By contrast, at 6 and 36 months after initiation of cART, the median (IQR) CD4 count was lower in IDUs compared with

non-IDUs [at 6 months, 297 (IQR 160–469) cells/μL vs. 323 (IQR 186–488) cells/μL, respectively; at 36 months, 405 (IQR 249–605) cells/μL vs. 462 (IQR 310–660) cells/μL, respectively]. The proportions of patients with undetectable viral load (defined as HIV-1 RNA ≤500 copies/mL) at 6 and 36 months after initiation of cART were also lower for IDUs compared with non-IDUs (at 6 months, 71.2 vs. 79.6%, respectively; P<0.001; at 36 months, 70.2 vs. 78.5%, PLX3397 concentration respectively; P<0.001). In a subset of 15 238 patients with data on coinfection with hepatitis C virus at baseline, there was a strong association between IDU status and a positive test result: 2204 (88%) of IDUs were coinfected compared with 1518 (12%) of non-IDUs (P<0.001). A total of 533 deaths (8.5%) were recorded in patients with a history of IDU, compared with 1564 (4.1%) among non-IDUs over the follow-up period: mortality rates were 2.08 [95% confidence interval (CI) 1.91–2.26] vs. 1.04 (95% CI 0.99–1.09), respectively, per 100 person-years (P<0.001). Rates of AIDS were also higher in IDUs than in non-IDUs [2.91 (95% CI 2.70–3.13) vs. 2.33 (95% CI 2.25–2.41), respectively, per 100 person-years; P<0.001]. The unadjusted mortality Bleomycin solubility dmso rate ratio (RR), comparing IDUs with non-IDUs, was higher for patients with baseline CD4 counts ≥200 cells/μL than for

those with CD4 counts <200 cells/μL [2.67 (95% CI 2.26–3.15) vs. 1.76 (95% CI 1.55–2.00), respectively; P-value for homogeneity 0.0001]. Mortality RRs increased with time since start of cART, from 1.28 (95% CI 0.98–1.65) in the first 6 months to 1.48 (95% CI 1.08–1.99) in months 6–12 and 2.41 (95% CI 2.11–2.75) in years 1–5 (P-value for homogeneity <0.0001). Table 2 shows hazard ratios for the association of patient characteristics at baseline with progression to death and AIDS (mutually adjusted

for other variables in the table and stratified by cohort) in patients who were and were not infected via IDU, together with P-values for interaction (differences in hazard ratios in IDUs and non-IDUs). Lower baseline CD4 cell count, higher baseline HIV viral load, clinical AIDS at baseline, and later year of cART initiation were associated with disease progression in both groups, consistent with associations reported previously [12,28]. However, mafosfamide the inverse association of baseline CD4 cell count with subsequent rates of AIDS (interaction P<0.0001) and death (interaction P=0.092) appeared to be stronger in IDUs than in non-IDUs. By contrast, the positive association of baseline HIV-1 RNA with subsequent AIDS appeared stronger in non-IDUs than IDUs (interaction P=0.006). While the positive association of a diagnosis of AIDS before starting cART with mortality appeared stronger in non-IDUs than IDUs (interaction P=0.003), the association with AIDS appeared stronger in IDUs (interaction P=0.013).