- What data does the MIMIC II database contain and how can I access them?
- How was the SAPS-I score calculated?
- Why do I keep getting 'certificate' errors?
- Is this all the data concerning a patient?
- Did you remove any patients?
- How and why were dates changed?
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What data does the MIMIC II database contain and how can I access them?
Descriptions of the data categories for both the Clinical and Waveform databases, as well as how to access them, can be found at the Clinical Database Overview and Waveform Database Overview pages.
How was the SAPS-I score calculated?
The SAPS-I score was calculated using the method outlined in this publication: Le Gall J-R, Loirat P, et al. A simplified acute physiology score for ICU patients. Crit Care Med. 1984; 12: 975-977.
Why do I keep getting 'certificate' errors?
All of our secure web pages are signed using SSL certificates. Install our certificate authority to remove these warnings.
Is this all the data concerning a patient?
No, not all data fall into a hospital or ICU stay. MIMIC II data are primarily restricted to the ICU stay, although laboratory results are continuous throughout the hospital stay, and the hospital discharge summary applies to the entire hospital stay. In addition, patients represented in the MIMIC II Database are likely to have a medical history before and after the six-year time period of our data collection. Patients also may be transferred to other hospitals for which MIMIC II contains no data.
The MIMIC II Database does contain all of the non-PHI data available to us for the patients represented in it, however. Occasionally additional information on these patients becomes available to us; in such cases, that information is added to the database.
Did you remove any patients?
Yes. We removed all VIPs (hospital-designated individuals deemed to be of increased public interest, i.e. celebrities).
How and why were dates changed?
Both dates of birth and of hospital visits are protected health information (PHI). The time intervals between events in a patient's record are very important elements of the MIMIC II Database, however, so we have replaced original dates with surrogate dates.
To avoid altering the time intervals between events, we chose a random number of weeks to add to all dates in a given patient's records. A patient who was admitted more than once to any ICU in the study group during the study period is represented by more than one MIMIC II Waveform Database record, but all of that patient's records have been date-shifted by the same number of weeks. The shifts are always an exact number of weeks, so that features of the record that may be affected by the weekday can be studied. In addition, the number of weeks is generally close to a multiple of 52, so that seasonal effects can also be studied.
Shifts applied to different patients are generally different, however. This has two significant implications for the use of the MIMIC II Database. First, it is not possible from the shifted dates to identify groups of patients who were in the ICU at the same time; and second, it is not possible from the shifted dates to separate groups of patients who were in the ICU before or after a given date.
Ages of patients who are more than 89 years old are also PHI (except that all such patients may be described as a single group aged "90 or more"). In the MIMIC II Clinical Database, the age of all such patients is represented as 200.