Table 1.

Study characteristic and outcomes for patients testing purified protein derivative – negative (PPD−)

Author, year	Trial location	Mean age (years)	Trial duration (months)	Trial follow-up (years)	Drug regimen (active)	Drug regimen (control)	No. patients (active)	No. patients (control)	TB incidence (active)	TB incidence (control)
Mohammed, 2007	South Africa	39	12	NA	INH 900 or 800 mg twice weekly	Placebo	48	50	9	6
Rivero, 2003	Spain	32	6	2	INH 5 mg/kg to a max of 300 mg daily	Placebo	83	77	3	4
Fitzgerald, 2001	Haiti	32	12	2.5	INH 300 mg daily + Vit B6 50 mg	Placebo + Vit B6 50 mg	126	111	6	4
Mwinga, 1998	Zambia	30	6	1.6	INH 300 mg twice weekly	Placebo	179	166	7	8
Gordin, 1997	USA	38	6	2.8	INH 300 mg + Vit B6 50 mg	Placebo	260	257	3	6
Hawken, 1997	Kenya	31	6	1.8	INH 300 mg	Placebo	67	69	7	10
Whalen, 1997	Uganda	30	6	1.3 (A) 1.0 (C)	INH 300 mg	Placebo	393	323	9	10
Pape, 1993	Haiti	31	12	2.5	INH 300 mg + 50 mg Vit B6	+Vit B6 50 mg	20	35	2	5
Wadhawan, 1993	Kenya	NA	6	1.7	INH 300 mg	Placebo	350	297	11	21

Abbreviations: NA, not applicable; INH, isoniazid; TB, tubercolosis.