Accuracy of death certification and hospital record linkage for identification of incident stroke

Replacement of Saturated Fatty Acids from Meat by Dairy Sources in Relation to Incident Cardiovascular Disease: The European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk Study

BACKGROUND

Prospective observational data revealed lower cardiovascular disease (CVD) incidence with modeled replacement of saturated fatty acids (SFA) from total meat by total dairy, but it is unknown what the associations are of replacing SFA from types of meat by types of dairy with CVD incidence.

OBJECTIVES

This study aimed to investigate the associations of replacing SFA from total, red, processed, and poultry meat by SFA from total dairy, milk, cheese, and yogurt with the incidence of CVD.

METHODS

We analyzed longitudinal data from 21,841 participants of the European Prospective Investigation into Cancer and Nutrition-Norfolk study (56.4% female; age, 40-79 years). Dietary data were collected by food frequency questionnaires at baseline (1993-1997). Incident fatal or nonfatal CVD (n = 5902), coronary artery disease (CAD; n = 4215), stroke (total: n = 2544; ischemic: n = 1113; hemorrhagic: n = 449) were identified up to 2018. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression for the risk associated with replacement of 2.5% of energy from SFA from meat by dairy, adjusted for sociodemographic, lifestyle, energy, dietary, and cardiometabolic factors.

RESULTS

Replacing SFA from total meat by total dairy was associated with a lower CVD incidence (HR: 0.89; 95% CI: 0.82, 0.96) and CAD (HR: 0.88; 95% CI: 0.80, 0.96). Replacing SFA from processed meat by cheese was associated with lower CVD (HR: 0.77; 95% CI: 0.68, 0.88); CAD (HR: 0.77; 95% CI: 0.66, 0.90), and stroke (HR: 0.81; 95% CI: 0.67, 0.99). Similarly, replacing SFA from red meat by cheese was associated with lower CVD (HR: 0.86; 95% CI: 0.76, 0.97). Higher incidence of stroke was found with replacement of SFA from poultry by milk (HR: 2.06; 95% CI: 1.09, 3.89), yogurt (HR: 2.55; 95% CI: 1.27, 5.13), or cheese (HR: 1.96; 95% CI: 1.04, 3.70), but the CI were relatively large, owing to low, narrow range of poultry SFA intake.

CONCLUSIONS

Findings indicate that different SFA-rich foods at baseline have differential associations with CVD risk. If confirmed by further studies, these findings could be used to inform specific food-based dietary guidance.

Sex-specific lifetime risk of cardiovascular events: the European Prospective Investigation into Cancer-Norfolk prospective population cohort study

AIMS

Better understanding of sex differences in cardiovascular disease (CVD) is essential in tailoring appropriate preventative strategies. Using a large population-based study with follow-up >25 years, we aimed to determine sex-specific lifetime risks of incident CVD and cardiovascular (CV) mortality amongst populations with and without prevalent CVD.

METHODS AND RESULTS

Participants were drawn from the European Prospective Investigation into Cancer-Norfolk and followed up for a median of 26.2 years. Sex-specific lifetime risks were ascertained accounting for the competing risk of death. Models were adjusted for ethnicity and time-updated covariates: material deprivation, CV risk factors, lifestyle factors, comorbidities, and medication. A total of 23 859 participants [54.5% women; mean age (standard deviation) 59.2 (9.3) years at baseline] were included. Adjusted lifetime risks of incident CVD were higher in men than in women (69.1 vs. 57.7% at age 75): cause-specific hazard ratio (cHR) (99% confidence interval)-1.49 (1.41-1.57), while the risks of CV mortality at age 75 were 4.4% (men) and 3.1% (women): cHR-1.42 (1.31-1.54). Myocardial infarction was the predominant first presentation in men until the eighth decade. In women, the first CVD manifestations after their sixth decade were predominantly atrial fibrillation and stroke. The male-associated excess relative risks of incident CVD and CV mortality were halved in people with prevalent CVD.

CONCLUSION

We characterized the sex-specific lifetime CV risks in a large cohort. Men had substantially higher risk of incident CVD and CV mortality than women, which was attenuated amongst people with prevalent CVD. Our findings provide an evidence base for sex-specific CV prevention.

Haemoglobin levels as a predictor for the occurrence of future cardiovascular events in adults-Sex-dependent results from the EPIC trial

BACKGROUND

The impact of hemoglobin levels on the occurrence of future health events remains equivocal. Due to its integral role in human hemostasis, both, high and low hemoglobin levels may play a significant role in the development of future cardiovascular (CV) events in otherwise healthy adults.

METHODS

Data from the European Prospective Investigation into Cancer (EPIC)-InterAct cohort was analyzed. In 13.648 individuals, physical activity, body mass index, family history of cardiovascular events, kidney function, smoking status, blood pressure and LDL levels were modelled to concomitant hemoglobin levels and correlated to the occurrence of clinically-overt cardiovascular events and death over a 21-year period. (Sex specific) cox regression analysis were used to develop hazard ratios (HRs) for CV events and all-cause mortality.

RESULTS

Anemia (hemoglobin (HGB) levels < 13.0 g/dl in men and < 12.0 g/dl in non-pregnant women) were associated with an increased all-cause mortality in men but not in women (HR anemia in men 1.4 (1.2; 1.6)) p=<0.0001).This was particularly visible with increasing age. Various sex specific Cox regression models, accounting for several CV risk factors confirmed these results. The incidence of future CV events and myocardial infarction was significantly influenced by underlying HGB levels in men with increasing age but not in women.

CONCLUSION

The influence of HGB levels on future cardiovascular events is sex-dependent. In men, presenting with anemia at baseline, the overall survival probability was impaired with increasing age. After adjusting for several CV risk factors, abnormal hemoglobin levels could be identified as a risk factor for the development of clinically-apparent future CV events in men. None of these effects were observed in women.

Long Term Prognostic Impact of Sex-specific Longitudinal Changes in Blood Pressure. The EPIC-Norfolk Prospective Population Cohort Study

AIMS

We aimed to determine the sex differences in longitudinal systolic and diastolic blood pressure (SBP and DBP) trajectories in mid-life and delineate the associations between these and mortality (all-cause, cardiovascular, and non-cardiovascular) and incident cardiovascular disease (CVD) in old age.

METHODS AND RESULTS

Participants were selected from the European Prospective Investigation into Cancer, Norfolk (EPIC-Norfolk) cohort study. Sex-specific trajectories were determined using group-based trajectory models using three clinic BP measurements acquired between 1993 and 2012 (mean exposure ∼12.9 years). Multivariable Cox regressions determined the associations between trajectories and incident outcomes over the follow-up (median follow-up 9.4 years). A total of 2897 men (M) and 3819 women (F) were included. At baseline, women were younger (F-55.5, M-57.1), had a worse cardiometabolic profile and were less likely to receive primary CVD prevention including antihypertensive treatment (F-36.0%, M-42.0%). Over the exposure period, women had lower SBP trajectories while men exhibited more pronounced SBP decreases over this period. Over the follow-up period, women had lower mortality (F-11.9%, M-20.5%) and CVD incidence (F-19.8%, M-29.6%). Compared to optimal SBP (≤120 mmHg) and DBP (≤70 mmHg) trajectories, hypertensive trajectories were associated with increased mortality and incident CVD in both men and women during follow-up at univariable level. These associations were nevertheless not maintained upon extensive confounder adjustment including antihypertensive therapies.

CONCLUSION

We report sex disparities in CVD prevention which may relate to worse cardiometabolic profiles and less pronounced longitudinal SBP decreases in women. Effective anti-hypertensivetherapy may offset the adverse outcomes associated with prolonged exposure to high blood pressure.

Calcium intake, calcium supplementation and cardiovascular disease and mortality in the British population: EPIC-norfolk prospective cohort study and meta-analysis

The role of dietary calcium in cardiovascular disease prevention is unclear. We aimed to determine the association between calcium intake and incident cardiovascular disease and mortality. Data were extracted from the European Prospective Investigation of Cancer, Norfolk (EPIC-Norfolk). Multivariable Cox regressions analysed associations between calcium intake (dietary and supplemental) and cardiovascular disease (myocardial infarction, stroke, heart failure, aortic stenosis, peripheral vascular disease) and mortality (cardiovascular and all-cause). The results of this study were pooled with those from published prospective cohort studies in a meta-analsyis, stratifying by average calcium intake using a 700 mg/day threshold. A total of 17,968 participants aged 40-79 years were followed up for a median of 20.36 years (20.32-20.38). Compared to the first quintile of calcium intake (< 770 mg/day), intakes between 771 and 926 mg/day (second quintile) and 1074-1254 mg/day (fourth quintile) were associated with reduced all-cause mortality (HR 0.91 (0.83-0.99) and 0.85 (0.77-0.93), respectively) and cardiovascular mortality [HR 0.95 (0.87-1.04) and 0.93 (0.83-1.04)]. Compared to the first quintile of calcium intake, second, third, fourth, but not fifth quintiles were associated with fewer incident strokes: respective HR 0.84 (0.72-0.97), 0.83 (0.71-0.97), 0.78 (0.66-0.92) and 0.95 (0.78-1.15). The meta-analysis results suggest that high levels of calcium intake were associated with decreased all-cause mortality, but not cardiovascular mortality, regardless of average calcium intake. Calcium supplementation was associated with cardiovascular and all-cause mortality amongst women, but not men. Moderate dietary calcium intake may protect against cardiovascular and all-cause mortality and incident stroke. Calcium supplementation may reduce mortality in women.

The relationship between alcohol intake and falls hospitalization: Results from the EPIC-Norfolk

AIM

To evaluate the relationship between habitual alcohol consumption and the risk of falls hospitalization.

METHODS

The EPIC-Norfolk is a prospective population-based cohort study in Norfolk, UK. In total, 25 637 community dwelling adults aged 40-79 years were recruited. Units of alcohol consumed per week were measured using a validated Food Frequency Questionnaire. The main outcome was the first hospital admission following a fall.

RESULTS

Over a median follow-up period of 11.5 years (299 211 total person years), the cumulative incidence function (95% confidence interval) of hospitalized falls at 121-180 months for non-users, light (>0 to ≤7 units/week), moderate (>7 to ≤28 units/week) and heavy (>28 units/week) were 11.08 (9.94-12.35), 7.53 (7.02-8.08), 5.91 (5.29-6.59) and 8.20 (6.35-10.56), respectively. Moderate alcohol consumption was independently associated with a reduced risk of falls hospitalization after adjustment for most major confounders (hazard ratio = 0.88; 95% confidence interval 0.79-0.99). The relationship between light alcohol consumption and falls hospitalization was attenuated by gender differences. Alcohol intake higher than the recommended threshold of 28 units/week was associated with an increased risk of falls hospitalization (hazard ratio 1.40 [1.14-1.73]).

CONCLUSIONS

Moderate alcohol consumption appears to be associated with a reduced risk of falls hospitalization, and intake above the recommended limit is associated with an increased risk. This provides incentive to limit alcohol consumption within the recommended range and has important implications for public health policies for aging populations. Geriatr Gerontol Int 2021; 21: 657-663.

Long-term effects of gestational diabetes on bone mineral density and fracture risk: Analysis of the Norfolk cohort of the European Prospective Investigation into Cancer (EPIC-Norfolk) population-based study

OBJECTIVES

Gestational diabetes mellitus (GDM) is a common pregnancy complication. This study aims to investigate the association between a history of GDM and bone mineral density (BMD), fractures, and falls in later life.

STUDY DESIGN

We used data from the Norfolk cohort of the European Prospective Investigation into Cancer (EPIC-Norfolk) where BMD at calcaneum was measured at second health check (1997-2000) using broadband ultrasound attenuation (BUA) and velocity of sound (VOS) in 7,515 women. Fractures and falls were documented from hospital admissions data via linkage with ENCORE (East Norfolk Commission Record) and history of GDM from health questionnaires at baseline. We examined the relationship between GDM and BUA/VOS using linear regression. Cox regression was used to estimate hazard ratios (HRs) for incident fractures and falls, controlling for age, BMI, smoking status, physical activity, area deprivation, self-reported stroke, use of diuretics, calcium and vitamin D supplements, social class and education, statin and total blood cholesterol, prevalent diabetes, hormone therapy and menopausal status.

RESULTS

History of GDM (n = 183) was not statistically significantly associated with BUA/VOS in fully adjusted linear regression models with unstandardised beta coefficients (standard error): -0.37 (1.40) and -5.41 (3.48). GDM was significantly (p < 0.05) associated with risk of hip and all fractures, fully adjusted HRs(95 %CI) 2.46(1.54-3.92) and 1.60(1.09-2.35), respectively. Median follow-up from first live birth to date of admission was 53 and 52 years, respectively.

CONCLUSION

There was an association between history of GDM and risk of any fracture as well as hip fracture specifically. Further research is required to confirm this.

Plasma Sulfur Amino Acids and Risk of Cerebrovascular Diseases: A Nested Case-Control Study in the EPIC-Norfolk Cohort

BACKGROUND AND PURPOSE

B-vitamin supplements lower circulating concentrations of homocysteine and may reduce stroke incidence. Homocysteine concentrations are associated with the incidence of stroke but other sulfur-containing compounds in the related metabolic pathway have not yet been investigated for an association with incident cerebrovascular diseases.

METHODS

Nested within the EPIC (European Prospective Investigation Into Cancer and Nutrition)-Norfolk cohort, we established a case-control study with 480 incident cases of cerebrovascular diseases and 480 controls matched by age, sex, and year of baseline examination (1993-1997). Using baseline plasma samples, we assayed sulfur-containing compounds including methionine, homocysteine, cystathionine, cysteine, glutathione, and taurine with liquid chromatography-tandem mass spectrometry. We examined the association of concentrations of each of the compounds and the ratio of methionine to homocysteine (representing activity of one-carbon metabolism) with risk of incident cerebrovascular diseases, adjusted for potential confounders.

RESULTS

Plasma methionine and the methionine/homocysteine ratio were inversely associated with risk of cerebrovascular diseases, with odds ratios per 1 SD of 0.83 (95% CI, 0.72-0.96) and 0.82 (95% CI, 0.71-0.95), respectively. The association of methionine remained significant after adjustment for homocysteine. None of the other examined compounds was significantly associated with incident cerebrovascular diseases.

CONCLUSIONS

These findings suggest that greater availability of methionine, an essential amino acid, may play a role in the prevention of cerebrovascular diseases and explain the previously recognized link between elevated homocysteine and stroke. Further research is needed to determine causation and the potential of circulating methionine as a target in cerebrovascular disease prevention.

Biomarker-estimated flavan-3-ol intake is associated with lower blood pressure in cross-sectional analysis in EPIC Norfolk

Flavan-3-ols are a group of bioactive compounds that have been shown to improve vascular function in intervention studies. They are therefore of great interest for the development of dietary recommendation for the prevention of cardio-vascular diseases. However, there are currently no reliable data from observational studies, as the high variability in the flavan-3-ol content of food makes it difficult to estimate actual intake without nutritional biomarkers. In this study, we investigated cross-sectional associations between biomarker-estimated flavan-3-ol intake and blood pressure and other CVD risk markers, as well as longitudinal associations with CVD risk in 25,618 participants of the European Prospective Investigation into Cancer (EPIC) Norfolk cohort. High flavan-3-ol intake, achievable as part of an habitual diet, was associated with a significantly lower systolic blood pressure (- 1.9 (- 2.7; - 1.1) mmHg in men and - 2.5 (- 3.3; - 1.8) mmHg in women; lowest vs highest decile of biomarker), comparable to adherence to a Mediterranean Diet or moderate salt reduction. Subgroup analyses showed that hypertensive participants had stronger inverse association between flavan-3-ol biomarker and systolic blood pressure when compared to normotensive participants. Flavanol intake could therefore have a role in the maintenance of cardiovascular health on a population scale.

Use of Medications with Anticholinergic Properties and the Long-Term Risk of Hospitalization for Falls and Fractures in the EPIC-Norfolk Longitudinal Cohort Study

The consumption of medications with anticholinergic activity has been suggested to result in the adverse effects of mental confusion, visual disturbance, and muscle weakness, which may lead to falls. Existing published evidence linking anticholinergic drugs with falls, however, remains weak. This study was conducted to evaluate the relationship between anticholinergic cognitive burden (ACB) and the long-term risk of hospitalization with falls and fractures in a large population study. The dataset comprised information from 25,639 men and women (aged 40-79 years) recruited from 1993 to 1997 from Norfolk, United Kingdom into the European Prospective Investigation into Cancer (EPIC)-Norfolk study. The time to first hospital admission with a fall with or without fracture was obtained from the National Health Service hospital information system. Cox-proportional hazards analyses were conducted to adjust for confounders and competing risks. The fall hospitalization rate was 5.8% over a median follow-up of ~ 19.4 years. The unadjusted incidence rate ratio for the use of any drugs with anticholinergic properties was 1.79 (95% CI 1.66-1.93). The hazard ratios (95% CI) for ACB scores of 1, 2-3, and ≥ 4 compared with ACB = 0 for fall hospitalization were 1.20 (1.09-1.33), 1.42 (1.25-1.60), and 1.39 (1.21-1.60) after adjustment for age, gender, medical conditions, physical activity, and blood pressure. Medications with anticholinergic activity are associated with an increased risk of subsequent hospitalization with a fall over a 19-year follow-up period. The biological mechanisms underlying the long-term risk of hospitalization with a fall or fracture following baseline ACB exposure remains unclear and requires further evaluation.

Self-Reported Fatigue Predicts Incident Stroke in a General Population: EPIC-Norfolk Prospective Population-Based Study

Background and Purpose- Fatigue is a common symptom among stroke survivors and in general practice. However, the clinical significance of fatigue and its relationship to incident stroke is unclear. The aim of this study was to examine the relationship between self-reported fatigue and the incidence of stroke in a general population. Methods- This was a prospective, population-based study. The study population was 15 654 men and women aged 39 to 79 years recruited in 1993 to 1997 and followed till March 2016. Fatigue was assessed at 18 months after baseline using the vitality domain of the Short Form 36 questionnaire. Cox proportional hazard models were constructed to describe the prospective relationship between baseline fatigue and incident stroke adjusting for age, sex, systolic blood pressure, cholesterol, physical activity, smoking status, alcohol consumption, fruit and vegetable consumption, diabetes mellitus, body mass index, vitamin supplement use, education level, Townsend deprivation index, and occupational social class. Incident stroke was ascertained using death certificates and hospital record linkage data. Results- Through 249 248 person-years of follow-up, 1509 incident strokes occurred. Participants who reported the highest level of fatigue (quartile 4) were more likely to be women, to be multimorbid, and to perceive their health as fair or poor. We observed ≈50% relative risk increase in stroke risk (hazard ratio, 1.49 [95% CI, 1.29-1.71]) in those who reported the highest level of fatigue compared with those who reported the lowest level of fatigue (Q4 versus Q1). This relationship remained unaltered regardless of anemia status, the presence or absence of chronic bronchitis, thyroid dysfunction, or depression. Conclusions- Self-report fatigue assessed by the vitality domain of the Short Form 36 questionnaire predicts the risk of future stroke at the general population level. Identifying and addressing stroke risk factors in those who report fatigue in general practice may have substantial benefit at the population level.

Plasma vitamin C concentrations and risk of incident respiratory diseases and mortality in the European Prospective Investigation into Cancer-Norfolk population-based cohort study

BACKGROUND/OBJECTIVES

Cancerous and non-cancerous respiratory diseases are common and contribute significantly to global disease burden. We aim to quantify the association between plasma vitamin C concentrations as an indicator of high fruit and vegetable consumption and the risk of incident respiratory diseases and associated mortality in a general population.

SUBJECTS/METHODS

Nineteen thousand three hundred and fifty-seven men and women aged 40-79 years without prevalent respiratory diseases at the baseline (1993-1997) and participating in the European Prospective Investigation into Cancer (EPIC)-Norfolk study in the United Kingdom were followed through March 2015 for both incidence and mortality from respiratory diseases.

RESULTS

There were a total of 3914 incident events and 407 deaths due to any respiratory diseases (excluding lung cancers), 367 incident lung cancers and 280 lung cancer deaths during the follow-up (total person-years >300,000 years). Cox's proportional hazards models showed that persons in the top quartiles of baseline plasma vitamin C concentrations had a 43% lower risk of lung cancer (hazard ratio (HR) 0.57; 95% confidence interval (CI): 0.41-0.81) than did those in the bottom quartile, independently of potential confounders. The results are similar for any non-cancerous respiratory diseases (HR 0.85; 0.77-0.95), including chronic respiratory diseases (HR 0.81; 0.69-0.96) and pneumonia (HR 0.70; 0.59-0.83). The corresponding values for mortality were 0.54 (0.35-0.81), 0.81 (0.59-1.12), 0.85 (0.44-1.66) and 0.61 (0.37-1.01), respectively. Confining analyses to non-smokers showed 42% and 53% risk reduction of non-smoking-related lung cancer incidence and death.

CONCLUSIONS

Higher levels of vitamin C concentrations as a marker of high fruit and vegetable consumption reduces the risk of cancerous and non-cancerous respiratory illnesses including non-smoking-related cancer incidence and deaths.

Temporal trends in the accuracy of hospital diagnostic coding for identifying acute stroke: A population-based study

Introduction

Administrative hospital diagnostic coding data are increasingly being used in identifying incident and prevalent stroke cases, for outcome audit and for 'big data' research. Validity of administrative coding has varied in previous studies, but little is known about the temporal trends of coding accuracy, which could bias analyses.

Patients and methods

Using all incident and recurrent strokes in a population-based cohort (Oxford Vascular Study/OXVASC) with multiple sources of ascertainment as the reference, we determined the temporal trends in sensitivity and positive predictive value of hospital diagnostic codes for identifying acute stroke from 2002 to 2017.

Results

Of 1883 hospitalised strokes, 1341 (71.2%) were correctly identified by coding. Sensitivity of coding improved over time for all strokes (p_trend = 0.005) and for incident cases (p_trend = 0.002). Of 1995 apparent stroke admissions identified by International Classification of Disease-10 stroke codes (I60-I68), 1588 (79.6%) used the stroke-specific codes (I60-I61/I63-I64). Positive predictive value was higher with the use of specific codes (83.2% vs. 69.2% for all codes) and highest if combined with the first admission only (88.5%), particularly during more recent time periods (2014-2017 = 90.3%). Of 2254 OXVASC incident strokes, 833 (37.0%) were not hospitalised. Sensitivity of coding increased over time for non-disabling stroke (p_trend = 0.001), but not for disabling/fatal stroke (p_trend = 0.40).

Conclusions

Although accuracy of hospital diagnostic coding for identifying acute strokes improved over the last 15 years, residual insensitivity supports linkage to other sources in large epidemiological studies. Moreover, differences in the time trends of coding sensitivity in relation to stroke severity might bias studies of trends in stroke outcome if only administrative coding is used.

Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: results from the prospective EPIC-Oxford study

OBJECTIVE

To examine the associations of vegetarianism with risks of ischaemic heart disease and stroke.

DESIGN

Prospective cohort study.

SETTING

The EPIC-Oxford study, a cohort in the United Kingdom with a large proportion of non-meat eaters, recruited across the country between 1993 and 2001.

PARTICIPANTS

48 188 participants with no history of ischaemic heart disease, stroke, or angina (or cardiovascular disease) were classified into three distinct diet groups: meat eaters (participants who consumed meat, regardless of whether they consumed fish, dairy, or eggs; n=24 428), fish eaters (consumed fish but no meat; n=7506), and vegetarians including vegans (n=16 254), based on dietary information collected at baseline, and subsequently around 2010 (n=28 364).

MAIN OUTCOME MEASURES

Incident cases of ischaemic heart disease and stroke (including ischaemic and haemorrhagic types) identified through record linkage until 2016.

RESULTS

Over 18.1 years of follow-up, 2820 cases of ischaemic heart disease and 1072 cases of total stroke (519 ischaemic stroke and 300 haemorrhagic stroke) were recorded. After adjusting for sociodemographic and lifestyle confounders, fish eaters and vegetarians had 13% (hazard ratio 0.87, 95% confidence interval 0.77 to 0.99) and 22% (0.78, 0.70 to 0.87) lower rates of ischaemic heart disease than meat eaters, respectively (P<0.001 for heterogeneity). This difference was equivalent to 10 fewer cases of ischaemic heart disease (95% confidence interval 6.7 to 13.1 fewer) in vegetarians than in meat eaters per 1000 population over 10 years. The associations for ischaemic heart disease were partly attenuated after adjustment for self reported high blood cholesterol, high blood pressure, diabetes, and body mass index (hazard ratio 0.90, 95% confidence interval 0.81 to 1.00 in vegetarians with all adjustments). By contrast, vegetarians had 20% higher rates of total stroke (hazard ratio 1.20, 95% confidence interval 1.02 to 1.40) than meat eaters, equivalent to three more cases of total stroke (95% confidence interval 0.8 to 5.4 more) per 1000 population over 10 years, mostly due to a higher rate of haemorrhagic stroke. The associations for stroke did not attenuate after further adjustment of disease risk factors.

CONCLUSIONS

In this prospective cohort in the UK, fish eaters and vegetarians had lower rates of ischaemic heart disease than meat eaters, although vegetarians had higher rates of haemorrhagic and total stroke.

Baseline anticholinergic burden from medications predicts incident fatal and non-fatal stroke in the EPIC-Norfolk general population

Background

Stroke is primarily a disease of older age, with a substantial impact on global mortality and morbidity. Medications with anticholinergic effects are widely used, but no studies have been conducted to examine the relationship between anticholinergic burden (ACB) and stroke in a general population.

Method

The sample was drawn from the EPIC-Norfolk cohort. Baseline assessments were carried out during 1993-97 and participants were followed up until March 2016. Participants were divided into four groups according to their total ACB score at baseline; these groups were those with a total ACB score of 0, 1, 2-3 and >3. After exclusion, Cox proportional hazards models were constructed to determine the associations between the ACB score groups and the risk of incident stroke and stroke mortality. Sensitivity analysis and propensity score matched analyses were performed.

Results

In total 25 639 participants attended the first health check; 3917 participants were excluded, leaving 21 722 participants to be included. Participants had a mean age [standard deviation (SD)] of 58.9 (9.2) years (54.4% women). Of these, 2131 suffered incident stroke and 562 died from stroke. Mean follow-up was approximately 18 years for both outcomes. In the fully adjusted model, those with an ACB of >3 had 59% relative risk of incident stroke {hazard ratio [HR] [95% confidence interval (CI) 1.59 [1.34-1.89]} and 86% relative risk of stroke mortality [1.86 (1.37-2.53)] compared with those in ACB 0 category. Sensitivity analyses and propensity score matched analyses showed similar results.

Conclusions

Our results provide an incentive for the cautious use of medications with anticholinergic properties, to help reduce the global burden of stroke.

Changing causes of death for patients with chronic respiratory disease in England, 2005-2015

BACKGROUND

Chronic respiratory diseases (CRD) are common, are increasing in prevalence, and cause significant morbidity and mortality worldwide. However, we have limited knowledge on causes of death of patients with CRD in the general population.

OBJECTIVE

We evaluated mortality rates and causes of death over time in patients with CRD.

METHODS

We used linked primary care and mortality data to determine mortality rates and the most common causes of death in people with CRD (including asthma, bronchiectasis, COPD and interstitial lung diseases (ILD)) during 2005-2015 in England.

RESULTS

We identified 558 888 patients with CRD (451 830 asthma, 137 709 COPD, 19 374 bronchiectasis, 10 745 ILD). The age-standardised mortality rate of patients with CRD was 1607 per 100 000 persons (asthma=856, COPD=1503, ILD=2609, bronchiectasis=1463). CRD mortality was overall 54% higher than the general population. A third of patients with CRD died from respiratory-related causes. Respiratory-related mortality was constant, while cardiovascular-related mortality decreased significantly over time. COPD accounted for the majority of respiratory-related deaths (66% overall) in all patient groups except ILD.

CONCLUSIONS

Patients with CRD continue to experience substantial morbidity and mortality due to respiratory diseases. Disease-modifying intervention strategies are needed to improve outcomes for patients with CRD.

Mediterranean Diet Reduces Risk of Incident Stroke in a Population With Varying Cardiovascular Disease Risk Profiles

Background and Purpose—

Although some evidence has found that the Mediterranean diet (MD) is protective for stroke risk, few studies have investigated whether this relationship differs by sex or cardiovascular disease risk.

Methods—

We investigated the relationship between adherence to the MD score, estimated using 7-day dietary diaries and risk of incident stroke in an observational prospective population-based cohort study of 23 232 men and women (54.5% women) aged 40 to 77 years who participated in the European Prospective Investigation into Cancer study in Norfolk, United Kingdom. Risk of incident stroke was calculated using multivariable Cox regression, in the whole population, and also stratified by sex and cardiovascular disease risk profile, using the Framingham risk score.

Results—

During 17.0 years of follow-up (395 048 total person-years), 2009 incident strokes occurred. Risk of stroke was significantly reduced with greater adherence to the MD score (quartile 4 versus quartile 1 hazard ratio [HR], 0.83; 95% CI, 0.74-0.94; P-trend <0.01) in the whole population and in women (quartile 4 versus quartile 1 HR, 0.78; 95% CI, 0.65, 0.93; P-trend <0.01) but not in men (quartile 4 versus quartile 1 HR, 0.94; 95% CI, 0.79-1.12; P-trend =0.55). There was reduced risk of stroke in those at high risk of cardiovascular disease and across categories of the MD score (quartile 4 versus quartile 1 HR, 0.87; 95% CI, 0.76-0.99; P-trend =0.04). However, this was driven by the associations in women (quartile 4 versus quartile 1 HR, 0.80; 95% CI, 0.65-0.97; P-trend =0.02).

Conclusions—

Greater adherence to the MD was associated with lower risk of stroke in a UK white population. For the first time in the literature, we also investigated the associations between the MD score in those at both low and high risk of cardiovascular disease. Although the findings in our study were driven by the associations in women, they have implications for the general public and clinicians for prevention of stroke.

Effect of Antiplatelet Therapy (Aspirin + Dipyridamole Versus Clopidogrel) on Mortality Outcome in Ischemic Stroke

The optimal regimen of antiplatelet therapy for secondary prevention in noncardioembolic ischemic stroke remains controversial. We aimed to determine which regimen was associated with the greatest reduction in adverse outcomes. We analysed prospectively collected data from the Norfolk and Norwich University Hospital Stroke Register. The sample population consisted of 3,572 participants (mean age 74.96 ± 12.67) with ischemic stroke, who were consecutively admitted between 2003 and 2015. Patients were placed on one of three antiplatelet regimens at hospital discharge; aspirin monotherapy, aspirin plus dipyridamole and clopidogrel. Clopidogrel and aspirin plus dipyridamole were compared to aspirin. A direct comparison between clopidogrel and aspirin plus dipyridamole was also performed. Outcomes included all-cause mortality and a combined end point of all-cause mortality and incidence of major adverse cardiac events (stroke or myocardial infarction). Cox-regression models adjusted for potential confounders at the following time periods after discharge; 0 to 90 days, 91 to 365 days, and 1 to 3 years. Aspirin plus dipyridamole was associated with a lower risk of mortality at 0 to 90 days; hazard ratio (HR) 0.62 (0.43 to 0.91). Clopidogrel was associated with a lower risk of mortality at 1 to 3 years; HR of 0.39 (0.26 to 0.60). Similar HRs were observed for the corresponding time points in the composite outcome. In conclusion, patients with noncardioembolic stroke may gain maximum benefits from aspirin plus dipyridamole initially (≤1 year) with a subsequent switch to clopidogrel, with regard to mortality and major adverse cardiac eventsoutcomes.

Association Between Ischemic Stroke and Tumor Necrosis Factor Inhibitor Therapy in Patients With Rheumatoid Arthritis

Objective

Patients with rheumatoid arthritis (RA) are at an increased risk of ischemic stroke. Tumor necrosis factor inhibitors (TNFi) may influence risk and mortality after ischemic stroke by reducing inflammation. This study was undertaken to examine the association of TNFi with the risk of incident ischemic stroke and with 30‐day and 1‐year mortality after ischemic stroke.

Methods

Patients with RA starting therapy with TNFi and a biologics‐naive comparator group treated with synthetic disease‐modifying antirheumatic drugs (DMARDs) only were recruited to the British Society for Rheumatology Biologics Register for Rheumatoid Arthritis from 2001 to 2009. Patients were followed up via clinical and patient questionnaires as well as the national death register. Incident strokes were classified as ischemic if brain imaging reports suggested ischemia or if ischemic stroke was reported as the underlying cause of death on a death certificate. Patients with a previous stroke were excluded. Risk of ischemic stroke was compared between patients receiving synthetic DMARDs only and those ever‐exposed to TNFi using a Cox proportional hazards regression model adjusted for potential confounders. Mortality after ischemic stroke was compared between synthetic DMARD–treated patients and TNFi‐treated patients using logistic regression, adjusted for age and sex.

Results

To April 2010, 127 verified incident ischemic strokes (21 in 3,271 synthetic DMARD–treated patients and 106 in 11,642 TNFi‐treated patients) occurred during 11,973 and 61,226 person‐years of observation, respectively (incidence rate 175 versus 173 per 100,000 person‐years). After adjustment for confounders, there was no association between ever‐exposure to TNFi and ischemic stroke (hazard ratio 0.99 [95% confidence interval (95% CI) 0.54–1.81]). Mortality 30 days or 1 year after ischemic stroke was not associated with concurrent TNFi exposure (odds ratio 0.18 [95% CI 0.03–1.21] and 0.60 [95% CI 0.16–2.28], respectively).

Conclusion

Exposure to TNFi does not appear to influence the occurrence of ischemic stroke in the medium term in patients with RA. The impact on mortality after ischemic stroke remains inconclusive.

Prospective association of the Mediterranean diet with cardiovascular disease incidence and mortality and its population impact in a non-Mediterranean population: the EPIC-Norfolk study

BACKGROUND

Despite convincing evidence in the Mediterranean region, the cardiovascular benefit of the Mediterranean diet is not well established in non-Mediterranean countries and the optimal criteria for defining adherence are unclear. The population attributable fraction (PAF) of adherence to this diet is also unknown.

METHODS

In the UK-based EPIC-Norfolk prospective cohort, we evaluated habitual diets assessed at baseline (1993-1997) and during follow-up (1998-2000) using food-frequency questionnaires (n = 23,902). We estimated a Mediterranean diet score (MDS) using cut-points projected from the Mediterranean dietary pyramid, and also three other pre-existing MDSs. Using multivariable-adjusted Cox regression with repeated measures of MDS and covariates, we examined prospective associations between each MDS with incident cardiovascular diseases (CVD) by 2009 and mortality by 2013, and estimated PAF for each outcome attributable to low MDS.

RESULTS

We observed 7606 incident CVD events (2818/100,000 person-years) and 1714 CVD deaths (448/100,000). The MDS based on the Mediterranean dietary pyramid was significantly associated with lower incidence of the cardiovascular outcomes, with hazard ratios (95 % confidence intervals) of 0.95 (0.92-0.97) per one standard deviation for incident CVD and 0.91 (0.87-0.96) for CVD mortality. Associations were similar for composite incident ischaemic heart disease and all-cause mortality. Other pre-existing MDSs showed similar, but more modest associations. PAF due to low dietary pyramid based MDS (<95th percentile) was 3.9 % (1.3-6.5 %) for total incident CVD and 12.5 % (4.5-20.6 %) for CVD mortality.

CONCLUSIONS

Greater adherence to the Mediterranean diet was associated with lower CVD incidence and mortality in the UK. This diet has an important population health impact for the prevention of CVD.

Heterogeneous impact of classic atherosclerotic risk factors on different arterial territories: the EPIC-Norfolk prospective population study

AIMS

Particular atherosclerotic risk factors may differ in their association with atherosclerosis across vascular territories. Few studies have compared the associations between multiple risk factors and cardiovascular disease (CVD) manifestations in one population. We studied the strength of the associations between traditional risk factors including coronary artery disease (CAD), ischaemic and haemorrhagic stroke, abdominal aortic aneurysms (AAAs), and peripheral arterial disease (PAD).

METHODS AND RESULTS

This analysis included 21 798 participants of the EPIC-Norfolk population study, without previous CVD. Events were defined as hospitalization or mortality, coded using ICD-10. The associations between the risk factors, such as low-density lipoprotein cholesterol, systolic blood pressure (SBP), and smoking, and the various CVD manifestations were compared using competing risk analyses. During 12.1 years, 3087 CVD events were recorded. The associations significantly differed across CVD manifestations. Low-density lipoprotein cholesterol was strongly associated with CAD [adjusted hazard rate (aHR) highest vs. lowest quartile 1.63, 95% CI 1.44-1.86]. Systolic blood pressure was a strong risk factor for PAD (aHR highest vs. lowest quartile 2.95, 95% CI 1.78-4.89) and ischaemic stroke (aHR highest vs. lowest quartile 2.48, 95% CI 1.55-3.97), but not for AAA. Smoking was strongly associated with incident AAA (aHR current vs. never 7.66, 95% CI 4.50-13.04) and PAD (aHR current vs. never 4.66, 95% CI 3.29-6.61), but not with haemorrhagic stroke.

CONCLUSION

The heterogeneity in the risk factor-CVD associations supports the concept of pathophysiological differences between atherosclerotic CVD manifestations and could have implications for CVD prevention.

Accuracy of Electronic Health Record Data for Identifying Stroke Cases in Large-Scale Epidemiological Studies: A Systematic Review from the UK Biobank Stroke Outcomes Group

Objective

Long-term follow-up of population-based prospective studies is often achieved through linkages to coded regional or national health care data. Our knowledge of the accuracy of such data is incomplete. To inform methods for identifying stroke cases in UK Biobank (a prospective study of 503,000 UK adults recruited in middle-age), we systematically evaluated the accuracy of these data for stroke and its main pathological types (ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage), determining the optimum codes for case identification.

Methods

We sought studies published from 1990-November 2013, which compared coded data from death certificates, hospital admissions or primary care with a reference standard for stroke or its pathological types. We extracted information on a range of study characteristics and assessed study quality with the Quality Assessment of Diagnostic Studies tool (QUADAS-2). To assess accuracy, we extracted data on positive predictive values (PPV) and—where available—on sensitivity, specificity, and negative predictive values (NPV).

Results

37 of 39 eligible studies assessed accuracy of International Classification of Diseases (ICD)-coded hospital or death certificate data. They varied widely in their settings, methods, reporting, quality, and in the choice and accuracy of codes. Although PPVs for stroke and its pathological types ranged from 6–97%, appropriately selected, stroke-specific codes (rather than broad cerebrovascular codes) consistently produced PPVs >70%, and in several studies >90%. The few studies with data on sensitivity, specificity and NPV showed higher sensitivity of hospital versus death certificate data for stroke, with specificity and NPV consistently >96%. Few studies assessed either primary care data or combinations of data sources.

Conclusions

Particular stroke-specific codes can yield high PPVs (>90%) for stroke/stroke types. Inclusion of primary care data and combining data sources should improve accuracy in large epidemiological studies, but there is limited published information about these strategies.

Validity of Diagnostic Codes for Acute Stroke in Administrative Databases: A Systematic Review

OBJECTIVE

To conduct a systematic review of studies reporting on the validity of International Classification of Diseases (ICD) codes for identifying stroke in administrative data.

METHODS

MEDLINE and EMBASE were searched (inception to February 2015) for studies: (a) Using administrative data to identify stroke; or (b) Evaluating the validity of stroke codes in administrative data; and (c) Reporting validation statistics (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), or Kappa scores) for stroke, or data sufficient for their calculation. Additional articles were located by hand search (up to February 2015) of original papers. Studies solely evaluating codes for transient ischaemic attack were excluded. Data were extracted by two independent reviewers; article quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool.

RESULTS

Seventy-seven studies published from 1976-2015 were included. The sensitivity of ICD-9 430-438/ICD-10 I60-I69 for any cerebrovascular disease was ≥ 82% in most [≥ 50%] studies, and specificity and NPV were both ≥ 95%. The PPV of these codes for any cerebrovascular disease was ≥ 81% in most studies, while the PPV specifically for acute stroke was ≤ 68%. In at least 50% of studies, PPVs were ≥ 93% for subarachnoid haemorrhage (ICD-9 430/ICD-10 I60), 89% for intracerebral haemorrhage (ICD-9 431/ICD-10 I61), and 82% for ischaemic stroke (ICD-9 434/ICD-10 I63 or ICD-9 434&436). For in-hospital deaths, sensitivity was 55%. For cerebrovascular disease or acute stroke as a cause-of-death on death certificates, sensitivity was ≤ 71% in most studies while PPV was ≥ 87%.

CONCLUSIONS

While most cases of prevalent cerebrovascular disease can be detected using 430-438/I60-I69 collectively, acute stroke must be defined using more specific codes. Most in-hospital deaths and death certificates with stroke as a cause-of-death correspond to true stroke deaths. Linking vital statistics and hospitalization data may improve the ascertainment of fatal stroke.

Associations between flavan-3-ol intake and CVD risk in the Norfolk cohort of the European Prospective Investigation into Cancer (EPIC-Norfolk)

Dietary intervention studies suggest that flavan-3-ol intake can improve vascular function and reduce the risk of cardiovascular diseases (CVD). However, results from prospective studies failed to show a consistent beneficial effect. Associations between flavan-3-ol intake and CVD risk in the Norfolk arm of the European Prospective Investigation into Cancer and Nutrition (EPIC-Norfolk) were investigated. Data were available from 24,885 (11,252 men; 13,633 women) participants, recruited between 1993 and 1997 into the EPIC-Norfolk study. Flavan-3-ol intake was assessed using 7-day food diaries and the FLAVIOLA Flavanol Food Composition database. Missing data for plasma cholesterol and vitamin C were imputed using multiple imputation. Associations between flavan-3-ol intake and blood pressure at baseline were determined using linear regression models. Associations with CVD risk were estimated using Cox regression analyses. Median intake of total flavan-3-ols was 1034mg/d (range: 0-8531mg/d) for men and 970mg/d (0-6695mg/d) for women, median intake of flavan-3-ol monomers was 233mg/d (0-3248mg/d) for men and 217 (0-2712mg/d) for women. There were no consistent associations between flavan-3-ol monomer intake and baseline systolic and diastolic blood pressure (BP). After 286,147 person-years of follow-up, there were 8463 cardiovascular events and 1987 CVD related deaths; no consistent association between flavan-3-ol intake and CVD risk (HR 0.93, 95% CI: 0.87; 1.00; Q1 vs Q5) or mortality was observed (HR 0.93, 95% CI: 0.84; 1.04). Flavan-3-ol intake in EPIC-Norfolk is not sufficient to achieve a statistically significant reduction in CVD risk.

The relationship between dietary magnesium intake, stroke and its major risk factors, blood pressure and cholesterol, in the EPIC-Norfolk cohort

BACKGROUND

Dietary magnesium could modify the major stroke risk factors, high blood pressure (BP) and cholesterol, but has been understudied in both sexes in a single population. This study aimed to investigate if dietary magnesium intake was associated with BP, total cholesterol (TC) and incident stroke risk in an adult population.

METHODS

We conducted cross-sectional analyses in a case-cohort study of 4443, men and women aged 40-75, representative of 25,639 participants years of the EPIC (European Prospective Investigation into Cancer)-Norfolk cohort. The cohort included 928 stroke cases (42,556.5 person years). Dietary data from 7 day food diaries were analysed using multivariate regression to assess associations between quintiles or data-derived categories of dietary magnesium intake and BP, TC and stroke risk, adjusted for relevant confounders.

RESULTS

We observed differences of -7 mmHg systolic BP (P trend ≤ 0.01) and -3.8 mmHg diastolic BP (P trend=0.01) between extreme intakes of magnesium in men, a significant inverse association with TC was observed (P trend=0.02 men and 0.04 women). Compared to the bottom 10%, the top 30% of magnesium intake was associated with a 41% relative reduction in stroke risk (HR 0.59; 95% CI 0.38-0.93) in men.

CONCLUSIONS

Lower dietary magnesium intake was associated with higher BP and stroke risk, which may have implications for primary prevention.

Total anticholinergic burden and risk of mortality and cardiovascular disease over 10 years in 21,636 middle-aged and older men and women of EPIC-Norfolk prospective population study

BACKGROUND

Studies have raised concerns that medications with anticholinergic property have potential adverse effects on health outcomes.

OBJECTIVES

The objective of this study is to examine the prospective relationships between total anticholinergic burden (ACB) from medications and mortality, and cardiovascular disease (CVD) in a general population.

DESIGN

Observational study.

SETTING

Community cohort.

SUBJECTS

We examined data collected from 21,636 men and women without cancer at the baseline who participated in a baseline survey 1993-97 in the European Prospective Investigation into Cancer (EPIC)-Norfolk. They were followed until 2009/11.

METHODS

We performed Cox-proportional hazards models to determine the associations between total ACB and the subsequent risk of all-cause mortality and incident CVD during the follow-up.

RESULTS

There were a total of 4,342 people died and 7,328 had an incident CVD during the study follow-up (total person years=322,321 years for mortality and 244,119 years for CVD event). Compared with people with no anticholinergic burden (ACB=0), people with total ACB≥3 from medications had hazards ratios of 1.83 (1.53, 2.20) and 2.17 (1.87, 2.52) for mortality and CVD incidence outcomes, respectively, after adjusting for potential confounders. Repeating the analyses after excluding people with prevalent illnesses, and events occurring within the first 2 years of follow-up, only slightly attenuated the results.

CONCLUSION

There appear to be a class effect as well as dose-response relationship between the ACB and both outcomes. Future research should focus on understanding the relationship between ACB and mortality, and cardiovascular disease and possibly minimising ACB load where feasible.

Tinned fruit consumption and mortality in three prospective cohorts

Dietary recommendations to promote health include fresh, frozen and tinned fruit, but few studies have examined the health benefits of tinned fruit. We therefore studied the association between tinned fruit consumption and mortality. We followed up participants from three prospective cohorts in the United Kingdom: 22,421 participants from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk cohort (1993-2012), 52,625 participants from the EPIC-Oxford cohort (1993-2012), and 7440 participants from the Whitehall II cohort (1991-2012), all reporting no history of heart attack, stroke, or cancer when entering these studies. We estimated the association between frequency of tinned fruit consumption and all cause mortality (primary outcome measure) using Cox regression models within each cohort, and pooled hazard ratios across cohorts using random-effects meta-analysis. Tinned fruit consumption was assessed with validated food frequency questionnaires including specific questions about tinned fruit. During 1,305,330 person years of follow-up, 8857 deaths occurred. After adjustment for lifestyle factors and risk markers the pooled hazard ratios (95% confidence interval) of all cause mortality compared with the reference group of tinned fruit consumption less often than one serving per month were: 1.05 (0.99, 1.12) for one to three servings per month, 1.10 (1.03, 1.18) for one serving per week, and 1.13 (1.04, 1.23) for two or more servings per week. Analysis of cause-specific mortality showed that tinned fruit consumption was associated with mortality from cardiovascular causes and from non-cardiovascular, non-cancer causes. In a pooled analysis of three prospective cohorts from the United Kingdom self-reported tinned fruit consumption in the 1990s was weakly but positively associated with mortality during long-term follow-up. These findings raise questions about the evidence underlying dietary recommendations to promote tinned fruit consumption as part of a healthy diet.

Body fat percentage, body mass index and waist-to-hip ratio as predictors of mortality and cardiovascular disease

OBJECTIVE

To study the utility of body fat percentage in predicting health outcomes when other obesity indices are considered.

METHODS

We conducted a prospective cohort study to evaluate the independent utility of body fat percentage and other obesity indices in predicting mortality and cardiovascular disease (CVD).

RESULTS

We prospectively followed 15 062 European Prospective Investigation into Cancer (EPIC)-Norfolk participants who attended a health examination during 1997–2000 for all-cause mortality and incidence of CVD up to end of December 2011 and end of March 2009, respectively. During the follow-up, 2420 died and 4665 had incident CVD. After exclusion of prior stroke, myocardial infarction and cancer and adjusting for potential confounders, body mass index (BMI) and waist-to- hip ratio (WHR), the HR of mortality for men were 0.86 (0.68 to 1.09), 0.81 (0.61 to 1.07) and 0.76 (0.55 to 1.05) and for women were 0.91 (0.70 to 1.17), 0.75 (0.55 to 1.02) and 0.87 (0.61 to 1.23) for second, third and fourth quartile compared with the first (bottom) quartile of body fat percentage. The respective HRs for incident CVD were 0.99 (0.83 to 1.19), 0.85 (0.69 to 1.04) and 0.81 (0.64 to 1.03) for men and 0.98 (0.82 to 1.17), 0.89 (0.73 to 1.10) and 1.02 (0.81 to 1.29) for women. In contrast, higher BMI and WHR were associated with an increased risk of both outcomes and WHR appeared to have the best predictive value among three indices.

CONCLUSIONS

Once BMI and WHR are taken into account, fat percentage does not add to prediction of mortality or CVD in middle-aged and older-aged adults.

Assessing the reliability of causes of death reported by the Vital Registration System in Sri Lanka: medical records review in Colombo

Information on causes of death is critical for informed decision making in the health sector. This paper reports findings from a study that measured the accuracy of registered causes of death and quality of medical records for a sample of deaths occurring in hospitals in Colombo, Sri Lanka. Five physicians, trained in medical certification of cause of death, reconstructed death certificates for hospital deaths from medical records and assessed the quality of medical records for this purpose. The majority of medical records were found to be of average quality. Concordance between the underlying cause of death in the vital registration data and that from the 'gold standard' (medical records review) diagnosis was 41.4% (n=249). The sensitivity of all leading causes of death and positive predictive value were below 67%. Major misclassification errors were found in identifying deaths due to vascular diseases and diabetes mellitus. Certified causes of death in Sri Lanka are frequently incorrect, thus limiting their value for health policy and for monitoring progress towards development goals. Sri Lanka, and other countries at a similar level of statistical development, should consider periodically conducting research to evaluate the quality of cause of death reporting at both local and national levels.

Bone mineral density and incidence of stroke: European prospective investigation into cancer-norfolk population-based study, systematic review, and meta-analysis

BACKGROUND AND PURPOSE

The prospective link between osteoporosis and future risk of stroke requires evidence from large-scale population-based long-term studies.

METHODS

Calcaneum broadband ultrasound attenuation was measured in the Norfolk cohort of the European Prospective Investigation into Cancer-Norfolk between 1997 and 2000. Incident strokes were ascertained by hospital record linkage and death certificates in March 2009 and December 2011, respectively. A search of MEDLINE and EMBASE was performed to evaluate the relationship between bone mineral density and incident stroke. After data extraction of relevant studies, pooled risk of stroke was estimated using meta-analysis.

RESULTS

In 14 290 participants (mean follow-up of 9.3 years; total person-years 132 574), there were 599 incident strokes. Participants in the lowest 10% of the calcaneum broadband ultrasound attenuation distribution had an increased stroke risk (hazard ratio 1.41; 95% confidence intervals, 1.02-1.94) compared with those in the top 30% of the distribution after adjustments. A decrease of ~1 standard deviation in broadband ultrasound attenuation (20 db/MHz) was associated with a 17% increase in relative risk of stroke (95% confidence intervals, 5%-30%). Meta-analysis of 4 studies (25 760 participants, 1237 cases of stroke) found that for every decrease in 1 standard deviation in bone mineral density, there was an increased risk of incident stroke among women (pooled relative risk 1.22; 95% confidence intervals, 1.09-1.37; I2=0%, 3 studies) but not in men (pooled relative risk 1.05; 95% confidence intervals, 0.94-1.17; I(2)=0%, 2 studies).

CONCLUSIONS

Bone mineral density predicts total stroke risk. The evidence is stronger in women with regard to the continuous relationship.

Validation of a model to investigate the effects of modifying cardiovascular disease (CVD) risk factors on the burden of CVD: the rotterdam ischemic heart disease and stroke computer simulation (RISC) model

BACKGROUND

We developed a Monte Carlo Markov model designed to investigate the effects of modifying cardiovascular disease (CVD) risk factors on the burden of CVD. Internal, predictive, and external validity of the model have not yet been established.

METHODS

The Rotterdam Ischemic Heart Disease and Stroke Computer Simulation (RISC) model was developed using data covering 5 years of follow-up from the Rotterdam Study. To prove 1) internal and 2) predictive validity, the incidences of coronary heart disease (CHD), stroke, CVD death, and non-CVD death simulated by the model over a 13-year period were compared with those recorded for 3,478 participants in the Rotterdam Study with at least 13 years of follow-up. 3) External validity was verified using 10 years of follow-up data from the European Prospective Investigation of Cancer (EPIC)-Norfolk study of 25,492 participants, for whom CVD and non-CVD mortality was compared.

RESULTS

At year 5, the observed incidences (with simulated incidences in brackets) of CHD, stroke, and CVD and non-CVD mortality for the 3,478 Rotterdam Study participants were 5.30% (4.68%), 3.60% (3.23%), 4.70% (4.80%), and 7.50% (7.96%), respectively. At year 13, these percentages were 10.60% (10.91%), 9.90% (9.13%), 14.20% (15.12%), and 24.30% (23.42%). After recalibrating the model for the EPIC-Norfolk population, the 10-year observed (simulated) incidences of CVD and non-CVD mortality were 3.70% (4.95%) and 6.50% (6.29%). All observed incidences fell well within the 95% credibility intervals of the simulated incidences.

CONCLUSIONS

We have confirmed the internal, predictive, and external validity of the RISC model. These findings provide a basis for analyzing the effects of modifying cardiovascular disease risk factors on the burden of CVD with the RISC model.

The impact of under and over-recording of cancer on death certificates in a competing risks analysis: a simulation study

BACKGROUND

With linked register and cause of death data becoming more accessible than ever, competing risks methodology is being increasingly used as a way of obtaining "real world" probabilities of death broken down by specific causes. It is important, in terms of the validity of these studies, to have accurate cause of death information. However, it is well documented that cause of death information taken from death certificates is often lacking in accuracy and completeness.

METHODS

We assess through use of a simulation study the effect of under and over-recording of cancer on death certificates in a competing risks analysis consisting of three competing causes of death: cancer, heart disease and other causes. Using realistic levels of misclassification, we consider 24 scenarios and examine the bias in the cause-specific hazard ratios and the cumulative incidence function.

RESULTS

The bias in the cumulative incidence function was highest in the oldest age group reaching values as high as 2.6 percentage units for the "good" cancer prognosis scenario and 9.7 percentage units for the "poor" prognosis scenario.

CONCLUSION

The bias resulting from the chosen levels of misclassification in this study accentuate concerns that unreliable cause of death information may be providing misleading results. The results of this simulation study convey an important message to applied epidemiological researchers.

Validating self-reported strokes in a longitudinal UK cohort study (Whitehall II): Extracting information from hospital medical records versus the Hospital Episode Statistics database

BACKGROUND

Valuable information on the determinants of non-fatal stroke can be obtained from longitudinal observational cohort studies. Such studies often rely on self-reported stroke events, which are best validated with external medical evidence. The aim of this paper is to compare the information on incident non-fatal stroke events arising from different sources.

METHODS

We carried out a validation of self-reported stoke events among participants in the Whitehall II Study, a large UK based cohort study (baseline sample size 10,308 men and women).

RESULTS

106 stroke events were self-reported in three self-administered questionnaires between 2002 and 2009. Eight (7.5%) of these events were discarded as false positives after medical review, 66 were validated by information from the NHS Hospital Episode Statistics (HES) database in England, 16 by manual searches of hospital records alone, and 12 by letters from general practitioners alone. HES provided information on an additional (i.e. not self-reported) 47 events coded as stroke during the period 2002 to 2009 in hospitals in England among the original baseline participants. Of these, 43 participants were no longer active in the study and 4 had completed questionnaires but not reported a stroke event.

CONCLUSIONS

Validating self-reported strokes in cohort studies with information from the NHS HES database was efficient and provided information on probable non-fatal stroke events among cohort members no longer in active follow-up. Manual extraction from hospital notes can provide supplementary information beyond that available in the HES discharge summary and was used to sub-type some strokes. However, the process was labour intensive. Multiple sources are needed to capture maximum information on stroke events but increasingly with hospitalisation in the acute phase of stroke, HES has an important role. Further development of HES is required to assure validity and coverage.

Assessing quality of medical death certification: Concordance between gold standard diagnosis and underlying cause of death in selected Mexican hospitals

BACKGROUND

In Mexico, the vital registration system relies on information collected from death certificates to generate official mortality figures. Although the death certificate has high coverage across the country, there is little information regarding its validity. The objective of this study was to assess the concordance between the underlying cause of death in official statistics obtained from death certificates and a gold standard diagnosis of the same deaths derived from medical records of hospitals.

METHODS

The study sample consisted of 1,589 deaths that occurred in 34 public hospitals in the Federal District and the state of Morelos, Mexico in 2009. Neonatal, child, and adult cases were selected for causes of death that included infectious diseases, noncommunicable diseases, and injuries. We compared the underlying cause of death, obtained from medical death certificates, against a gold standard diagnosis derived from a review of medical records developed by the Population Health Metrics Research Consortium. We used chance-corrected concordance and accuracy as metrics to evaluate the quality of performance of the death certificate.

RESULTS

Analysis considering only the underlying cause of death resulted in a median chance-corrected concordance between the cause of death in medical death certificates versus the gold standard of 54.3% (95% uncertainty interval [UI]: 52.2, 55.6) for neonates, 38.5% (37.0, 40.0) for children, and 66.5% (65.9, 66.9) for adults. The accuracy resulting from the same analysis was 0.756 (0.747, 0.769) for neonates, 0.683 (0.663, 0.701) for children, and 0.780 (0.774, 0.785) for adults. Median chance-corrected concordance and accuracy increased when considering the mention of any cause of death in the death certificate, not just the underlying cause. Concordance varied substantially depending on cause of death, and accuracy varied depending on the true cause-specific mortality fraction composition.

CONCLUSIONS

Although we cannot generalize our conclusions to Mexico as a whole, the results demonstrate important problems with the quality of the main source of information for causes of death used by decision-makers in settings with highly technological vital registration systems. It is necessary to improve death certification procedures, especially in the case of child and neonatal deaths. This requires an important commitment from the health system and health institutions.

Agreement on cause of death between proxies, death certificates, and clinician adjudicators in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study

Death certificates may lack accuracy and misclassify the cause of death. The validity of proxy-reported cause of death is not well established. The authors examined death records on 336 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study, a national cohort study of 30,239 community-dwelling US adults (2003-2010). Trained experts used study data, medical records, death certificates, and proxy reports to adjudicate causes of death. The authors computed agreement on cause of death from the death certificate, proxy, and adjudication, as well as sensitivity and specificity for certain diseases. Adjudicated cause of death had a higher rate of agreement with proxy reports (73%; Cohen's kappa (κ) statistic = 0.69) than with death certificates (61%; κ = 0.54). The agreement between proxy reports and adjudicators was better than agreement with death certificates for all disease-specific causes of death. Using the adjudicator assessments as the "gold standard," for disease-specific causes of death, proxy reports had similar or higher specificity and higher sensitivity (sensitivity = 50%-89%) than death certificates (sensitivity = 31%-81%). Proxy reports may be more concordant with adjudicated causes of death than with the causes of death listed on death certificates. In many settings, proxy reports may represent a better strategy for determining cause of death than reliance on death certificates.

Television viewing and incident cardiovascular disease: prospective associations and mediation analysis in the EPIC Norfolk Study

BACKGROUND

Although television viewing time is detrimentally associated with intermediate cardiovascular risk factors, the relationship with incident total (i.e. combined fatal and non-fatal) cardiovascular disease (CVD), non-fatal CVD and coronary heart disease is largely unknown. This study examined whether television viewing time is associated with these three outcomes, independently of physical activity energy expenditure and other confounding variables.

METHODOLOGY/PRINCIPAL FINDINGS

A population-based cohort of 12,608 men and women (aged 61.4±9.0), free from stroke, myocardial infarction and cancer at baseline in 1998-2000 were followed up until 2007 (6.9±1.9 years). Participants self-reported education, smoking, alcohol use, antihypertensive, lipid lowering and antidepressant medication, disease history, total energy intake, sleep duration, physical activity and television viewing. BMI, waist circumference, blood pressure, triglycerides, HDL cholesterol and glycated haemoglobin (HbA(1c)) were measured by standardized procedures; a clustered metabolic risk score was constructed. Every one hour/day increase in television viewing was associated with an increased hazard for total (HR = 1.06, 95%CI = 1.03-1.08; 2,620 cases), non-fatal CVD (HR = 1.06, 95%CI = 1.03-1.09; 2,134 cases), and coronary heart disease (HR = 1.08, 95%CI = 1.03-1.13; 940 cases), independent of gender, age, education, smoking, alcohol, medication, diabetes status, CVD family history, sleep duration and physical activity energy expenditure. Energy intake, BMI, waist circumference, blood pressure, triglycerides, HDL cholesterol, HbA(1c) and the clustered metabolic risk score only partially mediated these associations.

CONCLUSIONS

These results indicate that the most prevalent leisure time (sedentary) behaviour, television viewing, independently contributes to increased CVD risk. Recommendations on reducing television viewing time should be considered.

Validation of de-identified record linkage to ascertain hospital admissions in a cohort study

BACKGROUND

Cohort studies can provide valuable evidence of cause and effect relationships but are subject to loss of participants over time, limiting the validity of findings. Computerised record linkage offers a passive and ongoing method of obtaining health outcomes from existing routinely collected data sources. However, the quality of record linkage is reliant upon the availability and accuracy of common identifying variables. We sought to develop and validate a method for linking a cohort study to a state-wide hospital admissions dataset with limited availability of unique identifying variables.

METHODS

A sample of 2000 participants from a cohort study (n = 41 514) was linked to a state-wide hospitalisations dataset in Victoria, Australia using the national health insurance (Medicare) number and demographic data as identifying variables. Availability of the health insurance number was limited in both datasets; therefore linkage was undertaken both with and without use of this number and agreement tested between both algorithms. Sensitivity was calculated for a sub-sample of 101 participants with a hospital admission confirmed by medical record review.

RESULTS

Of the 2000 study participants, 85% were found to have a record in the hospitalisations dataset when the national health insurance number and sex were used as linkage variables and 92% when demographic details only were used. When agreement between the two methods was tested the disagreement fraction was 9%, mainly due to "false positive" links when demographic details only were used. A final algorithm that used multiple combinations of identifying variables resulted in a match proportion of 87%. Sensitivity of this final linkage was 95%.

CONCLUSIONS

High quality record linkage of cohort data with a hospitalisations dataset that has limited identifiers can be achieved using combinations of a national health insurance number and demographic data as identifying variables.

The changing prevalence of diagnosed diabetes and its associated vascular complications in a large region of the UK

AIMS

To characterize the prevalence of diabetes in a large health district in 2004 and compare it with a previous estimate made in 1996.

METHODS

The study population comprised the resident population of Cardiff and the Vale of Glamorgan. Routine record linkage was used to identify patients from various sources of hospital and mortality data. Patients with diabetes were identified according to biochemistry test results, coding on routine data or attendance at a diabetes-related clinic. Diabetes-related complications were ascribed according to coding on routine data.

RESULTS

It was possible to identify 17 088 people with diabetes alive on 1 January 2005. Of these patients, 9064 (53.0%) were male and 8024 (47.0%) were female. Mean age (+/- sd) was 59.6 +/- 18.9 years for males and 61.2 +/- 20.4 years for females. The crude prevalence of diabetes in 2005 was 3.9% (3.4% adjusted) compared with 2.5% in 1996 (2.3% adjusted). With the exception of females aged > or = 75 years, the prevalence of diabetes increased in all age- and sex-specific subgroups. Within the 2005 cohort, over two-thirds has no recorded complications compared with approximately one half of the 1996 cohort. The prevalence of individual complications decreased, with the exception of renal complications.

CONCLUSIONS

The prevalence of identified diabetes appears to have increased substantially over a relatively short period of 9 years to 2004. The increase in prevalence was 46%, with an increase in numbers of patients with diabetes of 53%. A number of factors are likely to have contributed to this, including an increase in case ascertainment.