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Table 1 Performance measures: physician billing ICD-9 codes (claims data) vs. laboratory confirmed pertussis cases (CDRS) 2004–2014

From: How well do ICD-9 physician claim diagnostic codes identify confirmed pertussis cases in Alberta, Canada? A Canadian Immunization Research Network (CIRN) Study

Billing codes from physician claimsa Laboratory confirmed pertussis caseb (CDRS)
Yes No Total
Pertussis specific ICD-9 codec 872 (TP) 4563 (FP) 5435
Non-pertussis ICD-9 code 1388 (FN) 15172 (TN) 16560
Total 2260 19735 21995
Sensitivity = 38.6% (95% CI: 36.6%–40.6%); Specificity = 76.9% (95% CI: 76.3%–77.5%).
Positive predictive value = 16.0% (95% CI: 15.1%–17.0%); Negative predictive value = 91.6% (95% CI: 91.2%–92.0%).
  1. TP true positive, FP false positive, FN false negative, TN true negative, CI confidence interval
  2. aTest measurement
  3. bReference standard
  4. c033 (whooping cough), 033.0 (Bordetella pertussis), 033.1 (B. parapertussis), 033.8 (whooping cough, other specified organism), 033.9 (whooping cough, other unspecified organism)