Determinants of Cluster Size in Large, Population-Based Molecular Epidemiology Study of Tuberculosis, Northern Malawi
2008

Factors Affecting Size of Tuberculosis Clusters in Malawi

Sample size: 948 publication 10 minutes Evidence: moderate

Author Information

Author(s): Glynn Judith R., Crampin Amelia C., Traore Hamidou, Chaguluka Steve, Mwafulirwa Donex T., Alghamdi Saad, Ngwira Bagrey M.M., Yates Malcolm D., Drobniewski Francis D., Fine Paul E.M.

Primary Institution: London School of Hygiene and Tropical Medicine

Hypothesis

Both epidemiologic and strain-related factors may contribute to large clusters of tuberculosis patients.

Conclusion

The study found that young age, male sex, and urban residence were associated with larger tuberculosis clusters, while HIV status did not significantly affect cluster size.

Supporting Evidence

  • Cluster size varied from 2 to 37 among 682 clustered patients.
  • Male patients, young adults, and town residents were over-represented in large clusters.
  • Cluster size was not associated with HIV status or death from tuberculosis.
  • Spoligotypes from 90% of large cluster strains were similar to common types found elsewhere.

Takeaway

This study looked at why some groups of tuberculosis patients are larger than others. It found that younger men living in towns are more likely to be in these larger groups.

Methodology

The study used molecular techniques to analyze tuberculosis strains and their clustering in a population-based study over seven years.

Potential Biases

Potential laboratory errors in strain identification could introduce bias.

Limitations

The study may not account for all potential confounding factors affecting cluster size.

Participant Demographics

The study included tuberculosis patients from northern Malawi, with a focus on age, sex, and area of residence.

Statistical Information

P-Value

0.3

Confidence Interval

0.66 (0.42–1.0)

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.3201/eid1407.060468

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