Background: Buffalo hump (BH) was one of the earliest changes in fat distribution reported in HIV infection. We assessed the prevalence of BH in HIV⁺ and control men (CON) in the FRAM study, then compared body composition in those with and without BH.

Methods: We compared 421 HIV⁺ men between the ages of 33 and 45 years from 18 centers to 151 similar age control (CON) men from the Coronary Artery Risk Development in Young Adults (CARDIA) study. The presence of BH was determined on exam and the X and Y dimensions measured with a Gulick tape measure. MRI was performed to quantify subcutaneous adipose tissue (SAT) in lower (abdomen/back) and upper (chest/back) trunk and visceral adipose tissue (VAT).

Results: BH was found on exam in 8.0% of HIV⁺ men and 11.3% of CON (p = 0.24, OR 0.68, CI 0.31-1.28). In HIV⁺ men, those with BH had higher BMI than those without BH, whereas in CON men, BMI was similar. In both HIV and CON, those with BH had higher trunk SAT and VAT measured by MRI than those without BH. However, while HIV⁺ men with BH had less lower trunk SAT than CON men with BH, both HIV⁺ and CON men with BH had similar BMI, upper trunk SAT, and VAT.

Measures		HIV+	CON	p-value HIV+ vs. CON
BMI (median Kg/m2)	BH	27.3	27.6	0.52
	No BH	24.2	27.0	<0.001
	p-value BH vs. No BH	<0.001	0.21
MRI trunk SAT (median L)	BH	7.54	11.3	0.12
	No BH	5.41	8.08	<0.001
	p-value BH vs. No BH	<0.001	0.027
MRI lower trunk SAT (median L)	BH	3.87	8.00	0.012
	No BH	3.55	5.63	<0.001
	p-value BH vs. No BH	0.0254	0.031
MRI upper trunk SAT (median L)	BH	3.75	2.71	0.24
	No BH	1.86	2.30	<0.001
	p-value BH vs. No BH	<0.001	0.059
MRI VAT (median L)	BH	3.02	2.83	0.89
	No BH	1.45	1.75	0.009
	p-value BH vs. No BH	<0.001	0.026

 

Finally, BH averaged 2.5x larger in HIV+ (9.0 x 8.2 cm) vs CON (5.5 x 5.4 cm; each dimension p < 0.001).

Conclusions: Although BH is not more common in HIV⁺, it is associated with different fat distribution: HIV⁺ men have larger BH and similar upper trunk SAT, but less lower trunk SAT compared to CON with BH. HIV⁺ men with BH have higher BMI than HIV⁺ men without BH. In both HIV⁺ and CON men, BH is associated with higher VAT. BH may be a surrogate marker for VAT.