Children in UK stay a long time on failing therapy

Since children started receiving HAART in the UK, they have been waiting an average of 3.1 years on failing first-line therapies before switching, the Eighth Glasgow International Congress on Drug Therapy in HIV Infection heard last week.

This departure from the standard approach to adult care is largely due to the lack of research on HAART in children, said Katherine Lee of CHIPS (the Collaborative HIV Paediatric Study), a multi-centre cohort study of HIV infected children in the UK. She added that an expectation that it was more difficult to achieve an undetectable viral load in children may have led physicians to prolong children’s time on failing regimens in order to prolong the time any HAART would work.

There was, however some relatively good news form the study too. Only 22% of children put on first-line therapy in the CHIPS cohort have switched to second-line therapy at all, and the time taken to switch to a second-line therapy has grown shorter in recent years. The average CD4 count at the time of switching was 485 which, even considering that young children have higher CD4 counts than adults, shows that reasonable immune function was maintained.

Altogether 595 children in CHIPS have been put on first-line HAART since the cohort was established in April 2000. Their average age at HAART initiation was 4.7 years.

Of these, 132 (22%) have switched to a second-line therapy, where switching was defined either as replacing all three drugs regardless of viral load or where at least two were replaced on a viral load over 50.

The average time taken to switch to a second-line therapy was seven years, meaning that the average child was at secondary school age when switching. Despite this, only 63 (48%) of the children who switched to second-line therapy had ever achieved a viral load under 400 during first-line therapy. Average time to switching was over seven years in those who had at some point achieved a viral load under 400 (the exact time can’t be ascertained because the cohort has not existed long enough). Average time to switching in those who had never achieved a viral load under 400 was 3.1 years.

The average viral load at the time of switching was 8206 (3.9 logs) in those who had achieved a viral response, but 79,569 (4.9 logs) in those who had not. Only 14% of children switched before reaching a viral load of 1000, and only 18% switched before reaching a viral load of 30,000: the median time to switching after reaching these thresholds was 3.3 and 1.0 years respectively.

An older age at the time of HAART initiation and later calendar year were predictive of earlier switching: children were 7% more likely to switch HAART earlier than average for every year older they were when starting HAART, and children after 2002 were 2.27 time more likely to switch HAART early.

“There is an urgent need for evidence on which to base switching” in children, the researchers conclude.