Association of Somatic Comorbidities and Comorbid Depression With Mortality in Patients With Rheumatoid Arthritis: A 14-Year Prospective Cohort Study

OBJECTIVE

Patients with rheumatoid arthritis (RA) have a significantly increased risk of mortality compared with the general population. One of the most important predictors for mortality is somatic comorbidity. Moreover, studies have demonstrated that comorbid depression is associated with mortality. Which specific comorbidities are associated with mortality is less investigated. The purpose of this study was to investigate the association of a wide range of comorbidities with mortality in patients with RA.

METHODS

Longitudinal data over a 14-year period were collected from 882 patients with RA. Data were assessed with questionnaires. The mortality status was obtained from the Statistics Netherlands for the period 1996-2011 for 99% of the patients. Somatic comorbidity was assessed in 1997, 1998, 1999, and 2008 and measured by a national population-based questionnaire including 20 chronic diseases. Comorbid depression was assessed in 1997, 1998, and 1999 and measured with the Center for Epidemiologic Studies Depression Scale. Cox regression was used to study the relationship between comorbidity and mortality.

RESULTS

At baseline, 72% of the patients were women. The mean ± SD age was 59.3 ± 14.8 years, and the median (interquartile range) disease duration was 5.0 (2.0-14.0) years. A total of 345 patients died during the study period. Comorbidities that were associated with mortality were circulatory conditions (hazard ratio [HR] 1.60 [95% confidence interval (95% CI) 1.15-2.22]), respiratory conditions (HR 1.43 [95% CI 1.09-1.89]), cancer (HR 2.00 [95% CI 1.28-3.12]), and depression (HR 1.35 [95% CI 1.06-1.72]).

CONCLUSION

Comorbid circulatory conditions, respiratory conditions, cancer, and depression are associated with mortality among patients with RA. Careful monitoring of these comorbidities during the course of the disease and adequate referral may improve health outcomes and chances of surviving.

Predicting the health impact of lowering salt consumption in Turkey using the DYNAMO health impact assessment tool

OBJECTIVE

To estimate the impact of three daily salt consumption scenarios on the prevalence and incidence of ischaemic heart disease (IHD) and cerebrovascular disease in 2025 in the Turkish population aged ≥30 years using the DYNAMO Health Impact Assessment tool.

STUDY DESIGN

Statistical disease modelling study.

METHODS

DYNAMO health impact assessment was populated using data from Turkey to estimate the prevalence and incidence of IHD and cerebrovascular disease in 2025. TurkSTAT data were used for demographic data, and national surveys were used for salt consumption and disease-specific burden. Three salt consumption scenarios were modelled: (1) reference scenario: mean salt consumption stays the same from 2012-2013 until 2025; (2) gradual decline: daily salt intake reduces steadily by 0.47 g per year by lowering salt intake from bread by 50% and from table salt by 40% by 2025; and (3) World Health Organization (WHO) advice: daily salt intake of 5 g per day from 2013 until 2025.

RESULTS

The gradual decline scenario would lead to a decrease in the prevalence of IHD and cerebrovascular disease by 0.3% and 0.2%, respectively, and a decrease in the incidence by 0.6 and 0.4 per 1000, respectively. Following WHO's advice would lead to a decrease in the prevalence of IHD and cerebrovascular disease by 0.8% and 0.5%, respectively, and a decrease in the incidence by 1.0 and 0.7 per 1000, respectively.

CONCLUSION

This model indicates that Turkey can lower its future cardiovascular disease burden by following the gradual decline scenario. Following WHO's advice would achieve an even greater benefit.

Health care costs attributable to overweight calculated in a standardized way for three European countries

This article presents a tool to calculate health care costs attributable to overweight in a comparable and standardized way. The purpose is to describe the methodological principles of the tool and to put it into use by calculating and comparing the costs attributable to overweight for The Netherlands, Germany and Czech Republic. The tool uses a top-down and prevalence-based approach, consisting of five steps. Step one identifies overweight-related diseases and age- and gender-specific relative risks. Included diseases are ischemic heart disease, stroke, hypertension, type 2 diabetes mellitus, colorectal cancer, postmenopausal breast cancer, endometrial cancer, kidney cancer and osteoarthritis. Step two consists of collecting data on the age- and gender-specific prevalence of these diseases. Step three uses the population-attributable prevalence to determine the part of the prevalence of these diseases that is attributable to overweight. Step four calculates the health care costs associated with these diseases. Step five calculates the costs of these diseases that are attributable to overweight. Overweight is responsible for 20-26% of the direct costs of included diseases, with sensitivity analyses varying this percentage between 15-31%. Percentage of costs attributable to obesity and preobesity is about the same. Diseases with the highest percentage of costs due to overweight are diabetes, endometrial cancer and osteoarthritis. Disease costs attributable to overweight as a percentage of total health care expenditures range from 2 to 4%. Data are consistent for all three countries, resulting in roughly a quarter of costs of included diseases being attributable to overweight.

Long-term physical functioning and its association with somatic comorbidity and comorbid depression in patients with established rheumatoid arthritis: a longitudinal study

OBJECTIVE

To describe long-term physical functioning and its association with somatic comorbidity and comorbid depression in patients with established rheumatoid arthritis (RA).

METHODS

Longitudinal data over a period of 11 years were collected from 882 patients with RA at study inclusion. Patient-reported outcomes were collected in 1997, 1998, 1999, 2002, and 2008. Physical functioning was measured with the Health Assessment Questionnaire and the physical component summary score of the Short Form 36 health survey. Somatic comorbidity was measured by a questionnaire including 12 chronic diseases. Comorbid depression was measured with the Center for Epidemiologic Studies Depression Scale. We distinguished 4 groups of patients based on comorbidity at baseline.

RESULTS

Seventy-two percent of the patients at baseline were women. The mean ± SD age was 59.3 ± 14.8 years and the median disease duration was 5.0 years (interquartile range 2.0-14.0 years). For the total group of patients with RA, physical functioning improved over time. Patients with somatic comorbidity, comorbid depression, or both demonstrated worse physical functioning than patients without comorbidity at all data collection points. Both groups with comorbid depression had the lowest scores. Only patients with both somatic comorbidity and comorbid depression showed significantly less improvement in physical functioning over time.

CONCLUSION

Both somatic comorbidity and comorbid depression were negatively associated with physical functioning during an 11-year followup period. Furthermore, their combination seems to be especially detrimental to physical functioning over time. These results emphasize the need to take somatic comorbidity and comorbid depression into account in the screening and treatment of patients with RA.

Modelling obesity outcomes: reducing obesity risk in adulthood may have greater impact than reducing obesity prevalence in childhood

A common policy response to the rise in obesity prevalence is to undertake interventions in childhood, but it is an open question whether this is more effective than reducing the risk of becoming obese during adulthood. In this paper, we model the effect on health outcomes of (i) reducing the prevalence of obesity when entering adulthood; (ii) reducing the risk of becoming obese throughout adult life; and (iii) combinations of both approaches. We found that, while all approaches reduce the prevalence of chronic diseases and improve life expectancy, a given percentage reduction in obesity prevalence achieved during childhood had a smaller effect than the same percentage reduction in the risk of becoming obese applied throughout adulthood. A small increase in the probability of becoming obese during adulthood offsets a substantial reduction in prevalence of overweight/obesity achieved during childhood, with the gains from a 50% reduction in child obesity prevalence offset by a 10% increase in the probability of becoming obese in adulthood. We conclude that both policy approaches can improve the health profile throughout the life course of a cohort, but they are not equivalent, and a large reduction in child obesity prevalence may be reversed by a small increase in the risk of becoming overweight or obese in adulthood.

Variety in vegetable and fruit consumption and the risk of gastric and esophageal cancer in the European Prospective Investigation into Cancer and Nutrition

Diets high in vegetables and fruits have been suggested to be inversely associated with risk of gastric cancer. However, the evidence of the effect of variety of consumption is limited. We therefore investigated whether consumption of a variety of vegetables and fruit is associated with gastric and esophageal cancer in the European Prospective Investigation into Cancer and Nutrition study. Data on food consumption and follow-up on cancer incidence were available for 452,269 participants from 10 European countries. After a mean follow-up of 8.4 years, 475 cases of gastric and esophageal adenocarcinomas (180 noncardia, 185 cardia, gastric esophageal junction and esophagus, 110 not specified) and 98 esophageal squamous cell carcinomas were observed. Diet Diversity Scores were used to quantify the variety in vegetable and fruit consumption. We used multivariable Cox proportional hazard models to calculate risk ratios. Independent from quantity of consumption, variety in the consumption of vegetables and fruit combined and of fruit consumption alone were statistically significantly inversely associated with the risk of esophageal squamous cell carcinoma (continuous hazard ratio per 2 products increment 0.88; 95% CI 0.79-0.97 and 0.76; 95% CI 0.62-0.94, respectively) with the latter particularly seen in ever smokers. Variety in vegetable and/or fruit consumption was not associated with risk of gastric and esophageal adenocarcinomas. Independent from quantity of consumption, more variety in vegetable and fruit consumption combined and in fruit consumption alone may decrease the risk of esophageal squamous cell carcinoma. However, residual confounding by lifestyle factors cannot be excluded.

Estimating net transition probabilities from cross-sectional data with application to risk factors in chronic disease modeling

A problem occurring in chronic disease modeling is the estimation of transition probabilities of moving from one state of a categorical risk factor to another. Transitions could be obtained from a cohort study, but often such data may not be available. However, under the assumption that transitions remain stable over time, age specific cross-sectional prevalence data could be used instead. Problems that then arise are parameter identifiability and the fact that age dependent cross-sectional data are often noisy or are given in age intervals. In this paper we propose a method to estimate so-called net annual transition probabilities from cross-sectional data, including their uncertainties. Net transitions only describe the net inflow or outflow into a certain risk factor state at a certain age. Our approach consists of two steps: first, smooth the data using multinomial P-splines, second, from these data estimate net transition probabilities. This second step can be formulated as a transportation problem, which is solved using the simplex algorithm from linear programming theory. A sensible specification of the cost matrix is crucial to get meaningful results. Uncertainties are assessed by parametric bootstrapping. We illustrate our method using data on body mass index. We conclude that this method provides a flexible way of estimating net transitions and that the use of net transitions has implications for model dynamics, for example when modeling interventions.

The influence of population characteristics on variation in general practice based morbidity estimations

Background

General practice based registration networks (GPRNs) provide information on morbidity rates in the population. Morbidity rate estimates from different GPRNs, however, reveal considerable, unexplained differences. We studied the range and variation in morbidity estimates, as well as the extent to which the differences in morbidity rates between general practices and networks change if socio-demographic characteristics of the listed patient populations are taken into account.

Methods

The variation in incidence and prevalence rates of thirteen diseases among six Dutch GPRNs and the influence of age, gender, socio economic status (SES), urbanization level, and ethnicity are analyzed using multilevel logistic regression analysis. Results are expressed in median odds ratios (MOR).

Results

We observed large differences in morbidity rate estimates both on the level of general practices as on the level of networks. The differences in SES, urbanization level and ethnicity distribution among the networks' practice populations are substantial. The variation in morbidity rate estimates among networks did not decrease after adjusting for these socio-demographic characteristics.

Conclusion

Socio-demographic characteristics of populations do not explain the differences in morbidity estimations among GPRNs.

Disability and health‐related quality of life among patients with rheumatoid arthritis: association with radiographic joint damage, disease activity, pain, and depressive symptoms

OBJECTIVE

To study the associations between disability and health-related quality of life (HRQoL), respectively, and radiographic joint damage, disease activity, pain, and depressive symptoms among patients with rheumatoid arthritis (RA).

METHODS

Data were collected through questionnaires and clinical examinations at baseline (1997) and at 2 years' follow-up among patients with RA (n = 307). Disability was measured with a validated Dutch questionnaire, derived from the Health Assessment Questionnaire (HAQ), and HRQoL with a validated Dutch version of the RAND-36, using physical (PCS) and mental (MCS) component summary scales. Multivariate linear regression analyses were performed to assess the relationship between disability or HRQoL and radiographic damage, disease activity, pain, and depressive symptoms.

RESULTS

Pain, with respect to disability and PCS, and depressive symptoms, with respect to MCS, were more important predictors than radiographic damage and disease activity.

CONCLUSIONS

Daily RA practice needs to be broadened by regular assessment of disease burden from the patients' perspectives. Patient-reported measures, such as disability or HRQoL, should be incorporated for monitoring health outcomes of individual patients and for initiating and evaluating therapy.

Long-term wine consumption is related to cardiovascular mortality and life expectancy independently of moderate alcohol intake: the Zutphen Study

BACKGROUND

Light to moderate alcohol intake lowers the risk of cardiovascular mortality, but whether this protective effect can be attributed to a specific type of beverage remains unclear. Moreover, little is known about the effects of long-term alcohol intake on life expectancy.

METHODS

The impact of long-term alcohol intake and types of alcoholic beverages consumed on cardiovascular mortality and life expectancy at age 50 was investigated in the Zutphen Study, a cohort of 1373 men born between 1900 and 1920 and examined repeatedly between 1960 and 2000. Hazard ratios (HRs) for total alcohol intake and alcohol from wine, beer and spirits were obtained from time-dependent Cox regression models. Life expectancy at age 50 was calculated from areas under survival curves.

RESULTS

Long-term light alcohol intake, that is < or =20 g per day, compared with no alcohol, was strongly and inversely associated with cerebrovascular (HR 0.43, 95% CI 0.26 to 0.70), total cardiovascular (HR 0.70, 95% CI 0.55 to 0.89) and all-cause mortality (HR 0.75, 95% CI 0.63 to 0.91). Independent of total alcohol intake, long-term wine consumption of, on average, less than half a glass per day was strongly and inversely associated with coronary heart disease (HR 0.61, 95% CI 0.41 to 0.89), total cardiovascular (HR 0.68, 95% CI 0.53 to 0.86) and all-cause mortality (HR 0.73, 95% CI 0.62 to 0.87). These results could not be explained by differences in socioeconomic status. Life expectancy was about 5 years longer in men who consumed wine compared with those who did not use alcoholic beverages.

CONCLUSION

Long-term light alcohol intake lowered cardiovascular and all-cause mortality risk and increased life expectancy. Light wine consumption was associated with 5 years longer life expectancy; however, more studies are needed to verify this result.

Reliability of biomarkers of iron status, blood lipids, oxidative stress, vitamin D, C-reactive protein and fructosamine in two Dutch cohorts

Biomarkers are widely used in epidemiology, yet there are few reliability studies to assess the appropriateness of using these biomarkers for the assessment of exposure-disease relationships. The aim of the study was to assess the reliability of 20 biomarkers in serum collected from two Dutch centres (Utrecht and Bilthoven) participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) at two points several years apart. Blood samples were collected from 30 men from Bilthoven and 35 women from Utrecht. Ferritin, total iron, total iron-binding capacity, transferrin saturation, transferrin, C-reactive protein, bilirubin, cholesterol, triglycerides, apo lipoprotein-A, apo lipoprotein-B, high-density lipoproteins, low-density lipoproteins, uric acid, creatinine, reactive oxygen metabolites, the ferric-reducing ability of plasma, protein thiol oxidation, fructosamine, and vitamin D biomarkers in serum were analysed from the blood samples at the two points of time. For all biomarkers, except C-reactive protein, there were no substantial changes in the mean levels over time. Uric acid, ferritin, creatinine, HDL, and apo lipoprotein-B levels consistently showed the highest reliability for men and women (intra-class correlation = 0.69-0.86). Among women, the ferric-reducing ability of plasma, and protein thiol oxidation had poor reliability; and among men iron-related biomarkers (except serum ferritin) had poor reliability. With the exception of a few gender-specific differences, most of the 20 biomarkers performed well and can be considered to have sufficient reliability to be used in future cohort studies.

High prevalence of methicillin resistant Staphylococcus aureus in pigs

Recently methicillin resistant Staphylococcus aureus (MRSA) was isolated from pigs and pig farmers in The Netherlands. In order to assess the dissemination of MRSA in the Dutch pig population, we screened 540 pigs in 9 slaughterhouses, where a representative portion of Dutch pigs (63%) was slaughtered in 2005. We found 209 (39%) of the pigs to carry MRSA in their nares. Forty-four of 54 groups of 10 consecutive pigs (81%), each group from a different farm, and all slaughterhouses were affected. All MRSA isolates belonged to 1 clonal group, showing Multi-Locus Sequence Type 398 and closely related spa types (mainly t011, t108 and t1254). Three types of the Staphylococcal Chromosome Cassette (SCCmec) were found: III (3%), IVa (39%) and V (57%). All 44 tested isolates (1 isolate per group) were resistant to tetracycline, reflecting the high and predominant use of tetracyclines in pig husbandry. Twenty-three percent of the isolates were resistant to both erythromycin and clindamycin and 36% to kanamycin, gentamicin and tobramycin but only a single isolate was resistant to co-trimoxazole and none to ciprofloxacin and several other antibiotics. The percentage of MRSA positive pigs was significantly different among slaughterhouses and among groups within slaughterhouses, indicating a high prevalence of MRSA in pigs delivered from the farms as well as cross contamination in the slaughterhouses.

Disparities in stroke preventive care in general practice did not explain socioeconomic disparities in stroke

OBJECTIVE

To assess socioeconomic disparities in stroke incidence and in the quality of preventive care for stroke in the Netherlands.

STUDY DESIGN AND SETTINGS

A total of 190,664 patients who registered in 96 general practices were followed up for 12 months. Data were collected on diagnoses, referrals, prescriptions, and diagnostic procedures. Hazard ratios (HR) were calculated to assess the association between educational level and stroke incidence. Multilevel logistic regression was used to assess socioeconomic disparities in the quality of preventive care for stroke precursors.

RESULTS

Lower educational level was associated with higher incidence of stroke in men (HR=1.36, 95% CI=1.06-1.74) but not in women. Among both men and women, there were socioeconomic disparities in the prevalence of hypertension, hypercholesterolemia, diabetes, angina pectoris, heart failure, and peripheral artery disease. Lower educated hypercholesterolemia patients under medication were less likely to be prescribed statins (odds ratio=0.62, 95% CI=0.42-0.91). However, for other precursors of stroke, there were no major disparities in the quality of preventive care.

CONCLUSION

There are socioeconomic disparities in stroke incidence among men but not among women. Socioeconomic differences in factors such as hypertension and diabetes are likely to contribute to stroke disparities. However, general practitioners (GPs) provide care of a similar quality to patients from different socioeconomic groups.

Effect size estimates of lifestyle and dietary changes on all-cause mortality in coronary artery disease patients: a systematic review

BACKGROUND

Guidelines for lifestyle and dietary modification in patients with coronary artery disease (CAD) are mainly supported by evidence from general population studies. CAD patients, however, differ from the general population in age (older) and treatment with preventive drugs. This review seeks to provide evidence for a prognostic benefit of lifestyle and dietary recommendations from studies in CAD patients.

METHODS AND RESULTS

A literature search was performed on the effect of lifestyle and dietary changes on mortality in CAD patients. Prospective cohort studies and randomized controlled trials of patients with established CAD were included if they reported all-causes mortality and had at least 6 months of follow-up. The effect estimates of smoking cessation (relative risk [RR], 0.64; 95% CI, 0.58 to 0.71), increased physical activity (RR, 0.76; 95% CI, 0.59 to 0.98), and moderate alcohol use (RR, 0.80; 95% CI, 0.78 to 0.83) were studied most extensively. For the 6 dietary goals, data were too limited to provide reliable effect size estimates. Combinations of dietary changes were associated with reduced mortality (RR, 0.56; 95% CI, 0.42 to 0.74).

CONCLUSIONS

Available studies show convincingly the health benefits of lifestyle changes in CAD patients. Effect estimates of combined dietary changes look promising. Future studies should confirm these findings and assess the contribution of the individual dietary factors.

Non-response in a survey of cardiovascular risk factors in the Dutch population: determinants and resulting biases

BACKGROUND

The aim of the research was to study the determinants of participation in a health examination survey (HES) which was carried out in a population that previously participated in a health interview survey (HIS) of Statistics Netherlands, and to estimate the effect of non-participation on both the prevalence of the main HES outcomes (risk factors for cardiovascular disease) and on relationships between variables.

METHODS

Logistic regression was used to study the determinants of participation in the HES (n=3699) by those who had previously participated in the HIS (n=12,786). Linear models were used to predict the main outcomes in non-participants of the HES. Item non-response was handled by multiple imputation.

RESULTS

HES participants had a higher socio-economic status and comprised more 'worried well', while the rural population were less likely to participate in the HES. Most predicted values of outcomes in HES non-participants differed from those in HES participants, but much of this was due to differences in the age and gender composition of both groups. Taking age and gender differences into account, most predicted values of outcomes in the entire HIS population were within the 95% confidence intervals of the HES values, with the exception of body height in men and high-density lipoprotein cholesterol, fasting glucose and body weight in women. These differences are most likely to be due to the higher socio-economic status of HES participants. Relationships between HIS variables did not change significantly when using HES participants alone compared with all HIS participants.

CONCLUSIONS

Despite a high rate of non-participation, some bias, mostly small, was seen in the prevalence rates of the main outcome variables. Bias in the relationships between variables was negligible.

Estimation of minimum infection rates with Legionella pneumophila in an exposed population

The distribution of antibody levels to Legionella (L.) pneumophila (serotypes 1-7) was compared between subjects who worked near the source of a large outbreak of Legionnaires' disease (n=668) and a population sample of comparable age (n=480). In a previous analysis of these data, it was estimated that 80% of those working near the source were infected with L. pneumophila. However, the estimation procedure implicitly assumes that the probability of infection does not depend on the antibody level of a person before exposure. This is questionable, as antibodies could protect against infection. We have now estimated the minimum value consistent with the data on the number of infected persons. We observed that a minimum of 40% [95% confidence interval (CI) 32-48] of those working near the source and 13% (95% CI 8-18) of those working further away were infected with L. pneumophila. Implications of these findings for design options in future research are discussed.

Effect of sporting activity on absenteeism in a working population

OBJECTIVES

To determine the effects of sporting activity on absenteeism in a working population.

METHODS

Data were used from a prospective cohort study in a working population with a follow up period of 3 years and were collected with yearly questionnaires or collected from company records. Complete data on absenteeism, sporting activity, and potential confounders were collected for 1228 workers. ANOVA was used to test differences in frequency and duration of absenteeism, correlations were computed to measure the association between number of sporting years (divided by age) and frequency and duration of absenteeism, and survival analysis, according to the Cox proportional hazards model, was used to test differences in relative risk at absenteeism and recovery. All analyses were adjusted for age, gender, smoking, and alcohol consumption, and were stratified for employees with sedentary and with more active jobs.

RESULTS

ANOVA showed a statistically significant higher mean duration of absenteeism among employees not practicing sports, of approximately 20 days over a period of 4 years. The survival analysis showed an increased relative risk at absenteeism (relative risk (RR) 1.09; confidence interval (CI) 1.01 to 1.18) and a decreased relative risk at recovery (RR 0.90; CI 0.85 to 0.95) for employees not practicing sports. The effect of sporting activity is larger in employees with sedentary work. No associations were found between number of sporting years and absenteeism.

CONCLUSION

Employees practicing sports take sick leave significantly less often than their colleagues not practicing sports, while their periods of sick leave are shorter, especially when their work is sedentary.

Life expectancy without chronic morbidity: trends in gender and socioeconomic disparities

OBJECTIVE

Life expectancy without chronic morbidity, or morbidity-free life expectancy (MFLE), was calculated to measure changes in population health status between 1989 and 2000 on the basis of gender and socioeconomic status.

METHODS

Sullivan's method was used to calculate morbidity-free life expectancy. Prevalence rates for chronic morbidity were derived from the Netherlands Continuous Health Interview Survey. Four socioeconomic groups were distinguished on the basis of educational level.

RESULTS

Between 1989 and 2000, total life expectancy increased for males and females and for all socioeconomic groups. Morbidity-free life expectancy decreased significantly for males (from 54.7 years to 53.9 years) and females (from 55.3 years to 51.0 years). The gap between males and females in MFLE has reversed, from 0.6 years in favor of females in 1989 to 2.9 years in favor of males in 2000. The gap between the upper and lower classes seems to have narrowed (for males from 11 years to 8.5 years and for females from 4.7 years to 4.0 years).

CONCLUSIONS

The results indicate that morbidity-free life expectancy is falling for males and females and in all socioeconomic groups. Part of this decrease could be attributed to earlier diagnosis of chronic diseases. A widening gap in MFLE was observed between males and females in favor of males. The gap between the upper and lower socioeconomic groups seems to be narrowing.

Plasma carotenoid levels in Dutch men and women, and the relation with vegetable and fruit consumption

OBJECTIVE

Fruit and vegetable intake is inversely associated with cancer risk in many epidemiological studies. Accurate assessment of consumption of these foods is difficult, and biomarkers of intake would overcome several drawbacks of currently used dietary assessment methods. Therefore, we investigated the relation between plasma carotenoids and usual vegetable and fruit intake.

DESIGN

Plasma carotenoid concentrations were measured and vegetable, fruit and juice consumption was assessed by a food frequency questionnaire (FFQ) in a random sample of 591 Dutch men and women aged 20-59 y from the MORGEN-project, one of the contributions to the European Prospective Investigation into Cancer and Nutrition (EPIC)-study.

RESULTS

In this sample of the general Dutch population, in both genders, relative to the other carotenoids, plasma beta-cryptoxanthin was the best indicator for fruit intake, and for the sum of vegetable, fruit and juice intake, while lutein concentrations best reflected intake of vegetables, although quartiles of intake were not consistently separated. Since levels of lycopene were not associated with any of the main food groups examined, associations with total carotenoids improved when excluding lycopene, and monotonously increasing plasma levels were seen for intakes of vegetables, of fruits, and of the sum of vegetables, fruits and juices. Several vegetable types and orange/grapefruit juice were associated with plasma levels of one of the carotenoids.

CONCLUSION

Plasma carotenoids were only crude indicators of vegetable and fruit intake as assessed by a FFQ; beta-cryptoxanthin for fruit intake and lutein for vegetable intake. None of the plasma carotenoids could distinguish all four quartiles of vegetables, fruit and/or juice intake.

Medical practice variations in hospital care; time trends of a spatial phenomenon

A persistent finding in health services research is that health care delivery and hospital utilisation in the Western world varies widely between areas, both within and between countries. Most studies have concentrated on cross-sectional variations in medical practice. The aim of this article is to investigate whether or not small area variation changed through time. We used hospital discharge rates in the Netherlands for 12 diagnostic or surgical categories to indicate medical practice patterns. The data cover a time span of almost two decades: 1980-1997. First, it was found that in most cases regions are consistently above or below the national trend in the study period. Second, the analysis revealed a statistically significant decline of regional variation in hospital discharges in general during the 1980s and the 1990s. In all but one medical category the results of the separate analyses point towards a downward trend. In one-third of the medical categories this downward trend was statistically significant. Potential parallel changes in regional disparities in need for care, e.g. morbidity or age composition of regional populations or changes in regional differences in care supply are discussed.

Physical activity and stroke. A meta-analysis of observational data

BACKGROUND

Based on studies published so far, the protective effect of physical activity on stroke remains controversial. Specifically, there is a lack of insight into the sources of heterogeneity between studies.

METHODS

Meta-analysis of observational studies was used to quantify the relationship between physical activity and stroke and to explore sources of heterogeneity. In total, 31 relevant publications were included. Risk estimates and study characteristics were extracted from original studies and converted to a standard format for use in a central database.

RESULTS

Moderately intense physical activity compared with inactivity, showed a protective effect on total stroke for both occupational (RR = 0.64, 95% CI: 0.48-0.87) and leisure time physical activity (RR = 0.85, 95% CI: 0.78-0.93). High level occupational physical activity protected against ischaemic stroke compared with both moderate (RR = 0.77, 95% CI: 0.60-0.98) and inactive occupational levels (RR = 0.57, 95% CI: 0.43-0.77). High level compared with low level leisure time physical activity protected against total stroke (RR = 0.78, 95% CI: 0.71-0.85), haemorrhagic stroke (RR = 0.74, 95% CI: 0.57-0.96) as well as ischaemic stroke (RR = 0.79, 95% CI: 0.69-0.91). Studies conducted in Europe showed a stronger protective effect (RR = 0.47, 95% CI: 0.33-0.66) than studies conducted in the US (RR = 0.82, 95% CI: 0.75-0.90).

CONCLUSIONS

Lack of physical activity is a modifiable risk factor for both total stroke and stroke subtypes. Moderately intense physical activity is sufficient to achieve risk reduction.

Trends in disability-free life expectancy

PURPOSE

To assess trends in Disability-Free Life Expectancy, in life expectancy with disabilities according to levels of severity and in Disability-Adjusted Life Expectancy in the Netherlands between 1989 and 2000.

METHOD

The disability-free life expectancy, a composite population health status measure, was calculated with data on long-term disability. Weights reflecting the impact of disability on personal functioning were assigned to different levels of severity of disability, in order to calculate a Disability-Adjusted Life Expectancy and to define cut-off points, in order to distinguish between levels of severity.

RESULTS

At an aggregated level, for both males and females at the ages of 16 and of 65 years, an increase in years with disabilities and a decline in disability-free life expectancy were observed. These trends were mainly caused by a rise in the number of years with mild disabilities, with the number of years with moderate and severe disabilities decreasing. The combined changes have resulted in an increase in the Disability-Adjusted Life Expectancy.

CONCLUSION

Trends in disability-free life expectancy and in years with disabilities provide support for a scenario of dynamic equilibrium. The number of years with moderate and severe disabilities has reduced, resulting in an increase in the number of years with minor disabilities. Further research should focus on the underlying causes of the increase of years with minor disabilities.

Avoidable mortality in Europe (1980-1997): a comparison of trends

STUDY OBJECTIVE

To analyse international variations of trends in "avoidable" mortality (1980-1997).

DESIGN

A multilevel model was used to study trends in avoidable and "non-avoidable" mortality and trends by cause of death.

SETTING

Fifteen countries of the European Union, the Czech Republic, and Hungary.

PARTICIPANTS

19 avoidable causes of death among men and women aged 0-64 years. Mortality and population data were derived from the WHO mortality database; and perinatal mortality rates, from the Health for All statistical database.

MAIN RESULTS

Avoidable mortality declined (1980-1997) in all the countries except Hungary. The difference between the trends in avoidable and non-avoidable mortality was small (-2.4% compared with -1.5%) and diminished over time. The largest trend variations between countries are attributable to causes mainly or partly amenable to prevention. For five of the 19 causes of death the international variations diminished over time. Various countries show trends that deviate significantly (p<0.003) from the mean trend.

CONCLUSIONS

One explanation for the small and diminishing difference between avoidable and non-avoidable mortality is that some large avoidable causes show unfavourable trends. Another possible explanation is that the category of non-avoidable mortality is "polluted" by causes that have become avoidable with time. It is therefore suggested that Rutstein's lists of avoidable outcomes (1976) be updated to enable the appropriate monitoring of healthcare effectiveness. In countries that show unfavourable developments for specific avoidable causes, further research must unravel the causes of these trends.

Dimension-specific burden of caregiving among partners of rheumatoid arthritis patients

OBJECTIVES

To assess subjective caregiver burden among partners of rheumatoid arthritis (RA) patients and to identify partner and patient variables and objective caregiver burden related to subjective caregiver burden.

METHODS

In 2001, 134 patients diagnosed with RA and their caregiving partners participated in a postal questionnaire survey. Information was gathered on age, gender and health problems of patient and partner, disease duration of the patient, objective caregiver burden and subjective caregiver burden of the partner (using the multidimensional Caregiver Reaction Assessment). Correlation coefficients were computed between the subjective caregiver burden dimensions. Multivariate analyses were performed to identify variables that explained the variation in subjective burden.

RESULTS

Partners of RA patients derived, on average, a high level of self-esteem from giving care. Negative subjective caregiver burden was to a large degree caused by a disrupted schedule and to a smaller degree by a lack of family support, financial problems and loss of physical strength. Problems of the partner with mobility or with pain/discomfort and problems of the patient with self-care activities and activities of daily life had the largest impact on negative levels of subjective caregiver burden.

CONCLUSIONS

Health parameters of the patient and partner have a considerable predictive value for the development of high levels of subjective burden in partners of RA patients. Support strategies should be developed for partners of RA patients, and should focus especially on reducing the burden caused by a disrupted schedule, and simultaneously on increasing the focus of caregivers on the positive aspects of caregiving.

Association of consumption of products containing milk fat with reduced asthma risk in pre-school children: the PIAMA birth cohort study

BACKGROUND

Environment and lifestyle contribute to the development of asthma in children. Understanding the relevant factors in this relationship may provide methods of prevention. The role of diet in the development of asthma in pre-school children was investigated.

METHODS

Data from 2978 children participating in a prospective birth cohort study were used. Food frequency data were collected at the age of 2 years and related to asthma symptoms reported at the age of 3 years.

RESULTS

The prevalence of recent asthma at age 3 was lower in children who consumed (at age 2) full cream milk daily (3.4%) than in those who did not (5.6%) and in those who consumed butter daily (1.5%) than in those who did not (5.1%). The prevalence of recent wheeze was lower in children who consumed milk products daily (13.7%) than in those who did not (18.4%) and in children who consumed butter daily (7.7%) than in those who did not (15.4%). These effects remained in a logistic regression model including different foods and confounders (adjusted odds ratio (CI) for recent asthma: full cream milk daily v rarely 0.59 (0.40 to 0.88), butter daily v rarely 0.28 (0.09 to 0.88)). Daily consumption of brown bread was also associated with lower rates of asthma and wheeze, whereas no associations were observed with the consumption of fruits, vegetables, margarine, and fish.

CONCLUSIONS

In pre-school children, frequent consumption of products containing milk fat is associated with a reduced risk of asthma symptoms.

Predicting cardiovascular risk in the elderly in different European countries

AIMS

The objective of this study was to develop risk functions for coronary heart disease and cardiovascular disease mortality for elderly men in different European countries.

METHODS AND RESULTS

The FINE Study is a prospective follow-up study of 2170 elderly men aged 65-84 years in Finland, Italy and The Netherlands. During 10 years of follow-up 289 men died from coronary heart disease and 545 men from cardiovascular disease. Risk functions were estimated using logistic regression analysis, in order to take competing causes of death into account. The results of the present study show that total cholesterol and smoking were the most important predictors of coronary heart disease mortality, and HDL cholesterol, systolic blood pressure and smoking of cardiovascular disease mortality. Left ventricular hypertrophy, being subject to coronary heart disease or cardiovascular disease in Finland and The Netherlands and use of antihypertensive medication in Italy, were also important predictors. For estimating the absolute risk of coronary heart disease and cardiovascular disease mortality in the elderly it is necessary to take into account the European country in which they live.

CONCLUSION

Total and HDL cholesterol, systolic blood pressure and smoking remain important predictors of coronary heart disease and/or cardiovascular disease mortality in elderly men, but also left ventricular hypertrophy, being subject to coronary heart disease, use of antihypertensive medication and country are predictive of coronary heart disease and cardiovascular disease risk.

Costs of different strategies for neonatal hearing screening: a modelling approach

OBJECTIVE

To compare the cost effectiveness of various strategies for neonatal hearing screening by estimating the cost per hearing impaired child detected.

DESIGN

Cost analyses with a simulation model, including a multivariate sensitivity analysis. Comparisons of the cost per child detected were made for: screening method (automated auditory brainstem response or otoacoustic emissions); number of stages in the screening process (two or three); target disorder (bilateral hearing loss or both unilateral and bilateral loss); location (at home or at a child health clinic).

SETTING

The Netherlands

TARGET POPULATION

All newborn infants not admitted to neonatal intensive care units.

MAIN OUTCOME MEASURE

Costs per child detected with a hearing loss of 40 dB or more in the better ear.

RESULTS

Costs of a three stage screening process in child health clinics are 39.0 pounds (95% confidence interval 20.0 to 57.0) per child detected with automated auditory brainstem response compared with 25.0 (14.4 to 35.6) pounds per child detected with otoacoustic emissions. A three stage screening process not only reduces the referral rates, but is also likely to cost less than a two stage process because of the lower cost of diagnostic facilities. The extra cost (over and above a screening programme detecting bilateral losses) of detecting one child with unilateral hearing loss is 1500-4000 pounds. With the currently available information, no preference can be expressed for a screening location.

CONCLUSIONS

Three stage screening with otoacoustic emissions is recommended. Whether screening at home is more cost effective than screening at a child health clinic needs further study.

Subclinical Legionella infection in workers near the source of a large outbreak of Legionnaires disease

A survey was conducted of exhibitors at a 1999 floral trade show, where a whirlpool spa on display caused a large outbreak of legionnaires disease (LD). In total, 742 exhibitors without LD returned a questionnaire on their whereabouts during the fair and their health afterward and supplied blood samples for the detection of IgM and IgG antibodies against Legionella pneumophila. The exhibitors had higher average antibody levels than did the general population. The closer to the whirlpool that the exhibitors worked, the higher their antibody levels. Both high-normal and high titer levels were found more frequently among workers with more exposure, suggesting that serosurveys among potentially exposed subjects are a valuable tool for outbreak investigation. Some differences in health complaints were observed between the more and less exposed groups, as estimated by the workplace location, but few differences were found between groups with different antibody levels.

Multiple imputation of missing blood pressure covariates in survival analysis

This paper studies a non-response problem in survival analysis where the occurrence of missing data in the risk factor is related to mortality. In a study to determine the influence of blood pressure on survival in the very old (85+ years), blood pressure measurements are missing in about 12.5 per cent of the sample. The available data suggest that the process that created the missing data depends jointly on survival and the unknown blood pressure, thereby distorting the relation of interest. Multiple imputation is used to impute missing blood pressure and then analyse the data under a variety of non-response models. One special modelling problem is treated in detail; the construction of a predictive model for drawing imputations if the number of variables is large. Risk estimates for these data appear robust to even large departures from the simplest non-response model, and are similar to those derived under deletion of the incomplete records.

Multiple imputation of missing blood pressure covariates in survival analysis

This paper studies a non-response problem in survival analysis where the occurrence of missing data in the risk factor is related to mortality. In a study to determine the influence of blood pressure on survival in the very old (85+ years), blood pressure measurements are missing in about 12.5 per cent of the sample. The available data suggest that the process that created the missing data depends jointly on survival and the unknown blood pressure, thereby distorting the relation of interest. Multiple imputation is used to impute missing blood pressure and then analyse the data under a variety of non-response models. One special modelling problem is treated in detail; the construction of a predictive model for drawing imputations if the number of variables is large. Risk estimates for these data appear robust to even large departures from the simplest non-response model, and are similar to those derived under deletion of the incomplete records.

Multiple imputation of missing blood pressure covariates in survival analysis

This paper studies a non-response problem in survival analysis where the occurrence of missing data in the risk factor is related to mortality. In a study to determine the influence of blood pressure on survival in the very old (85+ years), blood pressure measurements are missing in about 12.5 per cent of the sample. The available data suggest that the process that created the missing data depends jointly on survival and the unknown blood pressure, thereby distorting the relation of interest. Multiple imputation is used to impute missing blood pressure and then analyse the data under a variety of non-response models. One special modelling problem is treated in detail; the construction of a predictive model for drawing imputations if the number of variables is large. Risk estimates for these data appear robust to even large departures from the simplest non-response model, and are similar to those derived under deletion of the incomplete records.

Blood pressure and mortality in elderly people aged 85 and older: community based study

OBJECTIVE

To determine whether the inverse relation between blood pressure and all cause mortality in elderly people over 85 years of age can be explained by adjusting for health status, and to determine whether high blood pressure is a risk factor for mortality when the effects of poor health are accounted for.

DESIGN

5 to 7 year follow up of community residents aged 85 years and older.

SETTING

Leiden, the Netherlands.

SUBJECTS

835 subjects whose blood pressure was recorded between 1987 and 1989.

MAIN OUTCOME MEASURE

All cause mortality.

RESULTS

An inverse relation between blood pressure and all cause mortality was observed. For diastolic blood pressure crude 5 year all cause mortality decreased from 88% (52/59) (95% confidence interval 79% to 95%) in those with diastolic blood pressures <65 mm Hg to 59% (27/46) (44% to 72%) in those with diastolic pressures >100 mm Hg. For systolic blood pressure crude 5 year all cause mortality decreased from 85% (95/112) (78% to 91%) in those with systolic pressures <125 mm Hg to 59% (13/22) (38% to 78%) in those with systolic pressures >200 mm Hg. This decrease was no longer significant after adjustment for indicators of poor health. No relation existed between blood pressure and mortality from cardiovascular causes or stroke after adjustment for age and sex, but after adjustment for age, sex, and indicators of poor health there was a positive relation between diastolic blood pressure and mortality from both cardiovascular causes and stroke.

CONCLUSION

The inverse relation between blood pressure and all cause mortality in elderly people over 85 is associated with health status.

Maternal smoking during lactation: relation to growth during the first year of life in a Dutch birth cohort

A recent article by Little et al. (Am J Epidemiol 1994;140:544-54) reported that infants in Seattle, Washington, who were breastfed by mothers who smoked gained more weight than either infants who were breastfed by mothers who did not smoke or infants who were bottle-fed by mothers who smoked. In this study, the authors aimed to verify this result with the use of data from the Social Medical Survey of Children Attending Child Health Clinics (SMOCC) cohort, a nationally representative cohort of 2,151 children born in the Netherlands in 1988-1989. During the first year of life, data on type of milk feeding, weight, length, and head circumference were collected at 1, 2, 3, 6, 9, and 12 months of age. Infants of smokers who were mainly breastfed in the first 3 months of life (n = 117) were compared with similarly breastfed infants of nonsmokers (n = 572), with infants of smokers who had been mainly bottle-fed (n = 270), and with infants of nonsmokers who had been mainly bottle-fed (n = 535). The authors failed to observe any additional increase in body mass, length, or head circumference in infants of breastfeeding smokers compared with infants of the three other groups. When the authors used all of their data to study growth with a multivariate longitudinal regression model (general estimating equations (GEE) model), the data showed clearly reduced growth in breastfed children (limited to the period after the second month of life) and some "catch-up" growth in body mass and head circumference in children with intrauterine exposure to tobacco.

Average age at first occurrence as an alternative occurrence parameter in epidemiology

BACKGROUND

Current epidemiological methods focus mostly on incidence rates and their ratios as measures of occurrence and effect. Incidence rates and rate ratios can be hard to interpret when the outcome disease is common.

METHODS

The possibilities of using an alternative measure, average age at first occurrence of the disease, are discussed.

RESULTS

Methods for the analysis of average age at first occurrence are illustrated in a study of occupation and disability pension. We estimate that the average age at pension among crane drivers is only about 0.8 that of maintenance workers, regardless of the method, although the confidence intervals depend on the method.

CONCLUSIONS

Average age at first occurrence is easier to interpret than the incidence rate for a very common disease. Because estimates are not readily available in software packages, we encourage further development of packaged software for this measure.

Health expectancy calculations: a novel approach to studying population health in Bulgaria

The measurement of life expectancy in terms of either good or poor health is a novel approach to studying the health of the population in Bulgaria. The pilot study reported here-carried out among people aged > or = 60 years in a middle-sized Bulgarian town-was designed to obtain information on the years of functional restrictions expected among the elderly. In accordance with the answers to a series of questions (recommended by WHO), subjects were categorized as disabled, handicapped, or having different states of perceived health. The indicators "disability-free life expectancy", "handicap-free life expectancy" and "healthy life expectancy" (based on self-perceived health) were calculated according to Sullivan's method. The results show, for example, that 8.0 of the 16.0 years that men aged 60 years may expect to live, on average, will be free of disability. For men aged 80 years the figures are 1.3 of 5.5 years. For women at 60 years and 80 years the results are 7.3 and 0.5 disability-free years of 19.2 and 7.3 expected life years, respectively. Similar results were found for handicap-free life expectancies and healthy life expectancies. At all ages, the proportion of life in a condition free of disability, free of handicap, or in perceived good health is substantially lower for women than for men. Women may expect to live longer, but a greater proportion of their life will be spent in poor health. The approach presented here for measuring the health status of the elderly may be helpful as an aid to planning medical and social care and for the development of public health policies.

Dementia-free life expectancy (DemFLE) in The Netherlands

To gain an insight into the burden of dementia in an aging society, life expectancy with dementia and its counterpart dementia-free life expectancy (DemFLE) in The Netherlands are presented. Sullivan's method was used to calculate DemFLE. For elderly living either independently or in homes for the elderly prevalence figures on dementia were obtained from the Rotterdam Elderly Study (RES; n = 7528); for elderly in nursing homes the SIG Nursing home Information System was used. Conforming to other authors only the prevalence data on moderate and severe dementia as diagnosed with DSM-III-R criteria are used. The prevalence of mild dementia was not taken into account. At 65 years DemFLE for men is 14.0 years, that is 96.4% of the total life expectancy (14.5 years at this age). At age 90, DemFLE for men is 2.5 years, equal to 77.5% of the total life expectancy (3.3 years). For women DemFLE at age 65 is 17.7 years, that is 93.2% of their life expectancy (19.0 years), and at the age of 90, DemFLE for women is 2.8 years, equal to 74.7% of their remaining life expectancy (3.8 years). The absolute number of years with dementia remains relatively constant with increasing age. About 20-25% of these years with dementia are spent in nursing homes, the other 75-80% living independently. At each age compared with men women have both a higher DemFLE and a higher expectancy of years with dementia. The percentage of life expectancy without dementia however, is always lower for women, because of their higher total life expectancy. This indicates that the burden of dementia in absolute and relative terms is higher for women. Most years with dementia are spent at home, indicating that the burden of dementia rests mainly on the shoulders of informal caregivers.

Occupational handicap-free life expectancy in Bulgaria 1976-1992 based on the data of the medical expert commissions

This article presents health expectancy calculations from Bulgaria for 1976-1992. The calculations are based on mortality statistics and data from a national information system from the Expert Medical Commissions on Working Capacity about loss of working capacity. Following internationally accepted terminology, the most appropriate term for the health expectancies presented here is "occupational handicap-free life expectancy' (OHFLE). Life expectancies were calculated as partial life expectancies from ages 16 to 59. Health expectancy calculations followed Sullivan's cross-sectional method with age and sex specific prevalence data on occupational handicap. Around 1985 a three- to four-fold increase in these prevalences occurred. The distribution of occupational handicaps over sexes, age groups and severity levels, however, remained fairly constant. The results show a decrease both in partial life expectancy within the age range 16-59 and in OHFLE at the age of 16 for men. For women a more or less stable partial life expectancy and a decrease in OHFLE at the age of 16 was found around 1985. The introduction of more incentives for people who successfully registered probably caused the decrease around 1985. Major social changes may have acted as confounding factors for the fluctuations after 1985. On the other hand the findings may reflect real changes in population health due to an increasing incidence in some major disease categories. The nation-wide system for assessment and registration of health related working incapacity has proved a useful source for an attempt to calculate OHFLE. Given uncertainties about the population health underlying these changes in OHFLE, however, it is recommended that health interview and health examination surveys should be considered as alternative routes for achieving a more comprehensive picture of population health in Bulgaria.