Work Ability Index: Validation and Model Comparison of the Malaysian Work Ability Index (WAI)

Sobhan Lavasani, Nor Wahiza Abdul Wahat


Purpose: The study aimed to (1) measure the Work Ability of employees with disability; (2) assess the factor structure of different potential models of Work Ability Index (WAI) for employees with disability; and (3) identify the best factor structure of Work Ability Index for employees with disability in the Malaysian cultural context.

Methods: Data was collected using the Work Ability Index (WAI) translated into Malay language. The study sample consisted of 275 employees with physical disability, from both public and private sectors across Malaysia. Descriptive statistics were calculated using IBM SPSS 20 to evaluate the score of each subscale and the cumulative index of Work Ability among employees with disability. Confirmatory factor analysis (CFA) was conducted using IBM SPSS AMOS 21 to assess the factor structure of WAI and evaluate the validity of the proposed models for employees with disability.

Results: The WAI scores were 29.5% poor, 35.3% moderate, 28.7% good and 6.5% excellent. In the validation process, a non-orthogonal two dimensional structure was identified. In this model of WAI, the subscales were attributed to two factors: (1) subjective Work Ability factor that consisted of subscales 1, 2 and 7; and (2) health-related Work Ability factor, comprised of subscales 3, 5, 4 and 6. These two factors were positively correlated, which indicates that employees with disability who exhibit positive subjective Work Ability tend to also report positive health- related Work Ability.

Conclusion: This study has provided the first Malay version of WAI and has paved the way for future studies on work ability among employees with disability. The WAI translation has been validated among employees with disability and has shown adequate psychometric properties, thus making it suitable to investigate the associations between aspects of work and their impact on the health of employees with disability. 


Employees with disability; Work Ability Index; Validity and Reliability Test

Full Text:



Bentler P M(1990). Comparative fit indexes in structural models. Psychological Bulletin; 107(2): 238-246. PMid:2320703

Berg T I (2010). The role of work ability and health on sustaining employability, PhD thesis. Rotterdam, The Netherlands: Erasmus University.

Berg T I, Alavinia S M, Bredt F J, Lindeboom D, Elders L A, Burdorf A (2008). The influence of psychosocial factors at work and lifestyle on health and work ability among professional workers. International archives of occupational and environmental health;81(8):1029–1036. PMid:18175140 PMCid:PMC2413125

Chau PYK(1997). Reexamining a model for evaluating information centre success using a structural equation modelling approach. Decision Sciences; 28(2): 309–334.

Gould R, Ilmarinen J, Järvisalo J, Koskinen S (2008). Dimensions of Work Ability Results of the Health 2000 Survey. Helsinki (Finland): Finnish Institute of Occupational Health

Hooper D, Coughlan J, Mullen M(2008). Structural equation modelling: Guidelines for determining model fit. Electronic Journal of Business Research Methods; 6(1): 53-60.

Ilmarinen J (2009). Work ability- a comprehensive concept for occupational health research and prevention. Scandinavian journal of work, environment & health; 35(1): 1–5. PMid:19277432

Ilmarinen J, Tuomi K, Eskelinen L, Nygård C H, Huuhtanen P, Klockars M (1991). Background and objectives of the Finnish research project on ageing workers in municipal occupations. Scandinavian journal of work, environment & health; 17(1): 7–11. PMid:1792532

Ilmarinen J, Rantanen J(1999). Promotion of work ability during ageing. American Journal of Industrial Medicine; 36(S1): 21–23.<21::AID-AJIM8>3.0.CO;2-S

Ilmarinen J, Tuomi K (2004). Past, present and future of work ability. Helsinki: Finnish Institute of Occupational Health; People and Work, Research Reports 65: 1–25

Kline R B (2010). Principles and practice of structural equation modelling. New York: The Guilford Press, Third Edition

Lavasani S S, Wahat N W A, Ortega A (2015). Work Ability of employees with disabilities in Malaysia. Disability, CBR & Inclusive Development; 26(2): 22-46.

MacCallum R C, Browne M W, Sugawara H M (1996). Power analysis and determination of sample size for covariance structure modelling. Psychological Methods; 1(2):130-149.

Martus P, Jakob O, Rose U, Seibt R, Freude G (2010). A comparative analysis of the Work Ability Index. Occupational medicine (Oxford, England); 60(7): 517–24. PMid:20573840

Pohjonen T, Ranta R (2001). Effects of worksite physical exercise intervention on physical fitness, perceived health status, and work ability among home care workers: five-year follow-up. Preventive medicine; 32(6):465–475. PMid:11394950

Portal Rasmi PDKNet(2014). Career and employment opportunities for women with disabilities in Malaysia

Radkiewicz P, Widerszal-Bazyl M(2005). Psychometric properties of Work Ability Index in the light of comparative survey study. International Congress Series; 1280: 304–309.

Tuomi K, Ilmarinen J, Jahkola A, Katajarinne L, Tulkki A(1998). Work Ability Index. Helsinki: Finnish Institute of Occupational Health.

Tuomi K, Ilmarinen J, Jahkola A, Katajarinne L, Tulkki A(1998). An approved version of the Work Ability Index. Helsinki. Finnish Institute of Occupational Health, Occupational health-series 19.

Tuomi K, Huuhtanen P, Nykyri E, Ilmarinen J(2001). Promotion of work ability, the quality of work and retirement. Occupational Medicine; 51(5): 318–324.

Tuomi K, Vanhala S, Nykyri E, Janhonen M (2004). Organisational practices, work demands and the well-being of employees: a follow-up study in the metal industry and retail trade. Occupational Medicine; 54(2): 115–121.

Wheaton DE (1977). Assessing reliability and stability in panel models. In D. R. Heise (Ed), Sociological Methodology: 84-136. San Francisco: Jossey-Bass.

Wu M L (2009). Structural equation modelling: Amos operation and application. Taipei, Taiwan Wu-Nan Book Inc

de Zwart B C H, Frings Dresen M H W, Van Duivenbooden J C (2002). Test–retest reliability of the Work Ability Index questionnaire. Occupational medicine; 52(4): 177–181.


Copyright (c) 2016 Sobhan Lavasani, Nor Wahiza Abdul Wahat

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Supported by:


© Disability, CBR & Inclusive Development