Demographic and Clinical Factors Associated with Routine Outpatient Electroencephalography (EEG) Findings at King Abdulaziz University Hospital in Jeddah, Saudi Arabia

Routine EEG is the most commonly used EEG. It is limited by its short duration and difficulty capturing sleep. To improve its yield, hyperventilation, photic stimulation, and sleep deprivation are applied. Moreover, specific factors have been found to predict abnormal findings in a few studies. We aimed to further investigate the effect of more factors on routine EEG findings. We gathered routine outpatient EEG records between 2015 and 2018 from the EEG department and reviewed the demographic and clinical data from patients' files. Patients ≥18-year-old were included. We collected demographics, the indications of EEG tests, co-morbidities, anti-epileptic medications (AEDs) use, and detailed EEG reading records. We included 503 records, 58.6% of females, with a mean age of 39 ± 17 years. Of the recorded EEG's, 41.6% were abnormal, 13.4% of them had epileptiform discharges, 88.5% slowing. Half of epileptic patients had abnormal findings, 20.9% of them who were on ≥1 AED had epileptiform discharges (p < .05). Diabetes mellitus and AED use with stroke were associated with slowing, specifically with use of one AED (p < .05). AED combinations including levetiracetam were associated with all mentioned findings (p < .05). Seizure-related indications were associated with epileptiform discharges as opposed to other indications (p < .05). Using logistic regression, stroke and use of carbamazepine were predictors of abnormal EEG, while use of ≥1 AED predicted epileptiform discharges. Stroke also predicted the abnormal slowing. To improve the yield of routine EEG, priority can be given to epileptics, diabetics with stroke, those on AEDs, and those with indications more typical of seizures or brain lesions.