Record linkage in Scotland and its applications to health research

Novel linkage approach to join community-acquired and national data

BACKGROUND

Community optometrists in Scotland have performed regular free-at-point-of-care eye examinations for all, for over 15 years. Eye examinations include retinal imaging but image storage is fragmented and they are not used for research. The Scottish Collaborative Optometry-Ophthalmology Network e-research project aimed to collect these images and create a repository linked to routinely collected healthcare data, supporting the development of pre-symptomatic diagnostic tools.

METHODS

As the image record was usually separate from the patient record and contained minimal patient information, we developed an efficient matching algorithm using a combination of deterministic and probabilistic steps which minimised the risk of false positives, to facilitate national health record linkage. We visited two practices and assessed the data contained in their image device and Practice Management Systems. Practice activities were explored to understand the context of data collection processes. Iteratively, we tested a series of matching rules which captured a high proportion of true positive records compared to manual matches. The approach was validated by testing manual matching against automated steps in three further practices.

RESULTS

A sequence of deterministic rules successfully matched 95% of records in the three test practices compared to manual matching. Adding two probabilistic rules to the algorithm successfully matched 99% of records.

CONCLUSIONS

The potential value of community-acquired retinal images can be harnessed only if they are linked to centrally-held healthcare care data. Despite the lack of interoperability between systems within optometry practices and inconsistent use of unique identifiers, data linkage is possible using robust, almost entirely automated processes.

Maternal multimorbidity and preterm birth in Scotland: an observational record-linkage study

BACKGROUND

Multimorbidity is common in women across the life course. Preterm birth is the single biggest cause of neonatal mortality and morbidity. We aim to estimate the prevalence of multimorbidity in pregnant women and to examine the association between maternal multimorbidity and PTB.

METHODS

This is a retrospective cohort study using electronic health records from the Scottish Morbidity Records. All pregnancies among women aged 15 to 49 with a conception date between 1 January 2014 and 31 December 2018 were included. Multimorbidity was defined as the presence of two or more pre-existing long-term physical or mental health conditions, and complex multimorbidity as the presence of four or more. It was calculated at the time of conception using a predefined list of 79 conditions published by the MuM-PreDiCT consortium. PTB was defined as babies born alive between 24 and less than 37 completed weeks of gestation. We used Generalised Estimating Equations adjusted for maternal age, socioeconomic status, number of previous pregnancies, BMI, and smoking history to estimate the effect of maternal pre-existing multimorbidity. Absolut rates are reported in the results and tables, whilst Odds Ratios (ORs) are adjusted (aOR).

RESULTS

Thirty thousand five hundred fifty-seven singleton births from 27,711 pregnant women were included in the analysis. The prevalence of pre-existing multimorbidity and complex multimorbidity was 16.8% (95% CI: 16.4-17.2) and 3.6% (95% CI: 3.3-3.8), respectively. The prevalence of multimorbidity in the youngest age group was 10.2%(95% CI: 8.8-11.6), while in those 40 to 44, it was 21.4% (95% CI: 18.4-24.4), and in the 45 to 49 age group, it was 20% (95% CI: 8.9-31.1). In women without multimorbidity, the prevalence of PTB was 6.7%; it was 11.6% in women with multimorbidity and 15.6% in women with complex multimorbidity. After adjusting for maternal age, socioeconomic status, number of previous pregnancies, Body Mass Index (BMI), and smoking, multimorbidity was associated with higher odds of PTB (aOR = 1.64, 95% CI: 1.48-1.82).

CONCLUSIONS

Multimorbidity at the time of conception was present in one in six women and was associated with an increased risk of preterm birth. Multimorbidity presents a significant health burden to women and their offspring. Routine and comprehensive evaluation of women with multimorbidity before and during pregnancy is urgently needed.

Liver function tests in primary care provide a key opportunity to diagnose and engage patients with hepatitis C

Since the advent of direct-acting antiviral therapy, the elimination of hepatitis c virus (HCV) as a public health concern is now possible. However, identification of those who remain undiagnosed, and re-engagement of those who are diagnosed but remain untreated, will be essential to achieve this. We examined the extent of HCV infection among individuals undergoing liver function tests (LFT) in primary care. Residual biochemistry samples for 6007 patients, who had venous blood collected in primary care for LFT between July 2016 and January 2017, were tested for HCV antibody. Through data linkage to national and sentinel HCV surveillance databases, we also examined the extent of diagnosed infection, attendance at specialist service and HCV treatment for those found to be HCV positive. Overall HCV antibody prevalence was 4.0% and highest for males (5.0%), those aged 37–50 years (6.2%), and with an ALT result of 70 or greater (7.1%). Of those testing positive, 68.9% had been diagnosed with HCV in the past, 84.9% before the study period. Most (92.5%) of those diagnosed with chronic infection had attended specialist liver services and while 67.7% had ever been treated only 38% had successfully cleared infection. More than half of HCV-positive people required assessment, and potentially treatment, for their HCV infection but were not engaged with services during the study period. LFT in primary care are a key opportunity to diagnose, re-diagnose and re-engage patients with HCV infection and highlight the importance of GPs in efforts to eliminate HCV as a public health concern.

Metabolic dysfunction-related liver disease as a risk factor for cancer

Objective

The aim of this study was to investigate the association between obesity, diabetes and metabolic related liver dysfunction and the incidence of cancer.

Design

This study was conducted with health record data available from the National Health Service in Tayside and Fife. Genetics of Diabetes Audit and Research Tayside, Scotland (GoDARTS), Scottish Health Research Register (SHARE) and Tayside and Fife diabetics, three Scottish cohorts of 13 695, 62 438 and 16 312 patients, respectively, were analysed in this study. Participants in GoDARTS were a volunteer sample, with half having type 2 diabetes mellitus(T2DM). SHARE was a volunteer sample. Tayside and Fife diabetics was a population-level cohort. Metabolic dysfunction-related liver disease (MDLD) was defined using alanine transaminase measurements, and individuals with alternative causes of liver disease (alcohol abuse, viruses, etc) were excluded from the analysis.

Results

MDLD associated with increased cancer incidence with a HR of 1.31 in a Cox proportional hazards model adjusted for sex, type 2 diabetes, body mass index(BMI), and smoking status (95% CI 1.27 to 1.35, p<0.0001). This was replicated in two further cohorts, and similar associations with cancer incidence were found for Fatty Liver Index (FLI), Fibrosis-4 Index (FIB-4) and non-alcoholic steatohepatitis (NASH). Homozygous carriers of the common non-alcoholic fatty liver disease (NAFLD) risk-variant PNPLA3 rs738409 had increased risk of cancer. (HR=1.27 (1.02 to 1.58), p=3.1×10⁻²). BMI was not independently associated with cancer incidence when MDLD was included as a covariate.

Conclusion

MDLD, FLI, FIB-4 and NASH associated with increased risk of cancer incidence and death. NAFLD may be a major component of the relationship between obesity and cancer incidence.

Educational associations with missed GP appointments for patients under 35 years old: administrative data linkage study

BACKGROUND

There is an evidence gap about whether levels of engagement with public services such as schools and health care affect people across the lifespan. Data on missed patient appointments from a nationally representative sample of Scottish general practices (GP) (2013-2016) were probabilistically linked to secondary school pupil data. We tested whether school attendance, exclusions (2007-2011) or lower educational attainment (2007-2016) was associated with an increased risk of missing general practice appointments.

METHODS

School attendance data were classified into quartiles of possible days attended for years we had data. School exclusions were derived as a categorical variable of 'ever excluded'. Attainment data were categorised via the Scottish Credit and Qualifications Framework (SCQF) level 3 or 6; a cumulative measure of attainment on leaving school. The associations between school attendance, exclusions and attainment and risk of missing medical appointments were investigated using negative binomial models, offset by number of GP appointments made and controlling for potential confounders.

RESULTS

112,534 patients (all aged under 35) had GP appointment and retrospective school attendance and exclusion data, and a subset of 66,967 also had attainment data available. Patients who had lower attendance, had been excluded from school or had lower educational attainment had an increased risk of missing GP appointments (all rate ratios > 1.40).

CONCLUSIONS

This study provides the first evidence from a population-representative sample in a high-income country that increased numbers of missed appointments in health care are associated with reduced school attendance, higher levels of school exclusion and lower educational attainment. Insights into the epidemiology of missingness across public services can support future research, policy and practice that aim to improve healthcare, health outcomes and engagement in services.

'Missingness' in health care: Associations between hospital utilization and missed appointments in general practice. A retrospective cohort study

Objectives

Are multiple missed appointments in general practice associated with increased use of hospital services and missingness from hospital care? This novel study explores this in a population representative sample for the first time.

Design, setting, participants

A large, retrospective cohort (n = 824,374) of patient records from a nationally representative sample of GP practices, Scotland, 2013–2016. Requested data were extracted by a Trusted Third Party for the NHS, anonymised and linked to a unique patient ID, in the NHS Safehaven for analysis using established NHS Scotland linkage. We calculated the per-patient number of GP missed appointments from individual appointments and investigated the likelihood of hospital appointment or admission outcomes using a negative binomial model offset by number of GP appointments made. These models also controlled for age, sex, Scottish Index of Multiple Deprivation (SIMD) and number of long- term conditions (LTCs).

Main outcome measures

Hospital attendance: Outpatient clinic attendances; hospital admissions; Emergency Department (ED) attendances. Hospital missingness: ‘Did not attend’ (DNAs) outpatient clinic appointments, ‘irregular discharges’ from admissions, and ‘left before care completed’ ED care episodes.

Results

Attendance: Patients in the high missed GP appointment (HMA) category were higher users of outpatient services (rate ratio (RR) 1.90, 95% confidence intervals (CI) 1.88–1.93) compared to those who missed none (NMA) with a much higher attendance risk at mental health services (RR 4.56, 95% CI 4.31–4.83). HMA patients were more likely to be admitted to hospital; general admissions (RR 1.67, 95% CI 1.65–1.68), maternity (RR 1.24, 95% CI 1.20–1.28) and mental health (RR 1.23, 95% CI 1.15–1.31), compared to NMA patients. Missing GP appointments was not associated with ED attendance; (RR 1.00, CI 0.99–1.01).

Missingness: HMA patients were at greater risk of missing outpatient appointments (RR 1.62, 95% CI 1.60–1.64) than NMA patients; with a much higher risk of non-attendance at mental health services (RR 7.83, 95% CI 7.35–8.35). Patients were more likely to leave hospital before their care plan was completed-taking ‘irregular discharges’ (RR 4.56, 95% CI 4.31–4.81). HMA patients were no more at risk of leaving emergency departments ‘without care being completed’ (RR1.02, 95 CI 0.95–1.09).

Conclusions

Patients who miss high numbers of GP appointments are higher users of outpatient and inpatient hospital care but not of emergency departments, signalling high treatment burden.

The pattern of ‘missingness’ is consistent from primary care to hospital care: patients who have patterns of missing GP appointments have patterns of missing many outpatient appointments and are more likely to experience ‘irregular discharge’ from in-patient care. Missingness from outpatient mental health services is very high.

Policymakers, health service planners and clinicians should consider the role and contribution of ‘missingness’ in health care to improving patient safety and care.

Unveiling the Risk Period for Death After Respiratory Syncytial Virus Illness in Young Children Using a Self-Controlled Case Series Design

BACKGROUND

Respiratory syncytial virus (RSV)-related acute lower respiratory infection is an important cause of death in infants and young children. However, little is known about the risk period for RSV-related deaths after presentation to health services with an RSV illness.

METHODS

Using the Scottish national mortality database, we identified deaths from respiratory/circulatory causes (hereafter "respiratory/circulatory deaths") in young children aged <5 years during 2009-2016, whose medical history and records of laboratory-confirmed RSV infections were obtained by linking the mortality database to the national surveillance data set and the Scottish Morbidity Record. We used a self-controlled case series (SCCS) design to evaluate the relative incidence of deaths with respiratory/circulatory deaths in the first year after an RSV episode. We defined the risk interval as the first year after the RSV episode, and the control interval as the period before and after the risk interval until 5 years after birth. Age-adjusted incidence ratio and attributable fraction were generated using the R software package SCCS.

RESULTS

We included 162 respiratory/circulatory deaths, of which 36 occurred in children with a history of laboratory-confirmed RSV infection. We found that the mortality risk decreased with time after the RSV episode and that the risk was statistically significant for the month after RSV illness. More than 90% of respiratory/circulatory deaths occurring within 1 week after the RSV episode were attributable to RSV (attributable fraction, 93.9%; 95% confidence interval, 77.6%-98.4%), compared with about 80% of those occurring 1 week to 1 month after RSV illness (80.3%; 28.5%-94.6%).

CONCLUSIONS

We found an increased risk of death in the first month after an RSV illness episode leading to healthcare attendance. This provides a practical cutoff time window for community-based surveillance studies estimating RSV-related mortality risk. Further studies are warranted to assess the mortality risk beyond the first month after RSV illness episode.

[Administrative data linkage and its usefulness in public health: the case of EcuadorVinculação de dados administrativos e sua utilização em saúde pública: o caso do Equador]

Los objetivos de este artículo son describir las características del abordaje de vinculación de bases de datos administrativos y sus usos en investigación en salud pública, y discutir las potencialidades y retos para su implementación en Ecuador. La vinculación de bases de datos permite integrar datos de una misma persona dispersos en distintos subsectores como salud, educación, justicia, inmigración y programas sociales, y posibilita investigaciones que informen una gestión más eficiente de programas y políticas sociales y de salud. Las principales ventajas del uso de bases de datos relacionadas son la diversidad de datos, la cobertura poblacional, la estabilidad temporal y el costo menor en comparación con la recolección de datos primarios. A pesar de la disponibilidad de herramientas para procesar, vincular y analizar grandes conjuntos de datos, el uso de este abordaje es mínimo en los países de América Latina. Ecuador tiene un alto potencial para explotar este abordaje, debido a la obligatoriedad del uso de un identificador único en la prestación de servicios de salud, que permite la vinculación con otros sistemas de información nacionales. Sin embargo, enfrenta una serie de retos técnicos, ético-legales, culturales y políticos. Para aprovechar su potencial, Ecuador necesita desarrollar una estrategia de gobernanza de datos que incluya normativas de acceso y uso de los datos, de manera simultánea con mecanismos de control y calidad de los datos, una mayor inversión en formación profesional en el uso de los datos dentro y fuera del sector salud, y colaboraciones entre entidades gubernamentales, universidades y organizaciones de la sociedad civil.

Increased case-finding and uptake of direct-acting antiviral treatment essential for micro-elimination of hepatitis C among people living with HIV: a national record linkage study

OBJECTIVES

Micro-elimination of hepatitis C virus (HCV) in people living with HIV (PLHIV) and co-infected with HCV has been proposed as a key contribution to the overall goal of HCV elimination. While other studies have examined micro-elimination in HIV-treated cohorts, few have considered HCV micro-elimination among those not treated for HIV or at a national level.

METHODS

Through data linkage of national and sentinel surveillance data, we examined the extent of HCV testing, diagnosis and treatment among a cohort of PLHIV in Scotland identified through the national database of HIV-diagnosed individuals, up to the end of 2017.

RESULTS

Of 5018 PLHIV, an estimated 797 (15%) had never been tested for HCV and 70 (9%) of these had undiagnosed chronic HCV. The odds of never having been tested for HCV were the highest in those not on HIV treatment [adjusted odds ratio (aOR) = 7.21, 95% confidence interval (CI): 5.15-10.10). Overall HCV antibody positivity was 11%, and it was at its highest among people who inject drugs (49%). Most of those with chronic HCV (91%) had attended an HCV treatment clinic but only half had been successfully treated (54% for those on HIV treatment, 12% for those not) by the end of 2017. The odds of never having been treated for HCV were the highest in those not on HIV treatment (aOR = 3.60, 95% CI: 1.59-8.15).

CONCLUSIONS

Our data demonstrate that micro-elimination of HCV in PLHIV is achievable but progress will require increased effort to engage and treat those co-infected, including those not being treated for their HIV.

Trends in disease incidence and survival and their effect on mortality in Scotland: nationwide cohort study of linked hospital admission and death records 2001-2016

OBJECTIVES

Identify causes and future trends underpinning Scottish mortality improvements and quantify the relative contributions of disease incidence and survival.

DESIGN

Population-based study.

SETTING

Linked secondary care and mortality records across Scotland.

PARTICIPANTS

1 967 130 individuals born between 1905 and 1965 and resident in Scotland from 2001 to 2016.

MAIN OUTCOME MEASURES

Hospital admission rates and survival within 5 years postadmission for 28 diseases, stratified by sex and socioeconomic status.

RESULTS

'Influenza and pneumonia', 'Symptoms and signs involving circulatory and respiratory systems' and 'Malignant neoplasm of respiratory and intrathoracic organs' were the hospital diagnosis groupings associated with most excess deaths, being both common and linked to high postadmission mortality. Using disease trends, we modelled a mean mortality HR of 0.737 (95% CI 0.730 to 0.745) from one decade of birth to the next, equivalent to a life extension of ~3 years per decade. This improvement was 61% (30%-93%) accounted for by improved disease survival after hospitalisation (principally cancer) with the remainder accounted for by lowered hospitalisation incidence (principally heart disease and cancer). In contrast, deteriorations in infectious disease incidence and survival increased mortality by 9% (~3.3 months per decade). Disease-driven mortality improvements were slightly greater for men than women (due to greater falls in disease incidence), and generally similar across socioeconomic deciles. We project mortality improvements will continue over the next decade but slow by 21% because much progress in disease survival has already been achieved.

CONCLUSION

Morbidity improvements broadly explain observed mortality improvements, with progress on prevention and treatment of heart disease and cancer contributing the most. The male-female health gaps are closing, but those between socioeconomic groups are not. Slowing improvements in morbidity may explain recent stalling in improvements of UK period life expectancies. However, these could be offset if we accelerate improvements in the diseases accounting for most deaths and counteract recent deteriorations in infectious disease.

Interventions in the B-type natriuretic peptide signalling pathway as a means of controlling chronic itch

Chronic itch poses major health care and economic burdens worldwide. In 2013, B-type natriuretic peptide (BNP) was identified as an itch-selective neuropeptide and shown to be both necessary and sufficient to produce itch behaviour in mice. Since then, mechanistic studies of itch have increased, not only at central levels of the spinal relay of itch signalling but also in the periphery and skin. In this review, we have critically analysed recent findings from complementary pharmacological and physiological approaches, combined with genetic strategies to examine the role of BNP in itch transduction and modulation of other pruritic proteins. Additionally, potential targets and possible strategies against BNP signalling are discussed for developing novel therapeutics in itch. Overall, we aim to provide insights into drug development by altering BNP signalling to modulate disease symptoms in chronic itch, including conditions for which no approved treatment exists.

Correcting for non-participation bias in health surveys using record-linkage, synthetic observations and pattern mixture modelling

Surveys are key means of obtaining policy-relevant information not available from routine sources. Bias arising from non-participation is typically handled by applying weights derived from limited socio-demographic characteristics. This approach neither captures nor adjusts for differences in health and related behaviours between participants and non-participants within categories. We addressed non-participation bias in alcohol consumption estimates using novel methodology applied to 2003 Scottish Health Survey responses record-linked to prospective administrative data. Differences were identified in socio-demographic characteristics, alcohol-related harm (hospitalisation or mortality) and all-cause mortality between survey participants and, from unlinked administrative sources, the contemporaneous general population of Scotland. These were used to infer the number of non-participants within each subgroup defined by socio-demographics and health outcomes. Synthetic observations for non-participants were then generated, missing only alcohol consumption. Weekly alcohol consumption values among synthetic non-participants were multiply imputed under missing at random and missing not at random assumptions. Relative to estimates adjusted using previously derived weights, the obtained mean weekly alcohol intake estimates were up to 59% higher among men and 16% higher among women, depending on the assumptions imposed. This work demonstrates the universal value of multiple imputation-based methodological advancement incorporating administrative health data over routine weighting procedures.

Impact of maternal smoking on early childhood health: a retrospective cohort linked dataset analysis of 697 003 children born in Scotland 1997-2009

OBJECTIVE

Smoking during pregnancy is associated with adverse health impacts on mother and child. We used a large linked Scottish dataset to produce contemporary estimates of the impact on child health, particularly hospitalisation.

DESIGN

Retrospective cohort study linking birth, death, maternity, infant health, child health surveillance and admission records. We examined the association between smoking status at maternity booking and pregnancy outcomes, hospital admission and death during the first 5 years of life. Models were adjusted for maternal age, socioeconomic status, infant feeding, country of birth, sex, parity and delivery mode. We calculated population attributable fraction (PAF) for each outcome.

SETTING

Scotland, UK.

PARTICIPANTS

Singleton births between 1997 and 2009 (n=697 003) followed to March 2012.

RESULTS

332 386 children had at least one admission by 31 March 2012. There were 56 588 born small for gestational age, 40 492 prematurely and 1074 postneonatal deaths. Within the first 5 years of life, 56 615 children had at least one admission for acute respiratory infections, 24 088 for bronchiolitis and 7549 for asthma. Maternal smoking significantly increased admission for acute respiratory infections (adjusted HR 1.29, 95% CI 1.25 to 1.34, PAF 6.7%) and bronchiolitis (HR 1.43, 95% CI 1.38 to 1.48 under 1 year, PAF 10.1%), asthma (HR 1.29, 95% CI 1.22 to 1.37 age 1-5 years, PAF 7.1%) and bacterial meningitis (HR 1.49, 95% CI 1.30 to 1.71, PAF 11.8%) age 0-5 years. Neonatal mortality (adjusted OR 1.32, 95% CI 1.17 to 1.49, PAF 6.7%), postneonatal mortality (OR 2.18, 95% CI 1.87 to 2.53, PAF 22.3%), small for gestational age (OR 2.67, 95% CI 2.62 to 2.73, PAF 27.5%) and prematurity (OR 1.41, 95% CI 1.37 to 1.44, PAF 8.8%) were higher among the offspring of smokers.

CONCLUSION

Smoking during pregnancy causes significant ill health and death among children born in Scotland. These findings support continued investment to reduce smoking among women before, during and after pregnancy as 50% of women will go on to have further children.

Geographical Variations in the Clinical Management of Colorectal Cancer in Australia: A Systematic Review

Background

In Australia, cancer survival is significantly lower in non-metropolitan compared to metropolitan areas. Our objective was to evaluate the evidence on geographical variations in the clinical management and treatment of colorectal cancer (CRC).

Methods

A systematic review of published and gray literature was conducted. Five databases (CINAHL, PubMed, Embase, ProQuest, and Informit) were searched for articles published in English from 1990 to 2018. Studies were included if they assessed differences in clinical management according to geographical location; focused on CRC patients; and were conducted in Australia. Included studies were critically appraised using a modified Newcastle–Ottawa Scale. PRISMA systematic review reporting methods were applied.

Results

17 articles met inclusion criteria. All were of high (53%) or moderate (47%) quality. The evidence available may suggest that patients in non-metropolitan areas are more likely to experience delays in surgery and are less likely to receive chemotherapy for stage III colon cancer and adjuvant radiotherapy for rectal cancer.

Conclusion

The present review found limited information on clinical management across geographic regions in Australia and the synthesis highlights significant issues both for data collection and reporting at the population level, and for future research in the area of geographic variation. Where geographical disparities exist, these may be due to a combination of patient and system factors reflective of location. It is recommended that population-level data regarding clinical management of CRC be routinely collected to better understand geographical variations and inform future guidelines and policy.

Impact of endometriosis on risk of further gynaecological surgery and cancer: a national cohort study

OBJECTIVE

To evaluate the long-term risk of further gynaecological surgery and cancer in women with endometriosis.

DESIGN

Cohort study.

SETTING

Scotland.

PARTICIPANTS

281 937 women with nearly 5 million person years (4 923 628) of follow up from 1981 to 2010.

METHODS

In this national population-based study we compared 17 834 women with a new surgical diagnosis of endometriosis with 83 303 women with no evidence of endometriosis at laparoscopy, 162 966 women who underwent laparoscopic sterilisation, and 17 834 age-matched women from the general population. Cox proportional hazards regression was used to calculate crude and adjusted hazard ratios with 95% confidence intervals.

MAIN OUTCOME MEASURES

Risk of further gynaecological surgery, number and type of repeat surgery and time to repeat surgery from the diagnosis of endometriosis. Cancer outcomes included subsequent risk of all cancer, gynaecological and non-gynaecological cancers.

RESULTS

Women with endometriosis had a significantly higher risk of further surgery when compared with women with no evidence of endometriosis at laparoscopy [hazard ratio (HR) 1.69, 95% (confidence interval) CI 1.65-1.73], women who had undergone laparoscopic sterilisation (HR 3.30, 95% CI 3.23-3.37) and age-matched women from the general population (HR 5.95, 95% CI 5.71-6.20). They also have an increased risk of ovarian cancer when compared with general population counterparts (HR 1.77, 95% CI 1.08-2.89) or those with laparoscopic sterilisation (HR 1.75, 95% CI 1.2-2.45).

CONCLUSION

Women with surgically diagnosed endometriosis face an increased risk of multiple surgery. They have a higher chance of developing ovarian cancer in comparison with the general population and women with laparoscopic sterilisation.

TWEETABLE ABSTRACT

Women with endometriosis face an increased risk of recurrent surgery and developing ovarian cancer.

The Scottish school leavers cohort: linkage of education data to routinely collected records for mortality, hospital discharge and offspring birth characteristics

PURPOSE

The Scottish school leavers cohort provides population-wide prospective follow-up of local authority secondary school leavers in Scotland through linkage of comprehensive education data with hospital and mortality records. It considers educational attainment as a proxy for socioeconomic position in young adulthood and enables the study of associations and causal relationships between educational attainment and health outcomes in young adulthood.

PARTICIPANTS

Education data for 284 621 individuals who left a local authority secondary school during 2006/2007-2010/2011 were linked with birth, death and hospital records, including general/acute and mental health inpatient and day case records. Individuals were followed up from date of school leaving until September 2012. Age range during follow-up was 15 years to 24 years.

FINDINGS TO DATE

Education data included all formal school qualifications attained by date of school leaving; sociodemographic information; indicators of student needs, educational or non-educational support received and special school unit attendance; attendance, absence and exclusions over time and school leaver destination. Area-based measures of school and home deprivation were provided. Health data included dates of admission/discharge from hospital; principal/secondary diagnoses; maternal-related, birth-related and baby-related variables and, where relevant, date and cause of death. This paper presents crude rates for all-cause and cause-specific deaths and general/acute and psychiatric hospital admissions as well as birth outcomes for children of female cohort members.

FUTURE PLANS

This study is the first in Scotland to link education and health data for the population of local authority secondary school leavers and provides access to a large, representative cohort with the ability to study rare health outcomes. There is the potential to study health outcomes over the life course through linkage with future hospital and death records for cohort members. The cohort may also be expanded by adding data from future school leavers. There is scope for linkage to the Prescribing Information System and the Scottish Primary Care Information Resource.

Maternal gestational weight gain and offspring's risk of cardiovascular disease and mortality

OBJECTIVE

To examine the effect of maternal gestational weight gain (GWG) on adult offspring mortality, cardiovascular morbidity and cerebrovascular morbidity.

METHODS

The Aberdeen Children of the Nineteen Fifties (ACONF) is a population-based cohort of adults born in Aberdeen, Scotland between 1950 and 1956. GWG of the mothers of cohort members was extracted from original birth records and linked to the data on offspring morbidity and mortality up to 2011 obtained from Scottish national records. HRs for cardiovascular events and mortality in offspring according to maternal weight gain in pregnancy were estimated adjusting for maternal and offspring confounders using a restricted cubic spline model.

RESULTS

After exclusions, 3781 members of the original ACONF cohort were analysed. Of these, 103 (2.7%) had died, 169 (4.5%) had suffered at least one cardiovascular event and 73 (1.9%) had had a hospital admission for cerebrovascular disease. Maternal weight gain of 1 kg/week or more was associated with increased risk of cerebrovascular event in the offspring (adjusted HR 2.70 (95% CI 1.19 to 6.12)). There was no association seen between GWG and offspring's all-cause mortality or cardiovascular event. Adult offspring characteristics (smoking, body mass index (BMI) and diabetes) were strongly associated with each outcome.

CONCLUSIONS

Maternal GWG above 0.9 kg/week may increase the risk of cerebrovascular disease in the adult offspring, but not all-cause mortality or cardiovascular disease. Health and lifestyle factors such as smoking, BMI and diabetes in the adult offspring had a stronger influence than maternal and birth characteristics on their mortality and morbidity.

Association between miscarriage and cardiovascular disease in a Scottish cohort

OBJECTIVE

To assess if miscarriage, whether consecutive or not, is associated with an increased risk of subsequent cardiovascular disease.

METHODS

A cohort study was performed using women with at least one miscarriage or live birth recorded from 1950 to 2010 in the Aberdeen Maternity and Neonatal Databank. The exposed groups consisted of women with non-consecutive, two consecutive or three or more consecutive miscarriages; the unexposed group consisted of all women with at least one live birth and no miscarriages. Women were linked to Scottish Morbidity Records for hospital admissions for cardiovascular conditions, cardiac surgery and death registrations. Main outcome measures were ischaemic heart disease, cerebrovascular disease and a composite outcome of any disease of circulatory system. A sensitivity analysis was performed dividing the women into those who had one, two or three or more miscarriages irrespective of whether these events were consecutive or not.

RESULTS

After excluding women with pre-existing hypertension, type 1 diabetes mellitus, kidney disease and 'disease of circulatory system', 60,105 women were analysed; 9419 with non-consecutive, 940 with two consecutive, 167 with three or more consecutive miscarriages and 49,579 with no miscarriage. In the multivariate analyses, a significant association was found between ischaemic heart disease and women with two (HRs 1.75 (95% CI 1.22 to 2.52)) or three or more (HR 3.18 (95% CI 1.49 to 6.80)) consecutive miscarriages. Similar patterns of risk were observed in the sensitivity analysis.

CONCLUSION

Women with a history of two or more miscarriages, irrespective of whether consecutive or not, appear to have an increased risk of ischaemic heart disease.

Breastfeeding is associated with reduced childhood hospitalization: evidence from a Scottish Birth Cohort (1997-2009)

OBJECTIVE

To evaluate the risk of childhood hospitalization associated with infant feeding patterns at 6-8 weeks of age in Scotland.

STUDY DESIGN

A retrospective population level study based on the linkage of birth, death, maternity, infant health, child health surveillance, and admission records for children born as single births in Scotland between 1997 and 2009 (n = 502 948) followed up to March 2012. Descriptive analyses, Kaplan Meier tests, and Cox regression were used to quantify the association between the mode of infant feeding and risk of childhood hospitalization for respiratory, gastrointestinal, and urinary tract infections, and other common childhood ailments during the study period.

RESULTS

Within the first 6 months of life, there was a greater hazard ratio (HR) of hospitalization for common childhood illnesses among formula-fed infants (HR 1.40; 95% CI 1.35-1.45) and mixed-fed infants (HR 1.18; 95% CI 1.11-1.25) compared with infants exclusively breastfed after adjustment for parental, maternal, and infant health characteristics. Within the first year of life and beyond, a greater relative risk of hospitalization was observed among formula-fed infants for a range of individual illnesses reported in childhood including gastrointestinal, respiratory, and urinary tract infections, otitis media, fever, asthma, diabetes, and dental caries.

CONCLUSIONS

Using linked administrative data, we found greater risks of hospitalization in early childhood for a range of common childhood illnesses among Scottish infants who were not exclusively breastfed at 6-8 weeks of age.

Determinação de um ponto de corte para a identificação de pares verdadeiros pelo método probabilístico de linkage de base de dados

O objetivo deste estudo foi propor pontos de corte nos escores calculados no processo de linkage probabilístico, para as diversas topografias de câncer. Neste estudo foi utilizada a base de dados do RCBP-SP, composta por 343.306 casos incidentes de câncer do município de São Paulo, registrados no período de 1997 a 2005, com idades que variaram de menos um a 106 anos, de ambos os sexos. Para o linkage probabilístico, realizado no programa Reclink III, foram utilizadas a base de dados do PRO-AIM e APAC-SIA/SUS. Foram calculados os valores da área sob a curva, sensibilidade e especificidade para determinar o ponto de corte do escore de maior precisão na identificação dos pares verdadeiros. Na análise das topografias, verificou-se que o ponto de corte no escore 18 apresentou boa acurácia, com valores de sensibilidade que variaram de 73,7 a 96,7% e de especificidade de 98,5 a 99,4%. Conclui-se que, acima do escore 18 encontravam-se quase a totalidade dos pares verdadeiros, enquanto que abaixo deste, menos de 1% dos registros vinculados eram verdadeiros.

Assessing the representativeness of population-sampled health surveys through linkage to administrative data on alcohol-related outcomes

Health surveys are an important resource for monitoring population health, but selective nonresponse may impede valid inference. This study aimed to assess nonresponse bias in a population-sampled health survey in Scotland, with a focus on alcohol-related outcomes. Nonresponse bias was assessed by examining whether rates of alcohol-related harm (i.e., hospitalization or death) and all-cause mortality among respondents to the Scottish Health Surveys (from 1995 to 2010) were equivalent to those in the general population, and whether the extent of any bias varied according to sociodemographic attributes or over time. Data from consenting respondents (aged 20–64 years) to 6 Scottish Health Surveys were confidentially linked to death and hospitalization records and compared with general population counterparts. Directly age-standardized incidence rates of alcohol-related harm and all-cause mortality were lower among Scottish Health Survey respondents compared with the general population. For all years combined, the survey-to-population rate ratios were 0.69 (95% confidence interval: 0.61, 0.76) for the incidence of alcohol-related harm and 0.89 (95% confidence interval: 0.83, 0.96) for all-cause mortality. Bias was more pronounced among persons residing in more deprived areas; limited evidence was found for regional or temporal variation. This suggests that corresponding underestimation of population rates of alcohol consumption is likely to be socially patterned.

Treatment patterns among colorectal cancer patients in South Australia: a demonstration of the utility of population-based data linkage

RATIONALE, AIMS AND OBJECTIVES

Population level data on colorectal cancer (CRC) management in Australia are lacking. This study assessed broad level patterns of care and concordance with guidelines for CRC management at the population level using linked administrative data from both the private and public health sectors across South Australia. Disparities in CRC treatment were also explored.

METHOD

Linking information from the South Australian Cancer Registry, hospital separations, radiotherapy services and hospital-based cancer registry systems provided data on the socio-demographic, clinical and treatment characteristics for 4641 CRC patients, aged 50-79 years, diagnosed from 2003 to 2008. Factors associated with receiving site/stage-specific treatments (surgery, chemotherapy and radiotherapy) and overall concordance with treatment guidelines were identified using Poisson regression analysis.

RESULTS

About 83% of colon and 56% of rectal cancer patients received recommended treatment. Provision of neo-adjuvant/adjuvant therapies may be less than optimal. Radiotherapy was less likely among older patients (prevalence ratio 0.7, 95% confidence interval 0.5-0.8). Chemotherapy was less likely among older patients (0.7, 0.6-0.8), those with severe or multiple co-morbidities (0.8, 0.7-0.9), and those from rural areas (0.9, 0.8-1.0). Overall discordance with treatment guidelines was more likely among rectal cancer patients (3.0, 2.7-3.3), older patients (1.6, 1.4-1.8), those with multiple co-morbid conditions (1.3, 1.1-1.4), and those living in rural areas (1.2, 1.0-1.3).

CONCLUSIONS

Greater emphasis should be given to ensure CRC patients who may benefit from neo-adjuvant/adjuvant therapies have access to these treatments.

Informing the 'early years' agenda in Scotland: understanding infant feeding patterns using linked datasets

BACKGROUND

Providing infants with the 'best possible start in life' is a priority for the Scottish Government. This is reflected in policy and health promotion strategies to increase breast feeding, which gives the best source of nutrients for healthy infant growth and development. However, the rate of breast feeding in Scotland remains one of the lowest in Europe. Information is needed to provide a better understanding of infant feeding and its impact on child health. This paper describes the development of a unique population-wide resource created to explore infant feeding and child health in Scotland.

METHODS

Descriptive and multivariate analyses of linked routine/administrative maternal and infant health records for 731,595 infants born in Scotland between 1997 and 2009.

RESULTS

A linked dataset was created containing a wide range of background, parental, maternal, birth and health service characteristics for a representative sample of infants born in Scotland over the study period. There was high coverage and completeness of infant feeding and other demographic, maternal and infant records. The results confirmed the importance of an enabling environment--cultural, family, health service and other maternal and infant health-related factors--in increasing the likelihood to breast feed.

CONCLUSIONS

Using the linked dataset, it was possible to investigate the determinants of breast feeding for a representative sample of Scottish infants born between 1997 and 2009. The linked dataset is an important resource that has potential uses in research, policy design and targeting intervention programmes.

Early death in those previously hospitalised for mental healthcare in Scotland: a nationwide cohort study, 1986-2010

OBJECTIVES

To compare the mortality in those previously hospitalised for mental disorder in Scotland to that experienced by the general population.

DESIGN

Population-based historical cohort study using routinely available psychiatric hospital discharge and death records.

SETTING

All Scotland.

PARTICIPANTS

Individuals with a first hospital admission for mental disorder between 1986 and 2009 who had died by 31 December 2010 (34 243 individuals).

OUTCOMES

The main outcome measure was death from any cause, 1986-2010. Excess mortality was presented as standardised mortality ratios (SMRs) and years of life lost (YLL). Excess mortality was assessed overall and by age, sex, main psychiatric diagnosis, whether the psychiatric diagnosis was 'complicated' (ie, additional mental or physical ill-health diagnoses present), cause of death and time period of first admission.

RESULTS

111 504 people were included in the study, and 34 243 had died by 31 December 2010. The average reduction in life expectancy for the whole cohort was 17 years, with eating disorders (39-year reduction) and 'complicated' personality disorders (27.5-year reduction) being worst affected. 'Natural' causes of death such as cardiovascular disease showed modestly elevated relative risk (SMR1.7), but accounted for 67% of all deaths and 54% of the total burden of YLL. Non-natural deaths such as suicide showed higher relative risk (SMR5.2) and tended to occur at a younger age, but were less common overall (11% of all deaths and 22% of all YLL). Having a 'complicated' diagnosis tended to elevate the risk of early death. No worsening of the overall excess mortality experienced by individuals with previous psychiatric admission over time was observed.

CONCLUSIONS

Early death for those hospitalised with mental disorder is common, and represents a significant inequality even in well-developed healthcare systems. Prevention of suicide and cardiovascular disease deserves particular attention in the mentally disordered.