Table 6.
Multivariable analysis of factors associated with the school-level S. haematobium PRR among 199 schools surveyed during year 5 survey in Kenya
| Covariate | S. haematobium (Coefficient (95% CI), P-value)* | |
|---|---|---|
| Prevalence | PRR | |
| Baseline prevalence, % | ||
| < 1 | Insufficient obs | |
| 1–10 | 10.25 (4.27;16.23), P = 0.001 | |
| 10–50 | Insufficient obs | |
| > 50 | Reference | |
| Treatment covariates | ||
| Treatment rounds with PZQ | ||
| Zero | Reference | |
| One | −0.02 (−2.09;2.05), P = 0.988 | |
| Two | 2.58 (0.27;4.89), P = 0.029 | |
| Three | 1.42 (−0.19;3.02), P = 0.083 | |
| ≥ Four | Insufficient obs | |
| Environmental covariates | ||
| Aridity index† | ||
| < 0.50 (semiarid) | Reference | |
| 0.50–0.65 (dry sub-humid) | −1.02 (−2.71;0.66), P = 0.235 | |
| 0.65–0.75 (humid) | −1.09 (−2.85;0.67), P = 0.226 | |
| > 0.75 (hyper-humid) | −3.32 (−6.23;−0.41), P = 0.025 | |
| Precipitation (in mm/hour) | ||
| 20–70 (showers rainfall) | 39.43 (32.28;46.58), P < 0.001 | |
| 70–280 (thunderstorm rainfall) | Reference | |
S. haematobium = Schistosoma haematobium; PRR = prevalence relative reduction; WASH = water, sanitation, and hygiene.
Regression coefficients of association together with their 95% CIs were determined using multivariable mixed-effects linear regression models with a random intercept at county and subcounty levels. Statistical significance of the coefficients was determined by the absence of zero overlapping in the 95% CIs (values in bold). In all the models, negative values of the coefficients indicated a decrease in the rate of school-level infection or low values of PRR, whereas positive values of the coefficients indicated an increase in the rate of school-level infection or high values of PRR.
Classification of the values of aridity index was adapted from the UN Environment Programme (UNEP) (https://www.unenvironment.org/).