An Effectiveness Evaluation of a pay-for-performance Program for Diabetes Based on the Propensity Score Matching Method

[[abstract]]目標：健保局於2001年11月推行糖尿病論質計酬方案，過去研究雖呈正向的成效，但未考慮加入方案者選擇偏差的問題，因此本研究目的旨在以糖尿病可避免住院為品質結果指標，並以傾向分數法配對產生可比較之配對組，以釐清該方案之成效。方法：擷取2002-2003年承保抽樣歸人檔中因糖尿病至門診就診並申報檢查者前後一年之就醫資料，藉由傾向分數(PS, propensity score)配對法，先依病患各項特性建構加入方案之機率（即PS）模型，再自未加入方案者（即對照組，共6,855人）中，以1:1的方式配對產生與加入方案者（即介入組，共647人）加入機率相當之配對組樣本（647人），之後再以廣義估計方程式比較組間可避免住院勝算之比值。結果：對照組在前一年之病患特性、就醫情形、檢查申報比例及住院等變項上與介入組有顯著差異，但配對組與介入組各變項之差異均不顯著。方案實施後，介入組之各項檢查申報比例均顯著高於對照組與配對組，但其糖尿病相關可避免住院率增加幅度高於對照組（勝算比1.01, 95%信賴區間為0.98-1.04），卻低於配對組（勝算比0.98，95%信賴區間為0.94-1.02），惟均未達顯著意義。結論：參加論質計酬方案者與未參加者之特性及過去檢查申報比例並不相同。經傾向分數配對法產生與介入組條件相當之配對組，並據此評估論質計酬方案之成效，與傳統上以未參加者為對照組的比較方式有不同的結果。以傾向分數法做為政策評估的工具，或可提供健康政策成效評估的另一種觀點。 Objectives: This study aimed to evaluate the pay-for-performance (P4P) program for diabetes by using the propensity score method to construct a comparable matching group, and by using the frequency of diabetes-related avoidable hospitalizations to assess outcome. Methods: In order to construct the intervention group, we selected diabetic cases (N=647) from the NHI beneficiaries claim data from 2002 to 2003. Using the propensity score, we selected the matched group (N=647) from the control group (N=6,855) by matching their characteristics and covariates relating to the probability of their participation in the program. Subsequently, we took a generalized equation estimate (GEE) approach with logit link to compare the likelihood of avoidable hospitalization among groups. Results: The distributions of predicators such as patient characteristics, prior ambulatory care utilization, and the rates of laboratory tests and hospitalizations were significantly different between the intervention group and the control group while there were no significant differences between the intervention group and the matched group. Although the proportion of laboratory tests was higher in the intervention group, after the P4P program this group had a higher likelihood of avoidable hospitalization than did the control group with an odds ratio (OR) of 1.01 (95% C.I.: 0.98-1.04) while having a lower likelihood than the matched group with an OR of 0.98 (95% C.I.: 0.94-1.02). Neither difference was significant. Conclusions: The characteristics of the diabetics who participated in the P4P were different from those who did not. After using propensity scores to create a matched group with the same probability as those who participated in the P4P, we found that the results were different from comparisons made with traditional methods. The propensity score method may provide another insight into understanding the effectiveness of a particular health policy