Volume 14, Number 7—July 2008
Research
Determinants of Cluster Size in Large, Population-Based Molecular Epidemiology Study of Tuberculosis, Northern Malawi
Judith R. Glynn*
, Amelia C. Crampin*†, Hamidou Traore*, Steve Chaguluka†, Donex T. Mwafulirwa†, Saad Alghamdi*, Bagrey M.M. Ngwira†, Malcolm D. Yates‡, Francis D. Drobniewski‡, and Paul E.M. Fine*
, Amelia C. Crampin*†, Hamidou Traore*, Steve Chaguluka†, Donex T. Mwafulirwa†, Saad Alghamdi*, Bagrey M.M. Ngwira†, Malcolm D. Yates‡, Francis D. Drobniewski‡, and Paul E.M. Fine*
Table 1
Associations between patient characteristics and cluster size, Mycobacterium tuberculosis, bivariate analysis, Malawi
| Characteristic | N | Cluster size, % |
Odds ratio (95% CI)* | p value | |||
|---|---|---|---|---|---|---|---|
| 2–4 (n = 186) | 5–10 (n = 196) | 11–20 (n = 173) | >20 (n = 127) | ||||
| Age, y | 0.05 | ||||||
| <25 | 111 | 27.9 | 25.2 | 25.2 | 21.6 | 1 | |
| 25–34 | 266 | 24.4 | 26.3 | 27.8 | 21.4 | 1.1 (0.74–1.7) | |
| 35–44 | 160 | 26.3 | 32.5 | 25.0 | 16.3 | 0.87 (0.56–1.3) | |
| >45 |
145 |
33.1 |
31.7 |
21.4 |
13.8 |
0.66 (0.42–1.0) |
|
| Sex | 0.1 | ||||||
| F | 386 | 27.2 | 30.3 | 26.9 | 15.0 | 1 | |
| M |
296 |
26.7 |
26.7 |
23.3 |
23.3 |
1.2 (0.95–1.6) |
|
| HIV status | 1.0 | ||||||
| Negative | 141 | 26.2 | 30.5 | 23.4 | 19.9 | 1 | |
| Positive |
288 |
26.4 |
28.1 |
27.8 |
17.7 |
1.0 (0.7–1.4) |
|
| Area | 0.005 | ||||||
| South, near Chilumba | 70 | 38.6 | 22.9 | 24.3 | 14.3 | 0.51 (0.31–0.84) | |
| Middle, near Nyungwe | 89 | 20.2 | 22.5 | 30.3 | 27.0 | 1.2 (0.79–1.9) | |
| Around Karonga | 119 | 25.2 | 34.5 | 21.9 | 18.5 | 0.73 (0.48–1.1) | |
| Karonga central (urban) | 209 | 21.5 | 25.4 | 32.5 | 20.6 | 1 | |
| Kaporo area | 84 | 35.7 | 34.5 | 15.5 | 14.3 | 0.46 (0.29–1.1) | |
| Far north | 57 | 28.1 | 40.4 | 21.1 | 10.5 | 0.54 (0.32–0.9) | |
| Outside district |
16 |
26.9 |
28.9 |
25.6 |
18.6 |
0.41 (0.61–1.1) |
|
| Tuberculosis type | 0.6 | ||||||
| Smear positive | 485 | 26.2 | 29.5 | 25.4 | 19.0 | 1 | |
| Smear negative | 145 | 29.7 | 24.8 | 27.6 | 17.9 | 0.94 (0.68–1.3) | |
| Extrapulmonary |
52 |
30.8 |
32.7 |
19.2 |
17.3 |
0.78 (0.47–1.3) |
|
| Previous tuberculosis | 0.6 | ||||||
| No | 628 | 27.4 | 28.8 | 25.8 | 18.0 | 1 | |
| Yes |
47 |
27.7 |
25.5 |
21.3 |
25.5 |
1.2 (0.68–2.0) |
|
| Isoniazid resistance | 0.2 | ||||||
| No | 641 | 28.1 | 27.9 | 25.9 | 18.1 | 1 | |
| Yes |
39 |
12.8 |
43.6 |
15.4 |
28.2 |
1.5 (0.84–2.6) |
|
| Died† | 1.0 | ||||||
| No | 382 | 26.7 | 28.3 | 25.1 | 19.9 | 1 | |
| Yes | 155 | 25.8 | 29.0 | 26.5 | 18.7 | 1.0 (0.72–1.4) | |
*Odds ratio from ordered logistic regression. This represents the summary relative odds of larger clusters compared with smaller clusters across the 4 groups. Odds ratios >1 imply that the odds of being in a larger cluster are greater than in the baseline group. CI, confidence interval.
†Outcome recorded for 632 patients; those who were lost or transferred while receiving treatment are excluded from this analysis.
Page created: July 12, 2010
Page updated: July 12, 2010
Page reviewed: July 12, 2010
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.