjusted for a range of potential confounders. Results Approximately 40% of the sample had received NCPS training. At both 14 and 16 years, trained children were more likely to cycle to school (at 16 years: adjusted OR 1.56, 95% CI 1.20–2.02) and to own a cycle helmet (at 16 years: 2.03, 1.72–2.41) than those who had not attended a course. They were also more likely to have worn a helmet on their last cycle at age 14 (1.26, 1.07–1.49), and to have worn high-visibility clothing at age 16 (1.70, 1.22–2.39). NCPS training was not associated with self-reported involvement in a cycle accident (1.04, 0.61–1.78), and only six of those with HES data had been admitted to hospital due to a cycle accident. Irrespective of training, results indicate very low use of high-visibility clothing (around 5%), very few girls cycling as part of their school commute (<2% compared to >10% of boys), and less than half of helmet owners wearing one on their last cycle. Ownership and use of cycle helmets was particularly low in children from lower socio-economic position families. Conclusion Our results suggest cycle training courses for children can have benefits that persist into adolescence. However, the low use of cycle helmets, very low use of high-visibility clothing, and low levels of cycling to school for girls, indicate the further potential for interventions to encourage cycling, and safe cycling behaviours, in young people.

Applying coupon-collecting theory to computer-aided assessments

Computer-based tests with randomly generated questions allow a large number of different tests to be generated. Given a fixed number of alternatives for each question, the number of tests that need to be generated before all possible questions have appeared is surprisingly low.