title: Comparison of a French pediatric type 1 diabetes cohort's responders and non-responders to an environmental questionnaire.
abstract: BACKGROUND
  Type 1 diabetes (T1D) incidence has doubled since the 1980's for children aged <5 years old, potentially relevant environmental factors having thus to be sought early in the patient's life. The identification of environmental factors that can explain the changing epidemiology of T1D requires comprehensive environmental inquiries. However, a limitation is the willingness of patients and families to complete these environmental questionnaires. Our objective was to identify patients' personal and social characteristics predictive of the return, time to the return and completeness of a comprehensive environmental questionnaire.
  
  
  METHODS
  The parents of 2832 T1D patients aged <15 years old enrolled in the French Isis cohort were sent a 1379-item environmental questionnaire. A geographic information system was used to collect information on patients' socioeconomic environment. Multivariate statistical analyses were conducted to identify predictors of questionnaire return, time to its return and its completeness.
  
  
  RESULTS
  Within 6 months, 867 (30.6%) questionnaires were returned. Socioeconomic environment was strongly associated with the probability of response, with fewer responses from cities with high Townsend deprivation index (p =2 × 10-7), high unemployment (p =0.005), blue-collar workers' rate (p =0.0002) and household overcrowding (p =0.02). Response rates were similar for male and female patients, but were higher for less severely affected patients (p =0.006) and younger patients (p =5 × 10-5). When returned, completeness was high with a mean of 96%.
  
  
  CONCLUSIONS
  Identification of personal or socioeconomic characteristics differing between questionnaire responders and non-responders may help target future environmental investigations on those patients who will more likely return the information, and reduce bias using these variables to stratify the analyses.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale (U986), Paris Sud University, Le Kremlin Bicêtre, France. sophie.le-fur@inserm.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Le Fur
authors.forename: Pierre
authors.initials: P
authors.lastname: Bougnères
authors.forename: Alain-Jacques
authors.initials: AJ
authors.lastname: Valleron
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D005602:France / Q000453:epidemiology; D040362:Geographic Information Systems; D006442:Glycated Hemoglobin; D006801:Humans; D008297:Male; D012111:Residence Characteristics; D012720:Severity of Illness Index; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires
chemical_list: D006442:Glycated Hemoglobin