TABLE 3.

Risk factors for clustering of tuberculosis isolates in Alabama (1994 to 2000) from patients that were infected with M. tuberculosis strains harboring six or more IS6110 insertion sequences (HCS cohort)

Demographic or clinical parameter	No. of patients with characteristica	% of patients in cluster	OR (95% CI)b
			Crude	Age adjusted
Demographic parameters
Injection drug use
Yes	11	45	2.2 (0.7-7.3)	1.9 (0.6-6.3)
No	1,003	28	1	1
Noninjection drug use
Yes	54	41	1.9 (1.1-3.3)	1.6 (0.9-2.8)
No	952	27	1	1
Alcohol abuse
Yes	270	41	2.4 (1.8-3.3)	2.2 (1.6-3.0)
No	733	23	1	1
HIV positive
Yes	51	31	1.0 (0.6-1.9)	0.9 (0.5-1.7)
No	743	31	1	1
Homeless
Yes	57	61	4.4 (2.6-7.7)	4.0 (2.3-7.0)
No	1,070	26	1	1
Long-term care facility resident
Yes	27	22	0.7 (0.3-1.8)	0.9 (0.4-2.4)
No	1,108	28	1	1
Correction facility resident
Yes	23	52	2.9 (1.3-6.6)	2.3 (1.0-5.4)
No	1,113	27	1	1
Clinical parameters
Abnormal X ray
Yes	1,038	28	1.0 (0.6-1.7)	1.1 (0.7-1.9)
No	75	28	1	1
Abnormal X ray/cavitary disease
Yes	244	34	1.5 (1.1-2.0)	1.4 (1.0-1.9)
No	798	26	1	1
Sputum smear positive
Yes	501	31	1.2 (0.9-1.6)	1.2 (0.9-1.5)
No	491	27	1	1
Previously tuberculosis positive
Yes	55	31	1.2 (0.6-2.1)	1.2 (0.6-2.0)
No	1,081	28	1	1

^aThe totals are less than 1,136 due to missing data.

^bAs determined by the chi-square test.