Table 2.

Multiple regression analysis for D3+ rate among 840 cases, Eritrea, 2016–2019.

Multiple regression was used to analyze the relationship between age (which is related to host immunity and the capacity of the immune system to clear parasites independent of treatment), sex, initial parasitemia (a high parasitemia on day0 can lead to parasite persistence on day3) and Pfkelch13 622 variant on the persistence parasitemia at day 3 (D3+).

Covariate	Coefficient	Std. Error	Odds ratio (95% CI)
Age	−6.3E-03	0.016	0.99 (0.96–1.02)
Sex	−8.1E-03	0.487	0.98 (0.38–2.57)
Initial parasitemia	8.7E-06	5.8E-06	1.00 (1.00–1.00)
Pfkelch13 622I	1.824	0.466	6.2 (2.5–15.5)

95% CI: the 95% confidence interval for the estimated odds ratio

We found that holding all other covariates constant, the odds of D3+ were 6.2-fold higher (95% CI [2.5–15.5]) in patients carrying the Pfkelch13 R622I variant in isolates prior to ACT treatment compared to patients carrying Pfkelch13 wild-type parasites.

The goodness of fit of our multiple regression model was evaluated both from the Hosmer-Lemeshow test (p-value >0.05) and the ROC curve analysis (Area under the ROC curve estimate of 0.726; SD 0.07, 95% CI [0.69–0.75]).