The Effects of Viral Load Burden on Pregnancy Loss among HIV-Infected Women in the United States

Table 2

Risk ratios and risk differences of the association of pregnancy loss with most recent cross-sectional viral load measure before the pregnancy ended (), copy-years viremia from ART initiation to conception (), and copy-years viremia in the two years prior to conception ().

	Pregnancy loss	Relative effect measures		Absolute effect measures
	Losses/	RR (95% CI)	aRR (95% CI)	RD (95% CI)	aRD (95% CI)
Analysis 1: most recent viral load measure
Continuous exposure	158/454	1.27 (1.13, 1.42)	1.17 (1.01, 1.35)	0.10 (0.06, 0.14)	0.04 (−0.01, 0.08)
Dichotomous exposure
≤1.60	41/181	1.	1.	0.	0.
>1.60	117/273	1.89 (1.39, 2.58)	1.23 (0.87, 1.74)	0.20 (0.11, 0.29)	0.05 (−0.04, 0.14)^†
Categorical
Q1: ≤1.60	41/181	1.	1.	0.	0.
Q2: 1.61–3.00	30/91	1.47 (0.98, 2.19)	1.15 (0.79, 1.68)	0.10 (−0.01, 0.21)	0.03 (−0.06, 0.12)^†
Q3: 3.01–4.00	39/90	1.87 (1.27, 2.75)	1.20 (0.77, 1.87)	0.19 (0.07, 0.32)	0.04 (−0.09, 0.17)^†
Q4: >4.00	48/92	2.36 (1.68, 3.31)	1.59 (0.99, 2.56)	0.30 (0.18, 0.42)	0.14 (−0.01, 0.28)^†
Analysis 2: copy-years viremia since ART initiation
Continuous exposure	92/250	0.83 (0.73, 0.95)	0.80 (0.69, 0.92)	−0.07 (−0.13, −0.02)	−0.10 (−0.14, −0.05)
Quartile of exposure^‡
Q1: 0–3.78	29/62	1.	1.	0.	0.
Q2: 3.79–4.38	24/63	0.84 (0.55, 1.30)	0.85 (0.56, 1.30)	−0.07 (−0.25, −0.11)	−0.05 (−0.21, 0.12)
Q3: 4.39–4.94	22/63	0.72 (0.45, 1.14)	0.70 (0.44, 1.13)	−0.13 (−0.31, −0.05)	−0.15 (−0.32, 0.03)
Q4: >4.94	17/62	0.61 (0.37, 1.00)	0.60 (0.36, 0.99)	−0.18 (−0.35, −0.01)	−0.18 (−0.36, −0.01)
Analysis 3: copy-years viremia in two years before pregnancy
Continuous exposure	149/376	1.12 (1.01, 1.24)	1.00 (0.90, 1.11)	0.05 (0.01, 0.09)	−0.01 (−0.05, 0.03)
Quartile of exposure^‡
Q1: 0–4.26	28/94	1.	1.	0.	NC
Q2: 4.27–5.73	34/94	1.19 (0.78, 1.81)	0.90 (0.61, 1.32)	0.06 (−0.08, 0.20)	NC
Q3: 5.74–6.49	46/94	1.57 (1.07, 2.29)	1.07 (0.72, 1.57)	0.17 (0.03, 0.31)	NC
Q4: >6.49	41/94	1.43 (0.97, 2.09)	0.92 (0.63, 1.35)	0.13 (−0.01, 0.26)	NC

ART = antiretroviral therapy, RR = risk ratio, aRR = adjusted risk ratio, RD = risk difference, and aRD = adjusted risk difference. NC = nonconvergence of model.
Adjusted for maternal age (with a linear spline at age 35), race, income, noninjection drug use, prior pregnancy loss, smoking, CD4 count, and ART use (separately controlling for mono-/dual and HAART versus none) prior to viral load measurement (for analyses 1 and 3).
Point estimates controlled for any ART instead of separately controlling for mono-/dual and HAART due to model nonconvergence.
Categories of cross-sectional viral load measures (analysis 1) were based on clinically informative cut-points, while the categories for cumulative viremia measures (analysis 2) were based on statistical quartiles.