Table 1.

Sensitivity and PPV of various algorithms for confirming JIA and the incidence date.

				Using Chart Review as the Gold Standard
Concept	Operational Definition of Preliminary Case-finding Algorithm	No. in Population	No. in Random Sample^*	No. True Positives	No. False Positives	Sensitivity (%)	95% CI	PPV (%)	95% CI
Disease confirmation	≥ 1 diagnosis code from any provider	1153	97	67	30	100 by definition	—	69	59–78
	≥ 2 diagnosis codes from any provider^**	772	64	58	6	87	76–93	91	80–96
	≥ 1 diagnosis code from rheumatology	696	60	54	6	81	69–89	90	79–96
New-onset disease	≥ 1 diagnosis code from any provider	1153	97	44	53	100 by definition	—	45	35–56
	≥ 1 diagnosis code from rheumatology	696	60	42	18	95	84–99	70	57–81
	≥ 1 diagnosis code from rheumatology, ≥ 2 laboratory tests performed (ANA, RF, HLA-B27)	581	52	39	13	93	79–98	75	61–86
	≥ 1 diagnosis code from rheumatology, ≥ 2 laboratory tests performed (ANA, RF, HLA-B27), ≥ 12 months of prediagnostic enrollment	488	45	37	8	95	81–99	82	67–91

↵* A random sample of about 10% of all preliminary cases was selected by assigning random numbers from 0–1.00 to the 1153 cases and selecting all cases with numbers from 0–0.10 for validation using medical record review. The number in the random sample was 97 of 1153, with subsets of the 97 meeting various operational definitions tested as preliminary case-finding algorithms. PPV: positive predictive value; JIA: juvenile idiopathic arthritis; ANA: anti-nuclear antibody; RF: rheumatoid factor.