INTRODUCTION

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

From 1985 through 1992, after decades of decline, tuberculosis (TB) reemerged in epidemic proportions in the United States (1). The Centers for Disease Control and Prevention (CDC) reported that from 1986 to 1995, the proportion of TB cases occurring in foreign-born persons increased from 21.6% to 35.7% (4). In 1995, all U.S. reported TB cases dropped 6.4%, compared with 1994, primarily owing to the decline in TB among U.S.-born persons, but in 1996 CDC reported for the fourth consecutive year that the numbers of all TB cases including the TB cases in foreign-born persons decreased (5). In Santa Clara County (SCC), in the decade from 1985 through 1996, the proportion of TB cases occurring in foreign-born increased from 78% to 88%, and numbers of reported TB cases surged 68.2% (176 to 296) (5). Continuing immigration and, since 1994, intensified TB surveillance have contributed to this trend (9).

Recent studies (10) found a high incidence of active TB among new TB Class A/B1/B2 immigrants (TBIMs). In Hawaii, 15% of TB Class B1 TBIMs and in Los Angeles 11% of TB Class B1 were diagnosed with active TB. (See explanation of TB Class classification in METHODS.)

Unfortunately, in the U.S. TB control programs do not routinely monitor the proportion of TBIMs who actually present for TB screening after they immigrate or the results of their TB screening. There have been no studies evaluating simple and low-cost ways to encourage these TBIMs to report for screening after immigration to the U.S. Because of the increasing incidence of TB in foreign-born persons in SCC, we developed a strategic program aimed at encouraging TBIMs to present for timely screening through a hierarchy of public health interventions.

	METHODS

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

The CDC requires immigrants and refugees entering the U.S. to have a physical and mental health examination as part of the visa application process (13, 14). A panel of physicians overseas uses chest X-ray (CXR) to screen applicants 15 yr of age or older, to assure that they do not enter the U.S. with active infectious TB. If the CXR is compatible with TB, sputum smears for acid-fast bacilli (AFB) are examined. These persons are then classified as: (1) TB Class A (infectious), based on a CXR compatible with TB and one sputum smear positive for AFB; (2) TB Class B1 (clinically active, noninfectious), based on CXR compatible with TB and three negative sputum smears for AFB; (3) TB Class B2 immigrants (not clinically active, not infectious), based on an abnormal CXR, noncompatible with active TB; (4) TB Class B3 immigrants (other chest conditions) based on abnormal CXR not consistent with TB or compatible with old, healed TB (13, 14).

Upon entry into the U.S., the United States Immigration and Naturalization Services sends information about the classification of each TB immigrant and refugee to CDC's Division of Quarantine (DQ). The DQ then notifies the state and local health departments of the arrival of each of these persons to their jurisdiction (DQ Form 75.17) and informs the newcomers via letter that they need to report promptly to their local health department (LHD) upon entering the U.S. As there is no mechanism identifying the undocumented foreign-born immigrants when they enter the U.S. (about 5% of SCC TB cases) and the "Refugee Health Services Program" already exists to screen TB Class A/B1/B2 refugees, we focused our study on evaluating and screening TBIMs.

We studied prospectively all TBIMs who entered SCC from October 1, 1995 to June 30, 1996. Initially, we recorded the TBIM's country of origin, ethnicity, and overseas TB classification. To encourage the TBIMs to appear for TB screening we subjected them to a hierarchy of interventions beginning with a specifically designed letter mailed to the TBIMs immediately on the day of receipt of the DQ notification by SCC. The letter requested that the TBIM report within 2 wk to either the Santa Clara Valley Health and Hospital System's (SCVHHS) TB Clinic or with their private medical doctor (PMD) for medical examination. We provided each TBIM with a choice (drop-in) of four 1-h allotments of time for evaluation on three different days each week in the TB Clinic. If the TBIM failed to present for screening within 2 wk after the letter was mailed, up to three phone calls were made to the TBIMs by bilingual community workers (CW) or public health assistants (PHA). If the TBIM failed to present for screening within 2 wk after phone calls were initiated, CW or PHA attempted up to three home visits over the next 3 wk. If the immigrant failed to present for screening within this cumulative 7-wk period, the SCC TB Controller notified the California Department of Health Services (CDHS) by forwarding the DQ form (DQ 75.17). If the TBIM presented for the TB screening within the required 7-wk period, the TB Controller forwarded the DQ 75.17 form to the CDHS after the screening was completed noting the results of the initial evaluation, presumptive diagnosis, and plan for therapy/prophylaxis. Moreover, SCC TB Control notified the CDHS on the same DQ form about the disposition of the TBIMs who did not settle in SCC asking CDHS to inform the receiving jurisdictions about the new TBIM's arrival if the forwarding address was known.

For each TBIM we evaluated the time intervals between the date of U.S. entry and the date of TB screening and between the date of each intervention used by SCC and the date of TB screening. We also evaluated the incremental cost and efficacy of each intervention. To assess cost-effectiveness we used the costs of the personnel plus the cost of variable expenses for each of the interventions (Table 1). We considered one full-time work-year to consist of 1,720 work-hours [80% of (52 wk times 40 work-hours per week)]. In our estimation mailing one letter requires 10 min, one phone call 15 min, and one home visit requires 60 min. We calculated that to mail one letter cost $8.65, one phone call $10.60 to $11.86, and one home visit $31.67 to $36.73. We determined the average cost per TBIM presenting for screening by dividing the total cost of all interventions by the number of all TBIMs responding to all interventions (for the hierarchy of interventions) and by dividing the total cost of each individual intervention by the number of TBIMs responding to that intervention. Then we determined the average cost of finding one TBIM diagnosed with active TB by dividing the total cost of all interventions by the number of all TBIMs diagnosed with active TB and by dividing the total cost of each individual intervention by the number of TBIMs diagnosed with active TB found by that intervention.

	RESULTS

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

From October 1, 1995 to June 30, 1996, DQ notified SCC TB Control that 342 TBIMs entered SCC. These immigrants included 209 Filipinos (61.1%), 58 Vietnamese (16.9%), and 66 Chinese (19.3%); the remaining nine (2.7%) came from India, Korea, and Russia. Of these 342 TBIMs, 154 (45%) were classified as TB Class B1, 184 (53.8%) as TB Class B2, and three (1%) were TB Class B3. One person was classified as TB Class A. Of the 342 TBIMs, 14 did not settle initially in SCC but elsewhere within the U.S., five returned to their native country within 7 wk of entry, and 323 TBIMs remained in SCC. For the 10 of 14 TBIMs who moved we were successful in obtaining a correct forwarding U.S. address.

Of the 323 TBIMs who remained in SCC, 79 (24.5%) presented for TB screening before DQ notified SCC about their arrival and therefore SCC sent no letters. To the remaining 244 TBIMs, SCC sent letters and 213 (87.3%) TBIMs presented for screening within 2 wk of the mailing (Figure 1). Telephone calls were made to each of the 31 TBIMs who did not respond to letter; 12 received one, seven received two, and 12 received three phone calls. After a total of 62 phone calls to these 31 TBIMs, 17 (54.8%) presented for TB screening within 2 wk (Figure 1). Home visits were made to 14 immigrants who did not respond to the phone calls. Of the 14 TBIMs, 11 received one and three received two home visits. After a total of 17 home visits to these 14 TBIMs, 5 (36%) presented for screening within 2 wk (Figure 1). Nine TBIMs did not present for TB screening after letter, phone calls, or home visits during the 7-wk period. Eight had unknown or incorrect addresses and remained lost. One TBIM was reached by phone several weeks after the 7-wk period had elapsed. This TBIM was screened and diagnosed with active TB. Altogether, 315 of 323 TBIMs (97.5%) presented for TB screening. The TB Clinic staff screened 308 (97.8%) of them and local PMDs screened seven (2.2%).

View larger version (24K): [in this window] [in a new window]   Figure 1.   Tuberculosis screening summary of newly arrived TB immigrants (TBIMs) reported to Santa Clara County, October 1, 1995 to June 30, 1996.

Of the 315 TBIMs who presented for TB screening, 18 either moved within the U.S. or out of the country, two died, and 12 were lost to follow-up before their final TB diagnosis could be established. Of the remaining 283 TBIMs, 16 (5.7%) were diagnosed with active TB (TB Class 3) (15) and all completed the ATC/CDC recommended therapy (16) (Figure 2). Of the 16 TBIMs with active TB, two presented for screening without any interventions, 12 presented because of the letter, one because of phone calls, and one presented after a 7-wk period. Of the 16 TBIMs diagnosed with active TB, 11 were classified as TB Class B1 on immigration (8.5% of 129 TB Class B1 TBIMs) and four were TB Class B2 (2.7% of 150 TB Class B2 TBIMs). The only one TB Class A TBIM had active TB. No cases of TB were identified in the three TB Class B3 TBIMs.

View larger version (29K): [in this window] [in a new window]   Figure 2.   Final TB diagnosis of TBIMs entering Santa Clara County, October 1, 1995 to June 30, 1996.

Preventive therapy (16) was recommended for those of 171 TB Class 4 TBIMs (15) (TB not clinically active with abnormal stable CXR and positive tuberculin skin test) without previous adequate treatment, and for those of 47 TB Class 2 TBIMs (15) (TB infection, no disease with positive tuberculin skin test, no clinical or radiological evidence of TB) (Figure 2) if recommended by the CDC/ATS treatment guidelines (16).

Of the 315 TBIMs who presented for screening, the median time intervals from date of SCC notification by DQ to date of TB screening were 0 days for TBIMs presenting prior to mailing of the letter by SCC, 8 d for those presenting after the letter, 32 d for those presenting after phone calls, and 43.5 d for those presenting after home visits. For the entire prospective cohort, the median time interval from date of SCC notification by DQ to date of screening was 7 d. The median time interval from date of U.S. entry to date of SCC notification by DQ was 6 d, and from date of U.S. entry to date of TB screening was 14 d. The effectiveness of the hierarchy of interventions did not vary by country of origin.

We calculated that to reach one TBIM by letter cost $9.90, by phone calls $38.66 to $43.25, and by home visit $107.68 to $124.88 (Table 2). The total cost to encourage the 244 TBIMs to present for TB screening was $3,306.19 to $3,470.36 ($13.55 to $14.22 per TBIM). Fourteen cases of active TB were found in these 244 TBIMs (two additional cases were found in the 79 TBIMs who presented before our interventions.) Therefore the cost of the SCC interventions per case of active TB found is $236.16 to $247.88 (total cost divided by 14 TB cases). The cost of identifying one active TB case by letter was $175.88 ($2,110.60/12 active TB cases), and the incremental cost to identify the single case of TB by phone was $696.26. Because no cases were identified through home visits, the incremental cost for this intervention cannot be calculated.

	DISCUSSION

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

Sixteen of 277 TBIMs (5.77%) who entered SCC from October 1, 1995 through June 30, 1996 were diagnosed with active TB. We found that 8.5% (11 of 129) of the Class B1 TB (compared with 15% in Hawaii and 11% in Los Angeles) and 2.7% (4 of 129) of the Class B2 TBIMs (compared with 3% in Hawaii and 2% in Los Angeles) were diagnosed with active TB (10). Thus, in SCC the rate of active TB in TB Class B1 immigrants was 3 times as high as in TB Class B2 immigrants. Likewise, the rates of active TB were approximately 12 times higher among TB Class B1 immigrants and 4 times higher among TB Class B2 immigrants than 0.7% of active TB cases reported among close contacts of persons with active TB in the U.S. (10, 13). These data definitely established the need to target TBIMs Class B1 and B2 immigrants for prompt and active follow-up. This action would be of equal or superior priority for a TB control program as the contact investigation to an active case of TB.

Our interventions are more cost-effective than contact investigations in finding active TB cases. The cost of our interventions was similar to contact investigations in identifying persons at high risk for TB infection and disease ($14 per TBIM for our interventions versus $17 per contact in contact investigation) (17). But our yield in identifying active TB cases was much greater. In 1991, assuming that 1% of the contacts will have active disease, the cost of identifying an active case in contact investigation was $1,700 per active case ($17 per contact times 100 contacts) (17). In contrast, the cost of our interventions per active case found was only $240. The cost of contact investigations is likely an underestimate for SCC public health nurses initiate contact investigations and their salary is relatively high ($35 to $45 per hour).

In the U.S. TB treatment accounts for almost 90% of TB-related expenses (17). Moreover, studies confirm that 20 to 60% of close household contacts to an active case of TB become TB-infected (18) and of these TB-infected persons, 10% have potential risk of developing active TB during their lifetime (19). In 1990, in the U.S., preventive therapy for TB infection cost about $240 per person, cost of treating one case of uncomplicated TB (outpatient treatment only) was $3,250, and the cost of treating one moderately advanced case of TB disease (combined inpatient/outpatient) was $14,300 (20, 21). These costs are more than the cost of our total program in which we rapidly identified and treated 14 TB cases and prevented secondary spread of TB infection/disease to their contacts.

The high risk for active TB disease among recent TBIMs may be due to inadequacies in the design and implementation of the immigrant TB screening process, both overseas and in the U.S. (13, 22, 23). There is no formal certification process for the panel of physicians performing medical examination overseas. They are appointed by the U.S. Consulate and directly reimbursed by immigrant applicants using a fee scale set locally, resulting in potential conflict of interest and even potential fraud (22, 23). The examination is valid for an entire year, thus visa applicants free of TB at the time of examination may develop active TB before they arrive in the U.S. Immigrants are screened overseas for infectious TB by the examination of sputum smears for AFB, not sputum cultures for M. tuberculosis. Studies confirm that 20 to 60% of TB cases which are sputum culture positive might be AFB smear negative (24). CDC has been working intensively toward the elimination of all barriers preventing high-quality TB evaluation of U.S. visa applicants overseas.

After entry into the U.S., although the CDC DQ notifies LHDs of the arrival of TBIMs, the effort made to encourage these persons to present for screening vary widely between LHDs. For example, in 1993 DQ notified SCC TB Control of 532 TBIMs entering the county. That year, SCC staff mailed letters to all 532 TBIMs inviting them for TB screening. The letters were mailed after approximately 4 to 6 mo delay. Overall, 353 (66%) of the TBIMs were screened. Eighteen of the 353 TBIMs (5.1%) were diagnosed with active TB and all completed anti-TB therapy according to CDC/ATS treatment guidelines (16). However, 179 (34%) TBIMs did not present for screening. Using a plausible rate of 5% among all TBIMs, approximately 9 of 179 TBIMs with active TB were possibly not identified here.

We recommend that each LHD: (1) reviews its TB policy regarding the TBIMs' timely tracking and screening, (2) develops a system for encouraging TBIMs to present for TB screening in a timely manner, which uses a hierarchy of interventions of progressively more costly interventions as defined in our study, (3) reports to the state TB program and CDC the percentage of TBIMs settling in their locale who present for TB screening and the results of their screening, on a periodic basis. CDC should give consideration to placing the follow-up and reporting of the results of screening among newly arrived TBIMs at the same or higher level priority as currently given to the contact investigation of an active case of TB.

In conclusion, it has now been documented that the TBIMs newly arrived in the U.S. have high rates of TB. Improvements are required overseas in U.S. visa applicants' TB screening and in the U.S., in TBIMs' tracking, screening and follow-up procedures. Our study confirms that by using efficient, timely, and low-cost strategies encouraging the newly arrived TBIMs to come for TB screening, the vast majority, e.g., 97.5%, will report for examination promptly and the high rates of TB disease in the population may be significantly decreased.