In a multivariate linear regression model of covariates associated with CD4 count recovery , time on highly active antiretroviral therapy ( ART ) ( P < 0.0001 ) , patient satisfaction with care ( P = 0.038 ) , improvements in total lymphocyte count ( P < 0.0001 ) and haemoglobin concentration ( P = 0.05 ) were positively associated , whereas age at start of ART ( P = 0.0045 ) was negatively associated with this outcome .