Charted-time clock reconstruction¶

The absolute clock time of every event can be recovered from the admission date, which makes minute-of-hour distributions possible despite de-identification.

Background¶

• All times are in seconds relative to case start, the recording start set to 0 for de-identification. Absolute clock times are removed.
• Admission is stored as a date, so its value is the time from midnight to recording start. That gives the clock time of recording start, and from it the clock time of every event.

Data¶

• clinical_data.csv: 6,375 cases with valid admission dates.

Method¶

• Checked that −adm is a whole number of minutes from midnight to recording start.
• Checked where reconstructed recording starts fall in the day, and whether charted events land on 5-minute clock marks.

Results¶

• −adm is a whole number of minutes in 6,373 of 6,375 cases. The exceptions, case 1342 and case 5723, are flagged clock_uncertain.
• Reconstructed recording starts cluster at 07:00–07:59 (1,634 cases) and run through the working day: 07:40 to 18:53 (5th–95th percentile), median 11:33.
• Op start falls on a 5-minute clock mark in 92% of cases, op end in 91% and anaesthesia end in 95%; anaesthesia start in only 52%.

Discussion¶

• The reconstruction holds, so the charted event times can be modelled on clock minutes as in the digit-preferencing manuscript.
• The API needs the case's admission date and recording start or end to place a charted time on the clock.

The same question from the timing side: Recovering the time of day.

Limitations¶

• Admission and discharge are whole minutes from recording start, but only 1.5% are whole minutes from op start. They seem to have been computed from a recording start truncated to the minute.
• 93 charted times (92 op ends, 1 op start) do not share the sub-minute offset of the other charted times in their case, and are flagged clock_offset_mismatch.

Tags: from the resolution work