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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)