TABLE 4.

HOME WATER SUPPLY AS OF 5 YEARS BEFORE INDEX^*

			Odds Ratio	95% Confidence Interval
Feature	Cases Count (%) (N = 70)	Control Subjects Count (%) (N = 61)	(52 Matched Groups, 52 Cases, 61 Control Subjects)†
Home construction
1990s or later	15 (21.4)	8 (13.1)	Referent	—
1970s or 1980s	23 (32.9)	24 (39.3)	0.41	0.10–1.6
Before 1970	32 (45.7)	27 (44.3)	0.52	0.14–1.9
Well	10 (14.3)	8 (13.1)	0.67	0.16–2.8
Air conditioning	24 (34.3)	19 (31.2)	0.68	0.25–1.9
Inline water filters	8 (11.4)	8 (13.1)	0.62	0.19–2.1
Filtered pitchers	17 (24.3)	14 (23)	2.1	0.84–5.5

^*Subjects were questioned about the home they lived in during the calendar year 5 before index; if they moved over the course of the year, they were asked to give what would be the correct answer most months of that year.

^†Odds ratios were calculated using conditional logistic regression with age >70 in the model. Sex and area code were perfectly matched, and adjustment for other potential confounding variables did not appreciably change results. One or more matched control subjects were recruited and retained for 52 of the 70 cases enrolled in the study. Only matched groups of one case and one or more control subjects are included in conditional logistic regression.