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Background: A standard parameter to compare the disease incidence of a cohort relative to the population is the standardized incidence ratio (SIR). For statistical inference is commonly assumed that the denominator, the expected number of cases, is fixed. If a disease registry is available, incident cases can sometimes be identified by linkage with the registry, however, registries may not contain information on migration or death from other causes. A complete follow-up with a population registry may not be possible. In that case, end-of-follow-up date and therefore, exact person-years of observation are unknown.Methods: We have developed a method to estimate the observation times and to derive the expected number of cases using population data on mortality and migration rates. We investigate the impact of the underlying assumptions with a sensitivity analysis.Results: The method provides a useful estimate of the SIR. We illustrate the method with a numerical example, a simulation study and with a study on standardized cancer incidence ratios in a cohort of migrants relative to the German population. We show that the additional variance induced by the estimation method is small, so that standard methods for inference can be applied.Conclusions: Estimation of the observation time is possible for cohort studies with incomplete follow-up. [ABSTRACT FROM AUTHOR]

Background: The WHO Framework Convention on Tobacco Control was shown to effectively lower smoking prevalence in in high income countries, however knowledge for low and middle income settings is sparse. The objective of this study was to describe WHO MPOWER policy measures in thirteen West-African countries and to investigate their correlation with smoking prevalence.Methods: Age-standardized smoking prevalence data and policy measures were collected from various WHO reports. For analysis MPOWER measures from 2008 and 2010, were combined with prevalence data from 2009 and 2011. Multiple linear regression models were set up.Results: In West-Africa mean smoking prevalence was approximately 20% among males and approximately 3% among females. Policy measures were mostly at a middle or low level. Regression analysis showed that tobacco cessation programs, health warnings on cigarettes, and higher price of cigarettes were negatively correlated with smoking prevalence. Significant effects were observed for only one policy measure (tobacco cessation programs) and only within the male population where smoking prevalence is generally higher.Conclusions: Tobacco control policies are enforced at relatively low levels in West-African countries. However, improving tobacco control policy implementation according to the WHO Framework Convention on Tobacco Control should assist in the reduction of smoking prevalence in African countries, thereby counteracting pro-smoking initiatives set forth by the tobacco industry. [ABSTRACT FROM AUTHOR]

Abstract Introduction  There is a known difference in breast cancer survival between races in the US for which several factors such as social, lifestyle and genetic factors may be relevant. Method  This is a retrospective study among women entitled to free treatment in the US department of defense health care system. Within this group, we investigated the temporal trend of absolute survival of 13,793 of White and African American aged 20–59 years and diagnosed between 1980 and 1999 with breast cancer. Result  There is a 3% overall improvement in survival in whites which can be explained by an earlier detection, and a two percent decrease in AA with a distinct pattern by age group. In the 40–49 year age group, the survival in white increases from 84.5% in the year 1980–1984 to 87.4 % in the year 1995–1999, in AA we estimate a decrease from 79.7% to 78.5%. When accounting for stage at diagnosis a slight reduction in survival in whites and a strong reduction in AA indicates a significant interaction between race and calendar period. The differences in survival patterns between blacks and whites are mainly caused by breast cancer and not by other causes. Conclusion  The gap in survival which strongly increased with calendar period cannot be explained by unequal access to health care. Possible explanations include a lower participation of early detection programs for breast cancer in AA and an increasing prevalence of obesity over time which is more pronounced in AA than in whites. [ABSTRACT FROM AUTHOR]

A malaria survey of the entire population of a village in Western Burkina Faso (n=1,561) was conducted to assess malaria endemicity. The study population was examined for symptoms characteristic of malaria including fever, anaemia, splenomegaly and parasites present in thick blood films. In the overall study population, the prevalence of Plasmodium spp. infection by microscopic examination of thick blood films was 79.0% (1,233/1,561). In a subcohort with 201 individuals, PCR techniques found a prevalence rate for all Plasmodium spp. of 92.0% (185/201), while microscopy found one of 80.6% (162/201). A combination of both methods gives a rate of 95.5% (192/201). Though univariate logistic analyses of elevated body temperature, anaemia, splenomegaly and age showed them all to be predictors of or risk factors for an infection, only elevated body temperature and age were predictors in multivariate logistic analysis. However, the symptom of splenomegaly did show a highly significant association with infection by multiple species of Plasmodium. [ABSTRACT FROM AUTHOR]

Background Mortality in developing countries has multiple causes. Some of these causes are linked to climatic conditions that differ over the year. Data on season-specific mortality are sparse.Methods We analysed longitudinal data from a population of ∼35 000 individuals in Burkina Faso. During the observation period 1993–2001, a total number of 4098 deaths were recorded. The effect of season on mortality was investigated separately by age group as (i) date of death and (ii) date of birth. For (i), age-specific death rates by month of death were calculated. The relative effect of each month was assessed using the floating relative risk method and modelled continuously. For (ii), age-specific death rates by month of birth were calculated and the mean date of birth among deaths and survivors was compared.Results Overall mortality was found to be consistently higher during the dry season (November to May). The pattern was seen in all age groups except in infants where a peak was seen around the end of the rainy season. In infants we found a strong association between high mortality and being born during the time period September to February. No effect was seen for the other age groups.Conclusions The observed excess mortality in young children at or around the end of the rainy season can be explained by the effects of infectious diseases and, in particular, malaria during this time period. In contrast, the excess mortality seen in older children and adults during the early dry season remains largely unexplained although specific infectious diseases such as meningitis and pneumonia are possible main causes. The association between high infant mortality and being born at around the end of the rainy season is probably explained by most of the malaria deaths in areas of high transmission intensity occurring in the second half of infancy. [ABSTRACT FROM AUTHOR]

A population-based case-control study was performed in the Rhein-Neckar region, Germany, to evaluate occupational risk factors for the development of laryngeal cancer (“Rhein-Neckar-Larynx Study”). Between May 1998 and December 2000, 257 patients (236 males, 21 females), aged 37–80, with histologically confirmed laryngeal cancer, as well as 769 population control persons (702 males, 67 females), were included (1:3 frequency matched by age and sex). History of occupational exposures, as well as other risk factors (tobacco, alcohol), was obtained with face-to-face interviews using a detailed standardized questionnaire. The complete individual work history was assessed. A detailed assessment of work conditions was obtained by job-specific questionnaires (JSQs) for selected jobs known to be associated with exposure to potential laryngeal carcinogens. Estimates for total exposure hours by substance were calculated based on JSQs. Published occupational hygiene data were used to infer semiquantitative scores of exposure intensity for specific job tasks. After adjustment for tobacco and alcohol intake, a significant elevated odds ratios (OR) could be demonstrated for persons that were exposed to cement during their work as building and construction workers. An OR of 2.42 was calculated for workers of the high exposed subgroup (95% confidence interval: 1.14-5.15; p < 0.001). Smoking was the main confounding factor because the unadjusted cement OR of 3.20 dropped down to 2.42 after adjustment for tobacco intake. We conclude that there is good evidence for cement dust exposure acting as a tobacco, alcohol and asbestos independent risk factor for laryngeal carcinoma. Our study gives a base for further toxicologic investigations on this topic. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Record linkage is an invaluable tool for many epidemiological studies. So far, however, in Europe it has mainly been used in Scandinavian countries with nationwide registration systems. Using the example of a large retrospective cohort study among migrants, we show that this method is also feasible in Germany, a country without central registries and unique identi.cation numbers for citizens. [ABSTRACT FROM AUTHOR]