Screening CT of the brain determined by CD4 count in HIV-positive patients presenting with headache.

BACKGROUND AND
PURPOSE: Few studies have examined HIV-positive patients presenting with uncomplicated headache for clinical variables that might be predictive of those patients who would most benefit from CT. Because of the value of CD4 counts in predicting the relative risk of developing opportunistic infections and neoplasms, we assessed the diagnostic yield of screening CT in HIV-positive patients presenting with headache as sorted by CD4 count.
METHODS: We reviewed CT scan results and CD4 counts in patients presenting with headache uncomplicated by altered mental status, meningeal signs, neurologic findings, or symptoms of subarachnoid hemorrhage. For analysis, scans were considered positive or negative and were grouped according to CD4 counts of less than 200 cells/microL, 200 to 499 cells/microL, and equal to or greater than 500 cells/microL. The results were then analyzed using the chi2 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 mass lesions or white matter lesions. All cases that were positive for mass lesions or white matter lesions occurred in patients with CD4 counts less than 200 cells/microL (P = .04).
CONCLUSION: A recent CD4 count provides an important predictor variable when considering performing CT in HIV-positive patients presenting with uncomplicated headache. Performing CT of the head for patients with CD4 counts equal to or greater than 200 cells/microL is of questionable value considering the low prevalence of positive CT findings. For this select group of patients, MR imaging may be more appropriate than CT. Patients with CD4 counts less than 200 cells/microL should undergo CT because of the high prevalence of positive scans.