研究背景：自民國85年健保實施以來，台灣醫療市場環境經歷劇烈變化，整體醫院家數減少約42%；然而，在此期間，財團法人醫院的家數不減反增。此現象對市場集中度與競爭程度所造成的影響，至今仍未有明確結論。過去相關研究大多聚焦於市場競爭對醫療價格的影響，較少探討市場競爭程度與自費醫材使用之間的關係。此外，既有文獻多以「行政疆界法」作為市場競爭程度的測量方法，然而此方法未能考量病患跨行政區就醫的情形，無法真實反映醫院間的實際競爭關係。因此，本研究將同時採用「行政疆界法」與較能反映病患實際就醫行為的「病患來源法」來測量市場競爭程度，並進一步比較兩種市場劃分方式對市場競爭、民眾自付差額醫材使用情形與價格的影響。

研究目的：本研究旨在探討台灣醫療市場競爭程度對自付差額醫材使用情形與價格的影響，主要分析冠狀動脈塗藥支架與特殊功能人工水晶體兩項自付差額醫材，觀察市場競爭程度對其使用情形與自付價格的影響。此外，本研究將同時採用「行政疆界法」與「病患來源法」兩種市場劃分方式來建構市場競爭程度，比較不同市場劃分方式對市場競爭與自付差額醫材使用情形與收費價格之實證結果所造成的影響。

研究方法：本研究以衛生福利部健保資料庫中2015年至2020年患有急性心肌梗塞(Acute myocardial infarction, AMI)以及老年白內障(Cataract)之病患為研究對象，並串聯冠狀動脈塗藥支架以及特殊功能人工水晶體之自付差額醫材之資料。市場競爭程度的測量使用「行政疆界法」與「病患來源法」之兩種市場劃分方式，以了解不同市場競爭程度計算方法對結果的影響。採用廣義估計方程式(Generalized Estimating Equation, GEEs)搭配羅吉斯迴歸模型，探討市場競爭程度對自付差額醫材使用情形之影響。在此模型中，控制病患特性（性別、年齡、社經地位、查爾森共病症分數）、醫院特性（醫院權屬別、醫院評鑑等級）、地區特性（健保分區業務組、縣市不識字率、縣市65歲以上老年人口比例）及醫院群組效應；市場競爭程度對自付差額醫材收費價格之影響則使用GEEs搭配Gamma分布進行分析，其他控制變數則與前述羅吉斯迴歸相同。

研究結果：模型實證結果顯示，無論是冠狀動脈支架抑是人工水晶體，在市場競爭程度較低的地區，二者皆有較高的使用情形，但僅冠狀動脈塗藥支架的使用情形達統計顯著性(odd ratios [OR]: 1.218; 95% confidence interval [CI]: 1.149-1.292)。在探討自付差額醫材價格的模型中，兩項醫材亦呈現相同的結果，即於市場集中度較低的區域(即高度競爭環境)，自付差額醫材價格較高，顯示市場可能存在一定程度的品質競爭。然而，與使用情形結果一致，僅冠狀動脈塗藥支架的自費價格與市場競爭程度呈統計上的顯著負相關性(β=-0.019; p-value: 0.001)。在控制變數方面，經濟情況較佳(OR: 3.078; 95% CI: 2.879-3.291)及查爾森共病症分數較低(OR: 0.637; 95%CI: 0.618-0.657)的病患，傾向使用自付差額醫材。影響自付差額醫材價格的因素為病患之社經地位、醫院權屬別、地區差異，以及65歲以上老年人口比例。相較於低收入戶民眾，社經地位較高的族群有較高的自費醫療支出；醫院權屬別中，私立醫院與財團法人醫院相較公立醫院有較高的自付差額價格；而65歲以上老年人口比例較高的地區，反而會有較低的自費醫療費用。

結論與建議：本研究較不支持醫療市場競爭會導致自付差額醫材利用情形上升，但顯示醫療市場競爭確實會導致自付差額醫材價格上漲，顯示台灣醫療市場可能存在一定程度的「醫療競武」現象。然而，多數迴歸分析結果皆未達統計顯著性，因此醫療市場競爭程度對自付差額醫材使用情形以及價格的影響，仍有待未來更多研究進一步驗證。為避免民眾因醫病資訊不對稱或其他因素而影響其醫療決策，建議相關政府機構應可強化資訊透明度、提升醫療品質的監控，並加強民眾對醫材的相關知識，提供更完善的醫療照護環境。

Background: Since the implementation of Taiwan’s National Health Insurance (NHI) system in 1996, the healthcare market environment has undergone substantial changes. While the total number of hospitals has declined by approximately 42%; the number of non-profit hospitals has concurrently increased. The implications of this phenomenon for market concentration and competition remains unclear. Previous studies have largely focused on the effect of market competition on medical pricing, while few have examined the relationship between market competition and the utilization of out-of-pocket medical devices. Moreover, most existing literature adopts the “administrative boundary approach” to measure market competition, which fails to account for patient behavior involving cross-boundary healthcare utilization and therefore cannot accurately reflect actual competition among hospitals. To address this limitation, this study incorporates both the “administrative boundary approach” and the “patient origin approach”—the letter better captures actual patient behavior—to measure market competition. The study further compares the impact of these two market definitions on market competition levels.

Objective: The primary aims to examine the impact of market competition in Taiwan’s healthcare system on the utilization and pricing of out-of-pocket medical devices. The analysis focuses on two specific devices: drug-eluting coronary stents and premium intraocular lenses. The analysis investigates how market competition affects the utilization and price of these devices and compares the empirical results obtained using two different market definitions: the administrative boundary approach and the patient origin approach.

Methods: This study utilized data from Taiwan’s nationwide health insurance claims data between 2015 and 2020, focusing on patients diagnosed with acute myocardial infarction (AMI) and senile cataracts. These patient records were linked with information on the use of two out-of-pocket medical devices: drug-eluting coronary stents and premium intraocular lenses. Market competition was measured using both the administrative boundary and patient origin approaches to evaluate how different definitions influence results. Generalized Estimating Equations (GEEs) combined with logistic regression models were employed to examine the relationship between market competition and device utilization, controlling for patient characteristics (gender, age, socioeconomic status, Charlson Comorbidity Index), hospital characteristics (ownership type, accreditation level), and regional characteristics (NHI regional division, county illiteracy rate, proportion of the population aged 65 and over), as well as the cluster effect of hospital. The impact of market competition on device pricing was analyzed using GEEs with a gamma distribution, applying the same set of control variables.

Results: The findings of this study indicate that both drug-eluting coronary stents and premium intraocular lenses were more likely to be utilized in areas with lower market competition. However, only the increased use of drug-eluting coronary stents reached statistical significance (odds ratio [OR]: 1.218; 95% confidence interval [CI]: 1.149–1.292). In the pricing analysis, both devices exhibited a consistent trend whereby out-of-pocket prices were higher in less concentrated (i.e., more competitive) markets, suggesting potential quality competition. Nonetheless, similar to the utilization results, only the price of drug-eluting stents was significantly associated with market competition (β = –0.019; p-value = 0.001), indicating a significant negative relationship. Regarding the control variables, the analysis revealed that patients with higher socioeconomic status and those with lower Charlson Comorbidity Index scores were more likely to utilize use out-of-pocket medical devices. In terms of pricing, patients with higher socioeconomic status tended to incur higher out-of-pocket expenses. Hospital ownership type also influenced pricing, with private hospitals and non-for-profit hospitals charging higher prices for out-of-pocket devices compared to public hospitals. Furthermore, regional differences were observed, with device prices being significantly higher in central and eastern Taiwan. Conversely, areas with a higher proportion of residents aged 65 and over were associated with lower out-of-pocket medical expenses.

Conclusion: This study does not provide strong evidence supporting the hypothesis that greater market competition leads to increased utilization of out-of-pocket medical devices. However, the findings indicate that increased competition is associated with higher prices for such devices, suggesting the possible existence of a “Medical Arms Race” (MAR) in Taiwan’s healthcare system. Given that many of the regression results did not reach statistical significance, the relationship between market competition, out-of-pocket device utilization, and pricing remains inconclusive and warrents further investigation.

To prevent patients from making medical decisions under conditions of information asymmetry or external pressures, it is recommended that government agencies enhance transparency, strengthen the regulation of healthcare quality, and improve public awareness regarding medical devices. Such measures could foster a more equitable and informed healthcare environment.

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