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Scand J Public Health. 2017 Jun;45(4):350-356. doi: 10.1177/1403494817702759. Epub 2017 Apr 7.

Predictive validity of the Work Ability Index and its individual items in the general population.

Author information

1
1 Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden.
2
2 Center for Epidemiology and Community Medicine, Stockholm County Council, Stockholm, Sweden.
3
3 Swedish Social Insurance Inspectorate, Stockholm, Sweden.
4
4 Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
5
5 Department of Clinical Neuroscience, Karolinska Institutet, Division of Insurance Medicine, Stockholm, Sweden.
6
6 Department of Medical Science, Uppsala University, Uppsala, Sweden.

Abstract

AIM:

This study assesses the predictive ability of the full Work Ability Index (WAI) as well as its individual items in the general population.

METHODS:

The Work, Health and Retirement Study (WHRS) is a stratified random national sample of 25-75-year-olds living in Sweden in 2000 that received a postal questionnaire ( n = 6637, response rate = 53%). Current and subsequent sickness absence was obtained from registers. The ability of the WAI to predict long-term sickness absence (LTSA; ⩾ 90 consecutive days) during a period of four years was analysed by logistic regression, from which the Area Under the Receiver Operating Characteristic curve (AUC) was computed.

RESULTS:

There were 313 incident LTSA cases among 1786 employed individuals. The full WAI had acceptable ability to predict LTSA during the 4-year follow-up (AUC = 0.79; 95% CI 0.76 to 0.82). Individual items were less stable in their predictive ability. However, three of the individual items: current work ability compared with lifetime best, estimated work impairment due to diseases, and number of diagnosed current diseases, exceeded AUC > 0.70. Excluding the WAI item on number of days on sickness absence did not result in an inferior predictive ability of the WAI.

CONCLUSIONS:

The full WAI has acceptable predictive validity, and is superior to its individual items. For public health surveys, three items may be suitable proxies of the full WAI; current work ability compared with lifetime best, estimated work impairment due to diseases, and number of current diseases diagnosed by a physician.

KEYWORDS:

Self-assessment; WAI; absenteeism; discriminative ability; public health; sick leave; sickness absence; work capacity evaluation

PMID:
28385066
DOI:
10.1177/1403494817702759
[Indexed for MEDLINE]

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