Twelve participants were approached for inclusion in the study, and all accepted the invitation. None dropped out or rescinded consent at a later stage. Four vascular specialist nurses, four podiatrists and four vascular surgeons from 10 of the 12 hospitals previously involved in the process mapping were interviewed (Table 1). One further interview was included, from a medical clinician involved in the assessment process of one of the surgeon-led pathways, with whom the topic guide had been piloted. The interviews lasted between 30 and 64 min. All participants were known to EA prior to the study commencement. Participants knew EA’s background as a vascular surgeon, and understood the purpose of the research. Reflection on the content of our dataset during the familiarisation process found the 13 interviews to contain adequate richness to fulfil our research aims, as per the concept of information power [20].

Four key themes were developed: vascular surgery as the poor relation; some patients are more equal than others; life in the NHS is tough; and non-surgeons can help. These will be discussed in turn, with reference to sub-themes. They are linked by one overarching theme, the need for speed (Fig. 1).

Fig. 1Theme 1: vascular surgery as the poor relation

The theme “vascular surgery as the poor relation” reflects the core idea expressed across the dataset that vascular surgery, the specialty which deals with CLTI, is an unimportant specialty in the perception of others. This was reflected in a perceived lack of awareness of CLTI, across patients, primary care clinicians and hospital management.

“I think peripheral vascular disease has always been one of those things that hasn't really been studied, particularly through medical training. It's one of the things that's touched briefly on, but not really in depth. And it's, I think it's just lack of awareness really.” Vascular specialist nurse, podiatry-led pathway.

“Patients describe things like, a bit of a scab or, I banged my toe, or, it’s a bit weepy round my nail. Me and you would describe that as gangrene. And I think that the normal, generalised population haven’t got the words to be able to articulate what’s going on with their foot, so that it equals critical limb ischaemia in the clinician’s mind.” Vascular specialist nurse, nurse-led pathway.

This unimportance was demonstrated by participants in comparison to other conditions, including cancer, stroke and heart attack.

“But I do think that, you know, you get all this education for strokes and things like that, but is it as well thought out of, like publicized in the wider public about recognizing the symptoms of CLTI, than it is, you know, these like things like stroke and heart attack and things like that.” Podiatrist, podiatry-led pathway.

CLTI was described as a challenging condition – more challenging than others, which is a sub-theme within this idea.

“I think that it's very difficult to identify critical limb ischaemia. I think that our patients are very complex. They are presenting with neuropathic pain and vascular pain, and sometimes that can be difficult to differentiate.” Podiatrist, surgeon-led pathway.

The lack of awareness of CLTI perceived by participants was deemed responsible for delays. Participants described this in the context of poor referral quality, lack of a shared language between patients, primary care clinicians and secondary care clinicians, and in engagement of management to facilitate urgent treatment pathways. Vascular surgery’s status as the poor relation was expressed as something that could be changed, with national campaigns, education and improved relationships between primary care and clinicians who assess CLTI recommended.

Sub-theme: CLTI is a challenging condition

Participants presented the difficulty of making a diagnosis of suspected CLTI in primary care was as three-fold: a challenging group of patients who suffer from this condition; characteristics of the condition itself; and the wide range of primary care clinicians who it may present to.

“I think because the symptoms of rest pain, or perceived pain in in the extremity can overlap with lots of fairly benign conditions, and therefore they probably feel a little bit nervous about referring something urgent that could be something very benign.” Surgeon, podiatry-led pathway.

“I think with CLTI, though, and the variety of symptoms you've got, you're not necessarily gonna end up with a nurse. You could end up in a GP [general practitioner], in the podiatrist, in the diabetic centre, within the nursing service because—is it pain on your foot? Is it? Is it a scab? Is it a toenail? Is it an infection? And there's so many ways that it can be badged initially, that many, many people could see it in terms of that first recognition.” Vascular specialist nurse, nurse-led pathway.

Theme 2: Some patients are more equal than others

Inequalities in the pathway from first symptom to assessment were described within three sub-themes. They were presented throughout as undesirable – it was clear that participants thought that all patients with suspected CLTI should ideally be treated equally, with no discrimination against or in favour of a specific group of patients.

“…get rid of the diabetic foot clinic and just have a lower extremity wound clinic or something. You know, the limb salvage approach where, because it's the same, it's the same pathology. It's just some arbitrary cut-off which has been put there… It probably made sense 20 years ago and it doesn't anymore. And I think that is probably the direction we should be heading.” Medical clinician, surgeon-led pathway.

Each of the three sub-themes represents a different source of inequality.

Sub-theme 1: People with diabetes vs. people without diabetes

People with diabetes were viewed by participants as receiving better care than people without diabetes, with increased awareness of symptoms in patients and primary care clinicians, the availability of alternative (better) pathways into assessment by an appropriate clinician and services for people with diabetes being prioritised with funding.

“And I don't think that's the case with diabetes, because diabetic patients, patients with diabetes have a bit more general education, because it's more of a progressive illness over time, so they get regular checks and regular education. So I think they're probably a bit more switched on about attending when they develop…” Surgeon, nurse-led pathway.

“I think because the diabetic foot service is so good, they're very keen to flag patients that we need to see. And in some ways they probably get a better service, because they've been managed, you know, from early and I think those patients have rapid access to the podiatrists anyway. So a lot of those patients will know if they get a foot wound, they fall and they come and see podiatry, and podiatry will then flag it. So I think those patients probably do quite well actually out of their service.” Surgeon, surgeon-led pathway.

There was a sense of disappointment and unfairness, that people should be treated differently due to the presence of a comorbidity.

Sub-theme 2: Hub vs. spoke

Participants saw reconfiguration of vascular services into a network model as having led to difficulties in accessing care for patients, and reconfiguration has been seen as leading to substandard care for some of the populations covered by the network.

“Sadly, I think the, one of the downsides personally in my view would be with the, sort of, centralization of services, is that we've taken away the expertise out of the spoke hospitals, and so, many people with foot problems are managed by clinicians who have no experience.” Surgeon, surgeon-led pathway.

“I think the spoke patients have more delay to being seen. And that is because in [Unit] we have, you know, four times a week CLI clinic, whereas we don't have that in any of the other spokes.” Surgeon, surgeon-led pathway.

Sub theme 3: frail vs. non-frail

Patient frailty and the presence of comorbidities were said by participants to affect options for assessment negatively, particularly those patients who required hospital transport, or those who were unable or unwilling to travel long distances. More complex assessment processes were required in these cases, which took time and led to frustration.

“Now we know that not every ambulatory patient, or not every patient with CLTI is ambulatory and equally just because the patient is bedbound with CLTI, does not mean that they shouldn't be reviewed. But we do have a massive issue with being able to get these patients into hospital because we – ED [emergency department] is not an appropriate route for them, they can't come to the surgical triage unit because they come bedbound, they're hoisted and there isn't space or staff to care for them.” Vascular specialist nurse, nurse-led pathway.

Theme 3: life in the NHS is tough

This theme comprises two sub-themes. Overall, the theme notes that services in the NHS are struggling. Clinicians felt they could not offer optimum care to patients, or perceived that other clinicians were prevented from offering optimum care by constraints external to their individual clinical practice.

“I think one of the major barriers, especially for the community nursing team is just staffing turnover. So they get, they just seem to have a massive turnover of band five and six staff that just constantly move on. Recruitment battles is a big thing, so everything becomes so much more fraught.” Podiatrist, nurse-led pathway.

The first sub-theme considers the pressure across all services. In the second sub-theme, participants noted the lack of resource present for improvement, or indeed to provide an adequate service for patients with CLTI.

Sub-theme 1: We’re all under pressure

Participants reported working in a pressurised environment in the hospital. An increased demand for vascular surgery care was described, with challenges arising from inadequate staffing, the Covid-19 pandemic and competing priorities.

“So there's an issue from a staffing point of view as well is that we've had a significant increase in the number of patients that we receive into the service, and yet our staffing and our infrastructure remains exactly the same as it was five years ago.” Vascular specialist nurse, nurse-led pathway.

Participants had an appreciation that these pressures extend into primary care and affect primary care clinicians, as well as patient access to primary care clinicians.

“And again, like, I appreciate what it's like for clinicians in the community, and the time constraints, busy clinics, patient after patient coming in.” Podiatrist, podiatry-led pathway

Sub-theme 2: lack of resource

The idea that there was a lack of resource was strongly expressed throughout the interviews. This was detailed both in terms of the capacity to assess patients and treat them once the diagnosis of CLTI had been made.

“So we're capturing the patients in the much earlier stages, but actually getting them that angioplasty, or that surgical intervention has – it’s sort of highlighted that there's a bit of a delay. And certainly our consultant diabetologist, on Friday, I said, you know, we've seen this patient, he's gonna have—he's had his duplex scan, he's gonna have an angioplasty and there was no like, great we've done that in 24 h. It was like yes, but how long is he gonna wait for an angioplasty, you know what I mean?” Vascular specialist nurse, nurse-led pathway.

Improvement in the current service was perceived to require additional resource, or lead to the worsening of care for other patients. The lack of resource for timely intervention for CLTI once assessed and diagnosed was seen as a barrier to encouraging improvements in timely referral from primary care clinicians.

Theme 4: Non-surgeons can help

The final theme communicates a potential solution to the timely assessment of patients with suspected CLTI. Participants perceived non-surgeons involved in care pathways, such as podiatrists and vascular specialist nurses, to be key facilitators of the processes in place for assessment of patients referred with suspected CLTI.

“However, podiatry are very good at triage and stuff, so if they're not sure about presentations or what exactly is going on, I know that they will see their patients regardless and pass on quickly if needed. So they are very good at picking up stuff.” Vascular specialist nurse, podiatry-led pathway.

Participants said the involvement of non-surgeons, with support from vascular surgeons, was clinically sound and more cost-effective than the use of surgeon time, as well as, in the case of vascular specialist nurses, adding holistically to patient care.

“It's probably a better use of [vascular specialist nurse’s] time rather than our time, I suspect, if you're looking at the, you know, cost benefit.” Surgeon, nurse-led pathway

“Maybe it's that patients feel more comfortable with nurses. I think it's something about the caring role that nurses do that, I think, patients feel more comfortable telling nurses things they wouldn't necessarily tell doctors.” Vascular specialist nurse, nurse-led pathway.

Participants described increased responsibility within roles as enabling clinicians to work at the top of their game – including the vascular surgeons non-surgeons were seen to be protecting from the work of assessing patients.

“I also think as well, we have to ration consultants to be where they need to be. So to me, a consultant needs to be on call. They need to be responding to the trauma bleep. Or they need to be operating because they are all the things that only a surgeon can do.” Vascular specialist nurse, nurse-led pathway.

The importance of good administration support in enabling timely assessment was also a clear idea within this theme.

Overarching theme: The need for speed

The urgency required in the management of CLTI was an overarching theme, emphasised throughout the interviews and linking all four themes described. The perceived unimportance of CLTI represents a cause of delay according to the participants, whether because patients don’t present with symptoms they put down to other causes, primary care clinicians don’t recognise the symptoms as being due to CLTI, or vascular disease not being prioritised relative to other conditions.

“So I think GPs are very aware of all the two week cancer pathways. I don't think they're aware of the CLTI world. And I think that's very difficult as to how to tap into that.” Surgeon, surgeon-led pathway.

“Again, we see evidence of this all the time where GPs haven't picked up on this. They don't realize the repercussions and people have come in with late presentations, and obviously ultimately lost limbs.” Vascular specialist nurse, podiatry-led pathway.

Participants felt that inequalities can limit the speed at which some patients are assessed, and the pressure on services and lack of resource can explain delays in recognition, assessment and management of CLTI.

“If I have a diabetic patient in the same situation, I could get them to see vascular on Thursday. So there is quite a difference between, say, diabetes and non-diabetes. And having a diabetes label, certainly, you know, things move along a lot quicker, or have more access to services quicker.” Podiatrist, nurse-led pathway.

Delays in the pathway were thought to lead to adverse outcomes, and the importance of a timely process from first symptom to assessment by an appropriate clinician was evident throughout the dataset.

“One of the things I think that should happen is that the sooner we see someone and get a diagnosis about why they have a foot problem and what we're going to do about it the better.” Medical clinician, surgeon-led pathway.

“The big delays for us, as soon as the patient gets to us, is now cross-sectional imaging. And we've got huge delays, and that's a post-Covid thing. So an urgent scan now with us will take at least 6 to 8 weeks.” Surgeon, podiatry-led pathway.