Q&A: Hidden NHS waiting
Tackling waiting times has been seen as one of the success stories of the health service over the past decade.
But ministers have now ordered the NHS to tackle what they claim are the hidden waiting lists in England.
So what is the plan, and how will it work?
What is meant by the term a hidden wait?
Ministers are using it to describe patients who are still on the waiting list for non-urgent treatment, but have passed the magical 18-week mark. That is the deadline by which the NHS in England has to see patients.
There are nearly 250,000 patients in this position, over 100,000 of whom have waited more than six months with 20,000 of them waiting over a year.
Ministers argue that once a person has waited longer than 18 weeks there is little incentive to treat them.
The official data supports this to some degree.
Once the 18-week mark is passed the numbers being treated drops five-fold.
There are also a group of nearly 30 trusts which have backlogs that are above the acceptable levels, but are still meeting their targets.
One interpretation of this is that the trusts are fiddling the system by choosing to see shorter waiters so they can main a good performance record.
However the trusts deny this, with many saying the long-waiters are not real patients but data errors.
What is the government doing about it?
In simple terms, they have asked the NHS to tackle the backlog of long waiters.
They are doing this by introducing what is effectively a new target aimed at the waiting lists.
The two key targets by which hospitals are currently judged by measure when patients are seen. If you are not seen - and therefore still on a waiting list - you do not count.
From April, that will change. Senior NHS officials will be judging hospitals on how long patients have been on their waiting lists as well. The hope is that this will mean some of the backlog will be cleared.
If the NHS achieves the target, about 50,000 of the 250,000 long-waiters will be seen.
Is this a new problem?
No. The backlog of long-waiters has remained fairly constant since the spring of 2009. Before that it was much worse.
For example at the start of 2008 there were more than 400,000 patients who had waited for more than a year. For the past two years, it has mainly hovered between 15,000 and 20,000.
Going further back it was even worse, with two year waits not uncommon.
These really long waits were brought under control by Labour's targets, but despite the fanfare surrounding their success there has always been a rump of long waiters that never went away.
And while it is not getting worse, there are signs pressure is building in the system and the fear - in both government and NHS circles - was that a bad winter could prove a turning point.
By ordering the health service to tackle this backlog, ministers are making it clear that this must not happen.
Will it work?
The NHS sees about 1.2m patients a month and has a fairly constant waiting list of about 2.6m. So targeting 50,000 of these does not sound that much.
But that ignores the fact that the health service is already struggling to keep its head above water.
While the budget is being protected, the health service is still facing arguably its toughest funding settlement ever.
At the same time, it is under pressure to maintain the old waiting time target.
The prime minister himself made it clear this would not be allowed to slip during the summer when he was under attack about the government's reform programme.
It is hitting the target, but only just. And now it is facing another one. Some predict it could be a bridge too far.
There is also some surprise at how it is being done.
Ministers accept some long waits are justifiable. Patients may wait longer for treatment because they have to lose weight before under going surgery or it could be through choice because of their personal circumstances.
For example, teachers are known to put off minor operations until the long summer holidays.
As a result, the government is not demanding the entire 250,000 backlog is eradicated.
The NHS has been given some wriggle room, but that means some of what the government believes are unacceptable long waits may still not be tackled.
Experts have argued it would have been better to introduce a maximum waiting time to complement the minimum one.
That would mean that some of the long waits being seen would be pushed down.