Development of an asthma specific job exposure matrix and its application in the epidemiological study of genetics and environment in asthma (EGEA)

Abstract

Objectives-To develop a method suitable for estimating exposure risks in population studies of asthma from job titles and international codes, by combining a new job exposure matrix (JEM) with the expert judgement approach. The method was applied in the French epidemiological study of the genetics and environment in asthma (EGEA). Methods-The JEM contains 22 exposure groups including 18 high risk groups based on known risk factors for occupational asthma, divided into high molecular weight agents, low molecular weight agents, and mixed environments. After applying the JEM to job codes, exposure estimates for each subject were reevaluated by examining job title texts. Three high risk exposure estimates for asthma were compared: firstly, applying the JEM to original codes (from diVerent coders in each study centre); secondly, applying the JEM to revised codes (from one experienced coder); and thirdly, after reviewing JEM exposure estimates in the light of job title texts. Results-The study comprised 173 cases with asthma and 285 controls (age 18-65). Odds ratios (ORs) for asthma for high risk jobs were 1.0 (95% confidence interval (95% CI) 0.6 to 1.7), applying the JEM to original codes; 1.4 (95% CI 0.8 to 2.3), applying the JEM to revised codes; and 1.7 (95% CI 1.1 to 2.7), applying the JEM and subsequently re-evaluating exposure estimates from job title texts. Asthma ORs were 1.4 (95% CI 0.6 to 2.9) for high molecular weight agents, 2.3 (95% CI 1.2 to 4.4) for low molecular weight agents, and 2.1 (95% CI 0.9 to 5.2) for mixed environments. Conclusions-This asthma JEM, when enhanced by expert re-evaluation of exposure estimates from job title texts, may be a useful tool in general population studies of asthma. In this study, a 1.7-fold increase in prevalence odds of high risk exposures was found among asthmatic workers compared with controls, with risk magnitude varying for diVerent classes of exposure. (Occup Environ Med 2000;57:635-641)

Occupational exposures and uncontrolled adult-onset asthma in the European Community Respiratory Health Survey II

“…In the present analysis we evaluated occupational exposure to specific asthmagens by an asthma-specific JEM combined with an expert review step [13,19]. Re-evaluation by an expert blinded to disease status ensured the objectiveness of the method.…”

“…Re-evaluation by an expert blinded to disease status ensured the objectiveness of the method. To limit misclassification errors, specificity was favoured; a job was classified as exposed to asthmagen only if the probability of exposure was high for an important number of subjects in that job [19]. There is no evidence for recall bias in job history [22], but we are not aware of misclassification errors especially for 10-year exposure.…”

“…1) Uncontrolled asthma is associated with occupational exposure to asthmagens, including exposure to HMW agents, LMW agents and cleaning agents, but not to a priori defined nonasthmagenic agents [5,19]. 2) These associations are expected for adult-onset asthma but are unexpected for childhood-onset asthma [5].…”

“…Never asthma n=5867 job-exposure matrix (JEM) (cesp.vjf/inserm.fr/asthmajem) [19] followed by an expert re-evaluation step, as described elsewhere [13]. This classification of nonasthmagenic agents [5] may be discussed especially for possible exposure to irritants.…”

Job titles classified into socioeconomic and occupational groups identify subjects with increased risk for respiratory symptoms independent of occupational exposure to vapour, gas, dust, or fumes

“…Occupational exposure can be estimated using a single-item question of exposure or by using a JEM based on job titles [14,36]. Some argue that a JEM leads to more accurate measures of occupational exposure, while others have reported that the difference between self-reporting and JEM are less than expected and that a question of VGDF-exposure is applicable in epidemiological research [14–16].…”