Table 1

Association between infection levels and adherence to CDTI

Variable	Category	O. volvulus mf prevalence			O. volvulus mf load			Presence of nodules
Variable	Category	OR	95% CI	P value	IRR	95% CI	P value	OR	95% CI	P value
Effect of self-reported adherence in each age group*
5–8 years	Never taken IVM	1.00			1.00			1.00
	Up to 50% of rounds	1.65	1.13 to 2.41	0.010	1.43	1.07 to 1.90	0.017	1.84	0.96 to 3.53	0.066
	50% to 75% of rounds	1.32	0.76 to 2.29	0.325	1.20	0.76 to 1.90	0.426	1.28	0.44 to 3.75	0.649
	>75% of rounds	1.72	1.28 to 2.31	<0.0001	1.43	1.14 to 1.80	0.002	1.23	0.70 to 2.16	0.472
9–14 years	Never taken IVM	1.00			1.00			1.00
	Up to 50% of rounds	1.18	0.91 to 1.52	0.213	1.08	0.92 to 1.30	0.354	2.21	1.42 to 3.43	<0.0001
	50% to 75% of rounds	0.74	0.50 to 1.10	0.135	0.82	0.62 to 1.10	0.156	1.91	0.99 to 3.70	0.054
	>75% of rounds	0.37	0.70 to 1.42	0.990	1.04	0.82 to 1.30	0.744	1.89	1.05 to 3.42	0.034
15–29 years	Never taken IVM	1.00			1.00			1.00
	Up to 50% of rounds	0.69	0.54 to 0.88	0.003	0.78	0.68 to 0.90	0.001	1.01	0.75 to 1.36	0.958
	50% to 75% of rounds	0.50	0.33 to 0.75	0.001	0.62	0.46 to 0.80	0.002	1.11	0.66 to 1.88	0.687
	>75% of rounds	0.39	0.19 to 0.77	0.007	0.49	0.28 to 0.80	0.009	0.93	0.37 to 2.33	0.873
30–49 years	Never taken IVM	1.00			1.00			1.00
	Up to 50% of rounds	0.52	0.41 to 0.67	<0.0001	0.63	0.54 to 0.73	<0.0001	0.98	0.74 to 1.28	0.868
	50% to 75% of rounds	0.41	0.29 to 0.57	<0.0001	0.52	0.41 to 0.66	<0.0001	0.94	0.64 to 1.38	0.756
	>75% of rounds	0.26	0.16 to 0.41	<0.0001	0.36	0.25 to 0.53	<0.0001	1.43	0.89 to 2.30	0.139
≥50 years	Never taken IVM	1.00			1.00			1.00
	Up to 50% of rounds	0.63	0.47 to 0.85	0.002	0.70	0.58 to 0.90	<0.0001	1.51	1.01 to 1.09	0.741
	50% to 75% of rounds	0.55	0.37 to 0.82	0.003	0.63	0.48 to 0.80	0.001	1.28	0.82 to 1.99	0.279
	>75% of rounds	0.26	0.16 to 0.40	<0.0001	0.38	0.25 to 0.60	<0.0001	1.10	0.65 to 1.87	0.721
Effect of age in each self-reported adherence group*
Never taken IVM	30–49	1.00			1.00			1.00
	5–8	0.25	0.19 to 0.34	<0.0001	0.40	0.33 to 0.49	<0.0001	0.20	0.13 to 0.30	<0.0001
	9–14	0.80	0.58 to 1.10	0.163	0.94	0.77 to 1.15	0.576	0.22	0.14 to 0.36	<0.0001
	15–29	1.05	0.78 to 1.43	0.736	1.06	0.89 to 1.27	0.494	0.71	0.50 to 1.01	0.053
	≥50	0.81	0.59 to 1.12	0.211	0.88	0.72 to 1.07	0.186	0.97	0.68 to 1.40	0.882
up to 50% of rounds	30–49	1.00			1.00			1.00
	5–8	0.80	0.55 to 1.16	0.234	0.91	0.69 to 1.21	0.520	0.37	0.21 to 0.68	0.001
	9–14	1.79	1.44 to 2.23	<0.0001	1.63	1.40 to 1.89	<0.0001	0.50	0.38 to 0.67	<0.0001
	15–29	1.38	1.17 to 1.63	<0.0001	1.33	1.18 to 1.50	<0.0001	0.73	0.60 to 0.90	0.003
	≥50	0.98	0.81 to 1.18	0.825	0.98	0.86 to 1.13	0.807	1.50	1.22 to 1.85	<0.0001
50% to 75% of rounds	30–49	1.00			1.00			1.00
	5–8	0.82	0.46 to 1.47	0.508	0.93	0.58 to 1.49	0.751	0.27	0.09 to 0.79	0.016
	9–14	1.45	0.96 to 2.21	0.081	1.50	1.09 to 2.05	0.012	0.45	0.24 to 0.84	0.012
	15–29	1.28	0.84 to 1.96	0.250	1.28	0.92 to 1.77	0.138	0.84	0.49 to 1.44	0.527
	≥50	1.11	0.76 to 1.61	0.600	1.07	0.80 to 1.43	0.657	1.32	0.86 to 2.03	0.207
>75% of rounds	30–49	1.00			1.00			1.00
	5–8	1.70	1.05 to 2.74	0.030	1.57	1.06 to 2.32	0.025	0.17	0.09 to 0.32	<0.0001
	9–14	3.11	1.88 to 5.14	<0.0001	2.70	1.82 to 4.02	<0.0001	0.30	0.16 to 0.54	<0.0001
	15–29	1.59	0.74 to 3.43	0.233	1.42	0.76 to 2.66	0.269	0.46	0.18 to 1.21	0.116
	≥50	0.83	0.46 to 1.48	0.525	0.90	0.55 to 1.48	0.690	0.75	0.42 to 1.34	0.328
Time since last treatment	Any other case	1.00			1.00			1.00
	<1 year	0.60	0.54 to 0.68	<0.0001	0.71	0.65 to 0.77	<0.0001	0.79	0.68 to 0.92	0.002
Gender	Men	1.00			1.00			1.00
	Women	0.80	0.74 to 0.88	<0.0001	0.84	0.79 to 0.89	<0.0001	0.64	0.57 to 0.72	<0.0001
Occupation	Farmer	1.00			1.00			1.00
	None, child, N/A	0.95	0.79 to 1.16	0.626	0.93	0.81 to 1.06	0.257	1.07	0.86 to 1.35	0.531
	Student/pupil	0.99	0.84 to 1.18	0.939	0.96	0.86 to 1.08	0.528	0.85	0.68 to 1.06	0.143
	Other^†	0.68	0.54 to 0.86	0.001	0.71	0.60 to 0.85	<0.0001	0.64	0.47 to 0.87	0.004
Education attainment	No school	1.00			1.00			1.00
	Primary, secondary	0.85	0.70 to 1.03	0.106	0.87	0.76 to 0.99	0.032	0.96	0.77 to 1.20	0.743
	≥High school	0.88	0.74 to 1.05	0.146	0.87	0.77 to 0.98	0.019	1.03	0.84 to 1.26	0.771

Results were obtained by multivariate mixed logistic (O. volvulus prevalence and presence of nodules) and mixed negative binomial (O. volvulus infection intensity) regression models and data from a cross-sectional survey conducted in 2017 among 9115 participants with complete data living in 20 communities of South-West Region, Cameroon.
OR and IRR in bold are significant at 95% level.
*Age was an effect modifier of self-reported adherence.
†Occupation classified as ‘other’ included small businesses, workers, civil servants and liberal professions.
CDTI, community-directed treatment with ivermectin; IRR, incidence rate ratio; IVM, ivermectin; mf, microfilariae; O. volvulus, Onchocerca volvulus.