Malaria micro-stratification using routine surveillance data in Western Kenya
Alegana VA., Suiyanka L., Macharia PM., Ikahu-Muchangi G., Snow RW.
<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>There is an increasing need for finer spatial resolution data on malaria risk to provide micro-stratification to guide sub-national strategic plans. Here, spatial-statistical techniques are used to exploit routine data to depict sub-national heterogeneities in test positivity rate (TPR) for malaria among patients attending health facilities in Kenya.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>Routine data from health facilities (<jats:italic>n</jats:italic> = 1804) representing all ages over 24 months (2018–2019) were assembled across 8 counties (62 sub-counties) in Western Kenya. Statistical model-based approaches were used to quantify heterogeneities in TPR and uncertainty at fine spatial resolution adjusting for missingness, population distribution, spatial data structure, month, and type of health facility.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>The overall monthly reporting rate was 78.7% (IQR 75.0–100.0) and public-based health facilities were more likely than private facilities to report ≥ 12 months (OR 5.7, 95% CI 4.3–7.5). There was marked heterogeneity in population-weighted TPR with sub-counties in the north of the lake-endemic region exhibiting the highest rates (exceedance probability > 70% with 90% certainty) where approximately 2.7 million (28.5%) people reside. At micro-level the lowest rates were in 14 sub-counties (exceedance probability < 30% with 90% certainty) where approximately 2.2 million (23.1%) people lived and indoor residual spraying had been conducted since 2017.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>The value of routine health data on TPR can be enhanced when adjusting for underlying population and spatial structures of the data, highlighting small-scale heterogeneities in malaria risk often masked in broad national stratifications. Future research should aim at relating these heterogeneities in TPR with traditional community-level prevalence to improve tailoring malaria control activities at sub-national levels.</jats:p> </jats:sec>