Abstract:
Background: Most patients with malaria seek treatment first in retail drug shops. Myriad studies have examined
retailer behaviours and characteristics to understand the determinants to these behaviours. Geospatial methods are
helpful in discovering if geographic location plays a role in the relationship between determinants and outcomes. This
study aimed to discover if spatial autocorrelation exists in the relationship between determinants and retailer behav-
iours, and to provide specific geographic locations and target behaviours for tailoring future interventions.
Methods: Retailer behaviours and characteristics captured from a survey deployed to medicine retailers in the
Webuye Demographic and Health Surveillance Site were analysed using geographic weighted regression to create
prediction models for three separate outcomes: recommending the first-line anti-malarial therapy to adults, recom-
mending the first-line anti-malarial therapy to children, and selling that therapy more than other anti-malarials. The
estimated regression coefficients for each determinant, as well as the pseudo R2 values for each final model, were
then mapped to assess spatial variability and local areas of best model fit.
Results: The relationships explored were found to be non-stationary, indicating that spatial heterogeneity exist in
the data. The association between having a pharmacy-related health training and recommending the first-line anti-
malarial treatment to adults was strongest around the peri-urban centre: comparing those with training in pharmacy
to those without training (OR = 5.75, p = 0.021). The association between knowing the first-line anti-malarial and
recommending it to children was strongest in the north of the study area compared to those who did not know the
MOH-recommended anti-malarial (OR = 2.34, p = 0.070). This is also the area with the strongest association between
attending a malaria workshop and selling the MOH-recommended anti-malarial more than other anti-malarials, com-
pared to retailers who did not attend a workshop (OR = 2.38, p = 0.055).
Conclusion: Evidence suggests that spatial heterogeneity exists in these data, indicating that the relationship
between determinants and behaviours varies across space. This is valuable information for intervention design, allow-
ing efforts to focus on those factors that have the strongest relationship with their targeted behaviour within that
geographic space, increasing programme efficiency and cost-effectiveness.
