Evaluation of a School-Based Tuberculosis-Screening Program and Associate
Investigation Targeting Recently Immigrated Children in a Low-Burden
Country
Paul Brassard, Colin Steensma, Louise Cadieux and Larry C. Lands
Pediatrics 2006;117;e148
DOI: 10.1542/peds.2005-1534
The online version of this article, along with updated information and services, is
located on the World Wide Web at:
http://pediatrics.aappublications.org/content/117/2/e148.full.html
PEDIATRICS is the official journal of the American Academy of Pediatrics. A monthly
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ARTICLE
Evaluation of a School-Based Tuberculosis-Screening
Program and Associate Investigation Targeting
Recently Immigrated Children in a Low-Burden
Country
Paul Brassard, MD, MSca,b, Colin Steensma, MScb, Louise Cadieux, BScNc, Larry C. Lands, MD, PhDc
a
Departments of Medicine, McGill University, Montreal, Quebec, Canada; bDivision of Clinical Epidemiology, McGill University Health Center, Royal Victoria Hospital,
Montreal, Quebec, Canada; cDepartment of Pediatrics, McGill University Health Center, Montreal Children’s Hospital, Montreal, Quebec, Canada
The authors have indicated they have no financial relationships relevant to this article to disclose.
ABSTRACT
CONTEXT. In countries with a low incidence of tuberculosis (TB), screening programs
targeting recent immigrants from TB-endemic countries have been shown to be
effective in further reducing TB incidence; however, evaluative data on some
aspects of these programs remain sparse.
OBJECTIVE. We sought to retrospectively evaluate a school-based screening program
targeting children at high risk for TB infection in Montreal, Canada, as well as
subsequently investigate family and household associates of the schoolchildren
with latent TB infection (LTBI), based on adherence to LTBI therapy and costbenefit analysis.
DESIGN, SETTING, AND PARTICIPANTS. Newly arrived immigrant children (aged 4 –18 years)
in selected schools were screened for LTBI by using the tuberculin skin test (TST).
The TST was defined as positive at an induration of ⱖ10 mm. Each child who
tested positive on the TST was referred for medical evaluation. Family and household associates of the TST-positive child also were screened for LTBI. Classroom
attendance sheets and medical charts were reviewed for 16 elementary and
secondary schools that comprised the school-screening program of the Montreal
Children’s Hospital from 1998 to 2003. Medical charts of the child associates (⬍18
years old) who were screened were reviewed also.
www.pediatrics.org/cgi/doi/10.1542/
peds.2005-1534
doi:10.1542/peds.2005-1534
Key Words
tuberculosis, children, targeted screening,
associates, cost-effectiveness
Abbreviations
TB—tuberculosis
LTBI—latent tuberculosis infection
MCH—Montreal Children’s Hospital
TST—tuberculin skin test
INH—isoniazid
Accepted for publication Sep 6, 2005
Address correspondence to Paul Brassard, MD,
MSc, Division of Clinical Epidemiology, McGill
University Health Centre, Royal Victoria
Hospital, 687 Pine Ave West, R4-29, Montreal,
Quebec, Canada H3A 1A1. E-mail: paul.
brassard@mcgill.ca
PEDIATRICS (ISSN Numbers: Print, 0031-4005;
Online, 1098-4275). Copyright © 2006 by the
American Academy of Pediatrics
MAIN OUTCOME MEASURES. The main outcome measures were TST-positivity rate, rate of
adherence to LTBI therapy, estimation of factors associated with adherence, and
net cost/benefit of the school-screening and associate-investigation programs, both
respectively and as a combined program, compared with the cost of passive
treatment of TB disease.
RESULTS. Of 2524 immigrant children screened, 542 (21%) were TST-positive. Of
342 children started on therapy, 316 (92%) demonstrated adequate adherence.
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BRASSARD, et al
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The only predictor of adherence among the schoolchildren was having ⱖ2 family members brought in for TB
screening (adjusted odds ratio: 2.0; 95% confidence interval: 1.3–3.3). There were 599 associates investigated
from the 484 TST-positive schoolchildren seen at the TB
clinic. Of 555 associates with TST results, 211 (38%)
were found to be TST-positive. Of 136 TST-positive child
associates, 131 were seen at the Montreal Children’s
Hospital TB clinic and had their chart reviewed. Of these,
108 (82%) were started on LTBI therapy, and 78 (79%)
of 99 of those children with information complied adequately with their therapy. We found net benefits from
both school-based screening and associate investigation,
both as stand-alone programs and as 1 coordinated, targeted TB-screening program.
CONCLUSION. We demonstrated the effectiveness, including
cost-effectiveness, of a targeted, school-based screening
program in a low-burden country and the extra benefit
given by adding associates to such a program.
I
MMIGRANTS AND FOREIGN-BORN Canadians account for
more than half of all active tuberculosis (TB) cases in
Canada,1 and in Montreal their overall risk for developing active disease is 10 times higher than the non–
foreign-born population (37.5 and 3.3 cases per 100 000,
respectively).2 TB disease rates are at their highest during
the first few years of arrival to Canada.1 Furthermore,
the TB case rate among foreign-born children has been
found to be relatively high when compared with Canadian-born non-Aboriginal children.1 In Canada, there is
no systematic screening for latent TB infection (LTBI)
among newly arrived children. Children aged 11 years
and older are required to undergo a chest radiograph
and must either complete a course of treatment before
entry to Canada if they are found to have active TB or be
placed under medical surveillance as a condition of entry
if they are found to have inactive TB.3
In low-burden countries, screening programs that target recently immigrated populations, including children,
may be particularly effective in reducing the burden of
TB.4–6 Another strategy for targeted tuberculin skin testing is that of the associate investigation, in which family
members and other close contacts of children who are
diagnosed with LTBI are persuaded to receive TB screening and treatment as necessary.7 To maintain TB-prevention programming among foreign-born children in a
low-incidence area, it is necessary to assess the potential
effectiveness of such a program in terms of successful
screening, drug-therapy treatment, adherence to treatment, and cost-effectiveness. Furthermore, determining
which factors are associated with adherence to treatment allows for an assessment of strengths and opportunities for improvement in a particular targeted screening program.
Previous studies evaluating school-based screening
studies8–15 have not included any details of related associate investigations, nor have they determined factors
associated with adherence to TB drug therapy. Of the
few studies that have evaluated associate investigations
in children,16–19 only 1 included children ⬎8 years of age,
none were explicitly related to another targeted screening-program strategy, and none included a cost-benefit
analysis. We evaluated a school-based screening program that targeted children at high risk for TB infection
in Montreal, as well as subsequent investigation of family and household associates of the schoolchildren with
LTBI. This evaluation was a retrospective review of
available data and was based on screening, treatment,
and adherence rates, as well as on cost-effectiveness of
the program. A comparison was also made between the
net cost/benefit of the school-based screening alone and
that of the school screening with associate investigation.
The results of this study were presented in part elsewhere.20
METHODS
Each school year, the TB clinic at the Montreal Children’s Hospital (MCH) performs TB-screening clinics at
welcoming classes for newly arrived immigrant children
(aged 4 –18 years) in a selected number of elementary
and secondary schools. These welcoming classes are provided to help integrate the child into the school and the
new society, as well as to offer language-learning assistance to children whose first language is not French.
Schools were chosen primarily from multiethnic neighborhoods in which a large proportion of the families
were most likely to have immigrated to Canada from a
highly endemic TB country and in which students attending welcoming classes are more closely followed and
supported. A school also may have been visited by the
TB clinic because of a special request from the school
board or by notification from the Montreal health board
if cases of active disease had been reported in specific
schools over the previous years. Schools that were included in the screening program on a 1-time basis for the
sole purpose of investigation of contacts of an active TB
case within that school were excluded from our study.
For each school visited, a specific grade was usually
targeted. In elementary schools, that target was primarily grade 6.
The TB-screening program was conducted in connection with the local community health clinic. Each local
community health clinic provided the child with a written consent form to bring home to his or her family
along with information on TB infection, disease, and the
importance of screening. Children who were not present
in class at the time of the TB clinic were given an
appointment for screening at the MCH, provided their
parents had already signed the consent form.
The tuberculin skin test (TST) was performed by
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e149
trained nurses from the TB clinic of the MCH according
to Canadian tuberculosis standards.21 The TST was performed by using the Mantoux technique and injection of
0.1 mL or 5 TU of purified protein derivative-T, which is
bioequivalent to purified protein derivative-S (Connaught-Merieux Laboratories, Willowdale, Ontario,
Canada). A positive TST was defined as an induration of
ⱖ10 mm in diameter at the site of injection 48 to 72
hours after administration. Children with a TST result
between 5 and 9 mm (inclusive) were also referred to
the MCH for medical evaluation if symptoms characteristic of TB were observed by the TB nurse. Children
whose parents reported prior skin testing were retested
unless documentation of the results was provided. Each
child who tested positive on the TST was given an appointment sheet for the TB clinic, which gives instructions for the visit in French, English, Spanish, Russian,
and Chinese. At the appointment, the accompanying
parent(s) was asked about the family’s knowledge, beliefs, and personal experience with TB and the child’s
history with respect to immigration and TB treatment.
Bacille Calmette-Guérin (BCG) vaccination status was
assessed through report by the child’s parent or guardian
and was verified by any existing medical documentation,
vaccination records, and scarring at common sites. Associates of the child were also given a date for TB screening at this time. Associates were defined as those family
members and any other individual demonstrating close,
sustained contact with the child, primarily through cohabitation or recent long-term visits to the child’s household. Overlap between school screenings and investigation of siblings was prevented largely by the targeting of
1 particular grade in each school, as mentioned previously.
The medical evaluation was conducted by the TB
clinic physician and followed Canadian Thoracic Society
guidelines for TB control.22 Previous BCG vaccination
was ignored in the interpretation of the TST results.21 All
patients received a physical examination and posterioranterior and lateral chest radiograph; gastric lavage, sputum smear, and cultures were performed when active
TB disease was suspected. For children started on isoniazid (INH) therapy, follow-up visits were planned for the
second, fourth, and eighth month of treatment. Adherence to therapy was assessed by the clinic nurses
through pill counts, patient self-report, verification with
pharmacies, and general attendance to the scheduled
medical visits. Adherence to the LTBI regimen was considered adequate if patients took ⬎80% of the total
prescribed doses within 43 weeks of initiating therapy,
whereas the remainder were considered to have poor
adherence. Techniques such as availability of interpretation services at each appointment and, according to
the parents’ baseline level of knowledge, teaching and
provision of information for better comprehension of the
LTBI-treatment regimen were used to improve adhere150
BRASSARD, et al
ence. Children who were diagnosed with active pulmonary TB were seen on a monthly basis by the respirologist.
Records from these visits collected over a period of 5
school years (1998 –2003, inclusive) were reviewed by
using classroom attendance sheets used by the MCH TB
nurse as well as medical charts of those children who
presented at the TB clinic for evaluation. For each child
diagnosed with LTBI, a record of family members who
also were screened was entered in the medical chart.
Schoolchildren and associates who were screened and
treated at the MCH TB clinic had their medical chart
reviewed for information on initiation of treatment and
adherence to treatment. Associates ⱖ18 years of age
were not seen at the MCH and were not assessed for
treatment information in this study.
From the classroom attendance sheets, the proportion
of TST-positive children was determined, whereas the
medical charts of both the schoolchildren and their child
associates were evaluated to assess the proportion of
TST-positive children who had presented at the clinic,
been initiated on INH treatment, and completed treatment with adequate adherence. For schoolchildren only,
these values were also stratified by school year to view
any trends in how the program was being administered.
Among schoolchildren and associates with a positive
TST, the following demographic and treatment-factor
proportions were calculated: gender, age at test date,
years since immigration to Canada, region of origin,
self-reported BCG vaccination status, self-reported previous TST, chest radiograph results, treatment adverse
effects, and number of family members screened.
Among TST-positive schoolchildren, these factors were
assessed for potential associations with LTBI-treatment
adherence by using univariate and multivariate analyses. A comparison was also made between those who
were lost to follow-up during LTBI treatment and those
who were not based on these same demographic and
treatment factors. The 2 test was used to determine the
statistical significance of categorical variables, and analysis of variance was used for continuous variables. Analyses were conducted by using the SAS 8 software system
(SAS Institute, Inc, Cary, NC). A P value of ⬍.05 was
considered statistically significant. Multivariate analyses
were assessed by using a backward-selection procedure
with P ⫽ .2 assigned as the cutoff for selection.
The cost-benefit comparisons were made by first calculating the total material and labor costs associated with
the school-screening program and the associate investigations, respectively. All associates investigated, including adults, were included in this calculation. This figure
was compared with the cost of managing 1 case of active
TB through passive case finding as well as the investigation of contacts of the active case and treatment of
contacts with LTBI, which then was multiplied by the
estimated number of active TB cases that were prevented
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among the TST-positive children and adults who were
screened and treated through the school-based program
and subsequent associate investigation. The values for
the cost of treating 1 active TB case as well as contact
investigation and treatment of contacts were derived
from a recent cost-benefit analysis of treatment of TB in
Montreal.23 All reported figures for cost are in Canadian
dollars. The number of contacts per case of pediatric TB
disease was estimated by interpolating the average number of contacts investigated per case of pulmonary TB
among the ⱕ18-year-old age group and the immigrant
group based on observed data from an evaluation of
contacts of active cases seen in Quebec.24 The estimated
number of TB cases prevented was based on the total
number of subjects in the current study who successfully
adhered to therapy, as well as on estimates that 10% of
all LTBIs will become active cases later on in life,25 that
all children were HIV-negative, that sensitivity and specificity for the TST were 90%,26 and that adherence to
INH therapy was 90% effective in preventing TB.23 Rates
of INH-therapy adherence observed in this study were
also used. For adult associates seen at the other clinic, we
used the overall adherence rate of 70% that was reported for LTBI treatment in the recent-immigrant population.23
The sensitivity of the results to different cost assumptions was tested by varying the rate of hospitalization for
the treatment of active pediatric TB cases. In addition,
cases prevented were discounted at 3% annually over a
20-year period in both the original (76%) and the reduced-rate-of-hospitalization (50%) scenarios. Finally,
all of the above-mentioned scenarios were repeated by
substituting a 5% probability of lifetime risk of developing TB for those TST-positive subjects who had lived ⬎2
years in Canada at the time of original screening27 and,
separately, a 95% sensitivity and specificity for the skin
test.
RESULTS
From September 1998 to August 2003, a total of 3710
immigrant children were listed as available for TST testing in the 16 elementary and secondary schools that
were chosen for screening, of whom 2524 (68%) were
tested. Of these, 542 (21%) had a TST result of ⱖ10 mm,
and 484 (89%) of them presented at the MCH TB clinic.
The number of children started on LTBI treatment was
375 (77% of those without active TB disease who presented at the clinic), of whom 316 of 342 with information on this factor (92%) completed therapy with adequate adherence. The proportions for each of these
figures remained relatively stable throughout the 5-year
time period (see Table 1), although a significant decrease
was observed over this period in the proportion of referred children who presented at the TB clinic for treatment. There were also 99 children with TST results
between 5 and 9 mm who presented at the clinic, of
whom 9 (9%) were started on LTBI treatment. Three of
those children were treated because of the presence of
abnormalities on the chest radiographs, which were
compatible with inactive disease, whereas the other 6
had many family members who had already tested TSTpositive. INH was the drug used for treating LTBI in all
but 2 children. Two active cases of TB were detected
during this 5-year period: 1 15-year-old girl with pulmonary TB and a 12-year-old boy with pleural TB.
Descriptive characteristics of schoolchildren who
were TST-positive and attended the clinic at MCH (n ⫽
484) are detailed in Table 2. Abnormal chest radiographs
related to TB were primarily the result of the presence of
calcified granulomas, whereas peribronchial thickening
was present in the remaining abnormal chest radiographs that were not related to TB. The most common
symptoms recorded during treatment were abdominal
pain (45%) and associated minor weight loss (14%).
Loss to follow-up occurred in 78 (21%) cases. Those
who were lost to follow-up were found to be, on average, older at the time of testing (13.0 vs 12.1 year old; P
⬍ .05) and had been in Canada longer (15.8 vs 11.3
months; P ⬍ .05) compared with those who had completed LTBI treatment. Multivariate analysis demonstrated that, among screened schoolchildren, having ⱖ2
family members who were brought in for TB screening
was positively associated with adherence to treatment
(Table 3).
There were 599 associates investigated from the 484
TST-positive schoolchildren who were seen at the TB
clinic. The mean age of all associates was 24.9 years (SD:
15.8) and 314 (52.4%) were male. Of 555 associates
with TST results, 211 (38%) were found to be TSTpositive. Of the 136 TST-positive children associates
TABLE 1 Yearly Totals for TB School-Screening Program
School Year
No. Tested
(% High School)
TST ⱖ 10 mm
and Referred, n
(% Tested)
TST ⱖ 10 mm and
Presented at TB Clinic, n
(% TST⫹ and Referred)
No. Started on
Therapy at TB Clinic
(% Presented at TB Clinic)
No. Complied to Treatment
(% Started on Therapy
at TB Clinic)
1998–1999
1999–2000
2000–2001
2001–2002
2002–2003
Total
759 (22)
465 (31)
469 (46)
525 (49)
306 (79)
2524
157 (21)
113 (24)
117 (25)
97 (19)
58 (19)
542 (21)
140 (89)
109 (96)
105 (90)
83 (86)
47 (81)
484 (89)
107 (76)
94 (86)
84 (80)
56 (67)
36 (76)
377 (78)
64 (60)
59 (63)
52 (62)
36 (64)
23 (64)
234 (62)
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e151
TABLE 2 Characteristics of TST-Positive (>10 mm) Schoolchildren and Their Child Associates Presenting
at the TB Clinic
Variable
Gender, n (%)
Male
Age, y
Mean
Range
Region of origin, n (%)
East/Southeast Asia
Eastern Europe
Central Asia
South Asia
South/Central America
North Africa/Middle East
Caribbean
Sub-Saharan Africa
North America/Western Europe
Years since immigration to Canada, n (%)
⬍1
1–2
ⱖ2
Vaccinated (BCG), n (%)b
Yes
No
Unknown
Previous TST, n (%)b
Yes
No
Unknown
Chest radiograph results, n (%)
Normal
Abnormal, not TB
Abnormal, TB
Missing
Started on drug treatment, n (%)
Yes
No
Refused
Unknown
Type of drug treatment given, n (%)c,d
INH
Rifampin
Other
Unknown
Duration of treatment, n (%)c,d
ⱕ6 mo
9 mo
12 mo
Unknown
Adherence to treatment, n (%)c,d
Good
Poor
Unknown
Treatment adverse effects, n (%)c,d
Yese
No
Unknown
Loss to follow-up, n (%)c,d
None
Moved
Dropped out
Unknown
Family members screened, n (%)
0
1–3
ⱖ4
Unknown
Schoolchildren (n ⫽ 484)
Associates (n ⫽ 131)a
257 (53.1)
70 (53.4)
12.4
5.0–18.4
11.6
1.2–17.8
121 (25.0)
102 (21.1)
67 (13.8)
67 (13.8)
39 (8.1)
28 (5.8)
22 (4.5)
20 (4.1)
18 (3.7)
19 (14.6)
24 (18.5)
21 (16.2)
32 (24.6)
11 (8.5)
7 (5.3)
8 (6.1)
4 (3.0)
4 (3.0)
156 (32.2)
242 (50.0)
86 (17.8)
52 (39.7)
63 (48.1)
16 (12.2)
407 (84.1)
22 (4.5)
55 (11.4)
104 (79.4)
4 (3.1)
23 (17.6)
127 (26.2)
221 (45.6)
136 (28.1)
27 (20.6)
59 (45.0)
45 (34.4)
413 (85.3)
39 (8.1)
21 (4.3)
11 (2.3)
113 (86.3)
5 (3.8)
0 (0.0)
13 (9.9)
377 (77.9)
66 (13.6)
36 (7.4)
5 (1.0)
108 (82.4)
10 (7.7)
12 (9.2)
1 (0.8)
370 (98.1)
2 (0.5)
0 (0)
5 (1.3)
106 (98.1)
1 (0.9)
0 (0.0)
1 (0.9)
7 (1.9)
365 (96.8)
1 (0.3)
4 (1.1)
3 (2.8)
103 (95.4)
0 (0)
2 (1.9)
316 (83.8)
26 (6.9)
35 (9.3)
94 (87.0)
5 (4.6)
9 (8.3)
22 (5.8)
314 (83.3)
41 (10.9)
6 (5.6)
81 (75.0)
21 (19.4)
278 (73.7)
23 (6.1)
55 (14.6)
21 (5.6)
91 (84.3)
2 (1.9)
7 (6.5)
8 (7.4)
139 (28.7)
226 (46.7)
45 (9.3)
74 (15.3)
NA
NA
NA
NA
NA indicates not applicable.
aged ⬍18 years.
b Self-reported.
c Among those who had been started on treatment(n ⫽ 377).
d For associates: only among children started on treatment at MCH (n ⫽ 108).
e The most common adverse effects for schoolchildren were abdominal pain (n ⫽ 9), weight loss (n ⫽ 3), and headache (n ⫽ 2).
a Children
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TABLE 3 Adherence to LTBI Treatment and Associated Factors Among Schoolchildren (Among Those
Started on LTBI Treatment 关n ⴝ 377兴)
Variable
OR
Adjusted ORa
Adjusted OR 95% CI
Gender, male
Age, ⬎12 y old
Region of origin
North America/Western Europe
Developing countries/countries of former Soviet bloc
Time since arrival in Canada
⬍2 y
ⱖ2 y
BCG vaccination
Previous TST
Abnormal chest radiograph
Adverse effects from treatment
No. of family members screened
0–1
ⱖ2
0.72
0.82
0.76
0.88
0.47–1.23
0.54–1.43
1.00 (reference)
1.02
1.00 (reference)
0.81
—
0.27–2.50
1.00 (reference)
1.07
1.24
1.04
1.73
1.19
1.00 (reference)
1.16
NA
NA
1.51
1.19
—
0.58–2.31
—
—
0.73–3.14
0.44–3.20
1.00 (reference)
2.20b
1.00 (reference)
2.04
—
1.26–3.30
OR indicates odds ratio; CI, confidence interval; NA, not applicable.
a Adjusted for age, gender, region of origin, time in country, chest radiograph status, treatment adverse effects, and number of family members
screened.
b P ⬎ .01.
(⬍18 years of age), we reported on the 131 who presented at the MCH TB clinic with a positive TST result
(Table 2). Of 130 associates with information, 108 (83%)
started on drug therapy. Of 99 child associates who had
started therapy and had information, 94 complied adequately with therapy (95%). One active case of TB was
detected directly through screening of both child and
adult associates: a 65-year-old woman with sputumsmear–positive pulmonary TB.
The cost-benefit analysis (see Table 4) demonstrated
that during the 5-year period, an estimated 36.1 cases of
active TB were prevented by the school-screening program and the subsequent associate investigation. The
costs of the program totaled $193 461. Comparatively,
treating 36.1 active cases would yield a cost of $557 384,
giving the school-screening program approach a net savings of $363 923 ($72 785 per year). The associate investigation alone contributed $95 530 of savings
($19 106 per year). When the hospitalization rate of
active pediatric TB cases was reduced from 76% to 50%,
the annual net savings of the combined school screening
and associate investigation was reduced to $45 992. Furthermore, when discounting of the number of cases
prevented was applied to the 76% and 50% hospitalization rate, the results were an annual net savings of
$23 068 and an annual net cost of $8224, respectively.
When the scenarios above are recalculated with a lifetime risk of 5% for developing active TB for those diagnosed with LTBI and have lived in Canada for ⬎2 years,
the same pattern of reduction in savings was observed,
with only slightly lower values. Conversely, when a
sensitivity and specificity of 95% were used for the skin
test, this pattern was observed again but with slightly
higher savings values than in the original scenario.
DISCUSSION
The prevalence of TST-positive children found in the
present study was considerably higher than the 2.4% of
Canadian-born Montreal schoolchildren28 and still
higher than that which was reported in another young
population at high risk for TB in Canada (Aboriginal
peoples29). However, the proportion of children who
were TST-positive in this study was similar to that found
in other studies of school-based screening programs for
immigrant children both in Canada8–10 and other lowburden countries.11,15 Similarly, the proportion of associates who were TST-positive in this study (38%) was
comparable to that of the existing studies on household
associates of infected schoolchildren, which had TST
positivity ranging from 30% to 43%.16–19 The activecase–finding rate in this study was somewhat lower than
that found in 2 previous studies of school-based TBscreening programs that targeted high-risk populations8,11 but was higher than that of another evaluated
program in which no cases were found10 and was slightly
higher than that of a study of a screening program based
in schools with mixed Canadian-born and foreign-born
populations.15 It should be noted that the number of
cases found in all of the studies mentioned above did not
exceed 2, which may account for the variability in results.
Because the present study was conducted on a retrospective basis and the screening process observed was
not set up to be systematically evaluated, there was a
resultant inconsistency of data available for all schoolchildren and child associates not available for TST testing, as well as those who were non-TST reactors. However, future evaluations will profit from the recent
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TABLE 4 Cost-Benefit Analysis of School Screening and Associate Investigation Versus Passive Case Finding: 1998 –2003
Cost of School
Screening
Program costs for screening and treatment for schoolchildren and associates of schoolchildren, $a
TST testing, wages, and materialsb
TB clinic appointmentsc
Chest radiographsd
Interpreterse
Total
Grand total
Benefits from screening program and associate investigation
No. of TB cases prevented with school screening
No. of TB cases prevented with associate investigation
No. of TB cases prevented, total
Treatment costs, passively diagnosed active TB case, $
Hospitalized proportion of casef
Directly observed therapyg
Total cost per case
Contact investigation (per index case)h
Treatment of all contacts (per index case)i
Total cost for 1 active case
Treatment costs based on screening and associate benefits, $
Treatment of TB cases prevented, school
Treatment of TB cases prevented, associates
Treatment of TB cases prevented, total
Total net cost (savings) from school-screening program and associate investigation
Total net cost (savings) from school-screening program without associate investigation
Total net cost (savings) from associate investigation
Cost of Associate
Investigation
9518
102 445
12 645
2263
126 871
7983
51 086
5199
2322
66 590
193 461
25.6
10.5
36.1
10 848
1228
12 076
694
2670
15 440
395 264
162 120
557 384
(363 923)
(268 393)
(95 530)
All costs are expressed in Canadian dollars ($1 Canadian ⫽ $0.66 US).
wages used: $26.40/hour for nurses; $16.00/hour for clerical staff; and $15.50/hour for interpreters.
b Based on 6-hour work day for nurses and 3 hours for clerical staff, during which 100 children were screened; another 6 hours for reading results. Materials include syringes, swabs, and printed
educational materials.
c Includes costs of opening chart, pretreatment consultation, initial physician consultation ($32.60; $47.60 if ⬍5 years old), and 6 follow-up visits.
d Chest radiograph cost is $32.49 (for immigrants with papers).
e Based on estimated need for interpreter for 1 of 8 patients and billing for 2-hour session.
f Includes initial work-up costs ($391), average of 19 days of hospitalization ($13 141), and outpatient-therapy costs ($742), based on 76% hospitalization rate.23
g Based on 0.75-hour visit with daily visit for first 14 days, followed by twice-weekly visits for a duration of 6 months of therapy: 62 visits.
h Based on a local published study.23
i Based on a local published study23; 10 contacts per immigrant pediatric active TB case, based on interpolation of data on average number of contacts among ⱕ18-year-olds and immigrant
subgroups in local assessment.24
a Average
base program developed specifically to track the schooland associate-screening process.
The proportion of schoolchildren targeted by the
screening program who received a skin test was comparable with that of other studies in this population,8–11
although their results were highly variable (43–79%).
However, this proportion demonstrates the difficulty of
securing participation in a voluntary, community-based,
preventive medicine initiative. Efforts were made to include children in the screening through such activities as
distributing culturally appropriate information materials
translated into many of the mother tongues of the children’s parents, as well as engaging in thorough follow-up on children who were not in class during the
visit. Additional efforts may need to be made to further
increase the participation at this first step of the TBprevention process.
A high number of those with LTBI also presented at
the TB clinic and were started on treatment. The decline
over the course of the study period in referred children
who presented for treatment may have been caused by
e154
BRASSARD, et al
the increased proportion of high school students
screened over this period who may have had less parental supervision in attending TB clinic appointments. Although the proportion of schoolchildren who finished
their treatment with adequate adherence was found to
be comparable or even higher than rates found in similar
studies (range: 82–90%8–11), it only represented 58% of
those who were initially eligible (ie, with a positive TST:
316 of 542). Those children with a positive TST who
were not started on treatment often had parents who
indicated a history of previous LTBI treatment in the
child’s country of origin.
To our knowledge, this is the first study to report
LTBI-treatment adherence in associates in relation to a
school-based TB-screening program. The adherence rate
observed in these children are comparable to those of
successful screening programs and, together with favorable adherence from the initial school based screening,
implies that this targeted approach to screening is an
effective way of preventing TB in a low-incidence country. We also showed a significant independent associa-
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tion between adherence and number of family members
screened. This finding reinforces the importance of using
associate investigation in conjunction with school-based
screening.
The average number of associates screened per child
screened at school was lower than that found in other
studies on associate investigations of TST-positive children. The majority of these studies17–19 reported a much
higher proportion of non–foreign-born and naturalized
associates than the current study, which might account
for the relatively lower proportion of associates in the
current study if these more recently immigrated children
had a greater number of family members who were still
waiting to be sponsored for immigration to Canada. A
more systematic data-collection system may help to answer this question.
The school-based TB-screening program that we evaluated was found to be cost-effective. Other studies evaluating school-based screening that included a cost-benefit analysis were split between those reporting a
substantial net benefit11,14; 1 study only reported the
costs of the screening program but stated that their costs
were comparable to TB disease-treatment costs cited in
the existing literature,10 and 1 study reported a substantial net cost.8 However, the latter study evaluated a
screening program with poor prescription and participation rates and found a negligible net cost when more
ideal program conditions were substituted in the analysis. We found a net benefit from the investigation of
associates of schoolchildren with LTBI, both as a standalone program and as an addition to the targeted TBscreening program. To our knowledge, this is the first
study to examine the cost-effectiveness of associate investigations. Our investigation of different scenarios in
the determination of cost and benefit demonstrated that
our original estimate is sensitive to hospitalization rates
of active TB cases, especially when discounting is used.
The hospitalization rate used for this study was based on
a recent local assessment of TB-treatment costs and was
comparable to the rate found in a cost-benefit analysis of
school-based TB screening.14 However, communities
that are served by hospitals that emphasize outpatient
treatment for their active cases may experience lower
savings from targeted screening.
CONCLUSIONS
We demonstrated the cost-effectiveness of a targeted
school-based screening program in a low-burden country and the extra benefit given by adding associates to
such a program. The challenge is to scale up such community initiatives so that they cover all schools with a
large newly arrived immigrant population. A successful
school-screening program directed toward newly arrived
immigrants has to be built primarily on the initial relationship and trust that develops between the treating
team (mainly the nurses), the children, and their asso-
ciates. This is an important aspect that is difficult to
quantify in any cost analysis but remains, in our minds,
the basis of success for any program that deals with
issues related to continuity of care.
ACKNOWLEDGMENTS
Drs Brassard and Lands are supported by the Canadian
Institutes of Health Research and the Fonds de Recherche en Santé du Québec, respectively.
We thank the tuberculosis clinic and the medical
archives of the Montreal Children’s Hospital for their
invaluable help.
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Evaluation of a School-Based Tuberculosis-Screening Program and Associate
Investigation Targeting Recently Immigrated Children in a Low-Burden
Country
Paul Brassard, Colin Steensma, Louise Cadieux and Larry C. Lands
Pediatrics 2006;117;e148
DOI: 10.1542/peds.2005-1534
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