Receiver Operating Characteristic (ROC) Curves Demonstrating the Discriminatory Performance of Anthropometric Measures (BMI, waist circumference, neck circumference) to Predict Significant Sleep Disordered Breathing (Respiratory Disturbance Index (RDI) ≥ 15 events/hour) in HIV-seronegative men (a), HIV-infected, HAART-treated men (b), and HIV-infected, not receiving HAART (c)