Understanding psoriasis care costs and the impact of comorbidities: a time-driven activity-based costing analysis in an integrated practice unit

OBJECTIVES: The study aims to evaluate the cost of managing psoriasis and its comorbidities across multiple medical departments and to identify cost determinants based on patient, disease and treatment characteristics. Additionally, it compares the cost of care with reimbursements under the fee-for-service (FFS) system to assess how well they reflect patient-specific care needs. DESIGN: Seven-step, time-driven activity-based costing (TD-ABC) analysis based on direct observations and interviews to generate patient-level cost estimates over the full cycle of care for participants prospectively enrolled in a clinical trial. SETTING: An integrated practice unit (IPU) at a Belgian University Hospital, centred around the treatment of psoriasis, including the management of associated comorbidities. PARTICIPANTS: A total of 52 patients meeting the trial's inclusion criteria, enrolled between January 2023 and November 2023, undergoing treatment within the IPU. RESULTS: The individual cost of care over a 6-month period ranged from €169.78 to €1454.97, highlighting significant variability. Major cost drivers included mental health status and disease severity. Additionally, the presence of one or more comorbidities had a substantial impact on care costs, affecting not only expenses directly related to comorbidity management but often also those associated with dermatological care. Finally, a comparison between the TD-ABC cost variability and reimbursement tariffs variability revealed disparities, indicating that current tariffs do not sufficiently account for patient-specific cost differences. CONCLUSIONS: Healthcare delivery and costing studies often adopt a fragmented approach, limiting cost insights into the full cycle of care for a medical condition. The TD-ABC methodology can address this gap by generating detailed, patient-level cost estimates for both primary illness management and related comorbidities. Our findings underscore the importance of including comorbidity-related costs when discussing a condition's overall economic burden while also revealing significant cost variability among patients with the same disease. Notably, these variations are not sufficiently addressed by the current FFS reimbursement system. TRIAL REGISTRATION NUMBER: NCT05480917 (ClinicalTrials.gov).