Table 3.

Adjusted odds ratios and 95% confidence intervals of macro-level demographic and environmental factors and increased odds of legionellosis occurrence

	Model Aa		Model Bb
	OR	95% CI	OR	95% CI
% ≥ 65 years of age
< 10	–		–
≥ 10 to < 15	0.62	0.40–0.97	0.65	0.41–1.03
≥ 15	0.38	0.22–0.67	0.38	0.21–0.70
% non-white race
< 10	–		–
≥ 10 to < 50	0.85	0.49–1.48	0.82	0.45–1.51
≥ 50	1.68	0.92–3.07	1.27	0.61–2.65
% hispanic ethnicity
< 5	–		–
≥ 5 to < 20	0.46	0.28–0.74	0.46	0.28–0.75
≥ 20	0.10	0.05–0.19	0.10	0.05–0.21
% poverty
< 5	–		–
≥ 5 to < 15	1.52	0.91–2.52	1.39	0.82–2.33
≥ 15	7.21	4.04–12.86	6.26	3.46–11.34
% less or some high school
< 5	–		–
≥ 5 to < 10			1.37	0.78–2.39
≥ 10			1.25	0.67–2.32
% homes built pre-1950
< 5	–		–
≥ 5 to < 20	4.63	2.43–8.82	4.52	2.37–8.65
≥ 20	5.69	2.82–11.50	5.38	2.66–10.91
% renter occupied
< 10	–		–
≥ 10 to < 55			0.99	0.51–1.95
≥ 55			1.28	0.54–3.02
% vacant housing
< 5	–		–
≥ 5 to < 10			1.19	0.70–2.03
≥ 10			1.49	0.81–2.74
Primary water sourcec
Groundwater	–		–
Surface water			0.70	0.41–1.22

Missing values were excluded from analysis

Values in italics are statistically significantly at a significance level of 5%

Ecological study design at the census tract level

^aMultivariate stepwise logistic regression model

^bFull multivariate logistic regression model

^cPopulation-weighted centroids of census tracts were joined with public water system polygons