Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

Volume 12, Number 5—May 2006
THEME ISSUE
Tuberculosis Special Section

Research

Isoniazid Preventive Therapy and Risk for Resistant Tuberculosis

Maria Elvira Balcells*1, Sara L. Thomas*, Peter Godfrey-Faussett*, and Alison D. Grant*Comments to Author 
Author affiliations: *London School of Hygiene and Tropical Medicine, London, United Kingdom

Main Article

Table 2

Studies comparing isoniazid treatment with no treatment in HIV-uninfected populations*

Author, country, dates Population Intervention/comparison; blinding Enrolled (n) INH/control Follow-up; loss to follow-up; overall or INH vs. control TB cases: culture positive/total (%)
Definition of INH resistance Resistant cases/total tested (% culture positive tested)
Risk for resistant TB/1,000
INH Controls INH Controls INH Controls RR (95% CI)
Ferebee, USA, 1957–NS (18) Household contacts of TB patients 12 mo INH, 4–7 mg/kg/day/placebo; double blind 7,755/7,996 <10 y; 5.2% vs. 4.9% during Rx NS/86 NS/215 >50 colonies growth in 0.2 μg/mL INH 2/10 NS 2/31 NS 2.22 1.73 1.28 (0.20–8.07)
Katz, USA, 1958–1964 (19) Mental hospital patients with inactive lesions 2 y INH, 300 mg daily/no treatment; not blind 118/107 <4 y post-Rx; 30.6% overall† NS/9 NS/10 Resistance to >0.25 γ INH 1/1 NS 2/5 NS 76.27 37.38 2.04 (0.52–8.08)
Horwitz, Greenland, 1956–1963 (20) 76 villages 2 × 13 wk INH, 400 mg twice weekly/0.1 mg INH; double blind 4,174/3,907 6 y; NS 123/238 (51.7) 186/323 (57.6) (a) > 1 colony at >0.32 μg/mL INH (a) 2/46 (a) 5/66 (a) 2.48 (a) 6.26 (a) 0.40 (0.08–1.97)
(b) Equal to control tube at >0.32 μg/mL INH (b) 2/46 (37) (b) 1/66 (36) (b) 2.48 (b) 1.25 (b) 1.98 (0.18–21.31)
Comstock, USA (Alaska), 1957–1964 (21) Residents of 28 villages and 2 boarding schools 12 mo INH, 300 mg§ daily/placebo; double blind 3,047/3,017 Med.: 69.3 mo (range 43–76 mo); 5.3% observed for <40 mo NS/58 NS/141 NS 4/20 NS 1/50 NS 3.81 0.93 4.07 (0.47–34.98)
Ferebee, USA, 1960–1967 (9) Persons with inactive lesions 12 mo INH, 5 m g/kg/day/placebo; NS 701/714 5 y; 2.2% by 1967 NS/18 NS/49 >50 colonies growth in 0.2 μg/mL INH 2/5 NS 2/25 NS 10.27 5.49 1.87 (0.31–11.19)
Pamra, India, 1958–1968 (22) X-ray screening attendees with inactive TB 12 mo INH, 3–4 mg/kg/day/placebo; NS 139/178 <5 y post-Rx; 8.6% vs. 11.2% 10/18 (55.6) 57/76 (75) Growth on 1 μg/mL INH 3/9 (90) 6/52 (91) 43.17 49.27 0.88 (0.24–3.15)
Hong Kong Chest Service, Hong Kong, 1981–1987 (27) Men with silicosis 24 wk INH, 300 mg daily/placebo;double blind 167/159 2–5 y; 15.8% at 5 y 19/25 (76) 29/36 (80.6) >20 colonies in >1 culture at >0.2 mg/L INH 5/19 (100) 4/28 (97) 39.39 32.35 1.22 (0.34–4.32)

*INH, isoniazid; TB, tuberculosis; RR, relative risk; CI, confidence interval; NS, not stated; med., median; Rx, treatment.
†(a), definition of resistance as >1 colony growth at >0.32 μg/mL INH.
‡(b), definition of resistance as growth equal to control tube at >0.32 μg/mL INH.
§Children were given 5 mg/kg/day INH.

Main Article

1Current affiliation: Department of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile

TOP