Occupational Medicine Advance Access published online on June 20, 2008
Occupational Medicine, doi:10.1093/occmed/kqn070
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Psychometrics and validation of a screening instrument for sickness absence
1 Department of Epidemiology, Maastricht University, Maastricht, The Netherlands
2 Present address: Department of Psychosocial Research and Epidemiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
3 Present address: Dow Chemical Terneuzen, Terneuzen, The Netherlands
Background Absence from work due to psychosocial health complaints has considerable negative effects for employees, employers and society. A better and more effective strategy would be early identification of employees at risk for psychosocial sickness absence and early intervention to prevent sickness absence as far as possible.
Aims To assess psychometric characteristics and the external validation of a recently developed screening instrument, called ‘Werkwijzer’, for the identification of employees at risk for sickness absence due to psychosocial health complaints.
Methods Exploratory factor analysis was applied on items of the instrument. Cronbach's alpha coefficient was used to determine internal consistency of the subscales. Sum scores on the screening instrument were correlated to absenteeism data to determine their potential for predicting sickness absence. Predictive value was investigated, using objective sickness absence data as criterion measure. Sensitivity and specificity rates were calculated for external validation.
Results For both men and women, three interpretable factors were found. Sum scores on the instrument showed low correlations with sickness absence. The association between ‘being at risk’ (yes/no) and sickness absence (yes/no) was odds ratio (OR) 3.1 (95% CI 1.5–6.5) for men and OR 2.0 (95% CI 1.4–2.7) for women. Sensitivity scores were rather low, whereas specificity scores were remarkably high.
Conclusions The results of this study provide the screening instrument a theoretic and scientific basis. Predictive value is promising, when absence is treated as a dichotomous measure. Sensitivity and specificity were unvarying during the development and validation phases of the instrument.
Keywords Instrument; prediction; psychometric; sickness absence
Correspondence to: Saskia F. A. Duijts, The Netherlands Cancer Institute, NKI-AvL, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands. Tel: +31 20 5122485; fax: +31 20 5122322; e-mail: s.duijts{at}nki.nl