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Volume 13, Number 7—July 2007

Dispatch

Zinc Cream and Reliability of Tuberculosis Skin Testing

V. Bhargavi Rao*†, Tom F. Pelly*‡, Robert H. Gilman‡§¶, Lilia Cabrera‡, Jose Delgado‡, Giselle Soto‡, Jon S. Friedland*, A. Roderick Escombe*‡, Robert E. Black¶, and Carlton A. Evans*†‡§¶Comments to Author 
Author affiliations: *Imperial College London, London, UK; †London School of Hygiene and Tropical Medicine, London, UK; ‡Asociación Benéfica Prisma, Lima, Peru; §Universidad Peruana Cayetano Heredia, Lima, Peru; ¶Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA;

Main Article

Table

Population characteristics for the participants who had simultaneous skin tests with and without zinc and associations with size of tuberculosis (TB) skin-test reaction

Characteristic* Mean (SEM)† or %
(n = 50) Association with size of control TB skin-test reaction (mm)
Univariate analysis
Multiple regression
Coefficient p Coefficient p
Nutritional assessment‡§
Body mass index (kg/m2) 24 (0.52)
10% underweight (<20) 0.2 0.3
Anthropometric protein status
 (corrected arm muscle area; cm2) 36 (1.4) 0.2 0.09
Anthropometric fat status
 (arm fat area; cm2) 14 (1.1) 0.0008 1
Plasma zinc (mg/L; n = 49) 0.66 (0.17)
31% deficient (<0.6) 0.3 0.04 0.3 0.03
Minor incidental health symptoms 38% 0.06 0.7
TB risk factors
Age, y 32 (1.3) 0.2 0.2 0.3 0.02
Male 38% 0.3 0.03 0.4 0.01
Past close contact with a TB patient or 
 past proven diagnosis of TB 42% 0.1 0.4
Presence of Baccilus Calmette-Guérin 
 vaccine scar(s) 86% 0.2 0.3
Overcrowding (persons/room) 1.3 (0.08) –0.2 0.9 0.2 0.09
Poor household ventilation (subjective
 assessment) 24% –0.002 1
Socioeconomic status
Food spending/person/d ($US) 0.75 (0.05) 0.1 0.5
Dirt floor throughout the home 38% –0.06 0.7
Home built from temporary materials 72% 0.1 0.5
No in-house sanitation 84% 0.05 0.7
No piped water to home 84% –0.07 0.6

*Variables that may influence TB skin-test reaction size are shown together with their associations with the size of the control TB skin-test reactions associated with only zinc cream application.
†SEM, standard error of the mean.
‡Food frequencies: in the previous week, alcohol had been consumed a median of 1 time (median 1 U), dairy produce 3 times, fruit/vegetables 5 times, meat/fish 6 times, and rice/bread/cereals daily.
§Persons with infrequent meat/fish consumption had lower protein stores on muscle anthropometry (p = 0.02), and this tended to be associated with smaller skin-test reactions, as previously reported (1,2).

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