Screening Manual and Office Workers for Risk of Long-term Sickness Absence: Cut-off Points for the Work Ability Index

Objectives: The aim of this study was to investigate the Work Ability Index (WAI) as a tool to screen for risk of different durations of long-term sickness absence (LTSA) among manual and office workers.

Methods: The prospective study comprised a cohort of 3049 (1710 manual and 1339 office) workers participating in occupational health surveys between 2010-2012. The survey date was set as baseline and incident LTSA episodes of different duration (>14, >28, >42, >60, and >90 days) were retrieved from an occupational health register in the year following the survey. Baseline WAI scores were associated with LTSA episodes occurring (no/yes) during one-year follow-up by logistic regression analysis in a random sample (N=1000) of the cohort. Predictions of LTSA risk were then validated among the workers not included in the random sample.

Results: The odds of LTSA episodes at follow-up decreased with increasing baseline WAI scores (ie, better work ability). The WAI accurately predicted the risk of future LTSA episodes >28, >42, >60 days, but over-predicted the risk of LTSA episodes >14 and >90 days. The WAI discriminated between workers at high and low risk of LTSA episodes of all durations. Office workers had higher WAI scores than manual workers. Consequently, false-negative rates were higher among office workers and false-positive rates were higher among manual workers at each WAI cut-off point.

Conclusion: The WAI could be used to screen both manual and office workers for risk of LTSA episodes lasting >28, >42, >60 days. WAI cut-off points depend on the objectives of screening and may differ for manual and office workers.