By Liz Highleyman

Predictors of antiretroviral treatment failure are not well characterized for diverse clinic populations outside of clinical trials. As described in the January 1, 2007 Journal of Acquired Immune Deficiency Syndromes, researchers from Massachusetts General Hospital and Harvard Medical School performed a retrospective longitudinal analysis of HIV-infected patients followed in an urban HIV clinic. Participants had HIV RNA levels </= 400 copies/mL on antiretroviral therapy between January 2003 and December 2004.

Treatment failure was defined as virological failure (one or more HIV RNA measurement > 400 copies/mL), unsanctioned discontinuation of therapy, or loss to follow-up.

Results

• Of 829 total clinic patients, 614 (74%) had at least one HIV RNA measurement </=400 copies/mL during the study period.

• Of these, 167 (27%) experienced treatment failure.

• 108 patients (18%) experienced a rebound in HIV viral load.

• Among the 58 patients (9%) classified as poorly adherent at baseline, 40 (69%) experienced treatment failure.

• Baseline characteristics significantly associated with treatment failure in a multivariate model were:

- poor adherence (HR 3.44; 95% CI 2.34-5.05);

- absolute neutrophil count < 1000 cells/mm3 (HR 2.90; 95% CI 1.26-6.69);

- detectable HIV RNA at the start of the study (HR 2.69; 95% CI 1.78-4.07);

- less than 12 months of virological suppression (HR 1.64; 95% CI 1.10-2.45);

- CD4 count < 200 cells/mm3 (HR 1.90; 95% CI 1.31-2.76);

- use of regimens containing only nucleoside reverse transcriptase inhibitors (NRTIs) (HR 1.75; 95% CI 1.08-2.82);

- prior virological failure (HR 1.70; 95% CI 1.22-2.39);

- one or more missed clinic visit during the prior year (HR 1.56; 95% CI 1.13-2.16).

•Hepatitis C virus (HCV) coinfection was also linked to greater risk of virological failure, but was of borderline statistical significance (P = 0.059).

Conclusion

"More than one quarter of patients in a heterogeneous clinic population had treatment failure over a 2-year period," the investigators wrote in conclusion. "Prior antiretroviral therapy adherence and other [electronic health record] data readily identify patient characteristics that could trigger specific interventions to improve antiretroviral therapy outcomes."

Massachusetts General Hospital, Harvard Center for AIDS Research, and Harvard Medical School, Boston, MA.

1/19/07

Reference
G K Robbins, B Daniels, H Zheng, and others. Predictors of Antiretroviral Treatment Failure in an Urban HIV Clinic. Journal of Acquired Immune Deficiency Syndromes 44(1): 30-37. January 1, 2007.