Background: Growing health care costs resulting from the increasing number of total knee arthroplasty [TKA] patients will affect the financial status of both payers and the government. The current reimbursement system, version 5 of Thai Diagnosis Related Group [TDRG], will be replaced with version 6.

Objective: To compare hospital reimbursement by computing the relative weight [RW] among patients undergoing primary TKA under the old and new versions of TDRG.

Materials and Methods: Data on patients who underwent primary TKA was obtained from the Naresuan University Hospital Financial Department. Data on each patient consisted of 16 files which included demographic data, length of stay [LOS], TDRG code, and RW of TDRG5. The data from those 16 files was then evaluated using TDRG6.

Results: A hundred seventy patients underwent primary TKA during the study period, 152 females and 18 males. In the comparative evaluation, the overall RW using TDRG6 decreased by 0.0611 (-1.6%) compared to TDRG5, but the difference was not statistically significant (p = 0.10). The mean RW of TDRG6 and TDRG5 for 08030 knee replacement with no significant clinical or cost complexity [CCC] was 3.524 and 3.627, respectively; 08031 knee replacement with minimal CCC was 4.337 and 4.104; and for 08032 knee replacement with moderate CCC was 7.381 and 5.999. The RW for the least comorbid patients (code 08030) under TDRG6 significantly decreased by 0.103 (-2.8%) compared to the RW of TDRG5 (p<0.01).

Conclusion: Under TDRG6, the RW of for primary TKA performed on patients with the least clinical and cost complexity [CCC] will be significantly reduced by 2.8%, but the RW for patients in the high CCC subgroups will increase compared to TDRG5. Overall, reimbursement for all primary TKA patients with TDRG6 will be slightly decreased (1.6%).

Keywords: Thai diagnosis-related group (TDRG), Clinical and cost complexity (CCC), Reimbursement,
Total knee arthroplasty