Regarding laboratorial data, the following are the different characteristics between cases and controls: lymphopenia before first HAART (p = 0.026) and before the current HAART (p = 0.007), CD4 count prior to the first HAART (p = 0.001) and before the current HAART (p < 0.001), nadir CD4 count (the lowest CD4-count ever presented by patient during outpatient follow-up) (p < 0.001), time of undetectable HIVVL (p < 0.001) and time of HIVVL below 1 000 copies/ml (p < 0.001). Here, CD4 is linked to lymphopenia.