Table 2. Validation results from each step of the generation process of a pediatric mature B cell non-Hodgkin lymphoma cohort.

	True positives	False positives	False negatives	Sensitivity (95% CI)	Positive predictive value (95% CI)
Step 1: Identification via ICD-9 codes (200.0, 200.2, 200.5, 200.7, 200.8, 202.8, 202.9)	103	70	5	95.4% (89.5–98.5%)	59.5% (51.8–66.9%)
Step 2: Manual chemotherapy review*	97	5	9	91.5% (84.5–96.0%)	95.1% (88.9% - 98.4%)

*The validation cohort for sensitivity and PPV calculations included 178 patients aged 0–21 treated at CHOP during the study period.