Unravelling the potential of social prescribing in individual-level type 2 diabetes prevention: a mixed-methods realist evaluation | BMC Medicine

The extent to which SP succeeded in reaching high-risk people (quantitative findings) and the mechanisms by (and contexts in) which this was achieved (qualitative findings) are explained below.

Referral and non-referral to social prescribing in a population at high risk of type 2 diabetes: quantitative findings

A total of 447,360 people eligible for SP were enrolled between December 2016 and February 2022. Over a median follow-up period of 4.5 years, 15,450 referrals into SP were observed (1,604,194 person-years). As shown in Table 1, people referred into SP were more likely to be female (RR 1.74 (95% CI 1.68–1.80)), socio-economically deprived (RR 2.18 (95% CI 1.97–2.40)), black (RR 2.02 (95% CI 1.90–2.15)), South Asian (RR 2.27 (95% CI 2.18–2.36)) or Arab (RR 2.54 (95% CI 2.07–3.13)) than the general population eligible for the service. Those at high risk of T2D were four times more likely to be referred to SP (RR 4.31 (95% CI 4.17–4.46)), with adjustment for socio-demographic variables attenuating the association (RR 1.33 (95% CI 1.27–1.39)). Similarly, people living with long-term conditions (including cardiovascular diseases (RR 4.67 (95% CI 4.35–5.01)), obesity (RR 3.15 (95% CI 3.05–3.26)), mental health conditions (RR 4.70 (95% CI 4.54–4.85))) and multimorbidity (RR 5.53 (95% CI 5.35–5.71)) were at higher risk of SP referral, which also attenuated with adjustment for socio-demographic variables (see Fig. 2 and Additional file 1: Table S2).

Of the total population eligible for SP, 9.2% (41,378) were identified as high risk of T2D and were, therefore, included in cohort study 2. The median follow-up period for these high T2D risk individuals was 5.2 years, which resulted in 5226 referrals into SP (164,614 person-years). The pattern of findings for high-risk patients was similar to the general population. As shown in Table 2, those referred into SP were more likely to be female (RR 1.54 (95% CI 1.46–1.64)), socio-economically deprived (RR 1.83 (95% CI 1.53–2.19)) and South Asian (RR 1.16 (95% CI 1.08–1.25)). Similarly, living with cardiovascular disease (RR 1.43 (95% CI 1.31–1.55)), obesity (RR 1.30 (95% CI 1.23–1.37)), mental health conditions (RR 2.31 (95% CI 2.18–2.45)) or multimorbidity (RR 1.98 (95% CI 1.88–2.10)) significantly increased the risk of being referred into SP. Adjustment for confounders, however, resulted in a lower attenuation, suggesting greater homogeneity in terms of socio-demographic features across this high-risk sample (see Fig. 3 and Additional file 1: Table S3). In all cases, the referral rate was higher at older ages and during the first year of service roll-out (December 2016–December 2017) (Additional file 1: Tables S4 and S5).

Distribution of clinical features and their association with referral into SP among people at high risk of T2D, cohort study 2. Legend: See Additional File 1: Table S3 for information on the variables included in each adjusted model

Sixty-seven per cent (27,928) of people at high risk of T2D met the eligibility criteria for NDPP and were, therefore, included in our cross-sectional study. Of these people, 11% (3015) had been referred to SP, 10% (2899) to NDPP and 2% (518) to both services. As shown in Table 3, patients referred into SP were significantly more likely to be female (OR 1.99 (95% CI 1.78–2.24)) and socio-economically deprived (OR 2.12 (95% CI 1.56–2.88)) than those referred into NDPP, but less likely to be South Asian (OR 0.48 (95% CI 0.41–0.56)), black (OR 0.46 (95% CI 0.37–0.56)) or Chinese (OR 0.14 (0.07–0.27)). Supporting the findings from previous cohort studies, people diagnosed with mental health conditions (OR 3.25 (95% CI 2.86–3.69)) or multimorbidity (OR 1.80 (95% CI 1.63–2.00)) were also more likely to be referred into SP. Adjustments for relevant variables did not alter the results substantially (Fig. 4 and Additional file 1: Table S6).

Distribution of clinical features and their association with referral into SP amongst people eligible for NDPP, cross-sectional study. Legend: See Additional File 1: Table S6 for information on the variables included in each adjusted model

How did social prescribing contribute to meeting the complex health and social needs of people at high risk of type 2 diabetes? Qualitative findings

We identified the following four mechanisms through which SP operated to reach high-risk patients with greatest health and social need.

Accessible social prescribing: type 2 diabetes prevention as an inclusive and proactive care process

Unlike NDPP, SP had broad eligibility criteria (any patient 18+ and registered with a local GP could be invited). Lack of requirements for tests or medical assessments prior to a referral made the service easier to consider by referrers during routine consultations: “there’s no restrictions. We don’t have like; your blood pressure has to be this. Your weight has to be this. We can just refer” [Nurse 01.8]. Although patients were not necessarily referred based on their T2D risk, they often ended up accessing services relevant to its prevention: “[…] he was pre-diabetic and he was very, very overweight, which wouldn’t surprise me because often these conditions go together. Through [name of physical activity programme] and the support he got, he lost a lot of weight. His sugar levels were much more normal, things like that. I think that’s a good example of where he wasn’t actually there for the diabetes side but actually it really helped him more generally” [VCS 03.9].

Our study also revealed that patients often lacked confidence and felt guilty or helpless to reach out and access the services they required. As expressed by a patient referred into SP: “I know how to contact her [the link worker] but you know, […] I don’t want to feel that you know – I feel a bit guilty really that I didn’t follow up on a lot of the information that she gave me” [SPU 04.1]. Additional support was often needed to help them navigate (and reach) SP. Strategies included scheduling regular follow-ups with link workers, filling in referral forms in primary care (instead of signposting or encouraging self-referrals) or creating friendly and welcoming environments in the VCS with the help of volunteers, buddy systems and/or information packages, amongst others. However, the relationship between the provision of support and patients’ access or engagement was non-linear and hence unpredictable. Patients often failed to respond, did not turn up to sessions or refused to carry on despite these supportive environments. Making services accessible in such situations often relied on providers’ capacity (and willingness) to be tenacious and attentive: “She persevered, even though there would have been times when I did not pick up that phone and I did not want to talk to [name of link worker] or anyone. Yet again she would try and she would always inform me that ‘I could not get hold of you today, I will try in another five or six days’ time’ and she always kept her promise” [SPU 04.3]. Accessibility was no longer a static service attribute, but rather a proactive (creative and ongoing) process through which providers tried to overcome existing barriers and find ways to bring services closer to the patient.

Holistic social prescribing: type 2 diabetes prevention as a dynamic and personalised practice

Providers throughout the SP referral pathway proactively explored patients’ wider socio-economic circumstances in search of concerns influencing their wellbeing and clinical presentations. Open conversations led to diverse courses of action, depending on the identified priorities. This broadened the scope and understanding of T2D prevention beyond lifestyle recommendations to also include services related to employment, housing or welfare advice, amongst others: “It’s not just about ‘I want to change my diet’, it will be looking at the barriers to them changing the diet. We might refer for the diet and exercise classes, but we’ll also refer to English classes and things like that” [Nurse 01.8]. Providers tried to widen and diversify their service remit to better accommodate patients’ multiple, intertwined needs (e.g. by providing in-house legal advice alongside physical activity programmes, up-skilling link workers on relevant domains (such as health coaching, welfare advice) or even bringing welfare advisors and lifestyle programmes into GP practices): “for example on a Thursday it’d be the advisor here and the receptionist would say, come and see the advisor in the surgery at that time. They’d make an appointment with them in the same way you’d make an appointment with the nurse. That’s excellent service” [VCS 03.9].

Instead of adhering to established, pre-defined ways of working, we identified joint attempts to work around patients’ complex life circumstances and adapt services accordingly. This involved prioritising patients’ context and the provision of support over the specific content and consistency of lifestyle recommendations: “It’s not specifically saying, this is what you must do for cholesterol. This is what you must do for diabetes. Very often the advice is the same anyway. […] the issue is not about the actual specific condition, it’s more about getting that peer support to help that person manage whatever’s going on for them in their life” [VCS 03.9]. Some patients needed “taking” (“I took patients on walking groups […], just so that they go. […] I’ve taken a patient to an ESOL class because she didn’t want to go alone. So, I just took her to the first one” [LW 02.5]), while others needed to be listened to (“Sometimes also we receive referrals where they do not want any help; all they want is someone to listen to them” [LW 02.8]) or somebody to whom they could feel accountable (“I just needed somebody in a way to whom I could be answerable, if that sounds strange” [SPU 04.4]). Some patients preferred medicalised preventative approaches (where information about disease risk and anthropometric measurements were considered), while others responded better to “subtle” (opportunistic) lifestyle recommendations or regular follow-ups by health care assistants in primary care (instead of being referred into community-based lifestyle programmes).

Sustained social prescribing: type 2 diabetes prevention as an ongoing and unpredictable struggle

Patients reported that their capacity to follow a “healthy” lifestyle fluctuated over time, highly conditioned by the amount and consistency of support they received. Many patients had tried different weight management or physical activity programmes, managed to lose weight while being supported and then relapsed as the intensity of interventions decreased. Critically, the lack of a long-lasting response was interpreted by patients as a personal failure rather than a deficiency of the services in place or a consequence of underlying structural constraints (e.g. poverty, food insecurity, obesogenic environments, etc.): “when I did the [name of weight management programme] I’d gone down to 97kgs and that’s the best I ever did in my entire life. In the entire 35 years of my life that was the best I’d done and I felt great and I was a good size 18 and I was so happy. Then within stopping that programme because it’s again, for me, I think I lack and I don’t think it’s the services, for me I start something but […] I never sustain that, I never maintain anything. So, […] within a year I put all that back on plus more. So, it’s been very difficult” [SPU 04.3].

Regular services, conversely, allowed for the provision of ongoing support. Patients could build on previous work and share the burden of (and, hence, better cope with) critical social and health constraints: “I just felt a little bit better that I’m not dealing with this on my own” [SPU 04.3]. Continuity of care allowed providers to monitor patients’ progress (or lack thereof) and adapt their approach and next steps accordingly. “Testing and trying” involved making the erratic nature of prevention, as well as the limitations of existing interventions explicit beforehand. Knowing that interventions could fail, be insufficient or inappropriate prevented unrealistic expectations and shifted the responsibility of any potential failure from the individual to the intervention: “So, I think what the prescriber was saying was ‘my resources are limited and you could go to this walk-in therapy and hate it and that’s okay, you’d come back and tell me’. But I think so often people are referred to a social prescriber and they take up one offer and that doesn’t work and so they think nothing will work” [SPU 04.4].

Ongoing services allowed for the development of meaningful (“therapeutic”, “trustful”) relationships with patients, across sectors and amongst attendees in group sessions: “a lot of people have been coming for 10 plus years, so they’ve built up these really good bonds with each other. So, not only are we looking out for them but they’re looking out for each other” [R1 VCS 03.2]. Patients were made aware that “there [was] somebody there for them” [LW 02.5], which proved reassuring and had therapeutic effects by itself: “just knowing that there’s people available for us” [SPU 04.2]. It counteracted feelings of helplessness and mistrust towards a system that had previously let them down (“if [the service] stops it’s like, ‘oh they’re the same as everyone’.” [VCS 03.8]) and provided some stability within a context of great service and staff turnover (both within the health sector and the VCS): “with many services in the community coming and going, […] even in the NHS as well, programmes with different names each year, I think there’s real benefit in having someone stable, by having a known person in a GP surgery that they can come to whenever there is a change in their life situation because that often provides that window of opportunity to really change something” [LW 02.2].

Integrated social prescribing: type 2 diabetes prevention as a locally embedded and joint endeavour

Bidirectional communication across sectors and among professionals allowed providers to develop greater knowledge on patients’ needs, “build on other’s work” and deliver consistent care. Clinicians became increasingly aware of patients’ “underlying story” and able to adapt care practices accordingly because of the information that link workers had shared: “I quickly realised how much the GPs are really struggling to know what the story is behind the medical record and […] just by sharing a few lines, […] ‘well actually this person had an accident last year or lost their job’, just very simple things that make us able to humanise people and their choices” [LW 02.2]. Patients’ medical notes provided link workers with “a two-sided approach” and relevant “context” (“background information”) over which they could build their assessment and recommendations. Similarly, VCS organisations often received key information with or prior to a referral on how best to support a patient by avoiding specific “triggers” that had already been disclosed. Communication channels across and within sectors were also used to flag those patients requiring closer, urgent attention (“Usually, they give us one- or two-lines feedback […] There’s also something on the records […] and, for very specific people that I’m maybe a bit more worried about, I may just ask them to let me know what has happened” [GP 01.1]) and/or reach out if they had not been contacted. Service providers became effective advocates by ensuring patients were not left behind and received the support they required: “When I felt depressed about my weight and not getting any contact from the weight management programme, [name of link worker] was right on it sending emails and making telephone calls, whilst I was on the phone by the way, and getting in touch with them and saying ‘look, I’ve got a patient here named… she’s waited for that number of weeks, why has nothing come through?’ So, I felt like the support was first-hand” [SPU 04.1].

Integration (and embeddedness) within the local community and primary care system also enhanced the scope and responsiveness of services. Patients at risk of T2D ended up accessing physical activity programmes that would have been difficult to locate had it not been for the SP network (“any kind of exercise programmes that we have running or any health sessions we try and send out to the GPs and that’s where a lot of our referrals came from” [VCS 03.2]). Link workers informed the design of VCS activities (e.g. lifestyle programmes, physical activity sessions) by sharing relevant information on identified needs and facilitated their development in local GP practices: “we would often run services at GP surgeries to increase accessibility. For example, [name of GP practice] has a room, we’d meet in there” [VCS 03.9]. Clinicians and link workers often worked together (and learnt from each other) to support patients with complex needs: “if you’re having any difficult patients, challenging, you can bounce off or you can say, ‘How are you dealing with that patient?’ Maybe in a different way and you see whether you can make sense of it or not” [LW 02.4]. This not only led to greater service appropriateness but also strengthened the local community by creating new partnerships and opportunities: “there’s an opportunity here for us to develop physical and social activities together. So it’s about doing things together and one of the – we use local residents who’ve become qualified instructors, we try to keep everything local” [VCS 03.8].

Synthesis: primary care-based social prescribing as a means for successful individual-level type 2 diabetes prevention

Figure 5 brings together quantitative and qualitative findings by illustrating why and how primary care-based SP contributed to individual-level T2D prevention approaches relevant to patients in greatest social and health need. The four dimensions (represented as four horizontal lines in Fig. 5) summarise our final CMOCs, which are described in more detail in Additional file 3: Fig. S1.

Synthesis of study findings. How SP operates to deliver T2D prevention

Highly supportive (proactive, welcoming) environments and broad (inclusive) referral criteria made SP easier to access than NDPP by high T2D risk individuals in greatest health and social need (CMOC1). Holistic practices involved gaining understanding of these underlying health and social constraints (including what they meant for people at high risk) and providing tailored care and services accordingly. This was often achieved by holding broad conversations with patients and widening the scope and remit of available services (CMOC2). Following a “healthy” lifestyle proved highly demanding for patients at high risk (especially insofar as underlying drivers persisted) and hence benefitted from sustained (ongoing and open-ended) support by known and trustful service providers (CMOC3). Our quantitative data also clearly showed that people at risk of T2D with multiple physical and mental health morbidities were more likely to be referred to SP than NDPP and our qualitative data suggests that this likely reflects the integrated delivery of SP including cross-referrals, connected and seamless care within primary care and across sectors (CMOC4).

The identified mechanisms were interconnected and mutually dependent, meaning that they only became possible (and led to significant outcomes) as the rest of the dimensions co-existed. Holistic practices, for instance, were more than a set of questions asked in one consultation prior to a referral. They came about only over time (through sustained practice) as providers got acquainted with (and gained understanding of) the local population, their community and the specific patient involved. Similarly, providers were able to deliver proactive care and make sure services were accessed only through regular follow-ups and timely feedback from other practitioners (“I know she started because the [name of VCS organisation] updated me, so she has started” [LW 02.11]). Integrated SP facilitated a greater understanding of patients’ circumstances, enhanced service responsiveness and allowed to address their needs holistically. Yet, far from representing a static structural dimension, it relied on trustful interpersonal relations across providers and hence required time (sustained encounters) to be developed: “I’ve built such a good relationship with [VCS organisations], and it’s because you’ve been doing it for so long, you get to know people on the team as well because you’re backwards and forwards with emails” [LW 02.5].