Volume 24, Number 3—March 2018
Research
Prospective Observational Study of Incidence and Preventable Burden of Childhood Tuberculosis, Kenya
Table 2
Characteristic |
Confirmed TB, n = 73 |
Highly probable TB, n = 83 |
Treated for possible TB,
n = 141 |
Not TB/TB excluded,
n = 1,320 |
Not classifiable, n = 425 |
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---|---|---|---|---|---|---|---|---|---|---|
Case ascertainment | ||||||||||
Passive case detection | 71 (97) | 79 (95) | 141 (100) | 1,237 (94) | 410 (96) | |||||
Active case detection (contact tracing) |
2 (3) |
4 (5) |
0 (0) |
83 (6) |
15 (4) |
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Patient demographics | ||||||||||
Median age (interquartile range), mo | 52 (16–114) | 32 (13–70) | 17 (10–64) | 17 (10–41) | 17 (9–44) | |||||
0–4 y | 38 (55) | 59 (71) | 99 (70) | 1,119 (85) | 345 (81) | |||||
5–9 y | 17 (25) | 15 (18) | 27 (19) | 140 (11) | 56 (13) | |||||
10–14 y | 18 (25) | 9 (11) | 15 (11) | 61 (4) | 24 (6) | |||||
Sex | ||||||||||
M | 39 (53) | 43 (52) | 70 (50) | 696 (53) | 224 (53) | |||||
F |
32 (47) |
40 (48) |
71 (50) |
624 (47) |
201 (47) |
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Risk factors for TB | ||||||||||
HIV infected | 17 (23) | 21 (25) | 42 (30) | 160 (12) | 112 (26) | |||||
Severely malnourished | 30 (41) | 37 (45) | 58 (41) | 457 (35) | 162 (38) | |||||
BCG vaccination scar | 65 (89) | 86 (71) | 128 (91) | 1,172 (89) | 338 (80) | |||||
Close TB contact |
36 (49) |
33 (40) |
27 (19) |
246 (19) |
78 (18) |
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Clinical features of suspected TB | ||||||||||
Cough >2 wks | 48 (66) | 48 (58) | 95 (67) | 572 (43) | 225 (53) | |||||
Fever >2 wks | 45 (62) | 30 (36) | 92 (65) | 502 (38) | 196 (46) | |||||
Weight loss or failure to thrive >4 wks | 42 (58) | 39 (47) | 77 (55) | 575 (44) | 208 (49) | |||||
Pneumonia not responding to 1st-line ABX |
27 (37) |
25 (30) |
42 (30) |
308 (23) |
159 (37) |
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TB clinical syndrome | ||||||||||
Smear-positive pulmonary TB | 20 (27) | 4 (5) | 0 | NA | NA | |||||
Smear-negative pulmonary TB | 40 (55) | 69 (83) | 108 (77) | NA | NA | |||||
All pulmonary TB† | 60 (82) | 73 (88) | 108 (77) | NA | NA | |||||
Extrapulmonary TB† | 30 (41) | 17 (20) | 46 (33) | NA | NA | |||||
Miliary TB | 6 (8) | 3 (4) | 5 (4) | NA | NA | |||||
TB meningitis | 8 (11) | 2 (2) | 12 (9) | NA | NA | |||||
Pleural TB | 6 (9) | 2 (2) | 7 (5) | NA | NA | |||||
TB lymphadenitis | 6 (8) | 6 (7) | 6 (4) | NA | NA | |||||
Osteoarticular TB | 2 (3) | 3 (4) | 1 (1) | NA | NA | |||||
Abdominal TB | 9 (12) | 2 (2) | 10 (7) | NA | NA | |||||
Persistent fever without a focus |
0 |
1 (1) |
13 (9) |
NA |
NA |
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Drug resistance | ||||||||||
Isoniazid monoresistance | 0 | NA | NA | NA | NA | |||||
Multidrug-resistant TB | 1 (1.4) | NA | NA | NA | NA | |||||
*Values are no. (%) unless otherwise indicated. ABX, antibiotics; BCG, bacillus Calmette-Guérin; NA, not applicable; TB, tuberculosis.
†Some children had >1 focus of infection, including some with pulmonary TB and extrapulmonary TB. Among children with confirmed TB, microbiologic confirmation was required from >1 site; diagnosis of other sites of disease was based on the definitions of highly probable TB (online Technical Appendix Table 1, https://wwwnc.cdc.gov/EID/article/24/3/17-0785-Techapp1.pdf).
1The following members of the Kilifi Improving Diagnosis and Surveillance of Childhood TB (KIDS TB) Study Group also contributed to patient recruitment, investigation, and management: Victor Bandika, Jay Berkley, Kath Maitland, Susan Morpeth, Daisy Mugo, Robert Musyimi, Agnes Mutiso, John Paul Odhiambo, Monica Toroitich, and Hemed Twahir.
Prospective data on childhood tuberculosis (TB) incidence and case detection rates (CDRs) are scant, and the preventable burden of childhood TB has not been measured in prospective studies. We investigated 2,042 children (<15 years of age) with suspected TB by using enhanced surveillance and linked hospital, demographic, notification, and verbal autopsy data to estimate the incidence, CDR, risk factors, and preventable burden of TB among children in Kenya. Estimated TB incidence was 53 cases/100,000 children/year locally and 95 cases/100,000 children/year nationally. The estimated CDR was 0.20–0.35. Among children <5 years of age, 49% of cases were attributable to a known household contact with TB. This study provides much needed empiric data on TB CDRs in children to inform national and global incidence estimates. Moreover, our findings indicate that nearly half of TB cases in young children might be prevented by implementing existing guidelines for TB contact tracing and chemoprophylaxis.