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Table 5 Relative and absolute reduction, % (Wald test: Z-statistic, P-value), in prevalence and mean intensity of infection: Baseline to Y3 pre-MDA

From: Monitoring the impact of a national school based deworming programme on soil-transmitted helminths in Kenya: the first three years, 2012 – 2014

Infection Relative reduction (%) Relative reduction (%) Relative reduction (%) Absolute reduction (%)
Y1 to Y2 Y2 to Y3 Y1 to Y3 Y1 to Y3
STH combined     
 Prevalence reduction 42.3 (Z = -7.33, P < 0.001) 14.3 (Z = -2.10, P = 0.035) 50.6 (Z = -9.02, P < 0.001) 16.8 (Z = -11.46, P < 0.001)
 Intensity Reduction 36.6 (Z = -5.02, P < 0.001) 15.7 (Z = -1.45, P = 0.148) 46.6 (Z = -5.05, P < 0.001)
Hookworm     
 Prevalence reduction 72.6 (Z = -6.37, P < 0.001) 45.8 (Z = -3.07, P = 0.002) 85.2 (Z = -8.15, P < 0.001) 14.0 (Z = -8.12, P < 0.001)
 Intensity reduction 71.7 (Z = -3.60, P < 0.001) 66.3 (Z = -3.21, P = 0.001) 90.4 (Z = -6.36, P < 0.001)
A. lumbricoides     
 Prevalence reduction 35.2 (Z = -6.06, P < 0.001) 1.0 (increase)a (Z = 0.20, P = 0.843) 34.4 (Z = -6.17, P < 0.001) 6.7 (Z = -5.37, P < 0.001)
 Intensity reduction 35.8 (Z = -4.66, P < 0.001) 14.5 (Z = -1.30, P = 0.192) 45.1 (Z = -4.66, P < 0.001)
T. trichiura     
 Prevalence reduction 5.9 (Z = -0.43, P = 0.671) 40.5 (Z = -3.46, P = 0.001) 44.0 (Z = -3.86, P < 0.001) 2.4 (Z = -3.46, P < 0.001)
 Intensity reduction 45.5 (increase)a (Z = 1.35, P = 0.176) 44.3 (Z = -2.14, P = 0.033) 19.0 (Z = -1.06, P = 0.290)
  1. aIndicates increase in prevalence or mean intensity rather than relative reduction