Epidemiology of Extrapulmonary Tuberculosis in the United States, 1993–2006

Heather M. Peto () 1 2 3 Robert H. Pratt 0 2 3 Theresa A. Harrington 2 3 Philip A. LoBue 2 3 Lori R. Armstrong 2 3 0 Northrop Grumman Information Technology , McLean, Virginia 1 The CDC Experience Program, Centers for Disease Control and Prevention , Atlanta , Georgia 2 Received 7 October 2008; accepted 12 May 2009; electronically published 30 September 2009. The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. Prevention, National Center for HIV/AIDS, Viral Hepatitis, Sexually Transmitted Disease, and Tuberculosis Prevention, Division of Tuberculosis Elimination , 1600 Clifton Rd, Mailstop E-10, Atlanta, GA 30333 3 Division of Tuberculosis Elimination, National Center for HIV/AIDS , Viral Hepatitis, Sexually Transmitted Disease, and Tuberculosis Prevention Background. Almost one-fifth of United States tuberculosis cases are extrapulmonary; unexplained slower annual case count decreases have occurred in extrapulmonary tuberculosis (EPTB), compared with annual case count decreases in pulmonary tuberculosis (PTB) cases. We describe the epidemiology of EPTB by means of US national tuberculosis surveillance data. Methods. US tuberculosis cases reported from 1993 to 2006 were classified as either EPTB or PTB. EPTB encompassed lymphatic, pleural, bone and/or joint, genitourinary, meningeal, peritoneal, and unclassified EPTB cases. We excluded cases with concurrent extrapulmonary-pulmonary tuberculosis and cases of disseminated (miliary) tuberculosis. Demographic characteristics, drug susceptibility test results, and risk factors, including human immunodeficiency virus (HIV) status, were compared for EPTB and PTB cases. Results. Among 253,299 cases, 73.6% were PTB and 18.7% were EPTB, including lymphatic (40.4%), pleural (19.8%), bone and/or joint (11.3%), genitourinary (6.5%), meningeal (5.4%), peritoneal (4.9%), and unclassified EPTB (11.8%) cases. Compared with PTB, EPTB was associated with female sex (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.7-1.8) and foreign birth (OR, 1.5; CI, 1.5-1.6), almost equally associated with HIV status (OR, 1.1; CI, 1.1-1.1), and negatively associated with multidrug resistance (OR, 0.6; CI, 0.5-0.6) and several tuberculosis risk factors, especially homelessness (OR, 0.3; CI, 0.3-0.3) and excess alcohol use (OR, 0.3; CI, 0.30.3). Slower annual decreases in EPTB case counts, compared with annual decreases in PTB case counts, from 1993 through 2006 have caused EPTB to increase from 15.7% of tuberculosis cases in 1993 to 21.0% in 2006. Conclusions. EPTB epidemiology and risk factors differ from those of PTB, and the proportion of EPTB has increased from 1993 through 2006. Further study is needed to identify causes of the proportional increase in EPTB. - The decrease in tuberculosis case rates from 52.6 cases per 100,000 population in 1953 to 4.6 cases per 100,000 population in 2006 [1] demonstrates 53 years of improvement in United States tuberculosis control. This decrease was interrupted by a temporary tuberculosis resurgence from 1985 through 1992 [1, 2]. Factors contributing to the resurgence included deterioration of tuberculosis public health infrastructure, the human immunodeficiency virus (HIV)/AIDS epidemic, increased immigration from countries endemic for tuberculosis, and tuberculosis transmission in congregate settings [1, 2]. Of 13,779 reported tuberculosis cases in 2006, 9678 (70.2%) were pulmonary tuberculosis (PTB), 2889 (21.0%) were extrapulmonary tuberculosis (EPTB), 954 (6.9%) were concurrent extrapulmonary-pulmonary tuberculosis, and 251 (1.8%) were disseminated (miliary) tuberculosis [1]. Although EPTB and PTB case counts have both decreased, EPTB has increased as a proportion of total tuberculosis cases from 3963 (7.6%) of 52,255 cases in 1962 [3] to 3940 (15.7%) of 25,107 cases in 1993 [1, 4] and to 2889 (21.0%) of 13,779 cases in 2006 [1], a trend seen in other industrialized countries [2, 58]. Essential to achieving the national goal of tuberculosis elimination is understanding EPTB epidemiology and possible contributors to its proportional increase. The last summary of EPTB in the United States that used the National Tuberculosis Surveillance System (NTSS) analyzed data from 1986, the year the tuberculosis resurgence began [1, 5]. Our analysis offers the first evaluation of EPTB in the HIV era [9] that uses NTSS data from 1993 through 2006. In addition, it is the first nationwide review of EPTB to capture drug susceptibility test results and additional tuberculosis risk factors, including HIV status [10]. This review is limited to reported public health surveillance system data and is not a clinical case review. Our goal is to describe EPTB epidemiology, compare the incidence and characteristics of EPTB with those of PTB, and suggest possible factors that are contributing to the increased proportion of EPTB-attributable tuberculosis ca (...truncated)