Mortality risk associated with disability: a population-based record linkage study

Objectives. We assessed the association between mortality and disability and quantified the effect of disability-associated risk factors.Methods. We linked data from cross-sectional health surveys in the Netherlands to the population registry to create a large data set comprising baseline covariates and an indicator of death. We used Cox regression models to estimate the hazard ratio of disability on mortality.Results. Among men, the unadjusted hazard ratio for activities of daily living, mobility, or mild disability defined by the Organization for Economic Co-operation and Development at age 55 years was 7.85 (95% confidence interval [CI] = 4.36, 14.13), 5.21 (95% CI = 3.19, 8.51), and 1.87 (95% CI = 1.58, 2.22), respectively. People with disability in activities of daily living and mobility had a 10-year shorter life expectancy than nondisabled people had, of which 6 years could be explained by differences in lifestyle, sociodemographics, and major chronic diseases.Conclusions. Disabled people face a higher mortality risk than nondisabled people do. Although the difference can be explained by diseases and other risk factors for those with mild disability, we cannot rule out that more severe disabilities have an independent effect on mortality.Population aging is associated with an increase in the number of people who are disabled. This increase presents a challenge for society because elderly persons disabled in 1 or more domains of life are hospitalized more often,¹ need more medical and long-term care,^2–5 and face a higher risk of death than nondisabled persons do.^6–13Disablement refers to the impact that chronic and acute conditions have on people''s ability to perform tasks necessary for daily living and normal social functioning.¹⁴ In a broader context, the disablement process is described as a causal chain in which the progression of disease leads to functional limitations, loss of mobility, and eventually to inability to perform activities of daily living (ADLs).^14–17 Empirical studies have found numerous risk factors associated with disablement. These factors are usually seen as risks that increase the chance of developing a disability. The major underlying causes are (acute and progressive) chronic diseases,¹⁸ but other risk factors including sociodemographic factors (e.g., age, gender,¹⁹ socioeconomic status²⁰), behavioral factors (e.g., smoking),²¹ nutrition,²² physical activity,²³ comorbidity,¹⁸ self-rated health,²⁴ and cognitive impairment²⁵ are also associated with incident disability.Disability is most often assessed in cross-sectional studies without information on mortality. The few longitudinal studies that have been conducted tend to emphasize incident disability rather than the trajectory of disability following onset because of lack of statistical power.²⁶ Thus, although the onset of disability has been extensively researched, there has been far less investigation into the mortality risk associated with disability. In previous studies, the study populations were often limited to specific disease groups^9,12 or based on small sample sizes with few control variables.^{6–8,10,11,13} Moreover, the focus was often on other determinants of mortality rather than on disability. Nonetheless, disability has been found to be an independent predictor of death after adjustment for heart disease,⁹ depressive symptoms,¹⁰ physical activity,¹¹ socioeconomic status,¹³ or health status.¹⁰ However, no study has assessed the extent to which the relationship between disability and mortality can be explained by risk factors known to be associated with disablement. Assessment of this relationship may enhance understanding of the public health aspects of aging. If disability is found to be independently associated with mortality, developing strategies to prevent disability would not only increase disability-free life expectancy but also total life expectancy.We assessed the association between mortality and 3 disability measures reflecting different levels of disability severity. The linking of cross-sectional health surveys to municipal health registries in the Netherlands permitted the compilation of a large time-to-event data set with covariates measured at baseline.²⁷ We quantified the magnitude of the association between disability and mortality, unadjusted and adjusted for groups of risk factors. These risk factors included distal and proximal risk factors that may influence the speed of disablement.^28–31 We used hazard ratios (HRs) and life expectancy to summarize the association between disability and mortality.     

血糖控制与结核病风险: 基于人群队列研究

目的  探讨血糖控制与结核病发病风险之间的关系。方法  在中国东部地区对40 311名研究对象开展队列研究,通过10年的随访,探讨结核病发病的危险因素。排除了基线调查时发现的结核病患者,通过与南京市结核病管理信息系统进行匹配发现结核病患者。主要通过匹配身份证号码、姓名、年龄、出生日期和地址。并建立了Cox比例风险模型,调整了年龄、性别、吸烟状况等因素。结果  经过10年(中位随访时间为8.4年)的随访,共发现204名活动性结核病患者,发病密度为59.0/10万人年(95% CI：51.3~67.5)。其中,糖尿病患者有25人,占12.3%,发病密度为71.3/10万人年(95% CI：47.2~103.8)。共发现7名血糖控制不佳糖尿病患者发病,发病密度为84.4/10万人年(95% CI：50.8~132.4)。当把人群按照FPG是否≥7.0 mmol/L分组时,研究发现,与FPG < 7.0 mmol/L相比,FPG≥7.0 mmol/L人群发生结核病的风险提高0.89倍[风险比(hazard ratio, HR)=1.89,95% CI: 1.13~3.13,P=0.014]。结论  此次大规模的人群队列研究发现,糖尿病患者血糖控制不佳增加了其发生结核病的风险。因此,加强对血糖控制不佳糖尿病患者的筛查可以及早发现结核病,有利于降低中国结核病的发生与流行。     

Childbearing and the risk of scleroderma: a population-based study in Sweden

This study examined associations between childbearing and risk of scleroderma by using national population-based registry data from Sweden. Women with a discharge diagnosis of scleroderma from 1964 to 1999 (n = 2,149) were identified in the Swedish Inpatient Register. These cases were matched by year and month of birth and region of residence to as many as five controls obtained from the Multi-Generation Register. Pregnancy history (number of births, age at each birth) was restricted to births before the first scleroderma-related hospitalization for cases and the corresponding age for their matched controls. Risk estimates, measured by the odds ratio and 95% confidence interval, were obtained by using conditional logistic regression. Nulliparity was associated with an increased risk of scleroderma (odds ratio = 1.37, 95% confidence interval: 1.22, 1.55). Risk decreased with increasing number of births. Similar results were found when analyses were limited to births up to 2 years or up to 5 years before hospitalization. Among parous women, younger age at first birth was associated with an increased risk of scleroderma. The association between lower parity and increased risk of scleroderma could reflect subfecundity caused by scleroderma before disease became clinically evident, possible common causes of infertility and scleroderma, or a protective effect of pregnancy through an unknown mechanism.     

Helicobacter pylori infection and colorectal cancer risk: evidence from a large population-based case-control study in Germany

Evidence concerning the role of Helicobacter pylori infection in the development of colorectal cancer remains controversial. The authors assessed the association of H. pylori seroprevalence with risk of colorectal cancer in a large population-based case-control study from Germany in 2003-2007. Serum antibodies to H. pylori in general and the cytotoxin-associated gene A protein (CagA) were measured in 1,712 incident colorectal cancer cases and 1,669 controls. The association between H. pylori seroprevalence and colorectal cancer risk was estimated by logistic regression, with adjustment for potential confounders and stratification by age group, sex, anatomic subsites, and cancer stage. Overall, H. pylori seroprevalence was higher in cases (46.1%) than in controls (40.1%), resulting in an age- and sex-adjusted odds ratio of 1.30 (95% confidence interval (CI): 1.14, 1.50). Adjustment for established colorectal cancer risk factors decreased the odds ratio to 1.26 (95% CI: 1.09, 1.47), with a further reduction to 1.18 (95% CI: 1.01, 1.38) after additional adjustment for previous colorectal endoscopy. Stratified analyses showed risk elevation to be essentially confined to left-sided colorectal cancer, with an odds ratio of 1.22 (95% CI: 1.02, 1.45), suggesting that H. pylori infection may be associated with a small yet relevant risk increase in the left colorectum.     

Tuberculosis in Turkey: high altitude and other socio-economic risk factors

BACKGROUND: In Turkey, there are insufficient data regarding the relation between altitude and the incidence of tuberculosis (TB). OBJECTIVES: This study aimed to investigate the effect of high altitude and socio-economic conditions on the incidence of TB in Turkey. METHODS: The mean incidence of TB in 56 Turkish cities was measured as n/100,000 population between 1999 and 2005. The mean altitude of each city was recorded in metres. RESULTS: The incidence of TB was lower in cities located at high altitude (P=0.000) and higher in cities with a high population density (P=0.000). Multivariate analysis showed that the incidence of TB in low altitude cities was 3.28-fold higher than in high altitude cities (P=0.000). In cities with a population density >80 people/km(2), the incidence of TB was 4.18-fold higher than in cities with a lower population density (P=0.000) Other factors found to affect the incidence of TB were having a social insurance card and a low annual income. CONCLUSIONS: There was a strong negative correlation between altitude and the incidence of TB, and population density was significantly associated with the incidence of TB. Possession of a social insurance card and fertility rate were also risk factors for TB. The authors believe that altitude has a stronger influence on the incidence of TB than the other factors. The effect of altitude on TB may reveal new data, but further studies need to be undertaken to assess the effects of potential factors on the incidence of TB.     

Cigarette smoking and risk of Hodgkin's disease: a population-based case-control study

Previous reports offer limited support for an association between cigarette smoking and Hodgkin's disease. The authors investigated dose-response effects for smoking in relation to the risk of Hodgkin's disease using data from the Selected Cancers Study. Cases (n = 343) were men aged 32-60 years identified from eight US population-based cancer registries in 1984-1988. Controls (n = 1,910) were men recruited by random digit telephone dialing and frequency matched to cases by age and registry. Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals adjusted for age, registry, race/ethnicity, Jewish upbringing, education, and childhood domicile. Compared with never smokers, current smokers had a significantly increased risk of Hodgkin's disease (odds ratio (OR) = 1.8, 95% confidence interval (CI): 1.3, 2.9). Risks increased linearly (p < 0.001) with increasing packs per day (OR(>or=2) = 2.5, 95% CI: 1.6, 4.0), years (OR(>or=30) = 2.4, 95% CI: 1.5, 3.9), and pack-years (OR(>40) = 2.7, 95% CI: 1.8, 4.3) of smoking. These associations were significant for the nodular sclerosis and mixed cellularity subtypes but were much stronger for mixed cellularity. Stratified analyses by age (42 years) and subtype suggested that the effects of smoking are more closely related to histology than age. In contrast to findings from previous studies, these data suggest that smoking is an important preventable risk factor for Hodgkin's disease.     

Inflammation-sensitive proteins and risk of atrial fibrillation: a population-based cohort study

Low-grade inflammation has been repeatedly associated with cardiovascular diseases but the relationship with incidence of atrial fibrillation (AF) remains unclear. We explored the association between elevated plasma levels of inflammation-sensitive proteins (ISPs) and incidence of AF in a population-based cohort. Plasma levels of five ISPs (fibrinogen, haptoglobin, ceruloplasmin, α₁-antitrypsin and orosomucoid) and two complement factors (C3 and C4) were measured in 6,031 men (mean age 46.8 years) without history of myocardial infarction, heart failure, stroke or cancer. Incidence of hospitalizations due to AF during a mean follow-up of 25 years was studied both in relation to individual inflammatory proteins and the number of elevated ISPs. During follow-up, 667 patients were hospitalized with a diagnosis of AF. After adjustment for potential confounding factors, the hazard ratios (HR) for AF were 1.00 (reference), 1.08 (95% CI: 0.88–1.31), 1.07 (CI: 0.84–1.36), and 1.40 (CI: 1.12–1.74), respectively, in men with none, one, two and three or more ISPs in the 4th quartile (P for trend = 0.007). Ceruloplasmin was the only individual ISP significantly associated with incidence of AF after adjustment for confounding factors (HR 1.17 per standard deviation, 95% CI: 1.08–1.26). In conclusion, a score of five ISPs was associated with long-term incidence of hospitalizations due to AF in middle-aged men. Of the individual ISPs, a significant association was observed for ceruloplasmin, a protein previously associated with copper metabolism and oxidative stress.     

Dietary patterns and risk of oesophageal cancers: a population-based case-control study

Epidemiological studies investigating the association between dietary intake and oesophageal cancer have mostly focused on nutrients and food groups instead of dietary patterns. We conducted a population-based case-control study, which included 365 oesophageal adenocarcinoma (OAC), 426 oesophagogastric junction adenocarcinoma (OGJAC) and 303 oesophageal squamous cell carcinoma (OSCC) cases, with frequency matched on age, sex and geographical location to 1580 controls. Data on demographic, lifestyle and dietary factors were collected using self-administered questionnaires. We used principal component analysis to derive three dietary patterns: 'meat and fat', 'pasta and pizza' and 'fruit and vegetable', and unconditional logistic regression models to estimate risks of OAC, OGJAC and OSCC associated with quartiles (Q) of dietary pattern scores. A high score on the meat-and-fat pattern was associated with increased risk of all three cancers: multivariable-adjusted OR 2·12 (95 % CI 1·30, 3·46) for OAC; 1·88 (95% CI 1·21, 2·94) for OGJAC; 2·84 (95% CI 1·67, 4·83) for OSCC (P-trend <0·01 for all three cancers). A high score on the pasta-and-pizza pattern was inversely associated with OSCC risk (OR 0·58, 95 % CI 0·36, 0·96, P for trend=0·009); and a high score on the fruit-and-vegetable pattern was associated with a borderline significant decreased risk of OGJAC (OR for Q4 v. Q1 0·66, 95% CI 0·42, 1·04, P=0·07) and significantly decreased risk of OSCC (OR 0·41, 95% CI 0·24, 0·70, P for trend=0·002). High-fat dairy foods appeared to play a dominant role in the association between the meat-and-fat pattern and risk of OAC and OGJAC. Further investigation in prospective studies is needed to confirm these findings.     

Retinopathy of prematurity: risk factors in a prospective population-based study

A prospective study of risk factors for retinopathy of prematurity (ROP) in all very low birthweight (less than 1500 g) infants born in New Zealand in 1986 is reported. Of 413 liveborn infants admitted to neonatal units, 338 (81.2%) survived to be discharged home. Of surviving infants, 313 (93%) were examined by indirect ophthalmoscopy, as were eight infants who died before discharge. Sixty-nine infants (21.5% of 321) had acute retinopathy. On multiple logistic regression analysis, three variables made statistically significant independent contributions to the risk of any acute retinopathy; gestational age (P less than 0.0001), principal hospital caring for the infant (P less than 0.01) and treatment with indomethacin (P less than 0.01). Only two variables, gestational age (P less than 0.0001) and hospital (P less than 0.01), made significant contributions to the risk of stage 2 or more ROP. For both categories of ROP, timing of the examination also had a statistically significant effect (P less than 0.001). After adjustment for other significant predictor variables, it was estimated that approximately 70% of infants of less than 26 weeks' gestation were at risk of ROP and nearly 50% of stage 2 or more ROP, in comparison with less than 2% of infants of 32 weeks' gestation or more; infants treated with indomethacin were over 1.5 times more likely to have ROP than infants not so treated. Failure to enforce uniform timing of examination was the most serious defect in the study; only 205 (64%) of the 321 infants were examined at the recommended time. However, reanalysis of the model with information limited to these 205 infants yielded similar risk factors. The incidence of ROP, both observed (P less than 0.05) and adjusted for other significant variables in the regression model (P less than 0.01) was lowest in the two largest level III hospitals. These hospitals also had the best survival rates after adjustment for birthweight, gestation and gender (P less than 0.01). We speculate that the larger level III units obtained better results because their size and experience enabled them to provide a better overall quality of care.