Missed appointments in early years of HIV care associated with longer time to HIV suppression and higher cumulative viral load

Patients who miss clinic appointments in the two years after they enter HIV care take longer to suppress their viral load to undetectable levels and also have a higher cumulative viral load than patients with high levels of appointment attendance, US investigators report in the online edition of the Journal of Acquired Immune Deficiency Syndromes.

“Early retention in HIV care was associated with a time to viral load suppression and two year cumulative viral load burden among patients newly initiating HIV medical care,” write the investigators, who believe that their findings have implications for both the prognosis of their patients and the use of HIV treatment as prevention.

Few studies have explored the virological consequences of clinic attendance in the years immediately following entry into HIV care. Investigators from the HIV clinics at the University of Alabama and the University of Washington believed that “sub-optimal early retention in care represents a formidable obstacle to achieving HIV viral load suppression.”

They therefore designed a study involving 676 patients who entered care at their clinics between 2007 and 2010. The investigators hypothesised that missed appointments in the first two years after entering care would be associated with delayed time to viral load suppression, and that patients who had poorer levels of clinic attendance would have a higher cumulative viral load over the two years of observation.

At the time of entry into care the patients had a median age of 36 years, 44% were non-white males, and 36% were uninsured.

Median baseline viral load was approximately 40,000 copies/ml. A third of patients had an initial CD4 cell count below 200 cells/mm³, with 43% having a count above 350 cells/mm³.

Overall, a quarter of patients failed to attend two or more clinic appointments in their first two years of care.

A total of  79% of patients started HIV therapy, and the median time to the initiation of treatment was 35 days from entry into care. Approximately two-thirds of individuals achieved an undetectable viral load, and the median time to virological suppression was 308 days after the initial clinic visit.

Patients with private insurance (HR = 1.37 vs. uninsured; 95% CI, 1.08-1.73) and those with a baseline CD4 cell count below 200 cells/mm³ or 350 cells/mm³ (HR = 3.74; 95% CI, 2.83-4.95; HR = 2.95; 95% CI, 2.26-3.86) at baseline had a shorter time to virological suppression.

A higher baseline viral load (each 50,000 copies/ml, HR = 0.97; 95% CI, 0.96-0.99) and missed appointments (each “no show”, HR = 0.83; 95% CI, 0.76-0.92) were both associated with a longer interval between entry into care and the achievement of an undetectable viral load.

Next the investigators looked at the impact of missed appointments on cumulative viral load. Cumulative viral load fell as clinic adherence increased (attendance up to 79% = 4.6 log₁₀ copies x years; 80% to 99% attendance = 4.3 log₁₀ copies x years; 100% attendance = 4.1 log₁₀ copies x years; p < 0.001).

“Significantly greater viremia copy years, an estimate of cumulative HIV burden, were accumulated among patients with poorer visit adherence,” write the authors. “These findings have implications for patient outcomes as recent studies have identified increased risk of deleterious clinical events among patients experiencing greater cumulative viral load burden over time.”

Statistical analysis showed that lower clinic attendance (beta coefficient = 0.11 per 10% non attendance; 95% CI, 0.04-01.7) was associated with higher cumulative viral load.

Restricting analysis to patients with a baseline CD4 cell count below 350 cells/mm³ (the threshold for starting HIV treatment) showed that patients who missed appointments took longer to suppress their viral load (HR = 0.81 per additional “no show”; 95% CI, 0.72-0.92). Moreover, a higher cumulative viral load was associated with poor clinic attendance for these patients (beta coefficient = 0.14 per 10% visit adherence; 95% CI, 0.19-0.08).  

“We identified significant associations between early retention in care and viral load suppression among patients initiating outpatient HIV medical care,” conclude the investigators. “We demonstrated the importance of early visit adherence as it relates to cumulative HIV burden…longitudinal measures of cumulative viral load burden, like viremia copy years, may significantly contribute to the evaluation of test and treat HIV prevention interventions, the success of which are predicated on both rapidly achieving, and also longitudinally sustaining viral load suppression.”