By multivariate analysis , higher peak on-treatment bilirubin levels were found to be associated with the UGT1A1 rs887829 T allele ( P = 6.410 ( -12 ) ) , higher baseline hemoglobin levels ( P = 4.910 ( -13 ) ) , higher baseline bilirubin levels ( P = 6.710 ( -12 ) ) , and slower plasma atazanavir clearance ( P = 8.610 ( -11 ) ) .