title: How did market competition affect outpatient utilization under the diagnosis-related group-based payment system?
abstract: OBJECTIVE
  Although competition is known to affect quality of care, less is known about the effects of competition on outpatient health service utilization under the diagnosis-related group payment system. This study aimed to evaluate these effects and assess differences before and after hospitalization in South Korea.
  
  
  METHODS
  Population-based retrospective observational study.
  
  
  METHODS
  We used two data set including outpatient data and hospitalization data from National Health Claim data from 2011 to 2014.
  
  
  METHODS
  Participants who were admitted to the hospital for hemorrhoidectomy were included. A total of 804 884 hospitalizations were included in our analysis.
  
  
  METHODS
  The outcome variables included the costs associated with outpatient examinations and the number of outpatient visits within 30 days before and after hospitalization.
  
  
  RESULTS
  High-competition areas were associated with lower pre-surgery examination costs (rate ratio [RR]: 0.88, 95% confidence interval [CI]: 0.88-0.89) and fewer outpatient visits before hospitalization (RR: 0.98, 95% CI: 0.98-0.99) as well as after hospitalization compared with moderate-competition areas.
  
  
  CONCLUSIONS
  Our study reveals that outpatient health service utilization is affected by the degree of market competition. Future evaluations of hospital performance should consider external factors such as market structure and hospital location.
authors.affiliation: Department of Public Health, Graduate School, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03721, Republic of Korea.|Institute of Health Services Research, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03721, Republic of Korea.
authors.forename: Seung Ju
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Institute of Health Services Research, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03721, Republic of Korea.|Department of Preventive Medicine, Institute of Health Services Research, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea.
authors.forename: Eun-Cheol
authors.initials: EC
authors.lastname: Park
authors.affiliation: Department of Health Administration, Soonchunhyang University, 22 Soonchunhyang-ro, Eumnae-ri, Sinchang-myeon, Asan-si, Chungcheongnam-do, Republic of Korea.
authors.forename: Sun Jung
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Public Health, Graduate School, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03721, Republic of Korea.|Institute of Health Services Research, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03721, Republic of Korea.
authors.forename: Kyu-Tae
authors.initials: KT
authors.lastname: Han
authors.affiliation: Institute of Health Services Research, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03721, Republic of Korea.|Department of Preventive Medicine, Institute of Health Services Research, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea.
authors.forename: Sung-In
authors.initials: SI
authors.lastname: Jang
mesh_terms: D000328:Adult; D000553:Ambulatory Care / Q000191:economics* / Q000706:statistics & numerical data*; D003953:Diagnosis-Related Groups / Q000191:economics*; D004465:Economic Competition; D005260:Female; D061865:Hemorrhoidectomy / Q000191:economics*; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea; D012189:Retrospective Studies
keywords: health expenditure; health service; market competition