Incidence of HL and NHL by CD4 count at AIDS onset. (A) HL compared to NHL on the same scale. (B) Comparison of linear with quadratic model for HL. Linear models fit the observed data well and showed significant trends with CD4 counts (P = .002 for HL; P < .001 for NHL). A model including a quadratic term fit the HL data better than a linear model alone (P = .053).