title: Increased frequency and costs of ambulatory medical care utilization prior to the diagnosis of rheumatoid arthritis: a national population-based study.
abstract: OBJECTIVE
  To investigate the frequency and costs associated with ambulatory medical care utilization over an 8-year period in patients prior to the diagnosis of rheumatoid arthritis (RA).
  
  
  METHODS
  We used Taiwan's National Health Insurance Research Database to identify 691 newly diagnosed RA cases between 2005 and 2010. We selected 1,382 controls without RA, frequency matched by sex, age, and the catastrophic illness certificate application year of the cases. The frequency and costs of ambulatory medical care utilization between the RA patients and controls were compared using the 2-sample Kolmogorov-Smirnov test.
  
  
  RESULTS
  The median frequency of ambulatory medical care utilization was significantly higher in RA patients compared with controls (29 versus 13; P < 0.001) in the year before diagnosis. The differences remained significant throughout all 8 annual periods before diagnosis. Similarly, the inflation-adjusted costs of ambulatory medical care utilization in RA patients increased annually over the study period, from a median of $212 eight years preceding diagnosis to $798 one year preceding diagnosis. Frequency of ambulatory medical care utilization due to diseases of the musculoskeletal system and connective tissue (P < 0.001), acute respiratory infections (P < 0.001), diseases of the upper respiratory tract (P = 0.01), and diseases of the upper gastrointestinal tract (P = 0.04) were higher among RA patients in the 2-year period preceding diagnosis.
  
  
  CONCLUSIONS
  We found increased frequency and costs of ambulatory care utilization among RA patients in Taiwan preceding diagnosis of RA.
authors: Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, and School of Medicine, Tzu Chi University, Hualien, Taiwan.
authors: Ning-Sheng
authors: NS
authors: Lai
authors: Tzung-Yi
authors: TY
authors: Tsai
authors: Chung-Yi
authors: CY
authors: Li
authors: Malcolm
authors: M
authors: Koo
authors: Chia-Li
authors: CL
authors: Yu
authors: Ming-Chi
authors: MC
authors: Lu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000191:economics / Q000706:statistics & numerical data*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000191:economics*; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013624:Taiwan; D055815:Young Adult