title: Investigating the utilization of radiological services by physician patients: a population-based cohort study in Taiwan.
abstract: BACKGROUND
  Advances in radiology technology have contributed to a substantial increase in utilization of radiology services. Physicians, who are well educated in medical matters, would be expected to be knowledgeable about prudent or injudicious use of radiological services. The aim of this study was to evaluate differences in the utilization of radiology modalities among physician and non-physician patients.
  
  
  METHODS
  This nationwide population-based cohort study was carried out using data obtained from the Taiwan National Insurance Database from 1997 to 2008. Physicians and comparison controls selected by propensity score matching were enrolled in the current study. The claims data of ambulatory care and inpatient discharge records were used to measure the utilization of various radiology modalities. Utilization rates of each modality were compared between physicians and non-physicians, and odds ratios of the utilization of each radiology modality were measured. Multiple logistic regression analysis was used to examine the predictors of X-ray, MRI, and interventional procedures utilization during the study period.
  
  
  RESULTS
  The utilization of most radiologic services increased among physicians and the comparison group during the observation period. Compared to non-physicians, physicians had significantly higher utilization rates of computed tomography and magnetic resonance imaging (MRI) but lower utilization rates of X-rays, sonography, and interventional procedures. After adjusting for age, gender, major diseases, urbanicity, and residential regions, logistic regression analysis showed that, compared to non-physicians, the physicians used significantly more MRI (odds ratio [OR]: 2.19, 95% confidence interval [CI]: 1.68-2.84, P < 0.001) and significantly less X-rays and interventional procedures (OR: 0.85, 95% CI: 0.72-0.99, P = 0.04 for X-rays and OR: 0.67, 95% CI: 0.54-0.83, P < 0.001 for interventional procedures). Being a physician was a significant predictor of greater usage of MRI and of less usage of X-ray and interventional procedures.
  
  
  CONCLUSIONS
  This study revealed different utilization patterns of X-rays, MRI, and interventional procedures between physician and non-physician patients, even after controlling for such factors as socioeconomic status and major diseases.
authors.affiliation: Institute of Public Health, National Yang-Ming University, No. 155, Sec. 2,Li-Nong Street, Taipei, Taiwan.
authors.forename: Chen-Yi
authors.initials: CY
authors.lastname: Wu
authors.forename: Hsiao-Yun
authors.initials: HY
authors.lastname: Hu
authors.forename: Likwang
authors.initials: L
authors.lastname: Chen
authors.forename: Nicole
authors.initials: N
authors.lastname: Huang
authors.forename: Yiing-Jeng
authors.initials: YJ
authors.lastname: Chou
authors.forename: Chung-Pin
authors.initials: CP
authors.lastname: Li
mesh_terms: D000328:Adult; D015331:Cohort Studies; D016001:Confidence Intervals; D016208:Databases, Factual; D005260:Female; D006801:Humans; D016015:Logistic Models; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010820:Physicians; D057216:Propensity Score; D011859:Radiography / Q000379:methods / Q000706:statistics & numerical data*; D015641:Radiography, Interventional / Q000706:statistics & numerical data; D012189:Retrospective Studies; D013624:Taiwan