Frequency and Characteristics of Long-Term Non-Progressors and HIV Controllers in the Chelsea and Westminster Cohort

There is no internationally agreed definition of a long-term non-progressor (LTNP), in recent years more usefully referred to as a slow progressor, or an HIV controller (HIC). As a result several different interpretations of what parameters can make someone a LTNP or a HIC exist and these change both between and within countries. Either way these atypical patients are an important group to research as they have the potential to increase our understanding of HIV pathogenesis.

Mandalia and colleagues performed a retrospective review of the Chelsea and Westminster patient database to determine the prevalence of LTNPs or HICs and their associated rates of progression.

In this case LTNPs and HIC were defined as being HIV-1 positive for >7 years, with a CD4 T cell count >=450 cells/mm³, CD4 T-cell slope >=0 since entry to cohort, no OIs and naive to ART. LTNPs were defined as having varying HIV-1 RNA plasma load which is mostly low but detectable whereas HICs maintain undetectable levels of viral load.

The study cohort looked at all patients registered from January 1988 to February 2010. CD4 count slope was derived from a random intercept model. A stable CD4 T-cell count was defined as patients whose CD4 T-cell count slope was >=0. Survival analyses were used to estimate time to HIV progression and data were censored at the most recent visit to the clinic.

Out of a total cohort of 14,227 patients, only 12 people were LTNPs and 1 person was a HIC. These 13 patients account for 0.38% of the total cohort that is in line with the results from a similar cohort in France where 0.4% of patients were LTNPs (although their inclusion criteria was slightly different).

Of the 1,204 patients who had been HIV positive for over 7 years with no history of ART, 965 had a CD4 count <450 cells/mm³ whilst 239 had a CD4 count of >=450 cells/mm³. The median time of disease progression in the cohort with CD4 count <450 was 4.0 years (IQR: 1.0-7.3), while those in the cohort with CD4 count >=450 had a median time to progression of 6.2 years (IQR: 2.0–9.6). The difference in time taken for disease progression was statistically significant (p=<0.001) suggesting that patients whose CD4 counts remain within "normal" range progress less rapidly.

Reference

1. Mandalia S et al. Frequency and characteristics of long-term non-progressors and HIV controllers in the Chelsea and Westminster HIV cohort. 17th Annual BHIVA Conference, 6–8 April 2011, Bournemouth. Oral abstract O28.