Frequency of HIV-1 Viral Load Monitoring of Patients Initially Successfully Treated with Combination Antiretroviral Therapy

BACKGROUND: Although considered an essential tool for monitoring the effect of combination antiretroviral treatment (CART), HIV-1 RNA (viral load, VL) testing is greatly influenced by cost and availability of resources. ----- OBJECTIVES: To examine whether HIV infected patients who were initially successfully treated with CART have less frequent monitoring of VL over time and whether CART failure and other HIV-disease and sociodemographic characteristics are associated with less frequent VL testing. ----- METHODS: The study included patients who started CART in the period 1999-2004, were older than 18 years, CART naive, had two consecutive viral load measurements of <400 copies/ml after 5 months of treatment and had continuous CART during the first 15 months. The time between two consecutive visits (days) was the outcome and associated factors were assessed using linear mixed models. ----- RESULTS: We analyzed a total of 128 patients with 1683 visits through December 2009. CART failure was observed in 31 (24%) patients. When adjusted for the follow-up time, the mean interval between two consecutive VL tests taken in patients before CART failure (155.2 days) was almost identical to the interval taken in patients who did not fail CART (155.3 days). On multivariable analysis, we found that the adjusted estimated time between visits was 150.9 days before 2003 and 177.6 in 2008/2009. A longer time between visits was observed in seafarers compared to non-seafarers; the mean difference was 30.7 days (95% CI, 14.0 to 47.4; p<0.001); and in individuals who lived more than 160 kilometers from the HIV treatment center (mean difference, 16 days, p=0.010). ----- CONCLUSIONS: Less frequent monitoring of VL became common in recent years and was not associated with failure. We identified seafarers as a population with special needs for CART monitoring and delivery

Rate of viral load tests per one year according to different baseline patients characteristics.

<p>95% confidence intervals are in parenthesis.</p>a<p>Men who had sex with men <i>versus</i> other categories.</p>b<p>NNRT-based compared to PI-based.</p><p>VL, viral load; CART, combination antiretroviral therapy; NNRT, non-nucleoside reverse transcriptase inhibitor;</p><p>PI, protease inhibitor; NRT, nucleoside analogue reverse transcriptase inhibitor.</p

Comparison of baseline demographics and clinical characteristics according to frequency of viral load testing.

<p>Standard, subjects having <50% of measurements <5 months apart. Less frequent, subjects having ≥50% of measurements >5 months apart.</p><p>Values are N (%) or median (interquartile range).</p><p>MSM, men who have sex with men; CART, combination antiretroviral therapy; NNRT, non nucleoside reverse transcriptase inhibitor; PI, protease inhibitor.</p

Relationship between baseline or time-varying characteristics and interval (days) between viral load measurements on multivariable mixed model analysis^a.

<p>The intercept represents the average interval for a non-MSM who is a seafarer, lives ≥160 kilometers from Zagreb, has high school or lower education, has had at least one CART change, is taking a non-NNRT regiment, has a CD4 cell count of 350 per µL, is treated in 2008/09 and has a follow-up time of 2 years.</p>a<p>Adjusted for the linear and quadratic term of time.</p>b<p>Least square means estimates from the model.</p>c<p>When 47 potential outlying observations were removed the result became insignificant (p = 0.376).</p><p>MSM, men who have sex with men; CART, combination antiretroviral therapy; NNRT, non nucleoside reverse transcriptase inhibitor.</p

Relationship between baseline or time-varying characteristics and interval (days) between viral load measurements using crude mixed model analysis.

a<p>Adjusted for the linear and quadratic term of time and one independent variable.</p>b<p>Least square means estimates from the model. MSM, men who have sex with men;</p><p>CART, combination antiretroviral therapy; NNRT, non nucleoside reverse transcriptase inhibitor;</p><p>PI, protease inhibitor.</p