Although dates in MIMIC-III are shifted for patient confidentiality purposes, is there any way to extract days of the week? This would be useful for e.g. calculating severity of admissions on Saturday/Sunday vs regular week days.
Days of the week and approximate seasonality are preserved in the date shift - see section 1.4.4 of the MIMIC II user guide for more details: http://mimic.physionet.org/archive/mimic-ii-guide.pdf (the deidentification done in MIMIC-III followed the same process, with a few improvements but no systematic differences). This means that any analysis using day of the week can simply use the anonymized dates (i.e. 2154-03-09 can be treated as a Saturday).