The analysis will be performed by using statistical software, STATA (Texas, USA). Data will be expressed as mean±standard deviation. The multivariate analysis will be performed on the timings of vasospasm and abnormal AR, which will be computed as the number of days between the date of diagnosis of SAH and the date of the first detection of vasospasm and abnormal autoregulation in respect of variables likely to influence their occurrence: age, WFNS grade, Fisher's grade on CT scans, and treatment procedures, intraventricular haemorrhage and/or hydrocephalus by using the Cox Proportional Hazards regression. The measure of outcome will be the hazards ratio (HR), which expresses the probability of vasospasm or abnormal autoregulation for a specific category relative to the placebo group. Variables associated with EPO treatment (haematocrits, erythrocyte counts, reticulocyte counts, thrombocyte counts, serum iron levels, and viscosity) will be collected. The improvement in fit due to each variable will be tested for statistical significance at the 5% level with the likelihood ratio test. The test for departure from a linear trend (one degree of freedom) was used to assess the potential linear trend in certain categorical variables. Daily results from each patient will also be averaged to produce a patient-oriented database to satisfy the independence assumption for linear regression. The day-to-day variations in parameters will be calculated as the standard deviation divided by the average value from all examinations in each patient.