Physician experience strongly influences success of HIV treatment started at low CD4 count

Patients of doctors with greater experience of treating HIV are substantially less likely to die after starting treatment at a low CD4 cell count, according to research from the University of British Columbia published in the March 28 edition of the journal AIDS (now available online).

The researchers looked at survival rates in 1416 treatment-naïve individuals who started triple antiretroviral treatment in the Canadian province of British Columbia between August 1996 and July 2000, and asked whether physician experience had any impact on the survival of people who started treatment at CD4 counts below the threshold recommended by the British HIV Association as the lower limit for starting therapy (200 cells/mm³). The study also attempted to identify whether a point of no return truly exists beyond which antiretroviral therapy cannot influence survival, by looking at the effects of physician experience, adherence and other variables on the outcome.

The UK threshold, which is lower than the level recommended by the US Public Health Service guidelines, was partly informed by previous research from the British Columbia group showing no difference in survival between people who started treatment at CD4 counts above 350 cells/mm³ and between 200 and 350 cells/mm³.

Physician experience was defined according to number of patients cared for; a physician was defined as experienced if he or she had cared for more than five HIV-positive patients before a patient evaluated in this analysis started treatment.

The median baseline CD4 cell count was 270 cells/mm³, and 122 deaths occurred during the study, 22 of which were not attributed to HIV.

The researchers found that patients of experienced doctors who started treatment at CD4 counts below 50 cells/mm³ were substantially less likely to die than patients of inexperienced doctors (RH 5.07 (CI: 2.5 – 10.26) vs RH 11.99 (CI: 6.33 – 10.26)).

This effect was attributed to the greater knowledge of prophylaxis and treatment of opportunistic infections amongst experienced doctors rather than greater understanding of the importance of adherence among the experienced doctors, since no significant relationship was found between physician experience and patient adherence of greater than 75% (defined by prescription refill only).

At every CD4 cell level (> 200, 199-50, 3 can be modulated by factors within the control of doctor and patient, and that a CD4 cell count of 200 – 350 cells/mm³ “does not represent an irreversible biological threshold beyond which response to therapy is compromised. ” However the authors caution that their findings do not support delaying treatment initiation below 200 cells/mm³.