Approach: In the study described above, we will assess neuropsychological outcome among survivors at 180 days. Neuropsychological testing will use validated instruments across five cognitive domains (attention, Wechsler Adult Intelligence Scale-IV-digit span; (2) reasoning, Wechsler Adult Intelligence Scale-IV-similarities; (3) immediate and delayed memory, Wechsler Memory Scale-III-logical memory I and II; (4) verbal fluency, Controlled Oral Word Association Test; and (5) executive functioning, Hayling Sentence Completion Test). Among survivors, we will compare the 180-day neuropsychological measures (composite z-scores for each cognitive domain) between the same two groups using t-test or Mann-Whitney U as appropriate with corrections for multiple comparisons. We will also compare the proportions of patients able to return to work between the two groups using binomial test