Body mass index and risk of tuberculosis and death.
BACKGROUND
High BMI has been shown to be protective against tuberculosis (TB) among HIV-uninfected individuals, as well as against disease progression and mortality among those with HIV. We examined the effect of BMI on all-cause mortality and TB incidence among a cohort of HIV-infected adults in Soweto, South Africa.


METHODS
A clinical cohort of 3456 HIV-infected adults from South Africa was prospectively followed from 2003 to 2008 with regular monitoring. The primary exposure was BMI and the outcomes of interest were all-cause mortality and a newly diagnosed episode of TB. Cox proportional hazard models assessed associations with risk of mortality or incident TB.


RESULTS
Incidence rates of mortality were 10.4/100 person-years for baseline BMI of 18.5 or less, 3.6/100 person-years for baseline BMI 18.6-25, 1.7/100 person-years for baseline BMI 25.1-30, and 1.6/100 person-years for baseline BMI more than 30. Compared to those with normal BMI, overweight and obese participants had a significantly reduced risk of mortality [adjusted hazard ratio 0.59 (95% confidence interval, CI 0.40-0.87) and 0.48 (95% CI 0.29-0.80), respectively]. Incidence rates of TB by baseline BMI were 7.3/100 person-years for underweight, 6.0/100 person-years for normal, 3.2/100 person-years for overweight, and 1.9/100 person-years for obese. Compared to those with normal BMI, those with overweight and obese BMI were at a significantly reduced risk of developing TB [adjusted hazard ratio 0.56 (95% CI 0.38-0.83) and 0.33 (95% CI 0.19-0.55), respectively].


CONCLUSIONS
HIV-infected individuals with obese and overweight BMI have a significantly reduced risk of both mortality and TB, after adjusting for HAART use and CD4 cell count.
Hanrahan
Colleen F
CF
Johns Hopkins Bloomberg School of Public Heath, Baltimore, Maryland, USA.
Golub
Jonathan E
JE
Mohapi
Lerato
L
Tshabangu
Nkeko
N
Modisenyane
Tebogo
T
Chaisson
Richard E
RE
Gray
Glenda E
GE
McIntyre
James A
JA
Martinson
Neil A
NA
D017088:AIDS-Related Opportunistic Infections / Q000401:mortality*; D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D015992:Body Mass Index; D018791:CD4 Lymphocyte Count; D002423:Cause of Death; D005260:Female; D015658:HIV Infections / Q000401:mortality*; D015497:HIV-1; D006801:Humans; D015994:Incidence; D008297:Male; D009765:Obesity / Q000401:mortality; D011446:Prospective Studies; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D016019:Survival Analysis; D013851:Thinness / Q000401:mortality*; D014376:Tuberculosis / Q000401:mortality*