Estimating productivity costs in health economic evaluations: a review of instruments and psychometric evidence.

Health economic evaluations (i.e. cost-effectiveness appraisal of an intervention) are useful aids for decision makers responsible for the allocation of scarce healthcare resources. The relevance of including health-related productivity costs (or benefits) in these evaluations is increasingly recognized and, as such, reliable and valid instruments to quantify productivity costs are needed. Over the years, a number of work productivity instruments have emerged in the literature, along with a growing body of psychometric evidence. The overall aim of this paper is to provide a review of available instruments with potential for estimating health-related productivity costs. This included the Health and Labor Questionnaire, Health and Work Performance Questionnaire, Health-Related Productivity Questionnaire Diary, Productivity and Disease Questionnaire, Quantity and Quality method, Stanford Presenteeism Scale 13, Valuation of Lost Productivity, Work and Health Interview, Work Limitations Questionnaire, Work Productivity and Activity Impairment Questionnaire, and Work Productivity Short Inventory. Critical discussions on the instruments' overall strengths and limitations, applicability for health economic evaluations, as well as the methodological quality of existing psychometric evidence were provided. Lastly, a set of reflective questions were proposed for users to consider when selecting an instrument for health economic evaluations.