A treatment interruption is nearly five times more likely to result in a higher risk of subsequent illness for someone with a past AIDS diagnosis, according to a study conducted among patients at the Royal Sussex County Hospital in Brighton.
Dr Mary Poulton and Caroline Sabin, senior lecturer in Epidemiology and statistics at the Royal Free Medical School looked at 40 patients who stopped therapy for at least two months and who had at least two CD4 measurements available for the off-treatment period. They found that three factors predicted who would experience the biggest loss of CD4 cells (and who was most likely to experience a decline below 200 cells/mm3):
- Baseline CD4 count
- Nadir (lowest ever) CD4 count
- Prior rate of CD4 cell loss before starting treatment
People who experienced the largest viral load increases after stopping treatment did not necessarily experience the biggest CD4 cell declines
Those with a very low CD4 cell nadir but now doing well on treatment should be wary of treatment interruptions, the group reported, and patients in this category should have their CD4 cell counts monitored at least once a month rather than three-monthly. People who decide to stop treatment for any reason should inform their doctors so that they can be monitored carefully, said Caroline Sabin, so that any big falls in CD4 counts can be picked up before they lead to the development of opportunistic infections. Ten of those who interrupted treatment already had CD4 cell counts below 200 at the time they stopped treatment.
In the Brighton cohort the average CD4 count was 348 prior to treatment interruption, and this fell to an average of 216 before treatment was resumed, with the steepest falls seen in the first three months. Those with higher baseline counts tended to stabilise after this point, although this observation may be an artefact of the tendency for people with lower CD4 counts to resume treatment when they reached a level below 200 cells/mm3.
Reference
Poulton M et al. Immunological changes during treatment interruptions: risk factors and clinical sequelae. Seventh Annual Conference of the British HIV Association, abstract O22, 2001.