Figure 1
From: Lung cancer in the Swiss HIV Cohort Study: role of smoking, immunodeficiency and pulmonary infection
Box plotsa of CD4+ cell counts at yearly intervals prior to reference dateb, among lung cancer cases and controls. aHorizontal lines in box plots represent 10th, 25th, 50th (median), 75th and 90th (percentiles). bSee Materials and Methods section for definition of reference date.
