Page 112 - Invited Paper Session (IPS) - Volume 2

IPS186 Fagbamigbe, A. F.
of the 5753 children that had both tests. The overall sensitivity was 88%,
specificity was 76% while the diagnostic accuracy (that is the overall
agreement) of RDT stood at 79%. The overall positive and negative likelihood
ratio was 3.6 and 0.16 respectively while the overall PPV and NPV were 58%
and 94% respectively. The sensitivity of RDT increased significantly as the age
of the children increased (p<0.05), from 86% among those aged 0-6 months
to 86.1% in 7-23 month olds to 88.1% among those aged 24-59 months. The
reverse was the specificity, LR+, and the NPV but diagnostic accuracy of RDT
and the PPV increased with the age of the children (p<0.05). On the sex of the
children, there was no difference in the sensitivity of RDT but the specificity
differed with significantly higher proportions among females (77%) than males
(75%) (p<0.05). Interestingly, RDT was more sensitive in the rural area at 88%
than in urban areas (84%) but less specific in rural (68%) than in the (86%)
(p<0.05).
Also, there was a significant PPV gap of 14% in a rural area (60%)
compared with the urban area (46%) (p<0.05) but with a closer NPV (92% vs
98%) (p<0.05). The overall accuracy, the sensitivity, the specificity, LR+, and
NPV of the RDT were generally and significantly higher across the southern
regions in Nigeria than in the northern regions (p<0.05). For children with
severe anaemia, the sensitivity of the RDT was nearly 100% compared with a
specificity of 39% (p<0.05). It appeared that the discriminatory accuracy
reduced with children level of anaemia but the higher the severity of the
anaemia, the lower its specificity (p<0.05). However, both the LR+ and the LR-
increased as the severity of anaemia increased (p<0.05). For the predictive
accuracy, PPV reduced with reduced severity from 77% to 44% (p<0.05)
among children that didn’t have anaemia while the NPV increased significantly
from 90% among children that had severe anaemia to 97% among those that
didn’t have anaemia (p<0.05).
Among all the under-five children, the prior probability of malaria was
27%. For the positive tests (showed in blue line in Figure 1), the LR+ is 3.62
(95% CI: 3.42-3.83), the posterior probability (odds) is 58% (95% CI: 56%-59%)
and approximately 1 in 1.7 with positive test results actually had the parasite
while approximately 1 in 1.1 who tested negative was actually negative, LR- is
0.16(95% CI:0.14-0.19) with corresponding posterior probability (odds) of
0.06(95% CI: 0.05-0.07).
On the level of anaemia, AUC was 68% for those that had severe anaemia,
77% for moderate anaemia, 80% for mild anaemia and 84% for those with no
anaemia (p<0.05). The AUCs were significantly different across the age of the
children, the zone and location of their residence, their household wealth
quintile, mothers’ education, quality of housing material, haven had fever
within two weeks preceding the data collection as well as the level of anaemia
(p<0.05). The ROC and Lorenz curves for all children are shown in

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