Back in July 2022, when he was still Scotland's health secretary, Humza Yousaf pledged to "eradicate" the longest waits for NHS treatment. 

By the end of September 2022, there was supposed to be virtually no one left on inpatient and day case lists who had been waiting over over two years for their procedure. 

Waits in excess of one year were supposed to be gone by the end of September 2024. 

Neither of these targets has come close to being achieved, even with the £300 million waiting list fund unveiled exactly a year ago. 

EXC: One year on, just £30m of £300m wait list fund given to NHS

One of the obstacles has been delays to National Treatment Centres (NTCs) - the standalone elective hubs dedicated to carrying out planned procedures.

One of the first NTCs to open - the Highland NTC in Inverness - carried out 635 planned operations in August this year, exceeding the 457 performed at Raigmore Hospital, the region's main acute centre.

READ MORE: 

Overall, the number of planned procedures completed by NHS Highland was up by 31% year-on-year.

This demonstrates just how big a difference it can make to productivity when elective work is separated from acute sites, where planned operations can be cancelled to make way for emergency surgeries or where beds 'blocked' as a result of elderly patients waiting for social care mean there is no space for a new inpatient admission. 

Notably, Scotland's two largest health boards - NHS Greater Glasgow and Clyde and NHS Lothian, neither of which has an NTC - actually completed fewer planned operations in August this year than last year, down by 7.3% and 12% respectively.

Half the of 10 NTCs planned are currently on hold due to a squeeze on capital expenditure.

So how has NHS England slashed its backlogs?

The number of two year waits has gone from a peak of 24,424 in January 2022 to just 124 by August this year, versus 7,146 in Scotland by the end of June. 

NHS England refers more patients to private hospitals to speed up treatment - an option used comparatively rarely in Scotland.

Ken Hay, Scotland chair for the Independent Healthcare Provider Network (IHPN) - which represents the private sector - said its members "stand ready and able to support the Scottish Government in their efforts to reduce the backlog in NHS care, and are open to providing much needed outpatient, diagnostic and surgical services, free at the point of use for patients". 

But England has also made benefitted 108 NHS surgical hubs, 90 of which have been created since the pandemic.

While the overall size of waiting lists in NHS England remains high, it has succeeded in drastically reducing very long waits - including the number of people waiting over two yearsWhile the overall size of waiting lists in NHS England remains high, it has succeeded in drastically reducing very long waits - including the number of people waiting over two years (Image: PA) Some are standalone elective units - similar to the NTC model - but most are either "integrated hubs" (based within existing hospitals but physically segregated from acute areas) or "ring-fenced hubs" (theatre space and beds are set aside for their use).

In all cases, these hubs exclusively perform planned surgery, have their own pool of staff, and operate six days a week - or are working towards it.

Trusts are incentivised to ramp up activity in return for financial rewards.

Earlier this year, a report by the Health Foundation think tank found that the newly opened hubs were associated with a 22% increase in the number of "high volume low complexity" surgeries that trusts were able to carry out.

If the Scottish Government is serious about clearing the backlogs, it needs to come up with new ways to boost capacity.