Table 3. Multivariable regression analysis of V1V2 length vs. clinical variables.

	Time since infection (Model 1)			Infection Stage (Model 2)
Factor	All seqs	Plasma	PBMC	All seqs	Plasma	PBMC
Time since infection	0.59 (0.85)	0.77 (<0.001)	0.56 (0.86)
Stage 1				Ref	Ref	Ref
Stage 2				0.09 (0.9)	0.08 (0.9)	0.00 (0.9)
Stage 3				6.25 (<0.001)	6.65 (<0.001)	3.66 (0.10)
Stage 4				3.54 (0.02)	2.95 (0.06)	8.01 (0.01)

Beta coefficients for V1V2 Length vs. Time since Infection (Model 1), Stage of Infection (Model 2), CD4 counts (Model 3) or HIV Viral Load (Model 4). β values and p-values (in parentheses) are shown. Results are stratified by sample type (Plasma vs. PBMC), adjusting for year of sample collection. Time since infection was missing for 5 sequences, stage of infection for 242 sequences, CD4 count for 113 sequences, and viral load for 290 sequences with measured V1V2 length. Ref  =  Reference group. Analyses were performed for all sequences collectively as well as for sequences derived from plasma and PBMC considered separately.