ACCESS TO GENOTYPIC RESISTANCE TESTING IN ONTARIO

JM Raboud^1,2, R Saskin³, C Major⁴, A Rachlis^5,6, P Millson², G Robinson⁷, RS Remis^2,4, AM Bayoumi^6,7
1Division of Infectious Diseases, University Health Network, University of Toronto; Department of Public Health Sciences, University of Toronto; ³Department of Microbiology, Mount Sinai Hospital; ⁴Ontario Ministry of Health; ⁵Sunnybrook Health Sciences Centre; ⁶Faculty of Medicine, University of Toronto; ⁷Ontario HIV Treatment Network

Objective: To compare time to obtaining genotypic resistance testing by demographic and clinical factors.
Methods: Plasma viral load and genotypic resistance data were obtained from the Ontario Ministry of Health. Patient demographics and medication data were obtained from the HIV Ontario Observational Database (HOOD). Genotypic resistance testing was done by the BC Centre for Excellence. The time to testing was calculated as the first date that viral load exceeded 1000 copies/ml to the date of resistance testing.
Results: 944 patients had a viral load measurement above 1000 copies/mL after Feb 15, 2000, the first date resistance testing became generally available in Ontario. 92% of patients were male, 72% were MSM, mean age 42, 80% had at least high school, mean CD4=353 cells/mm³, mean log₁₀ viral load=4.3, 40% had PI experience. 302 patients had resistance testing by June 2001. The probability of resistance testing within 1 year of a viral load measurement >1000 c/mL was 39%. This probability varied by geographic region in the province (p=0.02) but was not significantly greater for men (35% vs 35%, p=0.62), MSM (40% vs 37%, p=0.71), those with more than high school education (40% vs 35%, p=0.29), for those with CD4 counts >300 cells/mm³ (40% vs 37%, p=0.65), for participants over 40 (40% vs 37%, p=0.12) or for patients with PI experience (37% vs 40%, p=0.39).
Conclusions: Time to resistance testing after a viral load measurement over 1000 c/mL varied among regions in the province. Gender, risk group, level of education and CD4 counts did not affect time to testing. Further analyses will be done to determine patient profiles most likely to result in resistance testing.