Tuberculosis Prevention Among Foreign-born Persons in Seattle King County, Washington

Tuberculosis Prevention Among Foreign-born Persons in Seattle King County, Washington CHARLES D. WELLS, PATRICK L. F. ZUBER, CHARLES M. NOLAN, NANCY J. BINKIN, and STEFAN V. GOLDBERG Division of Tuberculosis Elimination, National Center for HIV/AIDS, Sexually Transmitted Diseases, and Tuberculosis Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia; Seattle King County Department of Public Health, Tuberculosis Control Program, Seattle, Washington The purpose of this study was to evaluate the outcomes of classified immigrant and refugee (I&R) screening and of contact investigation (CI) of foreign-born TB cases in Seattle King County (SKC), Washington. We reviewed I&R evaluations from the SKC TB clinic for 1992 1994 and contact evaluation records for 54 randomly selected U.S.-born and foreign-born pulmonary TB patients from 1993. Among 942 I&R evaluated, 693 (74%) had positive tuberculin skin tests (TST). Preventive therapy (PT) was prescribed for 324 (34%) and treatment for 49 (5%). The remaining 377 were dismissed, of whom 96% did not meet American Thoracic Society PT criteria. Contacts of foreign-born cases were more numerous (6.0 versus 3.4 per case, p 0.04), and significantly more likely to be TST-positive (50% versus 18%) and to be started on PT (40% versus 23%). The large number of I&R eligible for treatment or PT emphasizes the benefit of prompt evaluation of new arrivals. CI provides an excellent opportunity to screen foreign-born persons at high risk for active TB. Wells CD, Zuber PLF, Nolan CM, Binkin NJ, Goldberg SV. Tuberculosis prevention among foreign-born persons in Seattle King County, Washington. AM J RESPIR CRIT CARE MED 1997;156:573 577. Foreign-born persons in the United States (U.S.) represent a growing number and proportion of the nation s reported tuberculosis (TB) cases. Between 1986 and 1995, the number of foreign-born cases increased from 4,925 (22% of national total) to 8,042 cases (36% of national total) (1). The increase appears to be the result of increased immigration in recent years from regions of the world with a high incidence of TB (2). Prospective immigrants and refugees applying to the U.S. for permanent resident status are required to undergo a medical examination that includes screening for TB before receiving a visa. Although the screening is relatively effective (3 6), not all foreign-born persons enter the U.S. as immigrants or refugees. Furthermore, two-thirds of the cases among foreignborn persons occur among persons who have been in the U.S. for more than a year at the time of diagnosis (2). In ten states, the percentage of cases among foreign-born persons now exceeds 50%; an additional 12 report that between 30% and 49% of their cases were born outside the U.S. (1). A challenge for TB programs, especially in states with a high percentage of their cases among foreign-born persons, is to diagnose cases of active TB in a timely manner and to identify persons at high risk of developing active TB so they can be placed on preventive therapy (PT). (Received in original form November 25, 1996) Supported by funding from the Centers for Disease Control and Prevention. Correspondence and requests for reprints should be addressed to Nancy J. Binkin, M.D., Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention, Centers for Disease Control and Prevention, 1600 Clifton Road (MS E-10), Atlanta, GA 30333. Am J Respir Crit Care Med Vol. 156. pp. 573 577, 1997 Two public health activities currently being conducted by many health departments provide an excellent opportunity for prevention of the development of active TB among foreignborn persons at high risk: follow-up evaluations of persons identified by overseas screening as B1 (chest radiograph suggesting active TB but negative sputum smear) or B2 (chest radiograph compatible with inactive TB), and contact investigation (CI) around foreign-born cases of active pulmonary TB. In this report, we present the experience of the Seattle King County (SKC) health department in identifying patients with TB infection using these two activities. We also compare the yield of CIs for foreign-born cases with that obtained for U.S.-born cases during the same period. Finally, we discuss the application of the current American Thoracic Society (ATS) guidelines on PT among the immigrants and refugees screened (7). Between January 1993 and July 1995, 195 (63%) of the 310 TB patients diagnosed in SKC were foreign-born. These patients had immigrated to the U.S. from 28 different countries. The majority had been born in Vietnam (24%), the Philippines (19%), China (8%), South Korea (8%), and Mexico (7%); most of the remaining 34% came from Africa and Southeast Asia. Of the 154 foreign-born cases for whom date of U.S. arrival was known, 48 (31%) were diagnosed with TB within 1 yr of arrival in the U.S., 52 (34%) were diagnosed between 1 and 5 yr of arrival, and 54 (35%) more than 5 yr after U.S. arrival. Sixty-four (64%) of the 100 diagnosed within 5 yr of arrival could be verified to have entered the U.S. as legal immigrants and refugees. The SKC TB control program places great emphasis on thorough and timely follow-up of newly arrived B1 and B2 immigrants and refugees to identify active TB cases as well as

574 AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE VOL. 156 1997 persons requiring PT. Immigrants and refugees are notified at the time of arrival by the local quarantine station of the need to report to a local health department for further follow-up; this follow-up is facilitated by direct notification of the arrival of B1 and B2 immigrants and refugees from the local Centers for Disease Control and Prevention (CDC) quarantine station to the SKC health department. Although the majority of immigrants and refugees come to the clinic on their own accord after being notified by the CDC quarantine station, a staff of nurses, outreach workers, and interpreters assists in completing the follow-up with phone calls and letters to residences of the B1 and B2 persons, urging them to present to the clinic for evaluation. The follow-up evaluation consists of a patient interview to ascertain any symptoms compatible with TB, a physical examination, a tuberculin skin test (TST), a chest radiograph, and collection of sputum for microbiologic cultures for all suspected active cases. Patients who are identified as suspected cases are started on a four-drug treatment regimen Figure 1. Guidelines for preventive therapy. Adapted from Treatment of Tuberculosis and Tuberculosis Infection in Adults and Children, 1994.

Wells, Zuber, Nolan, et al.: TB Control in Foreign-born Persons 575 for TB; those who are identified as being infected with TB, but not as an active case, are prescribed PT according to the ATS guidelines (7; see Figure 1). CI is also routinely conducted by the SKC health department. All newly diagnosed pulmonary TB cases are reviewed by the clinic physicians and nurses after the patient interview to determine the appropriate list of contacts to be screened based on the degree and duration of exposure to the case. As with follow-up of B1 and B2 immigrants and refugees, clinic personnel use phone calls and home visits to encourage contacts to come to the clinic for screening. Evaluation of case contacts consists of an interview of the contacts to ascertain any symptoms of TB, a TST, and a chest radiograph for any person with a positive TST or regardless of TST results if a household contact of a highly infectious case. For those who initially have a negative TST, repeat testing is performed 3 mo later. Cultures are obtained on all suspected active TB cases, who are then started on a four-drug treatment regimen. Contacts identified as being infected with TB, and close contacts who are children, prior to negative TST at 3 mo, but who do not have the disease are prescribed PT according to ATS guidelines (7; Figure 1). METHODS Outcome of B1/B2 Evaluation To determine clinical outcomes for new class B1 and B2 arrivals evaluated in the SKC TB clinic, we reviewed the clinic log for January 1992 through September 1994, which documented the date of entry in the U.S., the date of clinical evaluation, and the TST and chest radiograph results. The log also documented the clinical disposition for each immigrant and refugee: suspected of having active TB; candidate for PT; or dismissed, no further action required. Additionally, the log indicated persons known to have relocated to other counties or states prior to their evaluation in the clinic. Contact Investigation: Comparison of U.S. and Foreign-born Cases We reviewed CI performed on active TB cases among adults seen in the TB clinic during 1993 to ascertain any differences in outcome among contacts of foreign-born and U.S.-born cases. Twenty-seven foreign-born (36% of all foreign-born) and twenty-seven U.S.-born (69% of all U.S.-born) pulmonary TB cases were randomly selected from the clinic s case log. Information available from clinic charts included: the list of contacts for a given case; their sex and date of birth; the type of contact (household, close nonhousehold, or casual nonhousehold); the date of first and follow-up TSTs and results; and chest radiograph results. The final disposition, categorized as suspect active TB; candidate for PT; or dismissed, no further action required, was also available. Data Analysis Simple ratios of contacts per U.S.-born and foreign-born cases were compared using the Student s t test. Risk ratios and the Fisher exact test were also used to compare TST results and diagnostic outcomes among the two groups of case contacts (8). RESULTS Outcome of B1/B2 Evaluations For the period January 1992 through September 1994, 1,272 class B1 and B2 immigrants who listed SKC as their intended residence were identified by the CDC s Division of Quarantine tracking system. Of these, 66 persons (5.2%) relocated to another county or state before being evaluated in the clinic. Another 120 persons (9.4%) declined evaluation in the clinic or were otherwise lost to follow-up. An additional 17 class B1 and B2 immigrants were evaluated after moving to SKC from another county or state. Ultimately, 1,086 persons, including 1,069 of the 1,272 (84.0%) included in the tracking system list for SKC, were evaluated in the TB clinic. The median interval between U.S. arrival and first evaluation in the clinic was 32 d for the class B1 immigrants and 27 d for the class B2s. Table 1 presents the outcomes in the initial evaluations of Class B1 and B2 immigrants in the TB clinic. Of the 1,086 persons evaluated, 942 (86.7%) had complete information available on immigration classification status and final disposition as suspect active TB, candidate for PT, or dismissed, no further action required. Overall, 73% were TST-positive. The rate of positive TSTs in B1s and B2s was similar (76% versus 72%; risk ratio [RR] 1.1, 95% confidence interval 1.0 to 1.2). A total of 5.2% of the B1s and B2s evaluated were considered to be suspect TB cases and placed on TB treatment. An additional 34.4% were candidates for PT, and the remaining 60.4% were dismissed. The frequency of persons suspected on the basis of the evaluation to be TB cases was 10 times greater among B1s (10.5% versus 1.1%; RR 9.3, 95% confidence interval 4.0 to 21.7). More B1s were placed on PT as a consequence of the evaluation (45.7% versus 25.7%; RR 2.0, 95% confidence interval 1.7 to 2.3). A total of 973 persons had complete TST information available and were not considered active TB cases. Of the 973, 380 (39.1%) were started on PT and 593 were dismissed. Virtually all (95.5%) of those not suspected to have active TB but prescribed PT had positive TSTs; the remaining 4.5% had borderline positive results. Among the 593 dismissed from the clinic, 377 (63.6%) were TST-positive, and the remaining 216 (36.4%) were negative. To assess adherence to ATS guidelines, we evaluated the characteristics of persons who were candidates for PT and those who were dismissed from the clinic. Of the 363 persons in the PT group, including 324 with B1 and B2 classification and 39 with B classification otherwise unspecified, 323 (89.8%) had significant chest radiograph findings suggestive of TB, of whom 92% were 35 yr of age or more. Of the remaining 40, 32 (80.0%) were less than 35 yr of age and, therefore, were eligible for PT according to ATS guidelines (Figure 1). Thus, 97.6% of the PT group met either radiologic or age criteria for PT. Among the 373 immigrants with positive TSTs who were dismissed from the clinic, 298 (79.9%) had chest radiograph findings not consistent with TB, and 75 (20.1%) had received treatment for TB in the past. Of the 298 with benign chest radiographs, 275 (92.3%) were 35 yr of age or older. Therefore, 93.8% of those dismissed appeared, on the basis of record review, not to be candidates for PT. TABLE 1 OUTCOME OF IMMIGRANT AND REFUGEE EVALUATIONS BY OVERSEAS SCREENING CLASSIFICATION, SEATTLE KING COUNTY, WASHINGTON, JANUARY 1992 SEPTEMBER 1994 B1 (% of total) B2 (% of total) Total Tuberculin skin test Positive 312 (76.3) 381 (71.5) 693 (73.4) Negative 89 (21.8) 134 (25.1) 223 (23.6) Unknown 8 (2.0) 18 (3.4) 26 (2.8) Total 409 533 942 (100) Clinical disposition Suspected case 43 (10.5) 6 (1.1) 49 (5.2) Preventive therapy 187 (45.7) 137 (25.7) 324 (34.4) Dismissed 179 (43.8) 390 (73.2) 569 (60.4) Total 409 533 942 (100)

576 AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE VOL. 156 1997 TABLE 2 COMPARISON OF RESULTS OF CONTACT TRACING INVESTIGATIONS AMONG U.S.-BORN CASES AND FOREIGN-BORN CASES AS PERFORMED BY THE SEATTLE KING COUNTY TB CLINIC, WASHINGTON, 1993 U.S.-born Cases (n 27) Foreign-born Cases (n 27) p Value Risk Ratio (95% confidence interval) I. Total contacts identified 104 187 Casual contacts, not at risk 12 26 II. Total at risk contact 92 161 A. Contacts/case 3.4 6.0 0.04 B. Screening refused or contact not locatable (% of II) 29 (31) 23 (14) 0.5 (0.3 0.7) C. Number with prior positive reaction (% of II) 2 (2) 8 (5) 2.3 (0.5 10.5) III. Total initial TSTs performed (% of II) 61 (66) 130 (81) 1.2 (1.0 1.4) A. Number of positive reactions* (% of III) 11 (18) 65 (50) 2.8 (1.6 4.9) B. Number of follow-up TSTs performed (% of III-III.A) 19 (38) 40 (62) 1.6 (1.1 2.4) C. Number of positive reactions* (% of III.B) 0 (0) 11 (28) 0.01 IV. Contacts placed on preventive therapy (% of II) 21 (23) 64 (40) 1.7 (1.1 2.7) V. Number of active cases found (% of II) 1 (1) 0 (0) * A positive reaction is defined as 5 mm induration from tuberculin skin test. Student s t test. Fisher s exact test. Outcomes of Contact Investigations The outcome of CIs performed on the 54 randomly selected U.S.-born and foreign-born pulmonary TB patients is shown in Table 2. The foreign-born cases had a greater number of close contacts identified per case (6.0 compared with 3.4, p 0.04, Student s t test), and a greater frequency of positive TSTs among close contacts when initial testing was performed (RR 2.8, 95% confidence interval 1.6 to 4.9), Of the 40 contacts of the foreign-born cases who were TST-negative on initial testing, 11 (28%) were TST-positive on follow-up testing; this compares with none of the contacts of U.S.-born cases who were retested (p 0.01, Fisher exact test). Overall, 64 (40%) of 161 contacts of foreign-born cases received PT, compared with 21 (23%) of the 92 contacts of U.S.-born cases (RR 1.7, 95% confidence interval 1.1 to 2.7). DISCUSSION The findings in this report emphasize the benefit of prompt evaluation of immigrants with suspected TB upon arrival in the U.S., not only for initiating treatment among those found with active TB but also as a means of identifying high-risk candidates who can benefit from PT. In addition to identifying a number of cases of active TB, we found that almost half of the B1s and one-quarter of the B2s evaluated were eligible for PT based on TST and chest radiograph results. These individuals, most of whom were confirmed to have abnormal chest radiographs, are at high risk of developing active TB. It is estimated that the annual risk of developing active TB among persons with abnormal chest radiographs is 0.3%, 2.5 times higher than for persons with positive TSTs but no radiograph abnormalities (9). The comparably high proportions of positive TST results among the immigrants who were prescribed PT and those dismissed from the clinic reflect the high prevalence of TB in their respective countries of origin. For example, over 75% of the immigrants evaluated in the clinic came from Vietnam, the Philippines, the Republic of Korea, and China. Each of these countries has an estimated TB case rate in excess of 100 cases per 100,000 population (10). Furthermore, these countries routinely vaccinate large numbers of children with bacille Calmette-Guérin (BCG) which may account for some positive TST results, especially among younger immigrants (11, 12). Although TSTs are useful for evaluating immigrants for TB infection, the results should be correlated with the chest radiograph, the person s age, country of origin, likelihood of BCG vaccination, the risk of INH use, and the size of the TST reaction to determine the need for prescribing PT. The ATS guidelines for prescribing PT which are based on TST and chest radiograph results as well as determination of any underlying TB risk factors are summarized in Figure 1 (7). According to these recommendations, foreign-born persons from countries with a high TB prevalence are considered an at risk group and should be prescribed PT if they have a TST of 10 mm or greater and are less than 35 yr of age, even with a normal chest radiograph and no underlying medical conditions (7). The outcomes we observed in SKC adhered closely to the guidelines provided by ATS. In this study, we found that nearly 98% of TST-positive immigrants in SKC who were prescribed PT had fibrotic lesions on chest radiograph or were less than 35 yr of age. Conversely, 94% of TSTpositive immigrants who were dismissed from the clinic without PT were 35 yr of age or older, had a negative chest radiograph, or had a history of prior treatment for TB. From the review of contact investigations (CI), we found that contacts of foreign-born TB patients were more numerous, more likely to be TST-positive, and more likely to be started on PT than contacts of U.S.-born TB patients. The larger number of contacts for foreign-born patients might be explained by larger numbers of persons sharing the same household. For example, data from the national census of 1990 showed that foreign-born persons were 4.8 times more likely to live in a household with 7 or more persons than were U.S.-born persons (13, 14). Information on place of birth was not specifically available on the contacts, but it is likely that many contacts of foreignborn cases were also foreign born. A positive TST in a foreign-born contact may reflect recent infection; however, it is likely that a larger proportion of foreign-born contacts than U.S.-born contacts would have positive TSTs as a result of previous infection, or boosting due to BCG (15). Although results of TSTs do not necessarily permit distinction between recent and remote infection among those found to be positive, CIs nonetheless provide an excellent opportunity to offer

Wells, Zuber, Nolan, et al.: TB Control in Foreign-born Persons 577 screening to foreign-born persons who have not previously received this recommended intervention. Reducing the burden of TB disease among foreign-born persons residing in the U.S. is a complex issue. We have shown in SKC and previously in Hawaii and Los Angeles that active follow-up of recently arrived immigrants and refugees identified by the overseas screening system is useful for detection of active TB cases; the study also demonstrates the usefulness of active follow-up for prevention of future disease by identifying candidates for PT. However, immigrants and refugees screened overseas represent only a fraction of the at risk foreign-born population in the U.S. The majority of foreignborn TB cases in the U.S. occurs among persons who have resided in the country for 3 yr or more (16). As shown in SKC, CI offers useful access to those who may be at risk for infection and disease in this often hard-to-reach population. Additional prevention and control strategies involving not only health departments but also other medical facilities that are aimed at longer term residents should be explored if TB among the foreign-born is to be effectively prevented and controlled. Acknowledgment : The authors thank Kay Anderson for generously providing data from her jurisdiction. References 1. U.S. Department of Health and Human Services. 1996. Reported Tuberculosis in the United States, 1995. Public Health Service. Centers for Disease Control and Prevention, Atlanta, GA. 2. McKenna, M. T., E. McCray, and I. Onorato. 1995. The epidemiology of tuberculosis among foreign-born persons in the United States, 1986 93. N. Engl. J. Med. 332:1071 1076. 3. Binkin, N. J., P. L. F. Zuber, C. D. Wells, M. A. Tipple, and K. G. Castro. 1996. Overseas screening for tuberculosis among immigrants and refugees to the United States: current status. Clin. Infect. Dis. 23: 1226 1232. 4. Zuber, P. L. F., N. J. Binkin, A. C. Ignacio, K. L. Marshall, S. P. Tribble, M. A. Tipple, and R. L. Vogt. 1996. Tuberculosis screening for immigrants and refugees: diagnostic outcomes in the State of Hawaii. Am. J. Respir. Crit. Care Med. 154:151 155. 5. Zuber, P. L. F., L. S. Knowles, N. J. Binkin, M. A. Tipple, and P. T. Davidson. 1996. Tuberculosis among foreign-born persons in Los Angeles County, 1992 1994. Tubercle Lung Dis. (In press) 6. Centers for Disease Control and Prevention. 1995. Tuberculosis among foreign-born persons who had recently arrived in the United States Hawaii, 1992 1993, and Los Angeles County, 1993. M.M.W.R. Morb. Mortal. Wkly. Rep. 44:703 707. 7. Bass, J. B., Jr., L. S. Farer, P. C. Hopewell, R. O Brien, R. F. Jacobs, F. Ruben, D. E. Snider, and G. Thornton. 1994. Treatment of tuberculosis and tuberculosis infection in adults and children. Am. J. Respir. Crit. Care Med. 149:1359 1374. 8. Rothman, K. J. 1986. Modern Epidemiology. Little, Brown, Boston. 131 236. 9. International Union Against Tuberculosis, Committee on Prophylaxis. 1982. Efficacy of various durations of isoniazid preventive therapy for tuberculosis: five years of follow-up in the IUAT trial. Bull. WHO 60:555 564. 10. Raviglione, M. C., D. Snider, and A. Kochi. 1995. Global epidemiology of tuberculosis. J.A.M.A. 273:220 226. 11. World Health Organization. 1994. Expanded Programme on Immunization, Information System Summary for the WHO African, South East Asian, and Western Pacific Region. 94.2. Geneva, Switzerland. 12. Snider, D. E. 1985. Bacille Calmette-Guérin vaccinations and tuberculin skin tests. J.A.M.A. 253:3438 3439. 13. U.S. Department of Commerce. Bureau of the Census. 1990 Census of Population: The Foreign-born Population in the United States. 1990 CP-3-1. Washington, DC. 14. U.S. Department of Commerce. Bureau of the Census. 1990 Census of Population: General Population Characteristics, United States. 1990 CP-1-1. Washington, DC. 15. Menzies, R., B. Vissandjee, I. Rocher, and Y. St. Germain. 1994. The booster effect in two-step tuberculin testing among young adults in Montreal. Ann. Intern. Med. 120:190 198. 16. Zuber, P. L. F., M. T. McKenna, N. J. Binkin, I. M. Onorato, and K. G. Castro. 1996. High Risk Groups for Tuberculosis Among Foreignborn Persons in the United States. Abstract presented at meeting of the North American Region of the International Union Against Tuberculosis and Lung Disease, Chicago, IL, March 1 2, 1996.