Operations cancelled due to non-clinical/capacity reasons are an indicator of performance by NHS Scotland. Operations cancelled by patients themselves of for a clinical reason by doctors tend to remain constant and are, of course, not due to, for example, any shortages in beds, operating theatres or of staff. The former, always a small percentage of overall planned operations, less than 5% at a peak time, and typically less than 2%, have been falling for the last three months.
https://thoughtcontrolscotland.com/2018/11/07/fewer-operations-cancelled-in-nhs-scotland-again-with-only-1-6-due-to-lack-of-resources/