Respiratory symptoms and long-term risk of death from cardiovascular disease, cancer and other causes in Swedish men.
BACKGROUND: Depressed respiratory function and respiratory symptoms are associated with impaired survival. The present study was undertaken to assess the relation between respiratory symptoms and mortality from cardiovascular causes, cancer and all causes in a large population of middle-aged men. METHODS: Prospective population study of 6442 men aged 51-59 at baseline, free of clinical angina pectoris and prior myocardial infarction. RESULTS: During 16 years there were 1804 deaths (786 from cardiovascular disease, 608 from cancer, 103 from pulmonary disease and 307 from any other cause). Men with effort-related breathlessness had increased risk of dying from all of the examined diseases. After adjustment for age, smoking habit and other risk factors, the relative risk (RR) associated with breathlessness of dying from coronary disease was 1.43 (95% CI : 1.16-1.77), from stroke 1.77 (95% CI: 1.07-2.93), from any cardiovascular disease 1.48 (95% CI : 1.24-1.76), cancer 1.36 (95% CI : 1.11-1.67) and from any cause 1.62 (95% CI: 1.44-1.81). An independent effect of breathlessness on cardiovascular death, cancer death and mortality from all causes was found in life-time non-smokers, and also if men with chest pain not considered to be angina were excluded. An independent effect was also found if all deaths during the first half of the follow-up were excluded. Men with cough and phlegm, without breathlessness, also had an elevated risk of dying from cardiovascular disease and cancer, but after adjustment for smoking and other risk factors this was no longer significant. However, a slightly elevated independent risk of dying from any cause was found (RR = 1.18 [95% CI: 1.02-1.36]). CONCLUSION: A positive response to a simple question about effort related breathlessness predicted subsequent mortality from several causes during a follow-up period of 16 years, independently of smoking and other risk factors. (+info
A review of statistical methods for estimating the risk of vertical human immunodeficiency virus transmission.
BACKGROUND: Estimation of the risk of vertical transmission of human immunodeficiency virus (HIV) has been complicated by the lack of a reliable diagnostic test for paediatric HIV infection. METHODS: A literature search was conducted to identify all statistical methods that have been used to estimate HIV vertical transmission risk. Although the focus of this article is the analysis of birth cohort studies, ad hoc studies are also reviewed. CONCLUSIONS: The standard method for estimating HIV vertical transmission risk is biased and inefficient. Various alternative analytical approaches have been proposed but all involve simplifying assumptions and some are difficult to implement. However, early diagnosis/exclusion of infection is now possible because of improvements in polymerase chain reaction technology and complex estimation methods should no longer be required. The best way to analyse studies conducted in breastfeeding populations is still unclear and deserves attention in view of the many intervention studies being planned or conducted in developing countries. (+info
Hygiene behaviour in rural Nicaragua in relation to diarrhoea.
BACKGROUND: Childhood diarrhoea is a leading cause of morbidity and mortality in Nicaragua. Amongst the risk factors for its transmission are 'poor' hygiene practices. We investigated the effect of a large number of hygiene practices on diarrhoeal disease in children aged <2 years and validated the technique of direct observation of hygiene behaviour. METHODS: A prospective follow-up study was carried out in a rural zone of Nicaragua. From the database of a previously conducted case-control study on water and sanitation 172 families were recruited, half of which had experienced a higher than expected rate of diarrhoea in their children and the other half a lower rate. Hygiene behaviour was observed over two mornings and diarrhoea incidence was recorded with a calendar, filled out by the mother, and collected every week for 5 months. RESULTS: Of 46 'good' practices studied, 39 were associated with a lower risk of diarrhoea, five were unrelated and only for two a higher risk was observed. Washing of hands, domestic cleanliness (kitchen, living room, yard) and the use of a diaper/underclothes by the child had the strongest protective effect. Schooling (>3 years of primary school) and better economic position (possession of a radio) had a positive influence on general hygiene behaviour, education having a slightly stronger effect when a radio was present. Individual hygiene behaviour appeared to be highly variable in contrast with the consistent behaviour of the community as a whole. Feasible and appropriate indicators of hygiene behaviour were found to be domestic cleanliness and the use of a diaper or underclothes by the child. CONCLUSION: A consistent relationship between almost all hygiene practices and diarrhoea was detected, more schooling producing better hygiene behaviour. The high variability of hygiene behaviour at the individual level requires repeated observations (at least two) before and after the hygiene education in the event one wants to measure the impact of the campaign on the individual. (+info
Comparison of active and cancer registry-based follow-up for breast cancer in a prospective cohort study.
The authors compared the relative effectiveness of two distinct follow-up designs in prospective cohort studies--the active approach, based on direct contact with study subjects, and the passive approach, based on record linkages with population-based cancer registries--utilizing available information from the New York University Women's Health Study (WHS) and the New York State Cancer Registry (NYSCR). The analyses were limited to breast cancer cases identified during the period 1985-1992, for which follow-up was considered reasonably complete by both the WHS and the NYSCR. Among 12,947 cohort members who reported a New York State address, 303 pathologically confirmed cases were identified through active follow-up and 284 through record linkage. Sixty-three percent of cancers were identified by both sources, 21% by the WHS only, and 16% by the NYSCR only. The agreement was appreciably better for invasive cancers. The percentage of cases identified only by the NYSCR was increased among subjects whose active follow-up was incomplete, as well as among nonwhites, obese patients, and parous patients. This suggests that relying on either type of follow-up alone may introduce certain biases in evaluating risk factors for breast cancer. Combining both approaches appears to be a better strategy in prospective cohort studies. (+info
Capture-recapture models including covariate effects.
Capture-recapture methods are used to estimate the incidence of a disease, using a multiple-source registry. Usually, log-linear methods are used to estimate population size, assuming that not all sources of notification are dependent. Where there are categorical covariates, a stratified analysis can be performed. The multinomial logit model has occasionally been used. In this paper, the authors compare log-linear and logit models with and without covariates, and use simulated data to compare estimates from different models. The crude estimate of population size is biased when the sources are not independent. Analyses adjusting for covariates produce less biased estimates. In the absence of covariates, or where all covariates are categorical, the log-linear model and the logit model are equivalent. The log-linear model cannot include continuous variables. To minimize potential bias in estimating incidence, covariates should be included in the design and analysis of multiple-source disease registries. (+info
Premature morbidity from cardiovascular and cerebrovascular diseases in women with systemic lupus erythematosus.
OBJECTIVE: To determine rates of morbidity due to cardiovascular and cerebrovascular diseases among women with systemic lupus erythematosus (SLE). METHODS: I used the California Hospital Discharge Database, which contains information on all discharges from acute care hospitals in California, to identify women with SLE who had been hospitalized for treatment of either acute myocardial infarction (AMI), congestive heart failure (CHF), or cerebrovascular accident (CVA) from 1991 to 1994. I compared the proportions of hospitalizations for each cause among women with SLE with those in a group of women without SLE, for 3 age strata (18-44 years, 45-64 years, and > or =65 years). RESULTS: Compared with young women without SLE, young women with SLE were 2.27 times more likely to be hospitalized because of AMI (95% confidence interval [95% CI] 1.08-3.46), 3.80 times more likely to be hospitalized because of CHF (95% CI 2.41-5.19), and 2.05 times more likely to be hospitalized because of CVA (95% CI 1.17-2.93). Among middle-aged women with SLE, the frequencies of hospitalization for AMI and CVA did not differ from those of the comparison group, but the risk of hospitalization for CHF was higher (odds ratio [OR] 1.39, 95% CI 1.05-1.73). Among elderly women with SLE, the risk of hospitalization for AMI was significantly lower (OR 0.70, 95% CI 0.51-0.89), the risk of hospitalization for CHF was higher (OR 1.25, 95% CI 1.01-1.49), and the risk of hospitalization for CVA was not significantly different from those in the comparison group. CONCLUSION: Young women with SLE are at substantially increased risk of AMI, CHF, and CVA. The relative odds of these conditions decrease with age among women with SLE. (+info
Gallstones, cholecystectomy and risk of cancers of the liver, biliary tract and pancreas.
To examine the association between gallstones and cholecystectomy, we conducted a nationwide population-based cohort study in Denmark. Patients with a discharge diagnosis of gallstones from 1977 to 1989 were identified from the Danish National Registry of Patients and followed up for cancer occurrence until death or the end of 1993 by record linkage to the Danish Cancer Registry. Included in the cohort were 60 176 patients, with 471 450 person-years of follow-up. Cancer risks were estimated by standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) stratified by years of follow-up and by cholecystectomy status. Among patients without cholecystectomy, the risks at 5 or more years of follow-up were significantly elevated for cancers of liver (SIR = 2.0, CI = 1.2-3.1) and gallbladder (SIR = 2.7, CI = 1.5-4.4) and near unity for cancers of extrahepatic bile duct (SIR = 1.1), ampulla of Vater (SIR = 1.0) and pancreas (SIR = 1.1). The excess risk of liver cancer was seen only among patients with a history of hepatic disease. Among cholecystectomy patients, the risks at 5 or more years of follow-up declined for cancers of liver (SIR = 1.1) and extrahepatic bile duct (SIR = 0.7), but were elevated for cancers of ampulla of Vater (SIR = 2.0, CI = 1.0-3.7) and pancreas (SIR = 1.3, CI = 1.1-1.6). These findings confirm that gallstone disease increases the risk of gallbladder cancer, whereas cholecystectomy appears to increase the risk of cancers of ampulla of Vater and pancreas. Further research is needed to clarify the carcinogenic risks associated with gallstones and cholecystectomy and to define the mechanisms involved. (+info
Cancer incidence in the south Asian population of England (1990-92).
Cancer incidence among English south Asians (residents in England with ethnic origins in India, Pakistan or Bangladesh) is described and compared with non-south Asian and Indian subcontinent rates. The setting for the study was areas covered by Thames, Trent, West Midlands and Yorkshire cancer registries. The study identified 356 555 cases of incident cancer (ICD9:140-208) registered between 1990 and 1992, including 3845 classified as English south Asian. The main outcome measures were age specific and directly standardized incidence rates for all cancer sites (ICD9:140-208). English south Asian incidence rates for all sites combined were significantly lower than non-south Asian rates but higher than Indian subcontinent rates. English south Asian rates were substantially higher than Indian subcontinent rates for a number of common sites including lung cancer in males, breast cancer in females and lymphoma in both sexes. English south Asian rates for childhood and early adult cancer (0-29 years) were similar or higher than non-south Asian rates. English south Asian rates were significantly higher than non-south Asian rates for Hodgkin's disease in males, cancer of the tongue, mouth, oesophagus, thyroid gland and myeloid leukaemia in females, and cancer of the hypopharynx, liver and gall bladder in both sexes. The results are consistent with a transition from the lower cancer risk of the country of ethnic origin to that of the country of residence. They suggest that detrimental changes in lifestyle and other exposures have occurred in the migrant south Asian population. (+info