Table 4.

Negative binomial hurdles model to assess host factors associated with post-ivermectin O. volvulus microfilarial density.

	Post-Ivermectin O. volvulus Mf Density				Probability of Positive Skin Snip after Ivermectin Treatment
Factors	Coeff	95% CI		p-Value	Coeff	95% CI		p-Value
Female gender	−0.312	−0.946	0.323	0.336	−2.518	−4.913	−0.124	0.039
Male gender (reference)
Age (years)	0.012	−0.041	0.064	0.661	−0.391	−0.656	−0.125	0.004
Age*age (years)	−0.001	−0.003	0.001	0.349	0.012	0.003	0.020	0.007
Height in cm	−0.007	−0.055	0.041	0.773	0.091	−0.010	0.192	0.076
Number of previous CDTI rounds in site	−0.216	−0.515	0.083	0.157	−0.591	−1.252	0.069	0.079
>1 year since last ivermectin dose	0.455	−0.476	1.386	0.338	−2.020	−4.137	0.097	0.062
<1 year since last ivermectin dose (reference)
Follow-up skin snip at month 3	2.734	−1.823	7.290	0.240
Follow-up skin snip at month 4	0.533	−0.384	1.450	0.255
Follow-up skin snip at month 5 (reference)
Pre-ivermectin microfilarial density #	0.337	0.064	0.611	0.016	1.187	0.161	2.213	0.023

#: Log-transformed; Coeff = Negative binomial hurdle model coefficients, CI = Confidence interval; Age*age = Quadratic effect of age.