Screening CT of the brain determined by CD4 count in HIV-positive patientspresenting with headache

BACKGROUND AND PURPOSE: Few studies have examined HIV-positive patients pre senting with uncomplicated headache for clinical variables that might be pr edictive of those patients who would most benefit from CT. Because of the v alue of CD4 counts in predicting the relative risk of developing opportunis tic infections and neoplasms, we assessed the diagnostic yield of screening CT in HIV-positive patients presenting with headache as sorted by CD4 coun t. METHODS: We reviewed CT scan results and CD4 counts in patients presenting with headache uncomplicated by altered mental status, meningeal signs, neur ologic findings, or symptoms of subarachnoid hemorrhage, For analysis, scan s were considered positive or negative and were grouped according to CD4 co unts of less than 200 cells/mu L, 200 to 499 cells/mu L, and equal to or gr eater than 500 cells/mu L. The results were then analyzed using the chi(2) test. RESULTS: One hundred seventy-eight HIV-positive patients underwent a total of 204 unenhanced and contrast-enhanced CT examinations. One hundred twenty -eight (62.7%) of the scans were negative, and 76 (37.3%) were positive. Of the positive scans, 58 (76.3%) showed atrophy only and 18 (23.7%) showed m ass lesions or white matter lesions. All cases that were positive for mass lesions or white matter lesions occurred in patients with CD4 counts less t han 200 cells/mu L (P = .04), CONCLUSION: A recent CD4 count provides an important predictor variable whe n considering performing CT in HIV-positive patients presenting with uncomp licated headache. Performing CT of the head for patients with CD4 counts eq ual to or greater than 200 cells/mu L is of questionable value considering the low prevalence of positive CT findings. For this select group of patien ts, MR imaging may be more appropriate than CT. Patients with CD4 counts le ss than 200 cells/mu L should undergo CT because of the high prevalence of positive scans.