QUANTITATIVE EVIDENCE SYNTHESIS: A METHODOLOGICAL MAPPING OF INDIRECT COSTS IN PATIENTS WITH SEVERE MENTAL ILLNESS (SMI...
Author(s)
Sakkarin Srutavidyakula, RPh, PharmD1, Sitaporn Youngkong, PhD2, Unchalee Permsuwan, DPhil3, Piyameth Dilokthornsakul, PharmD, PhD4.
1Chiang Mai University, Mueang Chiang Mai, Thailand, 2Mahidol University, Bangkok, Thailand, 3Chiang Mai University, Chiang Mai, Thailand, 4Faculty of Pharmacy, Chiang Mai University, Mueang Chiang Mai, Thailand.
1Chiang Mai University, Mueang Chiang Mai, Thailand, 2Mahidol University, Bangkok, Thailand, 3Chiang Mai University, Chiang Mai, Thailand, 4Faculty of Pharmacy, Chiang Mai University, Mueang Chiang Mai, Thailand.
OBJECTIVES: Patient-related indirect cost is substantial in severe mental illness (SMI) patients; however, the components of indirect cost assessed are methodologically heterogenous. This systematic review aimed to identify which indirect cost components are included in quantitative economic studies of SMI, and to characterise how these components are measured and valued.
METHODS: A systematic review of economic evaluation reporting patient-related indirect costs in SMI was conducted. Data were extracted and synthesised descriptively to compare (i) indirect cost components included in the study, (ii) measurement instruments and data sources, and (iii) valuation techniques.Subgroup analyses were conducted by clinical diagnosis to examine valuation techniques.
RESULTS: Thirty-nine studies were included. Most studies were conducted in high-income countries. Cost-of-illness models and retrospective designs predominated, with sample sizes ranging from small cohorts to large administrative datasets. Economic framework specification was inconsistent; 43.59% applied the Human Capital Approach (HCA), 5.13% the Friction Cost Approach (FCA), and 53.85% did not report a formal measurement framework. Absenteeism was the most frequently included component (61.54%), followed by presenteeism (43.59%) and unemployment/workforce exit (43.59%). Premature mortality was least frequently incorporated (20.51%). Presenteeism was typically captured using self-reported instruments, most commonly the Work Productivity and Activity Impairment (WPAI) questionnaire. Severe depression was modelled primarily through active workplace impairments, whereas schizophrenia was evaluated predominantly as a condition of permanent structural displacement. Valuation of most studies relied on average national wages. Only 28.21% of included studies clearly separated patient indirect costs from caregiver time.
CONCLUSIONS: Indirect cost methods in patients with SMI are varied in component selection, measurement, and valuation, with a dominant focus on administratively observable absenteeism and limited transparency regarding economic framework. More standardised, clearly reported approaches, the application of equity-smoothed wage baselines for labour market exclusion, and separation of patient versus caregiver costs are needed to improve comparability and policy relevance of SMI economic evidence.
METHODS: A systematic review of economic evaluation reporting patient-related indirect costs in SMI was conducted. Data were extracted and synthesised descriptively to compare (i) indirect cost components included in the study, (ii) measurement instruments and data sources, and (iii) valuation techniques.Subgroup analyses were conducted by clinical diagnosis to examine valuation techniques.
RESULTS: Thirty-nine studies were included. Most studies were conducted in high-income countries. Cost-of-illness models and retrospective designs predominated, with sample sizes ranging from small cohorts to large administrative datasets. Economic framework specification was inconsistent; 43.59% applied the Human Capital Approach (HCA), 5.13% the Friction Cost Approach (FCA), and 53.85% did not report a formal measurement framework. Absenteeism was the most frequently included component (61.54%), followed by presenteeism (43.59%) and unemployment/workforce exit (43.59%). Premature mortality was least frequently incorporated (20.51%). Presenteeism was typically captured using self-reported instruments, most commonly the Work Productivity and Activity Impairment (WPAI) questionnaire. Severe depression was modelled primarily through active workplace impairments, whereas schizophrenia was evaluated predominantly as a condition of permanent structural displacement. Valuation of most studies relied on average national wages. Only 28.21% of included studies clearly separated patient indirect costs from caregiver time.
CONCLUSIONS: Indirect cost methods in patients with SMI are varied in component selection, measurement, and valuation, with a dominant focus on administratively observable absenteeism and limited transparency regarding economic framework. More standardised, clearly reported approaches, the application of equity-smoothed wage baselines for labour market exclusion, and separation of patient versus caregiver costs are needed to improve comparability and policy relevance of SMI economic evidence.
Conference/Value in Health Info
2026-09, ISPOR Asia Pacific 2026, Bangkok, Thailand
Value in Health, Volume 55, Issue S1
Code
SA4
Topic
Study Approaches
Topic Subcategory
Literature Review & Synthesis
Disease
No Additional Disease & Conditions/Specialized Treatment Areas