There are many reasons- perfectly understandable- why a GP may refuse a shared care agreement. They can decline both private and NHS. In all likelihood it has not got anything to do with questioning the validity of the diagnosis itself- it is only related the shared care agreement aspect. I think there seem to be a lot of people who do not understand what a shared care agreement actually is. It really is not “consultant said prescribe this” so GP just merrily does as they’re told, no questions asked!
A shared care agreement usually relates to a medication which is specialist initiation only, and requires specific ongoing monitoring in order for prescription to be deemed safe. The GP agrees to prescribe locally alongside specific monitoring (e.g. blood tests), but the specialist takes responsibility for initiating the prescription and deciding whether/how to continue at specific and agreed intervals, as well as an agreeing to advise should concerns arise/monitoring throw up an issue.
If a GP prescribes something, they are taking on responsibility for that, including adverse consequences. “The consultant told me to” is not going to be accepted as an excuse- it is never going to be taken as anything than a potentially mitigating factor. If a GP is not confident that the medication is safe, or they do not feel they have enough understanding of why it is recommended for that patient or perhaps don’t feel they have enough knowledge to monitor their end safely, then they are right to decline to prescribe. Similarly, if the GP feels the monitoring proposed is insufficient or unsafe in any way, then they should refuse to enter into the agreement. Equally. if they feel they cannot safely hold up their end if the agreement due to staffing or work pressures, then they must decline to take on the shared care agreement.
What can happen- not infrequently- with private care is that they are not bound by NICE or local formulary restrictions and so have more “freedom” in that sense. Some private Dr’s do go completely off-piste and that can be both a good thing (pushing boundaries, new treatments, for example) and also an absolute nightmare for other professionals. However, regardless of all of that, it is also true that GP’s are obliged to comply with all of the national and local restrictions if they are prescribing on their NHS budget. They have to justify failure to do so- especially if an expensive treatment- again “the consultant said so” will not be a sufficient justification. Similarly, prescribing “off license” is also fairly common, but again the GP is taking responsibility for this- and may not really have the expertise to say if this is a good idea one way or the other- if it is a fairly common/routinely accepted use, this is usually less of an issue. With something less usual/commonly accepted/experimental it is a completely different matter and is more likely to lead to a refusal to prescribe.
GP’s are also restricted in some cases re monitoring (blood tests in particular)- there are some things which are only available to specialists and if requested “as per consultant” will be told to get the specialist to put the request on the system and if they can’t, then it can’t be done. In our area, any mention to the lab that it is for a private consultant request and the GP will be charged in the expectation that the GP will pass that cost on to the patient. It may surprise some to know that, technically speaking, GP’s could/should charge patients for making private referrals and any correspondence/work in relation to working with the private doctor (e.g. bloods).
Finally, sometimes the private route is used as a diagnosis but then the patient thinks they can just switch over directly and GP can prescribe until then. This is not always possible- until the GP knows that there is definitely planned follow up and monitoring in place, they may well not agree to shared care. E.g. the consultant only works every third Tuesday- who do they go to outside of those times? If there is no plan in place, the GP won’t take on the shared care as it is not safe. The NHS specialist is unlikely to answer questions about a patient they don’t know anything about.
There is also an ethical issue about the consultant putting into their own NHS list- essentially queue jumping. It puts those who can’t afford a private consultation even further down the waiting list and there is a debate to be had around the fairness of that. On the other hand, it’s also understandable why a patient who has a diagnosis would want to access treatment right away.