The number of days is calculated by subtracting the Elective care waiting list episode—listing date for care, DDMMYYYY from the Elective surgery waiting list episode—waiting list removal date, DDMMYYYY, minus any days when the patient was 'not ready for surgery', and also minus any days the patient was waiting with a less urgent clinical urgency category than their clinical urgency category at removal.

Days when the patient was 'not ready for surgery' is calculated by subtracting the date(s) the person was recorded as 'not ready for surgery' from the date(s) the person was subsequently recorded as again being 'ready for surgery'.

If, at any time since being added to the waiting list for the elective surgical procedure, the patient has had a less urgent clinical urgency category than the category at removal, then the number of days waited at the less urgent Elective surgery waiting list episode—clinical urgency, code N category should be subtracted from the total number of days waited.

In cases where there has been only one category reassignment (i.e. to the more urgent category attached to the patient at removal) the number of days at the less urgent clinical urgency category should be calculated by subtracting the Elective care waiting list episode—listing date for care, DDMMYYYY from the Elective care waiting list episode—category reassignment date, DDMMYYYY. If the patient's clinical urgency was reclassified more than once, days spent in each period of less urgent clinical urgency than the one applying at removal should be calculated by subtracting one category reassignment date from the subsequent category reassignment date, and then adding the days together.

When a patient is admitted from an elective surgery waiting list but the surgery is cancelled and the patient remains on or is placed back on the waiting list within the same hospital, the time waited on the list should continue.

Therefore at the removal date, the patient's waiting time includes the number of days waited on an elective surgery waiting list, both before and after any cancelled surgery admission. The time waited before the cancelled surgery should be counted as part of the total time waited by the patient.

Elective surgery waiting times data collections include measures of waiting times at removal and at designated census dates. This metadata item is used to measure waiting times at removal whereas the metadata item Elective surgery waiting  list—waiting time (at a census date), total days N[NNN] measures waiting times at a designated census date.

The calculation of waiting times for patients who are transferred from an elective surgery waiting list managed by one public acute hospital to another will be investigated in the future. In this case, the amount of time waited on previous lists would follow the patient to the next. Therefore when the patient is removed from the waiting list (for admission or other reason), their waiting time would include the total number of days on all lists (less days 'not ready for surgery' and days in lower urgency categories).

This is a critical elective surgery waiting times metadata item. It is used to determine whether patients were overdue. It is used to assist doctors and patients in making decisions about hospital referral, to assist in the planning and management of hospitals and in health care related research.