目標：探討全民健康保險住院診斷關聯群(Taiwan Diagnosis Related Groups，簡稱Tw- DRGs)支付制度實施後，對於醫療機構申報健保醫療費用、病患轉院治療及出院成效之影響。方法：選取2008-2011年期間健保住院申報案件數，每一住院人次為一個案，排除Tw-DRGs不適用之案件後，將研究對象分成DRG組與非DRG組，以傾向分數(propensity score)進行一比一配對，配對條件為「同醫師ID」、「MDC別」、「年齡」、「性別」及「Tw-DRGs權重」等變項，配對後將兩組住院人次經由加權後歸戶至醫療機構，分為「DRG組」與「非DRG組」，以年代與組別的交互作用呈現制度實施後實驗組之影響，並以廣義估計方程式(generalized estimating equation; GEE)進行統計分析。結果：Tw-DRGs支付制度實施後，在醫療費用部分，2010年DRG組平均單次住院申報點數顯著低於非DRG組。在轉院治療部分，2010年DRG組住院轉院治療率顯著低於非DRG組。在結果成效部分，2010年DRG組180天內死亡率顯著低於非DRG組。然而，Tw-DRGs支付制度實施後，在結果成效部分，2010年DRG組180天內再住院率顯著高於非DRG組。結論：實施Tw-DRGs支付制度後，醫療院所受到影響為單次住院申報點數減少、病患轉院減少，但對於結果成效影響不同。建議仍需監控醫療機構住院病人其出院後之醫療利用與結果，以確保病患就醫之醫療品質及療效，此外，並建議重新定義結果成效指標，應採納計算同科或同診斷案件計算較具公平。

Objectives: The aim of this study was to determine the impact of the Taiwan Diagnosis Related Groups (Tw-DRGs) payment system on medical institutions with respect to medical expenses and quality of care. Methods: Inpatient-related data were obtained from the National Health Insurance research database (NHIRD) during the study period (2008-2011). Propensity score matching (PSM) was used to divide the subjects into DRG and non-DRG groups and differentiate the subjects according to the medical institutions at which they were treated. The difference-in-difference approach and the generalized estimating equation (GEE) model were used to compare the DRG and non-DRG groups with respect to changes in health care efficiency before and after the introduction of Tw-DRGs and to evaluate the impact of Tw-DRGs on medical institutions. Results: After Tw-DRGs were implemented, the DRG group had lower medical expenses, a lower inpatient transfer rate, and a lower mortality rate within 180 days after discharge compared to the non-DRG group. In contrast, after Tw-DRGs were implemented, the DRG group had a higher readmission rate within 180 days after discharge compared to the non-DRG group. Conclusions: After implementing the Tw-DRGs payment system, the medical expenses, mortality rate within 180 days after discharge, and inpatient transfer rate had decreased, but the readmission rate within 180 days after discharge had increased. We suggest that the NHI should continue monitoring medical institutions to ensure high-quality medical care, and the measurement of indicators, such as the readmission rate, should be more strictly and precisely defined.