TABLE 3.

Results of logistic regression analysis^a

Predictor	Variable type	P value	OR (95% CI)
Sex (male)	Patient	0.06	0.84 (0.69–1.01)
Age (yrs)	Patient	<0.001	1.01 (1.01–1.02)
Predisposed	Patient	<0.001	6.67 (3.88–11.51)
Interaction between age and predisposing condition	Patient	0.002	0.99 (0.98–0.99)
Sample yr	Patient	0.07	0.98 (0.96–1.00)
Driving distance to Michigan Medicine	Patient	0.69	1.00 (1.00–1.00)
Population density	City	0.06	1.00 (1.00–1.00)
Drinking water source (surface water)	City	0.04	1.46 (1.03–2.08)
Drinking water disinfectant (monochloramine)	City	0.24	1.22 (0.87–1.68)
% population older than 65 yrs	City	0.64	0.99 (0.96–1.03)
% population white	City	0.06	1.01 (1.00–1.01)
Log(median income)	City	0.44	1.18 (0.77–1.80)

^aSignificant predictors were based on α = 0.05.