Pregnancies among women living with HIV using contraceptives and antiretroviral therapy in western Kenya: a retrospective, cohort study

Table 2 Adjusted pregnancy incident rate ratios per 100 women-years (and 95% CI) by contraceptive method and ART category, individually by each sampling phase ignoring validation sampling strategy (unweighted) and accounting for validation sampling strategy (weighted)

Contraceptivemethod and ARTregimen category	Pregnancy	Women-years	EMR, aIRR^a (95% CI)	Chart review, aIRR (95% CI)		Telephone interview, aIRR (95% CI)
Contraceptivemethod and ARTregimen category	Pregnancy	Women-years	EMR, aIRR^a (95% CI)	Unweighted^a	Weighted^b	Unweighted^a	Weighted^b
Implant	466	11,978.6
Nevirapine	149	5612.7	Ref	Ref	Ref	Ref	Ref
Efavirenz	187	3244.4	1.9 (1.6, 2.4)	2.2 (1.7, 3.0)	2.3 (1.5, 3.5)	3.2 (1.9, 5.4)	3.2 (1.8, 5.7)
PI	20	759.7	1.0 (0.6, 1.6)	0.9 (0.5, 1.8)	0.6 (0.2, 1.4)	0.7 (0.2, 2.8)	0.9 (0.3, 2.7)
No ART	110	2344.9	1.3 (1.0, 1.6)	1.3 (0.9, 2.0)	0.9 (0.5, 1.5)	1.5 (0.8, 2.8)	1.9 (0.9, 3.7)
DMPA	2150	22,749.3
Nevirapine	940	10,827.1	Ref	Ref	Ref	Ref	Ref
Efavirenz	512	5000.9	1.1 (0.9, 1.2)	1.2 (0.9, 1.5)	1.0 (0.6, 1.8)	1.0 (0.7, 1.6)	1.0 (0.3, 2.9)
PI	142	1468.7	1.1 (0.9, 1.3)	1.5 (1.1, 2.1)	1.3 (0.6, 2.7)	1.0 (0.6, 1.8)	0.8 (0.2, 2.9)
No ART	553	5403.0	0.9 (0.8, 1.0)	1.4 (1.1, 1.7)	0.9 (0.5, 1.4)	1.0 (0.6, 1.5)	0.9 (0.3, 2.4)

Estimates in bold indicate statistically significant findings
ART, antiretroviral therapy; EMR, electronic medical record; DMPA, depomedroxyprogesterone acetate; PI, protease inhibitor
^aCalculated using Poisson models with interaction terms between ART and contraceptive method categories, program, various covariates (average age within the observation period, average age squared, marital status, education status, any number of living children, WHO clinical stage, CD4 cell count, square root of CD4 cell count, log BMI, square root of log BMI, use of any anti-tuberculosis medications, and calendar time), and robust standard errors. Unweighted analyses ignored the validation sampling strategy
^bCalculated using generalized raking inverse probability weighting and Poisson models with interaction terms between ART and contraceptive method categories, program, various covariates (average age within the observation period, average age squared, marital status, education status, any number of living children, WHO clinical stage, CD4 cell count, square root of CD4 cell count, log BMI, square root of log BMI, use of any anti-tuberculosis medications, and calendar time), and robust standard errors. Weighed analyses accounted for the validation sampling strategy

ISSN: 1741-7015