Evaluation of a tuberculosis screening program for high-risk students in Toronto schools.

OBJECTIVE: To evaluate the effectiveness of a tuberculosis (TB) screening program for high-risk students in elementary and secondary schools. DESIGN: Cross-sectional study of the 1992-93 school screening program conducted by the Department of Public Health of the City of Toronto. Program costs were calculated with the use of 1993 wages, and costs for medical care were based on the 1993 fee schedule of the Ontario Medical Association. SETTING: Elementary and secondary schools in the City of Toronto. PARTICIPANTS: Students enrolled for the first time in any grade who were born in a country where TB is endemic or who were aboriginal Canadians were eligible. Of 44,179 students in Toronto schools 1775 met the eligibility criteria. INTERVENTION: Students were administered a Mantoux skin test, and those with a significant reaction (an induration of 10 mm or more in diameter) were advised to consult a physician for follow-up. OUTCOME MEASURES: Participation rate, number of participants with a significant reaction, percentage of these who were prescribed isoniazid and who completed chemoprophylaxis, potential number of preventable cases and costs associated with preventing each case. RESULTS: Of 1775 eligible students 42.9% (761) agreed to participate, and 40.6% (720) were screened. Significant skin-test reactions were detected in 22.5% (162/720) of the participants screened. Of these, 87.7% (142/162) saw a physician; subsequently, 2 cases of TB (1 active and 1 inactive) were detected. Of the remaining 140 students 44.3% (62) were prescribed isoniazid, of whom 9.7% (6/62) refused chemoprophylaxis. Of the remaining 56 students 82.1% (46) completed at least 6 months of chemoprophylaxis and 10.7% (6) were completing treatment at the end of the study. An estimated 3.2 cases were prevented, at a cost of $13,493.15 per case, whereas the undiscounted cost of treatment for an uncomplicated active case of TB in a patient under 19 years of age was $4503.82. CONCLUSIONS: The effectiveness of this screening program was significantly reduced by poor participation and poor rates of prescription of isoniazid by physicians. Appropriate strategies are needed to reduce barriers to the implementation of these programs.