O5D.5 Construction of finnish ISCO-88 job exposure matrix: examination of dataset with two different classification of occupations in consecutive censuses

Finnish Job exposure matrix (FINJEM) assesses occupational exposure for 84 factors in 311 FINJEM occupations. Finnish version of ISCO-88 International Standard Classification of Occupations 1988 (F-ISCO-88) occupational codes (n=445), used in population censuses from 1995 to 2009, often split into more than one FINJEM code. We describe the construction of a crosswalk between F-ISCO-88 codes and FINJEM codes and the resulting F-ISCO88 job exposure matrix (F-ISCO-88-JEM). In total, we found 1144 conversion candidate pairs from two sources: 1) Statistics Finland crosswalks from three sequential classification of occupations (2001–1997, 1997–1987, 1987–1980) combined with crosswalk between the classification of occupations in 1980 and FINJEM, and 2) preliminary expert judgement-based conversion of F-ISCO-88–FINJEM. We counted frequencies for all 9900 F-ISCO88 (in 1995) and FINJEM (1990) occupational code pairs from a study of neurodegenerative disease (n=103,969). Correctness of every candidate pair and prevalent non-candidate pairs was checked using occupational coding manuals of FINJEM and F-ISCO88, including occupational titles. Final list of accepted pairs was agreed by the authors. The number of verified F-ISCO-88–FINJEM conversion pairs was 835, including 88 pairs from non-candidates. In total, 397 (34.7%) candidate pairs were incorrect. We could solve FINJEM occupation for 84 252 (81.0% from total population) persons with direct conversions or verified conversion pairs. Occupation of the remaining 19 717 persons changed between 1990 and 1995. Direct conversions totaled 27 716 (26.6%) solutions and split F-ISCO-88 codes 56 536 (54.4%) solutions. The resulting F-ISCO-88–JEM comprises original FINJEM exposure estimates for direct conversions and estimates for split F-ISCO-88 codes, calculated using proportions of corresponding FINJEM codes as weights. A quarter of F-ISCO-88 codes can be converted to FINJEM codes in data with F-ISCO-88 occupational codes. This proportion could be tripled in a dataset including FINJEM and F-ISCO88 codes in consecutive censuses, resulting in more accurate exposure estimates.