Table 1.

Factors associated with the annualised change in viral load and CD4⁺ cell count.

	Model parameter	Estimate	95% CI	P
Viral load model	Intercepta	0.093	0.086–0.10	<0.001
	Viral load at t−1 (per 1 log10 copies/ml higher)	−0.026	−0.031 to −0.021	<0.001
	CD4+ cell count at t0 (per 100 cells/μl higher)	−0.004	−0.007 to −0.002	<0.001
	Age at t0 (per 10 years higher)	0.022	0.017–0.027	<0.001
	Female	0.004	−0.006 to 0.014	0.42
	Black race	−0.019	−0.04–0.002	0.07
	Transmission by IDU	−0.011	−0.024 to 0.003	0.12
CD4+ cell count model	Interceptb	−69.0	−71.8 to −66.2	<0.001
	CD4+ cell count at t−1 (per 100 cells/μl higher)	−17.0	−18.1 to −15.9	<0.001
	Viral load at t0 (per 1 log10 copies/ml higher)	−37.6	−39.6 to −35.7	<0.001
	Age at t0 (per 10 years higher)	−1.7	−3.3 to −0.03	0.046
	Female	−0.8	−4.2 to 2.7	0.67
	Black race	2.3	−3.8 to 8.3	0.48
	Transmission by IDU	0.7	−4.6 to 6.0	0.80

Annualized change in viral load (copies/ml, log₁₀ scale) and CD4⁺ cell count (cells/μl, absolute scale) was defined as [(measurement at t₁ – measurement at t₀) × 365]/(t₁ – t₀). All continuous variables were centred, see ^a,bbelow), estimate sizes and 95% confidence intervals (CI) from a multivariable linear regression model. IDU, injecting drug use.

^aThe intercept in the viral load model is the annual change in viral load for an individual with viral load at t₋₁ = 4 log₁₀ copies/ml, CD4⁺ cell count at t₀ = 500 cells/μl, age at t₀ = 35 years, male, white race and transmission mode other than by IDU.

^bThe intercept in the CD4⁺ cell count model is the annual change in CD4⁺ cell count for an individual with viral load at t₀ = 4 log₁₀ copies/ml, CD4⁺ cell count at t_-1 = 500 cells/μl, age at t₀ = 35 years, male, white race and transmission mode other than by IDU.

Other comments: The reference race group is white race. All other people who were not classified as black or white race were also included in the model but in a separate category (not shown).