Work ability index and perceived work ability as predictors of disability pension: a prospective study among Finnish municipal employees.

OBJECTIVES: We analyzed the work ability index (WAI) and its first item (work ability score, WAS) - and subsequent four-year changes thereof - as predictors of disability pension (DP).

METHODS: We linked survey responses of 5251 Finnish municipal employees, aged 44-58 years, to pension and death register data until 2009. Job content (physical, mental, or mixed) was based on observation. Baseline (1981) WAI was divided into poor (<27), moderate (28-36), and good/excellent (>37) and WAS into poor (0-5), moderate (6-7), and good/excellent (8-10). Four-year changes in these scores were classified as strong decline (<lowest 15th percentile), slight decline, and no change/improved. Cox regression and receiver operating characteristic (ROC) analysis were used.

RESULTS: During follow-up, 2057 subjects were granted DP. Compared to those with good/excellent WAI, the hazard ratio (HR) for DP related to moderate and poor WAI, respectively, was 2.0 (95% CI 1.8-2.2) and 5.0 (95% CI 4.4-5.6), adjusted for sociodemographic variables and job content. For WAS, the HR were 1.8 (95% CI 1.6-2.0) and 3.4 (95% 3.0-3.8). Four-year decline in WAI/WAS further increased the risk. During the first four years of follow-up, the area under the curve (AUC) for WAI at cut-off point 27 was 0.66 (sensitivity 49.2% and specificity 82.9%) and 0.64 for cut-off point 36 (sensitivity 84.2% and specificity 44.3%). For WAS at cut-off point 5, the figures were AUC 0.63 (sensitivity 41.9% and specificity 85.0%) and AUC 0.65 for cut-off point 7 (sensitivity 78.2% and specificity 52.7%).

CONCLUSION: The single-item WAS can be considered a reasonable alternative to the seven-item WAI in describing the risk of DP and as a prognostic tool.