Abstract
BACKGROUND: Productivity is utilised inconsistently in value assessment and poses methodological and conceptual challenges for estimation. This systematic literature review aims to understand how productivity gain/loss for patients and caregivers was measured in health economic evaluation, identify the preferred instruments to capture productivity gain/loss and assess their properties. METHODS: A systematic literature review was conducted using PubMed, Ovid MEDLINE, Embase, Japan-specific (J-STAGE and Ichushi Web) and economic literature databases (Cost-Effectiveness Analysis (CEA) Registry, Paediatric Economic Database Evaluation (PEDE) and National Health Service Economic Evaluation Database (NHS EED)). Additional relevant data were identified using clinical trial registries and grey literature searches. Studies published between January 2021 and December 2023 which presented economic evaluations with outcomes relevant to productivity measures were included. Instruments were selected for practical relevance and frequent use in studies, while research-specific and single-study questionnaires were excluded. RESULTS: Among 1431 published health economic evaluations with productivity in the assessment, 152 were included in this review. These studies were almost equally distributed over the 3-year period, with a slightly higher number in 2023 versus 2021 [54 (35.5%) versus 48 (31.6%)]. In total, 118/152 studies reported patient measures only, 14/152 reported caregiver measures only and 20/152 reported both patient and caregiver measures. Based on the inclusion criteria, 20 of the 88 identified instruments were further investigated in this review. The Work Productivity and Activity Impairment Questionnaire (WPAI) [23 (15.1%)], Institute for Medical Technology Assessment (iMTA) Productivity Cost Questionnaire (iPCQ) [23 (15.1%)] and Trimbos/iMTA Questionnaire for Costs associated with Psychiatric Illness (TIC-P) [(8 (5.3%)] were the most commonly used instruments. All three instruments were reported as valid and reliable. All three instruments reported absenteeism, presenteeism and overall work impairment. WPAI additionally included information on daily activity impairment. The human capital approach (n = 18) and the friction cost approach (n = 17) were utilised to assign monetary value to the lost productivity. CONCLUSIONS: This review identified a significant number of health economic evaluations between 2021 and 2023, which included productivity loss in the assessment. Various instruments were used to measure productivity loss in these studies, while a few instruments were commonly used across studies. To ensure consistent measurement of productivity, it is crucial to establish a standard tailored to a country or region, considering differences across countries or regions. Furthermore, necessary adaptations should be made on the basis of the specific health intervention being studied. Last, maintaining transparency in all productivity evaluations is vital.