Table 2.
Prevalence, Attributable Fraction, and Incidence of NoV-Associated AGE Among Children in Southwest Guatemala, 2015–2016
| Outcome | PSS Cohort (n = 469) | RAS Survey 1 (n = 402) | RAS Survey 2 (n = 368) | P Value a |
|---|---|---|---|---|
| Cross-sectionalb | April–September 2015 | October–November 2015 | January–February 2016 | |
| AGE, n (%) | 49 (10) | 56 (14) | 29 (8) | .31 |
| Sample available, n (%) | 36 (73) | 42 (75) | 24 (83) | .38 |
| NoV+, n (%) | 4 (11) | 6 (14) | 5 (21) | .31 |
| Asymptomatic NoV, n (%) | 25 (11) | 20 (12) | 15 (8) | .36 |
| NoV+ PAF, %c | −1.6 | 3.2 | 12.4 | <.001 |
| Rapid Vesikari score (SD) | 7.2 (1.7) | 7.5 (1.5) | 7.1 (1.8) | .55 |
| Prospective follow upd | April 2015–August 2016 | |||
| AGE episodes reported | 50 | N/A | N/A | N/A |
| AGE incidencee | 11.4 per 100 PY | 1316/100 PY | 697/100 PY | <.001 |
| NoV+ AGE incidencee | 1.4 per 100 PY | 154/100 PY | 131/100 PY | <.001 |
| Rapid Vesikari score (SD) | 8.1 (1.6) | N/A | N/A | .005 |
Abbreviations: AGE, acute gastroenteritis; N/A, not applicable; NoV, norovirus; PAF, population-attributable fraction; PSS, participatory syndromic surveillance; PY, person-years; RAS, rapid active sampling; SD, standard deviation.
a P values for comparison of cross-sectional AGE, sample available, NoV+, and asymptomatic NoV calculated using the asymptotic Breslow-Day test for homogeneity. P values for comparison of cross-sectional NoV+ PAF, AGE incidence, and AGE NoV+ incidence calculated using pairwise t tests. P value for comparison of cross-sectional rapid Vesikari score calculated using general linear models for continuous variables, assuming equal variance across the 3 groups. Overall mean rapid Vesikari score of the 3 cross-sectional studies (PSS enrollment, RAS survey 1, and RAS survey 2) compared with the mean rapid Vesikari score of the prospective follow-up portion of the PSS study calculated using general linear models for continuous variables.
bIncludes the enrollment visits from the PSS and all visits from the RAS survey 1 and RAS survey 2.
cPopulation-attributable fractions adjusted for age and number of people living in the household.
dChildren who tested positive for NoV at enrollment were excluded from the analysis of the prospective follow-up data.
eTo compare the cross-sectional and prospective data, we converted the prevalence of AGE in the cross-sectional datasets into incidence rates using the following formula: Prevalence/(1-Prevalence) = Incidence × Duration of AGE.