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%). |