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
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.