Validation studies

The primary validation study was undertaken in 152 patients with Rheumatoid Arthritis in the UK.

Patients were administered the VOLP. Half of patients then randomised to complete work diary for 2 weeks (for reliability). Patients then completed a follow-up questionnaire based on the VOLP.

The objectives of the study were:

• To confirm face validity
• Assess construct validity in terms of discriminant validity and convergent validity
• Assess reliability using test-retest from baseline and follow-up questionnaires in patients with no change in health from visit 1, and a comparison of reported presenteeism with work diary

Reference

Zhang W, Bansback N, Kopec J, Anis AH. Measuring time input loss among patients with rheumatoid arthritis: validity and reliability of the Valuation of Lost Productivity questionnaire. J Occup Environ Med. 2011 May;53(5):530-6.