Validity of the Workers Productivity and Activity Impairment Questionnaire: Specific Health Problem (WPAI:SHP) in patients with systemic sclerosis

Kathleen Morrisroe, Wendy Stevens, Molla Huq, Joanne Sahhar, Gene Siew Ngian, Jane Zochling, Janet Roddy, Susanna M. Proudman, Mandana Nikpour, the Australian Scleroderma Interest Group (ASIG)

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Abstract

Objective. To evaluate the construct validity of the Workers Productivity and Impairment Activity Index: Specific Health Problem (WPAI:SHP) in Australian systemic sclerosis (SSc) patients. Methods. SSc patients, identified through the Australian Scleroderma Cohort Study database, completed the WPAI:SHP and a quality of life instrument (PROMIS-29) cross-sectionally. The construct validity of the WPAI:SHP was assessed by the correlations between the WPAI:SHP and a range of SSc health states. Non-parametric correlation, including Spearman's correlation (ρ), was used to test the validity of WPAI:SHP and ability to distinguish between different health states. Results. A total of 476 completed questionnaires was returned, equating to a response rate of 63.7%. Among those under 65 years of age, 155 patients (55.2%) were in paid employment. Employed patients had a mean (± SD) age of 56.5 (9.8) years and were predominantly female (87.3%) with limited disease subtype (75.6%). The WPAI:SHP showed construct validity based on moderate to strong correlations with health status as assessed by a range of health outcome measures including disease activity (ρ=0.34-0.39, p=0.001), physical function (ρ=0.55-0.62, p=0.001), disease severity(ρ=0.55-0.62, p=0.001), fatigue (ρ= 0.62-0.63, p=0.001), pain (ρ=0.68-0.71, p=0.001), and breathlessness (ρ=0.39-0.46, p=0.001). Furthermore, according to the effect size, the WPAI:SHP scores have a large discriminative ability (d=1.26-1.47) for distinguishing SSc patients with different health outcomes. Conclusion. The WPAI is a valid questionnaire for assessing impairments in paid employment and social activities in SSc patients, and for measuring the relative differences between SSc patients with varying health states.

Original languageEnglish
Pages (from-to)S130-S137
Number of pages8
JournalClinical and Experimental Rheumatology
Volume35
Issue number4 - Suppl. 106
Publication statusPublished - 1 Jan 2017

Keywords

  • Absenteeism
  • Presenteeism
  • systemic sclerosis
  • Workers productivity and activity impairment questionnaire

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