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Table 2 Prevalence of indicator markers and keywords in the records of rheumatoid arthritis patients in the year preceding diagnosis, and time interval before RA diagnosis

From: Optimising the use of electronic health records to estimate the incidence of rheumatoid arthritis in primary care: what information is hidden in free text?

  MEN N = 2,007 WOMEN N = 4,380
Indicator markers Prevalence of marker Interval Prevalence of marker Interval
(days before RA code) (days before RA code)
  N % Median IQR N % Median [IQR]
  Inflammatory arthritis diagnosis 237 11.8 79 [22–154] 469 10.7 71 [17–175]
  Synovitis 65 3.2 66 [22–153] 114 2.6 84 [28–188]
  RhF test 1,114 55.5 49 [9–137] 2,397 54.7 43 [6–127]
  DMARD prescription (not including steroids) 681 33.9 45 [0–309] 1353 30.9 71 [0–326]
  Referral to Rheum 811 40.4 66 [13–183] 1642 37.5 70 [11–193]
  Joint sign or symptom 1032 51.4 132 [54.5-245] 2202 50.3 133.5 [52–259]
Keywords Prevalence of keyword Interval Prevalence of keyword Interval
(days before RA code) (days before RA code )
  N % Median IQR N % Median IQR
  Rheumatoid A 590 29.4 37 [0–121] 1,262 28.8 28 [0–122]
  Positive RhF test 911 45.4 49 [7–136] 2,033 46.4 47 [7–151]
  Inflammatory arthritis 378 18.8 70 [17–168] 790 18.0 78 [21–183]
  Synovitis 379 18.9 57 [7–159] 789 18.0 55 [7–160]