For nonresponders (Fig. 2b), there

was no statistically significant decrease compared with day 1–45 rates in any category of admissions, although rates for ADI approached significance in the 91–180- and 181–365-day time periods (P=0.11 and 0.14, respectively). In each of four sensitivity/subgroup analyses, the pattern of relative hospitalization rates over time after HAART selleck chemical initiation for responders and nonresponders was identical to the pattern in the primary analysis. The first sensitivity analysis, which was restricted to subjects with HAART initiation CD4 counts <100 cells/μL, revealed qualitatively higher all-cause hospitalization rates than the primary analysis (responders' rates ranged from 50.3 to 137.9/100 PY and nonresponders' from

77.7 to 166.7/100 PY). The other two sensitivity analyses consisted of (1) defining virological response by a ≥2 log10 copies/mL drop in HIV-1 RNA at 6 months, and (2) excluding all subjects (13% of responders and 34% of nonresponders) who would have been censored for HAART regimen change. All-cause hospitalization rates in both of these sensitivity analyses were similar to rates in the primary analysis. The subgroup Screening Library chemical structure (44%) of subjects reporting IDU as an HIV risk factor had qualitatively higher all-cause hospitalization rates than the full cohort, with responders ranging also from 55.4 to 99.7/100 PY and nonresponders from 82.4 to 116.5/100 PY. Our study makes several important findings. First, the hospitalization rate of virological responders appeared stable at near the pre-HAART initiation rate for 45 days and then fell substantially before reaching a plateau after 90 days. This pattern of relative rates remained similar in a multivariate model adjusting for baseline CD4 cell count, CD4 cell

count response to HAART, and other potential confounders. Hospitalization rates for ADIs and non-AIDS-defining infections appeared to be the primary reasons for the overall change between 45 and 90 days after HAART initiation. The overall hospitalization rate, regardless of HAART use or nonuse, for patients in our urban clinical cohort during the years covered by this analysis was approximately 44/100 PY (data not shown). The hospitalization rate of virological responders reached a comparable level around 90 days after HAART initiation. For persons who achieve and maintain complete virological suppression, it is possible that the hospitalization rate would be appreciably lower. Notably, 44/100 PY is consistent with rates seen in several other cohort studies in which all-cause hospitalization rates since 1997 ranged from 11 to 49/100 PY [1,6,8,10,26]. Our high rate may be due to our relatively large proportion of IDUs [6]. In a Vancouver cohort, Fielden et al.