Table 4.
Logistic regression analysis of risk factors associated with TB clustering (recent TB transmission).
| Variable | MTBC (N = 2309) |
Univariate |
Multivariatea |
|||
|---|---|---|---|---|---|---|
| Total TB cases, n (%) | Clustered casesb, n (%) | OR (95% CI) | p-Value | Adjusted OR (95% CI) | p-Value | |
| Year diagnosed | 2309 (100) | 1229 (53·2) | ||||
| 2012 | 244 (10·6) | 147 (60·3) | 1·4 (1·0–1·8) | 0·043 | 1·3 (0·9–1·7) | 0·113 |
| 2013 | 776 (33·6) | 410 (52·8) | Reference | |||
| 2014 | 707 (30·6) | 365 (51·6) | 1·0 (0·8–1·2) | 0·642 | 0·9 (0·7–1·1) | 0·203 |
| 2015 | 582 (25·2) | 307(52·8) | 1·0 (0·8–1·2) | 0·975 | 1·0 (0·8–1·2) | 0·703 |
| Sex | 2294 (99·4) | |||||
| Male | 1631 (71·1) | 863 (52·9) | 1·0 (0·8–1·2) | 0·685 | ||
| Female | 663 (28·9) | 357 (53·8) | Reference | |||
| Age (years)c | 2224 (96·3) | |||||
| <15 | 37 (1·7) | 25 (67·6) | 1·6 (0·8–3·3) | 0·183 | 1·6 (0·8–3·2) | 0·221 |
| 15–29 | 639 (28·7) | 360 (56·3) | Reference | |||
| 30–39 | 570 (25·6) | 307 (53·9) | 0·9 (0·7–1·1) | 0·387 | 0·9 (0·7–1·2) | 0·688 |
| 40–59 | 778 (35·0) | 398 (51·2) | 0·8 (0·7–1·0) | 0·052 | 0·9 (0·7–1·1) | 0·241 |
| >59 | 200 (9·0) | 97 (48·5) | 0·7 (0·5–1·0) | 0·053 | 0·9 (0·6–1·1) | 0·211 |
| Nationality | 1781 (77·1) | |||||
| Ghanaian | 1714 (96·2) | 932 (54·4) | Reference | |||
| Other | 67 (3·8) | 38 (56·7) | 1·1 (0·7–1·8) | 0·706 | ||
| Locality | 2309 (100) | 1229 (53·2) | ||||
| Rural | 201 (8·7) | 74 (36·8) | Reference | |||
| Urban | 2108 (91·3) | 1155 (54·8) | 2·1 (1·5–2·8) | <0·001 | ||
| Residence classification | 1642 (71·1) | |||||
| Village | 69 (4·2) | 27 (39·1) | 0·5 (0·3–0·8) | 0·007 | ||
| Town | 182 (11·1) | 96 (52·7) | 0·9 (0·6–1·2) | 0·415 | ||
| City residential area | 52 (3·2) | 27 (51·9) | 0·8 (0·5–1·5) | 0·564 | ||
| City suburb | 1136 (69·2) | 636 (56·0) | Reference | |||
| City slum | 203 (12·4) | 112 (55·2) | 1·0 (0·7–1·3) | 0·83 | ||
| Residential district | 1538 (66·6) | |||||
| Ablekuma | 545 (35·4) | 298 (54·7) | Reference | |||
| Ashiedu Keteke | 170 (11·1) | 100 (58·8) | 1·2 (0·8–1·7) | 0·343 | ||
| Ayawaso | 220 (14·3) | 124 (56·4) | 1·1 (0·8 to 1·5) | 0·672 | ||
| Kpeshie | 224(14·6) | 121 (54·0) | 1·0 (0·7–1·3) | 0·867 | ||
| Mamprusi East | 70 (4·6) | 22 (31·4) | 0·4 (0·2–0·6) | <0·001 | ||
| Okaikoi | 176 (11·4) | 98 (55·7) | 1·0 (0·7 to 1·5) | 0·816 | ||
| Osu Klottey | 133 (8·6) | 78 (58·7) | 1·2 (0·8–1·7) | 0·409 | ||
| Household type | 1624 (70·3) | |||||
| Self-contained | 412 (25·4) | 221 (53·6) | 1·0 (0·8–1·2) | 0·797 | ||
| Compound house | 1212 (74·6) | 659 (54·4) | Reference | |||
| Education | 1748 (75·7) | |||||
| Primary | 222 (12·7) | 125 (56·3) | 1·1 (0·8–1·5) | 0·637 | ||
| Middle/JHS | 637 (36·4) | 347 (54·5) | Reference | |||
| Secondary | 429 (24·5) | 232 (54·1) | 1·0 (0·8–1·3) | 0·899 | ||
| Tertiary | 190 (10·9) | 110 (57·9) | 1·1 (0·8–1·6) | 0·405 | ||
| No education | 270 (15·4) | 141 (52·2) | 0·9 (0·7–1·2) | 0·534 | ||
| Occupation | 1722 (74·6) | |||||
| Unemployed | 390 (22·6) | 208 (53·3) | 0·9 (0·7–1·1) | 0·423 | ||
| Unskilled | 951 (55·2) | 530 (55·7) | Reference | |||
| Skilled | 381 (22·1) | 198 (52·0) | 0·9 (0·7–1·1) | 0·213 | ||
| Monthly income (GH) | 1622 (70·2) | |||||
| None | 371 (22·9) | 213 (57·4) | Reference | |||
| <301 | 807 (49·7) | 438 (54·3) | 0·9 (0·7–1·1) | 0·315 | ||
| 301–1000 | 407 (25·1) | 218 (53·6) | 0·8 (0·6–1·1) | 0·281 | ||
| >1000 | 37 (2·3) | 15 (40·5) | 0·5 (0·3–1·0) | 0·052 | ||
| Religion | 1771 (76·7) | |||||
| Christian | 1361 (76·9) | 739 (54·3) | Reference | |||
| Islam | 302 (17·0) | 161 (53·3) | 1·0 (0·7–1·2) | 0·755 | ||
| Other | 26 (1·5) | 14 (53·9) | 1·0 (0·4–2·1) | 0·963 | ||
| Not religious | 82 (4·6) | 49 (59·7) | 1·2 (0·8–2·0 | 0·366 | ||
| Ethnicity | 1760 (76·4) | |||||
| Akan | 570 (32·3) | 309 (54·2) | Reference | |||
| Ewe | 259 (14·7) | 143 (55·2) | 1·0 (0·8–1·4) | 0·788 | ||
| Ga/Adangbe | 544 (30·8) | 310 (57·0) | 1·1 (0·9–1·4) | 0·352 | ||
| Other | 392 (22·2) | 196 (50·0) | 0·8 (0·6–1·1) | 0·199 | ||
| Marital status | 1758 (76·1) | |||||
| Single | 766 (43·6) | 431 (56·3) | Reference | |||
| Married | 742 (42·2) | 395 (53·2) | 0·9 (0·7–1·1) | 0·237 | ||
| Divorced | 167 (9·5) | 99 (59·3) | 1·1 (0·8–1·6) | 0·476 | ||
| Widowed | 83 (4·7) | 35 (42·2) | 0·6 (0·3–0·9) | 0·015 | ||
| Smear positivity | 2208 (95·6) | |||||
| Scanty 1–9 | 173 (7·8) | 96 (55·5) | 1·1 (0·8–1·5) | 0·714 | ||
| 1+ | 474 (21·5) | 237 (50·0) | 0·9 (0·7–1·1) | 0·151 | ||
| 2+ | 546 (24·7) | 294 (53·9) | 1·0 (0·8–1·2) | 0·957 | ||
| 3+ | 1015 (46·0) | 548 (54·0) | Reference | |||
| Previous TB treatment | 1737 (75·2) | |||||
| Yes | 291 (16·8) | 153 (52·6) | 0·9 (0·7–1·2) | 0·535 | ||
| No | 1446 (83·2) | 789 (54·6) | Reference | |||
| Risk of TB contact | ||||||
| Close friend/household | 1665 (72·1) | |||||
| No contact | 1121 (67·3) | 594 (53·0) | Reference | |||
| 1 contact | 212 (12·7) | 118 (55·7) | 1·1 (0·8–1·5) | 0·475 | ||
| 2–5 contacts | 309 (18·6) | 179 (57·9) | 1·2 (0·9–1·6) | 0·123 | ||
| 6–10 contacts | 23 (1·4) | 15 (65·2) | 1·7 (0·7–4·0) | 0·249 | ||
| Imprisonment | 1660 (71·9) | |||||
| Yes | 97 (5·8) | 56 (57·7) | 1·1 (0·8–1·7) | 0·513 | ||
| No | 1563 (94·2) | 849 (54·3) | Reference | |||
| Health/laboratory worker | 1661 (71·9) | |||||
| Yes | 47 (2·8) | 25 (53·2) | 0·9 (0·5–1·7) | 0·85 | ||
| No | 1614 (97·2) | 881 (54·6) | Reference | |||
| Immunosuppressive condition | 1695 (73·4) | |||||
| Any | 893 (52·7) | 488 (54·6) | 1·0 (0·9–1·2) | 0·747 | ||
| None | 802 (47·3) | 432 (53·9) | Reference | |||
| Diabetes mellitus | 534 (23·1) | |||||
| Yes | 104 (19·5) | 54 (51·9) | 1·0 (0·7–1·5) | 0·957 | ||
| No | 430 (80·5) | 222 (51·6) | Reference | |||
| HIV status | 1166 (50·5) | |||||
| Positive | 144 (12·3) | 82 (56·9) | 1·1 (0·8–1·6) | 0·481 | ||
| Negative | 1022 (87·7) | 550 (53·8) | Reference | |||
| Smoking | 1518 (65·7) | |||||
| Yes | 434 (28·6) | 237 (54·6) | 1·0 (0·8–1·2) | 0·949 | ||
| No | 1084 (71·4) | 590 (54·4) | Reference | |||
| Substance abuse (excluding alcohol) | 1401 (60·7) | |||||
| Yes | 140 (10·0) | 84 (60·0) | 1·3 (0·9–1·8) | 0·172 | ||
| No | 1261 (90·0) | 680 (53·9) | Reference | |||
| Substance abuse (including alcohol) | 1474 (63·8) | |||||
| Yes | 460 (31·2) | 250 (54·3) | 1·0 (0·8–1·3) | 0·858 | ||
| No | 1014 (68·8) | 546 (53·8) | Reference | |||
| Lineage | 2309 (100) | |||||
| Lineage 1 | 38 (1·7) | 7 (18·4) | 0·2 (0·08–0·4) | <0·001 | 0·13 (0·05–0·36) | <0·001 |
| Lineage 2 | 65 (2·8) | 43 (66·2) | 1·5 (0·9–2·5) | 0·126 | 1·5 (0·9–2·5) | 0·155 |
| Lineage 3 | 26 (1·1) | 4 (15·4) | 0·1 (0·05–0·4) | <0·001 | 0·15 (0·05–0·45) | 0·001 |
| Lineage 4 | 1741 (75·4) | 984 (56·5) | Reference | |||
| Lineage 5 | 289 (12·5) | 143 (49·5) | 0·8 (0·6–1·0) | 0·026 | 0·7 (0·6–0·9) | 0·032 |
| Lineage 6 | 150 (6·5) | 48 (32·0) | 0·4 (0·3–0·5) | <0·001 | 0·3 (0·2–0·5) | <0·001 |
| Lineage 4 sub-lineage | ||||||
| Cameroon | 1046 (60·1) | 616 (58·9) | Reference | |||
| Ghana | 376 (21·6) | 206 (54·8) | 0·8 (0·7–1·1) | 0·167 | ||
| Haarlem | 156 (9·0) | 91(58·3) | 1·0 (0·7–1·4) | 0·895 | ||
| LAM | 50 (2·9) | 25 (50·0) | 0·7 (0·4–1·2) | 0·215 | ||
| Uganda | 40 (2·3) | 16 (40·0) | 0·5 (0·2–0·9) | 0·02 | ||
| Other | 51 (2·9) | 26 (51·0) | 0·7 (0·4–1·3) | 0·265 | ||
| Not determined | 22 (1·3) | 4 (18·2) | 0·2 (0·1–0·5) | 0·001 | ||
| Drug resistance | 2300 (99·6) | |||||
| Any | 313 (13·6) | 138 (44·1) | 0·6 (0·5–0·8) | <0·001 | 0·7 (0·5–0·9) | 0·002 |
| None | 1987 (86·4) | 1090 (54·9) | Reference | |||
| Isoniazid mono-resistant | 2300 (99·6) | |||||
| Yes | 295 (12·8) | 129 (43·7) | 0·6 (0·5–0·8) | <0·001 | ||
| No | 2005 (87·2) | 1099 (54·8) | Reference | |||
| Multidrug resistant (MDR) | 2300 (99·6) | |||||
| Yes | 81 (3·5) | 35 (43·2) | 0·7 (0·4–1·0) | 0·063 | ||
| No | 2219 (96·5) | 1193 (53·8) | Reference | |||
| Cluster size (n) | 1227 (53·1) | |||||
| Small (2) | 290 (23·6) | |||||
| Medium (3–5) | 262 (21·4) | |||||
| Large (6–20) | 452 (36·8) | |||||
| Very large (>20) | 223 (18·2) | |||||
MTBC, Mycobacterium tuberculosis complex; TB, tuberculosis; OR, odds ratio; CI, confidence interval; JHS, junior high school; GH, Ghanaian cedi.
a
For the multivariate model, only variables with p < 0.1 and with at least 90% of available data were included. However ‘locality’ was excluded due to the small sample size from the rural setting. Residence classification, marital status, isoniazid mono-resistance, and MDR were excluded due to collinearity with other variables in the model.
b
A cluster was defined as two or more isolates (same strain) that share an indistinguishable spoligotype and 15-locus MIRU-VNTR allelic pattern, but allowing for one missing allelic data at any one of the difficult-to-amplify MIRU loci.
c
A significant decreasing trend in the probability of belonging to a clustered case was found with increasing age category (p = 0.004).