Diverse questionnaires and scales were developed or validated in a French version: personality questionnaires (Consoli et al, 1993), a structured diagnostic interview to identify depressive episodes (Duburcq et al, 1999), and a diagnostic questionnaire for migraine (Nachit-Ouinekh F et al, 2005). French versions of two questionnaires widely used
internationally to assess exposure to psychosocial factors at work were established and validated for the first time in the GAZEL Cohort Study: Karasek's Job Content Questionnaire(Niedhammer, 2002), and Siegrist’s Effort/Reward Imbalance scale (Niedhammeret al, 2000); GAZEL data about the latter have been included in international analyses intended to improve the transcultural comparability of the measurement of stress at work (Tsutsumi et al, 2009). Factors associated with self-reporting of weight and height (Niedhammeret al, 2000) and of chronic diseases (Metzger et al, 2002) were also studied.Statistical work has also aimed at improving the ability to take into account the longitudinal nature of the data and their repeated collection, which involves the existence of missing data (Guéguen et al, 2000; Nakache et al, 2004) and to assess the effects of confounding due to smoking in the study of various diseases (Lagorio et al, 1992). The establishment of a biobank associated with the cohort was also the occasion to deepen ourunderstanding of the logistic and practical aspects of this research tool (Zins et al, 2003).Miscellaneous researchThe diversity of the data collected in GAZEL has made it possible to perform studies on various topics according to the interest of different researchers. Migraine was the topic of a research project covering a subsample of the cohort (Michel et al, 1997a; Michel et al, 1997b; Dartigues et al, 1998; Nachit-Ouinekh et al, 2005). Diverse characteristics of left-handers have been studied (Faurie et al, 2006; Faurie et al, 2008). Self-rated health status, an indicator widely used in epidemiology, was also the object of detailed analyses of its associations with incident morbidity (Goldberg et al, 2001) and with numerous risk factors of diverse types (Singh-Manoux et al, 2006).Special mention should be made of the study of the psychological disorders of the children of cohort participants. A project begun in 1991 allowed the inclusion of more than 2500 children
then aged from 4 to 16 years, who were first followed via their parent GAZEL Cohort Study volunteer, and then directly as they grew older. Several topics were covered: contacts with health and mental health care providers and special education personnel for psychological reasons (Fombonne et al, 1997a, 1997b), symptoms of hyperactivity (Galéra et al, 2005), consumption of tobacco, alcohol, and illegal drugs (Melchior et al, 2008; Galéra et al, 2008, Melchior et al, 2009b), suicidal behavior (Galéra et al, 2008), and school trajectory (Galéra et al, 2009). These subjects, who have recently become young adults, have been asked to participate directly in an independent cohort as part of the “Tempo” project.