Results of the multiple proportional hazards regression analysis performed (end-point: grade III LFTs elevation) in experienced patient group. Circles represent hazard ratio; orizontal lines represent 95% confidence interval. The following abbreviations were used: IFN = interferon; LFT = liver function test; ALT = alanine amino-transferase, AST = aspartate amino-transferase; DDX = dideoxynucleoside reverse transcriptase inhibitors (i.e., didanosine, stavudine, zalcitabine); PI = protease inhibitor; NNRTI = non nucleoside reverse transcriptase inhibitor. Initial models have been run using variables whose data were available for all patients. Results for these variables are reported in the present figure. Further separate models have been performed imputing variables whose data were not available in some patients, however predictive values of variables whose data set was complete did not differ from those obtained through the initial models performed.