Table 1.

Latent tuberculosis infection prevalence by birth cohort and sample year

Birth cohort	Age in years in 1971-1972	Age in years in 1999-2000	Latent tuberculosis infection prevalence 1971-1972	Latent tuberculosis infection prevalence 1999-2000	Prevalence difference	95% Confidence interval (CI) around difference
1942-1946	25-29	53-57	5.05%*	8.34%	3.29	-3.29	9.87
	(no. = 129)	(no. = 245)
1937-1941	30-34	58-62	7.30%*	5.28%*	-2.01	-9.64	5.61
	(no. = 123)	(no. = 293)
1932-1936	35-39	63-67	8.97%*	4.70%	-4.26	-10.23	1.70
	(no. = 130)	(no. = 321)
1927-1931	40-44	68-72	16.78%	8.51%*	-8.27	-18.84	2.31
	(no. = 110)	(no. = 270)
1922-1926	45-49	73-77	19.47%	7.06%	-12.41	-19.25	-5.57
	(no. = 179)	(no. = 217)
1917-1921	50-54	78-82	22.29%	2.71%*	-19.58	-29.18	-9.98
	(no. = 191)	(no. = 214)
1912-1916†	55-59	83-85+	16.05%	3.60%*	-12.46	-18.79	-6.12
	(no. = 150)	(no. = 150)
Selection bias analysis comparing ages available in 1971-1972 vs. 1999-2000
1912-1946†	TOTAL of cohorts	TOTAL of cohorts	13.47%	6.25%	-7.22	-3.31	-11.12
	25-59	53-85+
	(no. = 1012)	(no. = 1710)
Not applicable	TOTAL population	TOTAL population	14.25%	5.70%	-8.55	-5.067	-12.04
	25-74	25-74
	(no. = 1492)	(no. = 3012)
Not applicable	TOTAL population tested	TOTAL population tested	14.25%	4.18%	-10.07	-6.68	-13.46
	25-74	1-85+
	(no. = 1492)	(no. = 7386)

* Estimates are unstable because there are too few individuals represented in these subgroups.

† National Health and Nutrition Examination Survey 1999-2000 data were top-coded such that all people age 85 and older were identified as 85. Thus the 1912-1916 cohort as analyzed using 1999-2000 data may include persons born in earlier years.