MENTAL HEALTH COMORBIDITY DOUBLES LIFETIME HEALTHCARE COSTS IN INFLAMMATORY ARTHRITIS: EVIDENCE FROM A LINKED ELECTRONIC HEALTH RECORD COHORT
Author(s)
Xiaoyu Zhang1, James Galloway, PhD2, Sam Norton, PhD2, Peizhe Yan, MSc3, Kang Wang, MSc2, Huajie Jin, PhD4.
1PhDstudent, King's College London, LONDON, United Kingdom, 2King's College London, London, United Kingdom, 3King's Health Economics, King's College London, London, United Kingdom, 4King's College London, LONDON, United Kingdom.
1PhDstudent, King's College London, LONDON, United Kingdom, 2King's College London, London, United Kingdom, 3King's Health Economics, King's College London, London, United Kingdom, 4King's College London, LONDON, United Kingdom.
OBJECTIVES: Depression and anxiety affect up to one-third of patients with inflammatory arthritis (IA) yet are systematically underdetected in rheumatology care. Their contribution to lifetime NHS healthcare costs remains poorly quantified, limiting the economic case for integrated mental health identification. This study estimated the lifetime healthcare cost burden of comorbid common mental disorders (CMD) in IA using linked electronic health record data and evaluated the sensitivity of lifetime cost estimates to methodological approach.
METHODS: A retrospective cohort study was conducted using linked CRIS-HES-ONS data (n=1,288 IA patients with comorbid CMD; NHS South London, 2007-2019). Healthcare costs were estimated across disease phases (initial, continuing, terminal) using generalised linear models with Gamma family and log link, and a two-part hurdle model for the terminal phase, where a substantial proportion of patients had zero recorded costs. Lifetime costs were derived via phase-of-care integration using Hwang-Wang relative survival extrapolation and compared against conventional annual extrapolation to assess methodological sensitivity.
RESULTS: Phase-specific annual costs ranged from £9,900 in the continuing phase to £38,300 in the terminal phase. Lifetime cost estimates differed substantially by method: conventional annual extrapolation yielded £177,000 per patient versus £105,000 under phase-of-care integration, a £72,000 discrepancy arising from differential weighting of disease phases across survival time. All-cause outpatient utilisation in this comorbid cohort was approximately 1.6 times higher than published rates for general IA populations, consistent with the excess resource burden of unmanaged mental health comorbidity.
CONCLUSIONS: Comorbid CMD in IA is associated with substantial and previously underestimated lifetime healthcare costs. Conventional costing methods materially overestimate lifetime expenditure by ignoring disease phase heterogeneity. These findings establish an empirical cost foundation for evaluating integrated mental health screening in NHS rheumatology and highlight that the economic case for earlier CMD identification extends well beyond mental health services alone.
METHODS: A retrospective cohort study was conducted using linked CRIS-HES-ONS data (n=1,288 IA patients with comorbid CMD; NHS South London, 2007-2019). Healthcare costs were estimated across disease phases (initial, continuing, terminal) using generalised linear models with Gamma family and log link, and a two-part hurdle model for the terminal phase, where a substantial proportion of patients had zero recorded costs. Lifetime costs were derived via phase-of-care integration using Hwang-Wang relative survival extrapolation and compared against conventional annual extrapolation to assess methodological sensitivity.
RESULTS: Phase-specific annual costs ranged from £9,900 in the continuing phase to £38,300 in the terminal phase. Lifetime cost estimates differed substantially by method: conventional annual extrapolation yielded £177,000 per patient versus £105,000 under phase-of-care integration, a £72,000 discrepancy arising from differential weighting of disease phases across survival time. All-cause outpatient utilisation in this comorbid cohort was approximately 1.6 times higher than published rates for general IA populations, consistent with the excess resource burden of unmanaged mental health comorbidity.
CONCLUSIONS: Comorbid CMD in IA is associated with substantial and previously underestimated lifetime healthcare costs. Conventional costing methods materially overestimate lifetime expenditure by ignoring disease phase heterogeneity. These findings establish an empirical cost foundation for evaluating integrated mental health screening in NHS rheumatology and highlight that the economic case for earlier CMD identification extends well beyond mental health services alone.
Conference/Value in Health Info
2026-11, ISPOR Europe 2026, Vienna, Austria
Value in Health, Volume 29, Issue 12S
Code
EE503
Topic
Economic Evaluation, Real World Data & Information Systems
Topic Subcategory
Cost/Cost of Illness/Resource Use Studies
Disease
Mental Health (including addiction), Musculoskeletal Disorders (Arthritis, Bone Disorders, Osteoporosis, Other Musculoskeletal)