bluuebunny/crossref_metadata_2025 huggingface dataset:
OP47 Effect of High Profile Quality Failures On Patient Numbers in the English NHS
Authors: Laverty AA , Millett C
Published: September 2012

Background

Policy architects are keen to emphasise that releasing information on the quality of hospitals into the public domain will drive patients away from poor quality providers and thus motivate system wide improvements. However, previous evidence on the impact of releasing quality information to the public have been mixed, with various reasons being proposed as possible barriers, including patients being unaware of the information available, being unable to understand it, or feeling it to be irrelevant. We examined three cases of high profile reports into failings in quality and safety at English NHS hospitals in order to assess whether this negative publicity was associated with a decrease in patient numbers. These reports all garnered significant media attention and presented a stark picture of performance and so we hypothesise that such negative coverage may have induced a fall in patient numbers.

Methods

We analysed trends in admission for nonemergency admissions with a difference-in-difference approach, using four separate comparison groups: (1) matched on previous hospital numbers; (2) the five closest hospitals geographically; (3) hospitals in the same administrative area; (4) a national comparison group. We also employed waiting time as an instrumental variable to account for possible effects on waiting times on patient numbers. We used three outcomes: overnight admissions; day-case admissions; and patients not attending for their booked appointments, and used a model segmented into three month periods after report publication in order to examine the range of short and longer term effects.

Results

Two out of three of the hospitals we examined showed no difference in patient numbers at any point in the 12 months after negative reports were published. One of the hospitals showed a reduction in overnight patients for 3 months (–12%, p=0.003) and 6 months (–14%, p<0.001) after report publication, but patient levels returned to normal after this. Additional examination of patient numbers in advance of these reports coming out also did not change these results.

Conclusion

The publication and dissemination of highly critical reports by a health care regulator does not appear to have resulted in patients’ sustained avoidance of the hospitals involved. We only found an impact in one of the three hospitals we examined, and this only persisted for 6 months. This reminds us that simplistic assumptions regarding the power of information to drive patient numbers are unrealistic, and that reliance on these alone to drive quality improvement may be misguided.
OP52 Long-Term Exposure to Income Inequality: Implications for Physical and Mental Health at Older Ages
Authors: Vries R de , Blane D , Netuveli G
Published: September 2012

Background

The ‘inequality hypothesis’ proposes that higher levels of societal income inequality have a detrimental effect on both physical and mental health. Previous studies have provided only mixed support for this hypothesis, particularly among older people. However, by using only contemporary income inequality estimates, or estimates from a single lag period, the majority of previous studies have not accounted for people’s continued exposure to income inequality over the long-term. In this study, we addressed this problem by examining the association between older people’s experience of inequality over an extended period and their subsequent health.

Methods

The data for this project were taken from three comparable nationally representative surveys (covering 16 countries) of the health and circumstances of older people; the English Longitudinal Study of Ageing, the Survey of Health and Retirement in Europe, and the U.S. Health and Retirement Study. Standardised estimates of national income inequality from 1960–2006 were taken from the Standardised World Income Inequality Database. We used multilevel regression methods to model the association between average inequality over this period and four measures of individual health: Objectively measured grip strength and lung function, and subjectively reported physical limitation and depressive symptoms.

Results

We found that, after adjusting for individual and country-level covariates, exposure to higher average levels of inequality over the long-term was significantly negatively related to objectively measured grip strength and lung function, but unrelated to self-reported physical limitations or depressive symptoms.

Conclusion

Our results show that long-term exposure to income inequality may indeed be detrimental to the physical health of older people. However, we found no evidence of an effect of inequality on subjectively reported limitations or depressive symptoms. This may be an effect of unmeasured covariates, or it may be due to the greater accuracy afforded by the objective health measures. To our knowledge this study represents the first direct evidence linking experience of inequality to the health of older people which has made use of either objective measures of health at the individual level, or a measure of inequality exposure over the long term.
OP53 Defining the Long-Term Trend in a Public Health Intervention Study: A Cautionary Tale
Authors: Salway R , Gilmore A , Sims M
Published: September 2012

Background

Numerous studies have reported on the impact of comprehensive smoke-free laws on population health. Many early studies have ignored the potential effect of the long-term trend of the health outcome, and when included, subsequent studies have focused on either linear or non-linear trends. However, the choice of appropriate trend is not always straightforward. We illustrate this by investigating the short-term impact of smoke-free legislation in England, introduced on 1st July 2007, on myocardial infarction mortality.

Methods

We investigate the impact of the legislation using weekly counts of all cases aged 18 years or older residing in England with a primary cause of death of a myocardial infarction (ICD–10 I21) between July 2002 to December 2010 (providing 5 years pre-legislative and 3 years and 6 months post-legislative data). We compare a number of models based on an interrupted time series design with a quasi-Poisson generalised additive model that adjusts for seasonality and long-term trends.

Results

Myocardial infarction mortality shows a marked decline over the study period. We identify two competing models. The first shows evidence of a complex interaction between the introduction of smoke-free legislation and the long-term trend. We observe an initial statistically significant reduction in mortality (–8.5%, 95% CI –11.1% to –5.8%) coupled with a change in the long-term trend from a reduction of 4% over a six month period to a reduction of 3.5%. The second model fits a nonlinear trend and shows no significant smoke-free effect. Both models offer an almost identical fit.

Conclusion

Investigating small effects in the presence of a pronounced long-term trend is complicated by the limitations of the available data. In particular, it is not clear whether we observe a gradual change in the long term trend or a discrete effect directly attributable to the legislation. The two models have near-identical fitted values and GCV scores, but have very different interpretation. We conclude that the data alone are insufficient to distinguish between the two models and warn that overly-simplistic analyses in such situations may result in misleading conclusions.
OP55 Socioeconomic Inequalities in Childhood Exposure to Secondhand Smoke Before and after Smoke-Free Legislation in three UK Countries
Authors: Moore GF , Currie D , Gilmore G , Holliday JC , Moore L
Published: September 2012

Background

Secondhand smoke (SHS) exposure is higher among children from lower socioeconomic status (SES) families, contributing to the intergenerational reproduction of health inequalities. Legislation prohibiting smoking in enclosed public places was introduced in all UK countries between 2006 and 2007. Although opponents argued that it would displace smoking into the home, legislation has been associated with reduced childhood SHS exposure and increased prevalence of smoke-free homes. In some UK countries however, trends towards widening inequality in childhood SHS exposure have been reported following legislation. This paper combines datasets from 3 UK countries to examine socioeconomic patterning in childhood SHS exposure and smoking restrictions in homes and cars pre- and post-legislation.

Methods

We conducted a repeat cross-sectional survey of 10,867 schoolchildren in 304 primary schools in Scotland, Wales and Northern Ireland. Children provided saliva for cotinine assay, completing questionnaires before and 12-months after legislation, including the Family Affluence Scale (a measure of socioeconomic status), and reports of smoking restrictions in homes and cars. Multinomial regression analyses assessed differences between survey years in SHS exposure and private smoking restrictions, with interaction terms to assess SES patterning in changes.

Results

SHS exposure was highest, and private smoking restrictions least frequent, among lower SES children pre- and post-legislation in all countries. Proportions of samples containing <0.1ng/ml (i.e. undetectable) cotinine increased significantly (RR=1.63; 95%CI=1.45 to 1.83), from 31.0% to 41.0%. Although across the SES spectrum, there was no evidence of displacement of smoking into the home, socioeconomic inequality in the likelihood of samples containing detectable levels of cotinine increased (RR=1.10; 95%CI=1.05 to 1.16). Among children from the poorest and most affluent families respectively, 96.9% and 38.2% of post-legislation samples contained detectable cotinine. Socioeconomic gradients at higher exposure levels remained unchanged. Among children from the poorest families, 1 in 3 samples contained greater cotinine concentrations than Scottish bar worker’s samples prior to legislation (3ng/ml). Smoking restrictions in homes and cars increased. However, little more than half (55.1%) of children, and only 19.3% of children of smokers, lived in smoke-free homes following legislation. Significant socioeconomic patterning remained, with 26.3% and 72.0% of children from the poorest and most affluent families respectively living in a smoke-free home.

Conclusion

Urgent action is needed to reduce inequalities in SHS exposure. Such action should include emphasis on reducing smoking in cars and homes.
OP56 Differential Effects of Smoking Cessation During Pregnancy on Birth Weight in a Cohort of Disadvantaged Women
Authors: Hayes CB , Kearney M , Collins C , O’Carroll H , Wyse E , Geary M , Kelleher CC
Published: September 2012

Background

Smoking during pregnancy is recognized as the most important preventable risk factor. Maternal smoking accounts for 20–30% of low birth weight infants (<2,500g), the most common adverse outcome in pregnancy. The objective of this study was to explore the effects of maternal smoking habits: stopping smoking in the first and second trimesters, continuing to smoke, number of cigarettes smoked and socio-demographic factors on infant birth weight.

Methods

The study was a longitudinal cohort study of 1,000 pregnant smokers attending public hospital clinics in a disadvantaged catchment area at first pre-natal visit (V1), and assessed at 28–32 weeks (V2) and at one week after birth (V3) using an interviewer-administered questionnaire. The primary outcome variables were: change in smoking status based on self-reported response and urinary cotinine measurement for those who had quit. ANOVA was carried out to test for differences in mean birth weight. A multiple regression analysis with birth weight as the dependent variable was carried out on demographic and smoking characteristics and derived smoking category variables at V3: sustained quitters, continued smokers, successful quitters at V3 and intermittent quitters.

Results

The mean difference in birth weight between continued smokers and sustained quitters was significant, (mean difference = 233g, 95% CI=60 – 406g, p=0.008), as was the difference between continued smokers and intermittent quitters (mean difference = 202g, 95% CI =17 – 386g, p=0.03). Regression on baseline variables showed that only 2.4% of the variance (R2) was explained by smoking characteristics; that is, number of smokers in the home other than self or partner (p=0.008) and number of cigarettes smoked per day (p=0.02). A second regression model showed gestation at delivery to be the best predictor of birth weight (R2=44.2). The number of cigarettes smoked at V2 explained an additional 2.1% (p<0.001) and being a sustained quitter 0.5% (p=0.02).

Conclusion

In this study a clear gradient was observed around smoking behaviour and birth weight with continued smokers having infants with lowest birth weights, sustained quitters the highest and intermittent quitters somewhere in between. The study also demonstrated that the negative effects of maternal smoking on birth weight are at least partly reversible. It thus showed a beneficial effect of quitting smoking for at least part of pregnancy and a link between passive smoking and birth weight. These findings are important for the delivery of targeted health promotion messages to smoking women in early pregnancy.
OP58 Is the Excess Risk of Myocardial Infarction Among People with Diabetes Falling Over Time?
Authors: Hardoon SL , Whincup PH , Petersen I , Morris RW
Published: September 2012

Background

Incidence of myocardial infarction (MI) in the UK general population has declined considerably in recent years. However it is unclear whether the decline in MI risk has occurred among people with diabetes. People with diabetes have an estimated two-fold excess risk of MI, compared to those without diabetes. A differential trend in MI incidence among diabetic patients could correspond to a rise or fall in this excess risk, which has implications for prognosis and management of diabetes. We compared recent trends in MI incidence among those with and without diabetes in a representative UK population sample, and estimated the excess risk of MI among diabetic patients in different calendar periods.

Methods

The population sample comprised 2,927,137 patients (49% men) aged 30 years and over, with no prior MI, from 434 general practices belonging to The Health Improvement Network (THIN) UK-wide primary care database in 1995–2008. Incidence of MI in 1995–1998 was compared with that 10 years later in 2005–2008. Rate ratios comparing incidence over these intervals were estimated from multi-level Poisson regression (patients nested in practices), with an indicator for time interval as a covariate, adjusting for age and gender, with practice as a random effect. An interaction between time interval and an indicator for diabetes was used to assess whether the rate ratios comparing intervals differed among those with and without diabetes, and equivalently whether the excess relative risk among diabetic patients has changed over time.

Results

In 1995–1998 age-standardised incidence rates for MI (per 1000 person years) among those without and with diabetes were 3.22 (95% CI 3.10–3.34) and 9.56 (8.42–10.7) respectively. In 2005–2008, corresponding incidence rates were 1.47 (1.44–1.50) and 4.43 (4.23–4.65). Among people without diabetes, the rate ratio comparing incidence in 2005–2008 with 1995–1998 was 0.46 (0.44–0.48). Among people with diabetes, the corresponding rate ratio was 0.31 (0.28–0.35), indicating a greater decline in MI incidence over the period (p<0.001 for interaction between interval and diabetes). Correspondingly, the rate ratio comparing incidence among those with diabetes to those without diabetes was attenuated from 2.70 (2.42–3.02) in 1995–1998 to 1.90 (1.80–2.00) in 2005–2008. Gender-specific analyses revealed the attenuation of the relative risks to be significant among both women and men.

Conclusion

The excess risk of MI among diabetic patients appears to be falling over time. However, despite their improved prognosis, people with diabetes remain at a considerable excess risk of MI, emphasizing the need for continued concerted efforts to manage diabetes.
OP59 Do Demands and Worries from Close Social Relations Increase the Risk of Subsequent Incident IHD Hospitalization? A 7 Year Longitudinal Study of Middle-Aged Danish Men and Women
Authors: Lund R , Rod NH , Thielen K , Christensen U
Published: September 2012

Background

The association between support from social relations and ischemic heart disease is well described, however the possible hazardous effects of negative aspects of social relations on cardiovascular health are less well known. The purpose of the present study was to analyze the possible influence of negative aspects of social relations (NASR) at baseline on the risk of development of ischemic heart disease (IHD) defined as incident hospitalized cases of acute myocardial infarction and chronic IHD during 7 year follow-up. NASR were defined as demands or worries from partner, children, family, and friends.

Methods

Participants were included in a questionnaire-based study in 2000 and were a random sample (N=6767) of Danish men and women aged 40 or 50 years by October 1st 1999 from the Danish Longitudinal Study on Work, Unemployment and Health. Data for the present study are based on baseline questionnaire data in 2000 and register linked data from the period 2000–2007 on hospitalization for IHD (ICD10: I21–25). Cases of IHD (I21–25) four years prior to baseline were excluded from the analyses. In total 127 new cases of IHD were identified during follow-up.

Results

Men who always or often experienced worries or demands from their partner had an increased risk of incident IHD compared to those who seldom/never experienced worries and demands HR(95%CI)=2.28(1.14–4.53) adjusted for age, socioeconomic status, cohabitation status, depressive symptoms, smoking and emotional support from all social relations . There was no association between demands/worries from partner and risk of development of IHD among women. Both men and women who experienced frequent worries and demands from their family (other than partner and children) were at increased risk of IHD HR=1.76(1.10–2.81) adjusted for above mentioned covariates and gender. Demands and worries from children and friends were not associated with significantly increased risk of IHD although estimates were in the same direction as for demands/worries from partner and family.

Conclusion

For men, frequent demands and worries from a partner seem to be associated with increased risk of incident IHD hospitalization during 7 year follow-up. Demands/worries from family are risk factors for both women and men. Adjustment for the level of social support from all social relations did not change these conclusions. These findings confirm earlier findings of an association between NASR and self-reported angina pectoris. The weaker findings for women may partly be explained by the substantially smaller number of cases in this middle-aged cohort.
OP62 The Influence of Prenatal Maternal and Paternal Anxiety and Depression on Cardiovascular Biomarkers in the Child at age 10: Findings from the Avon Longitudinal Study of Parents and Children (ALSPAC)
Authors: Dawe K , Dijk AE Van , Stronks K , Gemke RJBJ , Vrijkotte TGM , Eijsden M Van , Lawlor DA
Published: September 2012

Background

The aim of the current study was to investigate whether exposure to prenatal maternal anxiety and depression influenced later offspring glucose, lipid and inflammatory markers via intrauterine mechanisms.

Methods

Data from a prospective birth cohort based in the South West of England were used. Our analysis included 2839 mother-children duos and 2361 father-child duos for outcomes assessed at mean age 9.9 years (non-fasting cholesterol, triglycerides, low density and high density lipoprotein cholesterol (LDLc and HDLc), C-reactive protein (CRP) and interleukin 6 (IL–6) and 2011 and 1726 parent-child duos for outcomes at mean age 15.4 years (fasting glucose, insulin, lipids and CRP). We compared associations of maternal exposures with offspring outcomes to those of the same paternal exposures with offspring outcomes. The rationale for this comparison was that if maternal depression/anxiety influenced offspring outcomes via intrauterine mechanisms we would expect stronger maternal compared with paternal associations. We also examined whether any association of exposures during pregnancy reflected a postnatal effect, with persistence of depression/anxiety into the postnatal period.

Results

Maternal anxiety at 18 and 32 weeks gestation, and maternal depression at 32 weeks gestation were associated with increased CRP in children at 9.9 years (mean difference (95% CI): 0.031 (0.005 to 0.057), 0.030 (0.004 to 0.056), and 0.021 (0.003 to 0.040) respectively), but not at 15.4 years. These associations remained when adjusting for potential confounders (maternal age, ethnicity, pre-pregnancy BMI, parity, social class, smoking and alcohol consumption). Paternal anxiety and depression (measured at 18 weeks gestation)were also associated with increased CRP in children at 9.9 years (mean difference (95% CI): 0.039 (0.003 to 0.076) and 0.026 (0–0.052) respectively), but not at 15.4 years. The magnitudes of the paternal associations were similar to those seen in mothers. Maternal and paternal postnatal depression/anxiety symptoms were also associated with offspring CRP at age 9.9 and appeared to explain much of the antenatal association.

There were no consistent associations between maternal or paternal anxiety or depression during the antenatal or postnatal periods and any of offspring glucose, insulin, IL-6 or lipids at either age.

Conclusion

We have found evidence of a relationship between maternal and paternal anxiety and depression during pregnancy and CRP levels in childhood, which does not persist to adolescence. Our results suggest that these associations are unlikely to be explained by intrauterine mechanisms and may be explained by shared familial confounding or postnatal effects.
OP65 Parent Understanding and Management of Rtis in Children: Implications for Health Practitioner Communication
Authors: Cabral CL , Horwood JP , Hay AD , Ingram JC
Published: September 2012

Background

Respiratory tract infections (RTIs) are among the commonest reason parents consult their GP, representing a significant burden on primary health care services. Many of the symptoms associated with RTIs are a cause of anxiety for parents, but they are often unsure when to consult. This study investigated parents’ experiences of consulting for RTI in their child as part of a wider TARGET programme to improve the care of children with RTIs.

Methods

Parents were recruited through 6 practices in areas of high, middle and low deprivation to capture a range of patient populations. Parents with a child aged between 3 months and 12 years who had consulted for acute RTI within the previous 3 months (excluding children with serious or chronic health problems) were invited to participate. Sampling ensured that parents with younger and older children and parents who were more or less frequent consulters were sampled. Semi-structured interviews explored parent’s experience of consulting for RTIs in their children, information and advice needs; and their understanding of RTIs and treatment options. Interviews were audio-recorded, transcribed and imported into NVivo8 for coding. A thematic analysis was conducted using constant comparison techniques.

Results

Thirty parents were interviewed and the sample captured a range of socio-economic backgrounds, both single and double parent families, with between 1 and 4 children. Consultation rates ranged from 1 to 24 times per year. New parents often had little knowledge of RTIs in children; felt uncertain about which symptoms might indicate a serious illness; and were surprised at how long a RTI could persist for and how frequently a child could get a RTI, particularly in the first years of life. This was true for parents from all socio-economic backgrounds and with different levels of education. When consulting, parents were often seeking a medical assessment and reassurance. However, parents felt that clinicians were often dismissive and had not properly evaluated the child, often leading to re-consultations. In addition, clinician explanations of diagnosis and treatment recommendations were not well understood by parents, and they remained unclear about how to manage an RTI and when to consult.

Conclusion

Parents’ poor knowledge and un-realistic expectations in relation to RTIs in children contribute to high rates of consultation. Despite awareness of parental perspectives, there remains a problem with parent-HP communication in relation to key information needed by parents to manage child’s illness confidently and know when to consult in future.
OP66 A Profile of Undiagnosed Diabetics in the Community: Results from the Boston Area Community Health (Bach) Pre-Diabetes Survey
Authors: Piccolo RS , McKinlay JB , Marceau LD
Published: September 2012

Background

Research suggests almost 30% of the United States population has undiagnosed diabetes and that diabetics typically have the disease for 4 to 7 years before eventual diagnosis. Delay in initial diagnosis results in greater diabetes-related complications, poorer patient outcomes, and reduced quality of life. Most diabetes research is necessarily confined to diagnosed diabetes. Our objective was to identify risk factors for remaining undiagnosed.

Methods

The Boston Area Community Health (BACH) Pre-Diabetes study is an ongoing community-based random-sample cohort study that has enrolled 2,974 participants to date. Participants were asked to fast for 8 hours prior to their interview. Fasting glucose (FG) and glycated hemoglobin (HbA1c) were collected during in-home interviews. Undiagnosed diabetes was defined as FG >125 mg/dL or HbA1c ≥ 6.5%. Risk factors were organized into four logical groupings: 1) socio-demographics, 2) lifestyle/behavioral, 3) utilization/access to healthcare, and 4) health status/comorbidities. Logistic regression was used to estimate the odds ratio (OR) for diagnosed vs. undiagnosed diabetes.

Results

The prevalence of diabetes in the BACH study was 27.8% (n=827). 21.2% of diabetes cases were undiagnosed. The data indicate that healthcare utilization and the presence of co-morbid conditions had a large impact on diabetes diagnosis. Participants who visited a health care provider 5 or more times in the past year were 90% more likely to be diagnosed (OR=1.9, p<0.001) than participants who had 5 or fewer visits. Participants with a history of high cholesterol were more than twice as likely to be diagnosed (OR=2.7, p<0.001). High blood pressure or a history of heart disease also increased the likelihood a participant was diagnosed. Participants with a documented family history of diabetes were more likely to be diagnosed (OR=2.9, p<0.001). Finally, English-speaking participants were more than twice as likely to be diagnosed (OR=2.6, p=0.01) than their Spanish-speaking counterparts.

Conclusion

Undiagnosed diabetes is highly prevalent problem in the United States that leads to poorer patient outcomes and significant health-care costs. These results indicate that access to care, health care utilization and the presence of co-morbid conditions have an important impact on diabetes diagnosis. Individuals who do not have the traditional risk factors for diabetes (i.e. family history) have a greater risk of remaining undiagnosed. These findings suggest that improving access to care in the United States may greatly increase the likelihood of diagnosing previously undiagnosed diabetes.
OP69 The use of NHS Routine Data to Analyse The Effects of Healthcare Interventions
Authors: Cecil E V , Soljak M , Osipovic D , Peckham S , Majeed A
Published: September 2012

Background

In 2007, the strategy ‘Healthcare for London’ planned the establishment of polyclinics in each PCT to help improve the primary care infrastructure. These polyclinics serve as a hub for a group of GP practices which combined form a polysystem. We aimed to investigate the impact of services provided in a polysystem on unplanned (emergency) admissions, using routine NHS activity data. In one polysystem case study, a pulmonary rehabilitation service for COPD was established. In another, a diabetes patient education programme was offered.

Methods

We used routine Hospital Episodes Statistics inpatient data from 2004/5 to 2009/10 covering around 1500 London practices. Differences in adjusted trends in emergency admission rates were compared between the polysystem GP practices case studies and other London practices. Multilevel regression models assessed standardized rate ratios, controlling for year variation, GP practice and population factors. We incorporated interaction terms to allow the effects of the polysystem to vary independently by year.

Results

Over the study period COPD emergency admission rates fell across London with a yearly admission rate ratio of (95% CI) 0.98 (0.97, 0.99, p<0.001). The rates in the study polysystem did not differ from the rest of London at baseline and there was not enough evidence to suggest that the introduction of the polysystem service in May 2007 had any effect on the admission rates. A total of 12% of the registered COPD population was seen as new contacts in the first year of the service.

Diabetes emergency admission rates have been falling across London over the study period with a yearly admission rate ratio (95% CI) of 0.98 (0.96, 0.99, p=0.001). In the first year of the diabetes intervention, the rate of emergency admissions for diabetes fell by 80% in patients from the polysystem practices compared with London, with an interaction factor (95% CI) of 0.20 (0.13, 0.31) p<0.001 and this fall was maintained in the following year. Intervention in this London Polysystem covered 70% of the diabetic population. The power to detect an effect was increased due to the coverage.

Conclusion

NHS routine data can be used to assess the impact of health service interventions that are aimed at reducing admissions. Commissioners must be aware that to assess the impact of interventions, the implementation needs to be on a large scale and that medium term follow up is required in order to study the trends.
OP71 Discriminating Clinical Outcome Models May Drift Unacceptably: Example of Cardiac Surgery Mortality
Authors: McAllister K , Hickey G , Grant S , Bridgewater B , Buchan I
Published: September 2012

Background

Clinical prediction models are used for different purposes, but purpose-specific validation is not usually carried out. The ability of a model to discriminate between true positives and false positives has applications in clinical decision making, screening, and service evaluation. The calibration (goodness-of-fit) of a model is a key indicator of how well a model’s predicted outcomes reflect those actually observed. Initial validation of models usually includes assessment of these features but re-evaluation over time might not be performed.

EuroSCORE is an adult cardiac surgery risk model which has been in use since 1998. It predicts in-hospital mortality and is used for clinical decision making and service evaluation. It is widely acknowledged to have demonstrated ‘calibration drift’, but this has not been formally evaluated in the UK population.

Methods

We assessed the performance of EuroSCORE in the Central Cardiac Audit Database (CCAD), covering all NHS cardiac procedures in the UK. Discrimination was tested using the area under the Receiver Operator Characteristic (ROC) curve (AUC). Calibration was assessed with the Hosmer-Lemeshow goodness of fit test. In addition, we developed new models with longer-term outcomes using the data, and tested year-on-year model performance.

Results

A total of 399,314 eligible procedures from 1st April 1998 to 31st March 2011 were included in the analysis. Assessing the discrimination of EuroSCORE by financial year showed consistency across the period (AUC values ranging from 0.788 to 0.818). Model calibration, however, drifted considerably with a cumulative mortality over-estimate of 10,801 deaths by the end of the period (increasing from 147 over-estimated deaths in 1998 to 1,500 in 2010). This represented a predicted overall mortality rate of 6.0% compared with the observed rate of 3.4%. We will also present findings relating to year-on-year performance of a panel of models tailored to longer-term outcomes in specific procedures.

Conclusion

Models that retain accurate discrimination while undergoing calibration drift may be implemented in settings for longer than is appropriate. A model that maintains good discrimination may be useful in a subset of scenarios, but for most purposes good calibration is also crucial. For models developed for multiple applications, purpose-specific validation and recalibration should be considered. Model performance should be appraised in context and not by indicators in isolation.
OP72 Prospective External Validation of Risk Prediction Models for Acute Traumatic Brain Injury in UK Critical Care Units: The Rain Study
Authors: Harrison DA , Griggs KA , Gomes M , Menon DK , Rowan KM
Published: September 2012

Background

Acute traumatic brain injury (TBI) is the leading cause of death and disability in adults aged under 40 years. Statistical models have been developed to predict the risk of mortality or unfavourable outcome (death or severe disability) at six months following acute TBI but to date these risk prediction models have only been validated using existing data sources. The Risk Adjustment In Neurocritical care (RAIN) Study aimed to validate these risk prediction models among adults with acute TBI admitted to UK critical care units.

Methods

Ten risk prediction models were identified: four for mortality at six months (the Hukkelhoven model and IMPACT Core, Extended and Lab models); and six for unfavourable outcome at six months (as mortality plus CRASH Basic and CT models). Risk factor data were collected from 67 UK critical care units (including 90% of regional neuroscience centres) from August 2009 to March 2011. Patients were followed up to six months for mortality by linkage with death registration and unfavourable outcome using the Glasgow Outcome Scale (Extended) administered by postal or telephone questionnaire.

The risk prediction models were validated for calibration (c index), discrimination (Hosmer-Lemeshow test and Cox calibration regression) and overall fit (Brier score). Missing data were handled with multiple imputation.

Results

Data were collected for 2,975 eligible patients admitted to critical care following acute TBI. 97% of patients were followed-up for mortality and 81% for unfavourable outcome at six months. Following multiple imputation, mortality and unfavourable outcome at six months were 26% and 57%, respectively. Risk prediction models for mortality at six months had good discrimination (c index 0.75–0.78) and the Hukkelhoven and IMPACT Lab models were well calibrated, although the IMPACT Core and Extended models over-predicted mortality. The models for unfavourable outcome at six months had worse discrimination (c index 0.69–0.71) and all models substantially under-predicted risk of unfavourable outcome. The best performance overall was found for the IMPACT Lab model, which was the most complex model, incorporating laboratory measurements. Models of the next level of complexity (Hukkelhoven, CRASH CT, IMPACT Extended) all performed similarly.

Conclusion

Risk prediction models for acute TBI had acceptable discrimination among a large, representative sample of patients admitted to UK critical care units. Calibration was good for mortality but poor for unfavourable outcome, and these models therefore require recalibration for use in this setting.
OP76 Households and Health: How Small Clusters Can Influence Results
Authors: Leyland AH , Gray L
Published: September 2012

Background

There have been studies suggesting that various measures of health, health behaviours or health seeking cluster within households. Previous research on the impact of omitting small clusters from analyses have suggested little impact on parameter estimates or standard errors but have typically assumed small intraclass correlations – not usually the case for the household. Since there are typically few individuals per household, and many households contain just one person, several studies have excluded household from the analysis. We examine what difference it makes in practice when the level of household is excluded for a variety of outcomes.

Methods

7901 adults from 5063 households in 356 small areas were interviewed in the 2003 Scottish Health Survey; in 2512 (49.6%) of households just one adult participated. We analysed systolic blood pressure (SBP), BMI, current smoking status, eating 5+ portions of fruit and vegetables per day, eating oily fish at least once per week, and having seen a GP within the past 2 weeks. All results were adjusted for age and sex; in addition, we examined the effects of education, social class and area deprivation. Interactions were fitted between sex and all terms in the fixed and random parts of the model. Multiple imputation was used to account for item non-response. Multilevel linear and logistic regression models including and excluding household were fitted by Markov chain Monte Carlo and the results compared, with population average estimates obtained for logistic regression models.

Results

The extent of clustering varied by outcome and gender; the proportion of the total unexplained variance at the household level ranged from 8.6% (95% Credible interval 0.3–24.5) for systolic blood pressure for women to 87.5% (83.7–90.7) for eating oily fish for women. Bias was evident in both the fixed parameter estimates and their standard errors. The bias in the fixed parameters tended to be higher for outcomes for which the household variance was higher.

Conclusion

For all outcomes the inclusion of household provided an improvement in model fit. Excluding the level of household led to biases not just in the standard errors but also in the parameter estimates themselves. This has implications not only regarding the need to account for clustering within households but also regarding the use of “sandwich estimators” that adjust the standard error but not the regression coefficient.
OP80 Minimum Unit Pricing for Alcohol: A Document Analysis of Evidence Submissions to the Scottish Parliament
Authors: Katikireddi S V , Hilton S , Bond L
Published: September 2012

Background

Minimum unit pricing (MUP) of alcohol is a novel policy intervention aimed at increasing the price of the cheapest forms of alcohol to reduce alcohol consumption and associated harms. In Scotland, alcohol-related harms have increased exponentially during the past few decades and Scotland currently experiences the greatest level of alcohol-related mortality within the UK. Scotland would be the first country in the world to introduce the measure and therefore both advocates and critics have seized the opportunity to put forward the different arguments in the case of MUP. This study examines the evidence submitted to the Scottish Parliament with the aim of examining how arguments for and against MUP have been framed and to consider what forms of evidence have been drawn upon by different policy stakeholders to debate MUP.

Methods

The Scottish Parliament received evidence submissions from a wide variety of stakeholders in its first consideration of MUP as part of the Stage 1 scrutiny process for the Alcohol (etc.) Bill 2010. Sixty-five documents submitted by 47 different stakeholders (including politicians, health professionals, industry representatives, supermarkets and researchers) considered within meetings of the Select Committee were analysed. Data management was assisted using Nvivo 9, framework matrices, and thematically analysed using constant comparative methods.

Results

Arguments around alcohol policy have been actively constructed as a health issue by advocates for MUP in comparison to critics who highlight economic, ideological, and social aspects. Constructions of alcohol overconsumption as a population health issue, rather than an individual-level health problem, were contested. Alcohol epidemiology was drawn upon by advocates (to support a whole population approach) but also by critics (to argue alcohol harms are reducing). Issues raised in opposition include important potential secondary impacts such as exacerbating inequalities, increasing cross-border and illicit trade and perverse incentives (such as increases in profitability driving retailers to encourage increased sales).

Conclusion

Framing of alcohol policy as a health (rather than, for example, trade or justice) issue that requires a whole population approach has been important in creating conditions amenable to MUP being seriously considered by policymakers. The initial framing of an issue in different ways can lead to similar sources of evidence, such as routine epidemiological data, being used to suggest different actions are appropriate. Public health researchers and practitioners should be aware of the active construction process occurring in policy definition and adapt research and advocacy accordingly.
OP81 Estimating the Potential of Population Level Changes in Cholesterol and Blood Pressure for Reducing UK Coronary Heart Disease Mortality Rates: A Novel Modelling Approach
Authors: O’Flaherty M , Couch P , Sperrin M , Green N , Ainsworth J , Huffmann M , Lloyd-Jones D , Buchan I , Capewell S
Published: September 2012

Background

Coronary heart disease (CHD) mortality is declining. However, population ageing and increasing obesity and diabetes might reverse this trend. Strategies to reduce salt and saturated fat intake could substantially decrease population-wide cholesterol and blood pressure levels and consequently reduce CHD events. Our aim was to explore the potential reduction in CHD mortality burden that might be achieved by population shifts in these risk factors.

Methods

The novel Stock of Health (SoH) modelling approach integrates demographic and risk factor data from the Office for National Statistics and the Health Survey for England, and risk factor effects from the US Cardiovascular Lifetime Risk Pooling Project. The SoH approach estimates the latent “stock” of CHD-related health for each individual within the entire population of England and Wales (51 million). It then computes failure times for CHD mortality, allowing for multiplicative risk factor effects and competing mortality risks.

We first simulated CHD deaths for England and Wales over the period 2000-2010. We then extended the simulations to 2030, and compared “FEASIBLE” and “IDEAL” population intervention scenarios, targeted to systolic blood pressure (SBP) and cholesterol under two future trend assumptions: I) assuming mortality rates in 2010 remain stable through to 2030, or II) assuming CHD mortality continue falling.

Results

The mean simulated failure times closely mirrored those actually observed(1993–2004: men=72 vs. 71 years; women=74 vs. 75 years). In 2030, about 81200 CHD deaths are expected to occur under trend assumption I (+14% compared to 2010, reflecting population ageing) and 47600 under trend assumption II (–18% compared to 2010). SBP: For trend I, a FEASIBLE SBP reduction of 1mmHg and IDEAL reduction of –5mmHg could result in approximately 77300 (+9%, baseline: 2010)and 64500 (–9%, baseline: 2010) deaths respectively in 2030. Assuming falling trends (II), about 45500 (–22%, baseline: 2010) and 38300 (–34%, baseline: 2010) deaths would result in 2030 under the feasible and ideal scenarios respectively. Total cholesterol (TC): Under trend I, a FEASIBLE TC reduction of 0.1 mmol/l and IDEAL reduction of 0.5 mmol/l could result in about 74800 and 57000 deaths (5% and –20%) by 2030. Assuming trend II, the resulting deaths would be approximately 43900 and 33400 (–25% and –43%, baseline: 2010) respectively.

Conclusion

Under both trend assumptions, the adoption of evidence-based dietary policies to reduce salt and saturated fat intake, resulting in population-wide decreases in blood pressure and cholesterol could result in substantial declines in forecasted CHD mortality.
OP87 Healthy Behaviours in Middle Age and Long-Term Consequences for Mortality, Physical and Cognitive Function, and Mental Health
Authors: Lang IA , Goodwin V , Hubbard R , Llewellyn DJ
Published: September 2012

Background

Physical activity, healthy body weight, smoking, and alcohol consumption are each related to mortality, physical and cognitive function, and mental health but their combined long-term effect is unknown. We examined the individual and combined influence of these risk factors on mortality and subjective and measured function in middle-aged adults followed for 18 years.

Methods

Data were from the US Health and Retirement Study (HRS), a biennial, longitudinal, nationally representative survey of older adults. 11,597 participants aged 51 to 61 were followed from study enrolment for an 18-year period. A health behaviour score was calculated with one point for each behaviour: moderate physical activity three times per week; BMI 20 to 25; alcohol consumption less than 7 drinks/week; non-smoking. Outcomes were all-cause mortality, problems with activities of daily living (ADLs), lung function, grip strength, walk speed, measured cognitive function, and depressive symptoms. Adjusted logistic and linear regression models were used to examine the relationships between health behaviours and outcomes separately by gender.

Results

For all outcomes except grip strength there was a dose-response relationship between healthy behaviour score and outcomes. For example, in men with four healthy behaviours and no baseline ADL problems, at 18-year follow-up 78.4% had no ADL problems, 6.6% had ADL problems, and 15.0% had died. In men with no healthy behaviours and no ADL problems at baseline, at follow-up 35.1% had no ADL problems, 8.8% had ADL problems, and 56.1% had died. Results in women were comparable but ADL differences were more marked. Number of healthy behaviours was related to follow-up cognitive function, mental health, walk speed, and lung function but not grip strength. Results were robust to adjustment for socioeconomic status (SES: measures of health, income, and level of education) and in analyses stratified by SES similar differences were found in relation to healthy behaviours within strata.

Conclusion

Simple differences in lifestyle behaviours in middle age are associated with major differences in mortality, functioning and health risks as people progress into old age. Effective health promotion in these age groups could bring substantial health benefits for individuals across SES groups.