Predictors of Rebound Viremia in Treatment Experienced Patients with Undetectable Viral Load

Background:

With the advent of combination antiretroviral therapy, durable suppression of plasma HIV RNA (VL) is achievable in the majority of HIV- infected patients. Yet, a significant number experience viral rebound (VR). This study aims to determine factors associated with VR in patients at our urban HIV clinic.  

Methods:

Our retrospective cohort study identified treatment experienced patients, with undetectable HIV VL, who attended the HIV clinic between 01/2013 and 06/2015. We excluded patients with fewer than 2 VL measurements during the study period. VR was defined as 1 HIV VL ≥ 200 copies/mL or 2 consecutive VL ≥ 50 copies/mL. Sociodemographic, clinical and treatment factors were analyzed with respect to the occurrence of VR.  

Results:  

Of 828 treatment-experienced patients with undetectable VL, 183 (22%) experienced VR. On univariate analysis, younger age, African American race, hospitalized patients, Medicaid beneficiaries and substance abuse were associated with higher likelihood of VR (table 1). Patients with VR had significantly lower CD4 count and CD4/CD8 ratio. There was no association between gender, pill burden, educational level or income and likelihood of VR.  On multivariate analysis, African American race, hospitalization and lower CD4 counts were associated with a significantly higher odds of VR.

Conclusion:

Despite highly effective therapies, failure to maintain viral suppression continues to be a frequent occurrence, influenced by various sociodemographic and clinical factors. Contrary to previous studies, our study did not demonstrate an association between single tablet regimens and lower risk of VR.

Analysis	Univariate			Multivariate
	Controls	VR	p-value	Adjusted OR	95% CI
N	645	183
Age*	49.1	45.5	0.001	1.35 α	0.95 – 1.93
Female Gender	128 (20%)	37 (20%)	0.91
African American	387 (60%)	133 (73%)	0.007	1.59	1.09 – 2.33
Hospitalized	139 (22%)	62 (34%)	0.001	1.56	1.04 – 2.32
Hepatitis C	77 (12%)	27 (15%)	0.31
Substance Abuse	221 (34%)	80 (44%)	0.02	1.26	0.88 – 1.80
Mood Disorder	126 (20%)	38 (21%)	0.71
CD4 count*	501	376	0.001	2.16 β	1.34 – 3.49
CD4/CD8*	0.87	0.65	0.001
Medicaid Beneficiary	214 (33%)	80 (44%)	0.009
Lower then State Median Income	435 (71%)	126 (72%)	0.69
Single Tablet Regimen	312 (48%)	97 (53%)	0.27
Once Daily Regimen	463 (72%)	144 (79%)	0.06

* mean

^α <50 vs. ≥ 50 years

^β <200 vs. ≥ 200 cells/mm³