Similarly, individuals entering the Strategies for the Management of Antiretroviral Therapy (SMART) study who were either treatment-naive or who had not been on therapy for the previous 6 months, and who deferred treatment until their CD4 cell count was below 250 cells/mm3 had a more than 4 fold higher risk of opportunistic infections and serious non-AIDS clinical events compared to patients who started treatment with CD4 cell count above 350 cells/mm3[3]. Here, CD4 is linked to Opportunistic infection.