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. 2010 Sep 14;4(9):e820. doi: 10.1371/journal.pntd.0000820

Table 3. Results from multivariable logistic models examining associations between demographic factors and 12 month reinfection*.

Model 1a Model 2b Model 3c
OR** (CI95%) P-value OR** (CI95%) P-value OR** (CI95%) P-value
Ethnic group (Bagungu) 0.08 (0.02, 0.27) <0.0001 0.14 (0.04, 0.53) 0.002 0.31 (0.08, 1.23) 0.09
Sex (Male) 0.32 (0.10, 1.03) 0.05 0.66 (0.18, 2.46) 0.54 0.39 (0.11, 1.39) 0.14
Ethnicity x sex interaction 27.18 (5.67, 130.35) <0.0001 6.80 (1.13, 40.88) 0.04 4.65 (0.75, 28.83) 0.10
Age d
7–9 years 1.00 1.00 1.00
10–12 years 1.17 (0.23, 6.08) 1.40 (0.23, 8.49) 0.51 (0.06, 4.37)
13–16 years 1.85 (0.34, 10.02) 1.63 (0.27, 9.98) 0.67 (0.08, 5.35)
17–23 years 0.72 (0.16, 3.26) 0.95 (0.18, 5.03) 0.37 (0.06, 2.42)
24–30 years 0.38 (0.09, 1.64) 0.32 (0.06, 1.62) 0.13 (0.02, 0.85)
31–38 years 0.43 (0.10, 1.73) 0.31 (0.06, 1.50) 0.15 (0.02, 0.93)
39–50 years 0.22 (0.05, 1.03) 0.05 0.19 (0.03, 1.03) 0.03 0.07 (0.01, 0.51) 0.02
Water contact duration † e 3.87 (2.18, 6.90) <0.0001
Cercarial exposure ‡ e 5.12 (2.71, 9.66) <0.0001

*Models examined associations between ethnicity, sex and age, and S. mansoni reinfection 12 months after treatment. Model 1 is without adjustment for behaviour or cercarial exposure, Model 2 adjusts for observed water contact duration and Model 3 adjusts for estimated cercarial exposure.

a

Model included ethnic group, sex and age; excludes individuals with detectable eggs at 5 weeks.

b

Model included ethnic group, sex, age and observed water contact duration; excludes individuals with detectable eggs at 5 weeks.

c

Model included ethnic group, sex, age and cercarial exposure score; excludes individuals with detectable eggs at 5 weeks.

**OR  =  odds ratio.

d

6 degrees of freedom used to fit age.

†: Ln (minutes +1).

e

OR per unit S.D. increase.

‡: Ln(exposure units +0.01); derived by weighting water contact duration by water contact site, time of day and degree of immersion.