Patterns of working and living conditions: a holistic, multivariate approach to occupational health studies

The objective of the study was to develop a multivariate approach to occupational health studies that is: capable of identifying groups with similar working conditions; relevant for studies of associations between working and living conditions and health; and an appropriate basis for preventive actions. Data at the individual level were obtained through measurements, observations, interviews and questionnaires, and at the organizational level, through interviews with managers. Cluster analyses were applied with the purpose of identifying groups of individuals with small, within-group differences. Eighty work sites and a sample of employees at each site were strategically selected. The study group comprised 203 men and women, and was characterized by large variation. The final analysis produced eight clusters of individuals, denoted according to their best-defining characteristic, i.e. 'decent', 'boundary-less', 'locked', 'exposed', 'heavy and monotonous', 'changed', 'mobile' and 'restrained'. The clusters differed with regard to 'what' characterized working conditions, 'where' on the labour market they were found, and 'who' clustered in these groups. The holistic approach revealed conditions that were important for health and had higher explanatory power in relation to ill-health than applying socio-economic groupings or the demand-control-support model. It showed how psychosocial, ergonomic-physical and occupational hygiene factors combine and interact to create settings with different risks of ill-health. The chosen strategy is recommended for future occupational health studies and is particularly suitable as guidance for preventive actions relevant to specific clusters of working and living conditions.     

Investigating disease clusters: why, when and how?

The investigation of disease clusters, aggregations of a few to several cases of disease, remains a controversial issue in epidemiology and public health. Reported at the rate of more than three per day nationally, a response commands substantial resources. This paper considers whether scientists or public health officials should investigate disease clusters, when they should, and, if so, how. Part of the disparity in opinions arises from differing goals: trying to identify new carcinogens versus identifying situations in which people are at risk. There are also differences in investigation strategies: passive versus active. This paper suggests that a more active surveillance programme with occasional investigation may best meet the needs of the public while accommodating the limited resources of public health officials and some of the concerns of epidemiologists.     

Correcting for regression dilution bias: comparison of methods for a single predictor variable

In an epidemiological study the regression slope between a response and predictor variable is underestimated when the predictor variable is measured imprecisely. Repeat measurements of the predictor in individuals in a subset of the study or in a separate study can be used to estimate a multiplicative factor to correct for this 'regression dilution bias'. In applied statistics publications various methods have been used to estimate this correction factor. Here we compare six different estimation methods and explain how they fall into two categories, namely regression and correlation-based methods. We provide new asymptotic variance formulae for the optimal correction factors in each category, when these are estimated from the repeat measurements subset alone, and show analytically and by simulation that the correlation method of choice gives uniformly lower variance. The simulations also show that, when the correction factor is not much greater than 1, this correlation method gives a correction factor which is closer to the true value than that from the best regression method on up to 80% of occasions. We also provide a variance formula for a modified correlation method which uses the standard deviation of the predictor variable in the main study; this shows further improved performance provided that the correction factor is not too extreme. A confidence interval for a corrected regression slope in an epidemiological study should reflect the imprecision of both the uncorrected slope and the estimated correction factor. We provide formulae for this and show that, particularly when the correction factor is large and the size of the subset of repeat measures is small, the effect of allowing for imprecision in the estimated correction factor can be substantial.     

Women's frequency of alcohol consumption prior to pregnancy and at their pregnancy-booking visit 2001–2006: A cohort study

BackgroundWith evidence of offspring harms and concern for younger women's drinking behaviours, this study uses a hospital cohort to trend the use and changes in women's reported alcohol consumption.AimsTo examine (i) the trend of women's reported alcohol consumption over time, (ii) whether any increases in the frequency of alcohol consumption prior to a pregnancy are accompanied by increases in the frequency of alcohol consumption in pregnancy and (iii) the characteristics of women consuming alcohol at these times.MethodsMidwives collected routine data on 19,699 women between 2001 and 2006. Data on women's alcohol use prior to pregnancy and at their pregnancy-booking visit were analysed using a non-parametric test for trend and with bivariate and multivariate tests adjusting for possible confounders.FindingsThe proportion of women reporting at-least weekly alcohol use prior to pregnancy was 25.4% and 5.9% at their pregnancy-booking visit. A significant linear increase over time (p < 0.001) was found in the rate of women aged 20 years and older reporting at-least weekly alcohol use prior to pregnancy. Tertiary-educated women were more likely to consume alcohol at-least weekly prior to pregnancy. Women aged less than 20 years were less likely to report at-least weekly alcohol use at both time points. Having more children and Asian ethnicity were associated with a lower risk of at-least weekly alcohol use at these times.ConclusionThe majority of women reduce their alcohol consumption once they learn they are pregnant, with some evidence this trend may have increased in recent years.     

昆明地区老年人高尿酸血症与代谢综合症的流行病学调查

目的针对昆明地区60岁以上老年人进行高尿酸血症和代谢综合征患病率的流行病学调查。方法对我院2006年至2007年进行体检的昆明地区60岁以上健康老年人．在排除有严重心、脑、肺、肾等疾病及服用影响嘌呤代谢、血糖代谢、血压及血脂肪代谢等药物的患者,进行空腹血尿酸、血糖、血压、体重等测定。结果本次实际检测人数为2007例,其中男性1272例,占63．4％;女性735例,占36．6％,高尿酸血症（UA）619例,占30．8％;高血糖389例,占19．4％;高血压1级404例,占20．1％,2级308例,占18．9％,3级232例,占11．6％,肥胖492例,占24．5％,高胆固醇血症997,占49．7％,高甘油三酯血症764例,占38．1％;高低密度脂蛋白血症1027例,占51．2％;低高密度蛋白血症177例,占8．8％。结论由于高尿酸血症与代谢综合征可能与多种疾病有关,且多数无任何明显症状,故及早在人群中开展健康教育工作,特别是注意饮食卫生,加强体育运动,定期体检,对提高老年人生活质量和健康水平具有重要意义。     

A Scenario‐Based Evaluation of the Middle East Respiratory Syndrome Coronavirus and the Hajj

Between April 2012 and June 2014, 820 laboratory‐confirmed cases of the Middle East respiratory syndrome coronavirus (MERS‐CoV) have been reported in the Arabian Peninsula, Europe, North Africa, Southeast Asia, the Middle East, and the United States. The observed epidemiology is different to SARS, which showed a classic epidemic curve and was over in eight months. The much longer persistence of MERS‐CoV in the population, with a lower reproductive number, some evidence of human‐to‐human transmission but an otherwise sporadic pattern, is difficult to explain. Using available epidemiological data, we implemented mathematical models to explore the transmission dynamics of MERS‐CoV in the context of mass gatherings such as the Hajj pilgrimage, and found a discrepancy between the observed and expected epidemiology. The fact that no epidemic occurred in returning Hajj pilgrims in either 2012 or 2013 contradicts the long persistence of the virus in human populations. The explanations for this discrepancy include an ongoing, repeated nonhuman/sporadic source, a large proportion of undetected or unreported human‐to‐human cases, or a combination of the two. Furthermore, MERS‐CoV is occurring in a region that is a major global transport hub and hosts significant mass gatherings, making it imperative to understand the source and means of the yet unexplained and puzzling ongoing persistence of the virus in the human population.