Table 2.

Multivariable Cox proportional hazards analysis of risk of reinfection during the 1984–1992 Msambweni school-based schistosomiasis control program: multiply-adjusted risk-ratios according to subject characteristic^*

Characteristic	RR	95% CI	P
Age category, years
12–20	1.00	Reference
5–11	1.82	1.51–2.19	< 0.0001
Sex
Male	1.00	Reference
Female	1.32	0.77–2.24	0.30
Village of residence
Vingujini	1.00	Reference
Bomani	1.64	1.02–2.64	0.04
Mwaembe	1.31	0.69–2.47	0.40
Sawa Sawa	1.43	0.81–2.52	0.21
Maigiza	2.92	1.18–7.20	0.02
Vindungeni	3.45	1.72–6.92	0.0005
Kisimachande	1.81	1.07–3.07	0.03
Nganja	3.78	2.24–6.36	< 0.0001
Milalani	3.23	1.97–5.29	< 0.0001
Treatment in first year
Praziquantel	1.00	Reference
None	NA	NA	NA
Three doses of metrifonate	1.16	0.97–1.39	0.09
One or two doses of metrifonate	1.48	1.08–2.01	0.01
Missed, placebo, unknown	2.14	1.35–3.40	0.001
Hematuria at entry
None	1.00	Reference
Trace	1.21	0.75–1.94	0.43
1+	1.30	1.00–1.71	0.05
2+	1.39	1.05–1.84	0.02
3+	1.63	1.26–2.11	0.0002
Sex/village interaction
Male × Vingujini	1.00	Reference
Female × Bomani	0.42	0.22–0.82	0.01
Female × Mwaembe	1.30	0.58–2.88	0.52
Female × Sawa Sawa	1.03	0.49–2.17	0.93
Female × Marigiza	0.79	0.24–2.61	0.71
Female × Vindungeni	0.53	0.17–1.62	0.27
Female × Kisimachande	1.42	0.72–2.79	0.30
Female × Nganja	0.49	0.23–1.05	0.07
Female × Milalani	1.08	0.56–2.08	0.80

^*RR = relative risk; CI = confidence interval; NA = not applicable.