Table 1 Results of the quality assessment of 20 selected studies with quantitative information on associations between individual and work-related factors and work ability, as measured with the Work Ability Index
Study (first author)DesignQuality score (0–7)Study populationSample sizeResponseSelection biasMeasurement errorBlindingConfounding
Aittomaki et al 200312Cross-sectional61101111
Eskelinen et al 199113Cross-sectional411?0101
Fischer et al 200614Cross-sectional51011011
Goedhard et al 199815Cross-sectional201??1?0
Kaleta et al 200628Cross-sectional30101?11
Laitinen et al 200516Cross-sectional511011?1
Laitinen et al 200516Prospective cohort51101011
Martinez et al 200629Cross-sectional51111010
Monteiro et al 200617Cross-sectional61111?11
Nygard et al 199118Cross-sectional411?1100
Pohjonen 2001a19Prospective cohort511??111
Pohjonen 2001b20Cross-sectional61111011
Pranjic et al 200621Cross-sectional51111010
Punakallio et al 200422Cross-sectional611111?1
Punakallio et al 200422Prospective cohort71111111
Sjogren-Ronka et al 200223Cross-sectional61111101
Tuomi et al 199124Prospective cohort511?1011
Tuomi et al 199726Prospective cohort61111011
Tuomi et al 200125Cross-sectional51110011
Tuomi et al 200427Prospective cohort51101011
  • 1, “sufficiently met”; 0, “not sufficiently met”; ‘?’, information was lacking.