Validity of medical record documented varicella-zoster virus among unvaccinated cohorts

Figures & data

Table 1. Validity of reported varicella history according to source

Age groups	5- to 9-y-olds (n = 48)			10- to 14-y-olds (n = 305)			15- to 19-y-olds (n = 183)
Source of history	Sick visit	Any MR	Patient/parent	Sick visit	Any MR	Patient/parent	Sick visit	Any MR	Patient/parent
Seropositivity, %	73	73	73	88	88	88	98	98	98
Positive history, n (%)	6 (13)	28 (58)	29 (60)	29 (10)	243 (80)	263 (86)	11 (6)	155 (85)	167 (91)
TP, n^a	6	27	26	28	224	240	11	153	165
FP, n^b	0	1	3	1	19	23	0	2	2
FN, n^c	29	8	9	239	43	27	169	27	15
TN, n^d	13	12	10	37	19	15	3	1	1
PPV (95% CI), %	100 (54–100)	96 (82–100)	90 (73–98)	97 (82–100)	92 (88–95)	91 (87–94)	100 (72–100)	99 (95–100)	99 (96–100)
NPV (95% CI), %	31 (18–47)	60 (36–81)	53 (29–76)	13 (10–18)	31(20–44)	36 (22–52)	2 (0.4–5)	4 (0.9–18)	6 (0.2–30)
Sensitivity (95% CI), %	17 (7–34)*	77 (60–90)	74 (57–88)	10 (7–15)*	84 (79–88)^†	90 (86–93)	6 (3–11)*	85 (79–90)^†	92 (87–95)
Specificity (95% CI), %	100 (75–100)	92 (64–100)	77 (46–95)	97 (86–100)*	50 (33–67)	39 (24–57)	100 (29–100)	33 (0.8–91)	33 (0.8–91)

TP, true positive; FP, false positive; FN, false negative; TN, true negative; PPV, positive predictive value; NPV, negative predictive value; MR, medical record. *p < 0.0001 when history source was compared with Patient/Parent recall. ^†p < 0.05 when history source was compared with Patient/Parent recall. ^aParticipants with positive histories who were seropositive. ^bParticipants with positive histories who were seronegative. ^cParticipants with no/uncertain histories who were seropositive. ^dParticipants with no/uncertain histories who were seronegative.