In the on-treatment analysis , the median ( interquartile range ) increase in the CD4 count after 48 weeks was +193 ( 129-349 ) cells per microliter in the efavirenz arm , +197 ( 146-238 ) cells per microliter in the ritonavir-boosted atazanavir arm , and +205 ( 178-327 ) cells per microliter in the ritonavir-boosted lopinavir arm ( P = 0.73 ) .