[Prevalence of asthma among adults in France, data from the Constances cohort study]. / Prévalence de l'asthme chez l'adulte en France, données de la cohorte Constances.

INTRODUCTION: The objectives of our study were to estimate the prevalence of asthma in adults in France and to study the effects of gender on the associations of asthma with the corpulence and socio-economic characteristics of individuals. METHODS: We estimated the prevalence of current asthma (asthma attack in the past 12 months or current treatment for asthma) from data collected at inclusion in the Constances cohort study in 2013-2014. Analyses were performed separately in men and women, using robust Poisson regression for multivariate analysis. RESULTS: Using data from 34,100 participants in the cohort (men: 47.7 %; mean age: 44.6 years), the prevalence of current asthma was estimated to be 5.8 % (5.1 % in men, 6.4 % in women). The risk of asthma was increased in women with high body mass index (BMI) or waist circumference. In men, only a high waist circumference was associated with an increased risk of asthma. An association with low socioeconomic status was observed only among women. CONCLUSION: The associations of asthma with corpulence and socioeconomic status differed between men and women. Additional analyses should provide a better understanding of the mechanisms responsible for these differences.

A two-phase sampling survey for nonresponse and its paradata to correct nonresponse bias in a health surveillance survey.

BACKGROUND: The decline in participation rates in surveys, including epidemiological surveillance surveys, has become a real concern since it may increase nonresponse bias. The aim of this study is to estimate the contribution of a complementary survey among a subsample of nonrespondents, and the additional contribution of paradata in correcting for nonresponse bias in an occupational health surveillance survey. METHODS: In 2010, 10,000 workers were randomly selected and sent a postal questionnaire. Sociodemographic data were available for the whole sample. After data collection of the questionnaires, a complementary survey among a random subsample of 500 nonrespondents was performed using a questionnaire administered by an interviewer. Paradata were collected for the complete subsample of the complementary survey. Nonresponse bias in the initial sample and in the combined samples were assessed using variables from administrative databases available for the whole sample, not subject to differential measurement errors. Corrected prevalences by reweighting technique were estimated by first using the initial survey alone and then the initial and complementary surveys combined, under several assumptions regarding the missing data process. Results were compared by computing relative errors. RESULTS: The response rates of the initial and complementary surveys were 23.6% and 62.6%, respectively. For the initial and the combined surveys, the relative errors decreased after correction for nonresponse on sociodemographic variables. For the combined surveys without paradata, relative errors decreased compared with the initial survey. The contribution of the paradata was weak. CONCLUSION: When a complex descriptive survey has a low response rate, a short complementary survey among nonrespondents with a protocol which aims to maximize the response rates, is useful. The contribution of sociodemographic variables in correcting for nonresponse bias is important whereas the additional contribution of paradata in correcting for nonresponse bias is questionable.