Hospital Ventilation and Risk for Tuberculous Infection in Canadian Health Care Workers

21 November 2000 | Volume 133 Issue 10 | Pages 779-789

Background: The risk for and determinants of transmission of tuberculosis in hospitals caring for moderate numbers of patients with tuberculosis remain uncertain.

Objective: To study the association of tuberculin conversion among health care workers with ventilation of patient care areas.

Design: Cross-sectional observational survey.

Setting: 17 acute-care community or university hospitals.

Participants: All personnel who worked at least 2 days per week in the respiratory and physiotherapy departments or in selected nursing units.

Measurements: Participating workers underwent tuberculin skin testing and completed self-administered questionnaires. Previous tuberculin tests and bacille Calmette-Guérin vaccinations were verified. Records of patients with tuberculosis who were hospitalized in the 3 years preceding the study were reviewed. Air exchanges per hour in patient care areas were measured by using a tracer gas technique. Multivariate proportional hazards regression was used to estimate the effect of occupational factors on documented tuberculin conversion, after adjustment for nonoccupa- tional factors, among participants with at least one previous negative result on tuberculin skin testing.

Results: Tuberculin conversion was associated with ventilation of general or nonisolation patient rooms of less than 2 air exchanges per hour (adjusted hazard ratio, 3.4 [95% CI, 2.1 to 5.8]); with work in moderate- to high-risk hospitals (adjusted hazard ratio, 2.2 [CI, 1.3 to 3.5]); and with work in the nursing (adjusted hazard ratio, 4.3 [CI, 2.7 to 6.9]), respiratory therapy (adjusted hazard ratio, 6.1 [CI, 3.1 to 12.0]), and physiotherapy (adjusted hazard ratio, 3.3 [CI, 1.5 to 7.2]) departments or housekeeping (adjusted hazard ratio, 4.2 [CI, 2.3 to 7.6]). Conversion was not associated with inadequate ventilation of respiratory isolation rooms (adjusted hazard ratio, 1.0 [CI, 0.8 to 1.3]).

Conclusion: Tuberculin conversion among health care workers was strongly associated with inadequate ventilation in general patient rooms and with type and duration of work, but not with ventilation of respiratory isolation rooms.

*For members of the Canadian Collaborative Group in Nosocomial Transmission of TB, see Appendix.

Author and Article Information

From Montreal Chest Institute, McGill University, Montreal, Quebec; University of Alberta, Edmonton, Alberta; University of Toronto, Toronto, Ontario; and University of British Columbia, Vancouver, British Columbia, Canada.

Acknowledgments: The authors thank the administration, infection control, and employee health departments of the participating hospitals, and particularly the participating health care workers, for their time, help, and collaboration.

Grant Support: By grant 6605-4437-502 from the National Health Research and Development Programme of Health Canada and by the Association Pulmonaire du Québec. Dr. Menzies was supported by a Chercheur boursier clinicien award from the Fonds de Recherche en Santé du Québec 1993–1998 and by a Medical Scientist award from the Medical Research Council of Canada since 1998.

Requests for Single Reprints: Dick Menzies, MD, MSc, Montreal Chest Institute, 3650 St. Urbain Street, Montreal, Quebec, Canada H2X 2P4; e-mail, menzies{at}meakins.lan.mcgill.ca.

Current Author Addresses: Dr. Menzies: Montreal Chest Institute, 3650 St. Urbain Street, Montreal, Quebec H2X 2P4, Canada.

Dr. Fanning: Division of Infectious Diseases, University of Alberta, 2E4.11 WC McKenzie Health Sciences Centre, Edmonton T6G 2B7, Alberta.

Dr. Yuan: Department of Preventive Medicine and Biostatistics, University of Toronto, McMurrich Building, 12 Queens Park Crescent West, 4th Floor, Toronto M5S 1A8, Ontario.

Dr. FitzGerald: B.C. Centre for Disease Control Society, 655 West 12th Avenue, Vancouver, British Columbia V5Z 4R4, Canada.

Author Contributions: Conception and design: D. Menzies, A. Fanning, L. Yuan, J.M. FitzGerald.

Analysis and interpretation of the data: D. Menzies, L. Yuan.

Drafting of the article: D. Menzies, J.M. FitzGerald.

Critical revision of the article for important intellectual content: D. Menzies, A. Fanning, L. Yuan, J.M. FitzGerald.

Final approval of the article: D. Menzies, A. Fanning, L. Yuan, J.M. FitzGerald.

Provision of study materials or patients: D. Menzies, A. Fanning, L. Yuan, J.M. FitzGerald.

Statistical expertise: D. Menzies.

Obtaining of funding: D. Menzies, L. Yuan, J.M. FitzGerald.

Administrative, technical, or logistic support: D. Menzies, A. Fanning, L. Yuan, J.M. FitzGerald.

Collection and assembly of data: D. Menzies, A. Fanning, L. Yuan, J.M. FitzGerald.