Economic evaluation of inpatient medication reconciliation with a subtraction strategy

Abstract

Background: University-based hospitals in Thailand face increasing financial strain due to insufficient reimbursement for inpatient care. The public health financing system comprises three major schemes: the Universal Coverage Scheme (UCS), Social Security Scheme (SSS), and Civil Servant Medical Benefit Scheme (CSMBS), which differ in funding mechanisms and reimbursement rates. Although all schemes apply the Diagnosis-Related Groups (DRG) system for inpatient payment, variations in base rates and case-mix complexity often leave tertiary hospitals underfunded. Medication reconciliation (MR) with a subtraction strategy-deducting patients' home medications from discharge prescriptions-has been implemented to optimize hospital resources. This study aimed to evaluate cost savings and identify key determinants influencing the economic outcomes of MR across public insurance schemes.

Methods: We conducted a retrospective cohort study of 563 hospitalized internal medicine patients at a university-based hospital. Of these, 324 underwent MR with subtraction. Cost savings and reimbursement margins were calculated from the provider's perspective. Patients were stratified by healthcare scheme (CSMBS, UCS, SSS) and length of stay (LOS). Generalized Linear Mixed Models were used to identify factors associated with cost savings.

Results: The highest mean cost savings per patient were observed in the SSS group (508.5 ± 56.1 THB [~ 14.1 USD]), and the lowest in CSMBS (133.5 ± 23.6 THB [~ 3.7 USD]). Prolonged LOS was associated with significantly greater savings (LOS > 21 days: IRR = 2.45, p < 0.001). SSS patients achieved the greatest overall savings (IRR = 3.95, p < 0.001). Nonetheless, negative reimbursement margins persisted across all schemes.

Conclusions: Although MR with subtraction achieved measurable cost savings, it failed to offset reimbursement deficits. Broader financial reforms are needed to ensure sustainability, with MR positioned as a potentially scalable strategy within value-based care frameworks.

Keywords: Cost minimization; Economic efficiency; Hospital policy; Medication reconciliation.

Fig. 1

Effect of Healthcare Schemes and Length of Stay on Cost Savings Using a Mixed-effects Generalized Linear Model (GLMM): - A: Healthcare schemes: Compared to CSMBS (reference group), patients under UCS (out-of-province) and UCS (in-province) exhibited 22.6% and 61.6% higher cost savings, respectively. The SSS group showed the highest cost savings, nearly 4 times greater than CSMBS (IRR = 3.95, 95% CI: 3.86–4.04, p < 0.001). B: Length of Stay (LOS): Cost savings increased with longer hospital stays. Compared to 0–7 days (reference group), patients with 8–21 days had 2.09 times higher cost savings (IRR = 2.09, 95% CI: 2.05–2.13, p < 0.001), while those staying > 21 days had 2.45 times higher cost savings (IRR = 2.45, 95% CI: 2.34–2.56, p < 0.001). However, there was no significant interaction effect between healthcare scheme and LOS on cost savings (F = 0.11, p = 0.95), suggesting that the effect of LOS on cost savings was independent of healthcare scheme type. All estimates were adjusted for adjusted RW (Adj.RW) to account for variations in case severity and reimbursement adjustments. Abbreviations: CSMBS = Civil Servant Medical Benefit Scheme, UCS = Universal Coverage Scheme, SSS = Social Security Scheme, LOS = Length of Stay, IRR = Adjusted Incidence Rate Ratio, CI = Confidence Interval