Identifying and measuring the behavioural, dietary, and physical activity components of weight management consultations delivered by general practice nurses in routine care

Obesity affects over 25% of the UK’s population and is a major preventable risk factor for morbidity and mortality [1]. In addition to affecting individuals, obesity places considerable financial strain on healthcare systems and the wider society [2].

Weight loss achieved through changes in diet and physical activity has many benefits including reducing the risk of developing type 2 diabetes, significantly reducing levels of cardiovascular risk factors, such as hypertension, and is associated with a reduction in premature mortality [3‐5]. Therefore, weight loss interventions for people with obesity are an important part of wider strategies to reduce non-communicable diseases.

The National Institute for Health and Care Excellence (NICE) recommends that primary care professionals offer behavioural weight management support to people with obesity [6]. One-to-one weight management consultations with a practice GPN are common in the primary care setting. Randomised control trials (RCTs) also frequently use ‘usual care’ interventions as a comparator setting, although the content of these sessions is often neither standardised nor recorded. It is recommended by NICE that weight management consultations should involve discussion of behavioural, dietary, and physical activity change, aiming to achieve a 600 kcal daily energy deficit [6]. This is expected to lead to a 0.5-1 kg weight loss per week [7]. Despite this, most literature finds primary care weight management consultations, including those delivered by practice GPNs, lead to minimal average weight loss, but with substantial variation [8, 9].

Improvements in outcomes may be facilitated by improvements in intervention delivery, but this requires an initial understanding of how GPNs typically conduct weight management consultations [10]. One method of characterising the content of weight management consultations is through the use of taxonomies. Taxonomies enable reporting of complex interventions by identifying ‘active ingredients’: replicable and irreducible components that make an intervention effective. They also establish a common language and can be helpful in translating effective interventions into practice [10]. Characterising the behavioural, diet and physical activity components of GPN-led weight management consultations may allow for the active ingredients of more effective routine consultations to be identified and facilitate intervention optimisation.

This study aimed to address the evidence gap in the content of nurse-led weight management consultations by characterising the behavioural, diet and physical activity components in a small group of consultations. In addition, based on evidence that greater use of behaviour change techniques (BCTs) leads to greater weight loss [11], we aimed to identify whether more intensive use of techniques and recommendations would be associated with weight loss in this study.

This was a secondary analysis of data from the Doctor Referral of Overweight People to Low Energy total diet replacement Treatment (DROPLET) trial. The DROPLET trial recruited 278 participants seeking to lose weight and with a BMI ≥ 30 kg/m². Participants were then randomly allocated to a total diet replacement programme or usual care. One hundred and forty participants were allocated to the usual care group, and of this group, 53 participants had their consultations audio-recorded. We report on data from all 53 individuals in the usual care group that had their consultations recorded to avoid introducing further selection bias.

Usual care comprised consultations with a GPN for the explicit purpose of weight loss [12]. The GPNs conducting the consultations had self-identified as confident in delivering a weight management programme. They were asked to continue consultations in their usual manner but additionally received the British Heart Foundation booklet ‘So you want to lose weight for good’ to use at their discretion. Consultations took place in general practices in the UK. Consultations from the trial were audio-recorded, and participants’ weights were recorded at baseline, 3, 6, and 12 months [12].

Characterising the use of BCTs, dietary recommendations, and physical activity recommendations in this small group of GPN-led weight management consultations showed their use to be infrequent and variable. Despite consultations lasting longer (13.8 min) than typical primary care consultations (9.2 min) [21], few recognised BCTs, dietary or physical activity recommendations were used. Only 31% of BCTs were used and although 80% of the possible dietary recommendations were used, only 3/30 recommendations were used per consultation. Only 1/10 physical activity recommendation was used per consultation. GPNs used less than one BCT or recommendation per minute of consultation, and the number of BCTs or recommendations used were not significantly associated with weight loss.

This study has several strengths. Three different taxonomies were used to comprehensively characterise the relevant consultation components. The BCT taxonomy is well established, and the existing dietary taxonomy was adapted to improve characterisation. The novel physical activity taxonomy was developed based on an existing framework, and for the first time allowed coding of physical activity recommendations. GPNs were encouraged to carry out consultations as they had routinely done in their practice without the use of a prescriptive protocol, or additional training, allowing a more realistic characterisation of consultations in everyday clinical practice. Consultations were coded blind to outcome and inter-rater agreement levels were good. Although this is a specific and selected group of GPNs leading weight management consultations, this study indicates that what happens in "usual care” may or may not be grounded in guidelines. In the future, analysis of the content of usual care groups, potentially with the methods proposed here, and more standardised reporting, could help to identify effective components and improve reproducibility.

The study also has some limitations. About a third of consultations were recorded, which may reflect reluctance on the part of the GPN to record their consultations. There were no significant differences between weight change in the groups with and without audio recordings, but it is not possible to know whether the content of the recorded consultations are representative of the whole usual care group. Out of 11 GPNs, 8 GPNs submitted recordings and data were unavailable regarding the number or length of consultations participants without audio recordings received. There was no information on whether any additional consultations occurred outside of the recorded consultations, but we consider it unlikely that a significant number of additional consultations would exist, since this is neither routine care nor was advised in the trial. Overall, the small sample size limits the generalisability of our findings. The amount or type of training each GPN had on weight management was not recorded, but we found no evidence of differences in the components of the consultations or participants’ weight loss between GPNs. Lack of formal analysis of the appropriateness and individualisation of recommendation use is also a limitation. Multiple testing might have led to increased probability for type I error, which limits our confidence in the few significant correlations identified. The observational design does not allow for casual inferences.

Previous research has found that primary care staff feel ill-equipped to help people with obesity, often reporting that they have inadequate training [22]. GPNs in this group, with previous training in weight management used only 46% of possible techniques/ recommendations on one occasion, and only 17% were used in more than 10% of consultations. Though it would not be expected for GPNs to use all BCTs and recommendations in one consultation, this low usage may reflect lack of awareness of effective weight-loss strategies. The literature suggests that increased and more adherent usage of BCTs is associated with greater weight loss [11], and the low and infrequent use of BCTs might explain the lack of association with weight loss shown here. Direct comparisons with other studies are difficult regarding dietary and physical activity recommendations as this is the first study using the taxonomies developed, but the lack of correlation between the frequency of dietary and physical activity recommendations given in consultations and weight loss may also result from low levels of use.

GPNs’ use of techniques/ recommendations was confined to a small group of specific BCTs and recommendations. The most frequently used BCT was ‘feedback on outcome of behaviour’, which has been linked to improved weight loss outcomes [23]. Reviews of weight management consultations commonly report ‘self-monitoring of behaviour’, used in almost 80% of introductory consultations, as one of the most effective BCTs to promote weight loss too [24, 25] and participants’ weight loss, though modest, was better than other UK GPN led BMWCs [8, 26]. ‘Social reward’ was the third most commonly used BCT and used significantly more in the group that lost ≥ 5% baseline weight at 6 months. NICE recommends healthcare professionals should ‘praise successes’ when offering weight management support [6] and it may be that as patients lost weight, GPNs congratulated patients. Additionally, it has been found that positive reinforcement of behaviour can be effective in other health behaviours, such as in increasing physical activity levels [27]. In terms of specific dietary recommendations, reference to ‘energy’ and ‘total energy intake’ were used in just over 15% of consultations characterised. Energy restriction is known to be a key component for weight loss [28, 29]. However, there was very limited discussion of specific energy deficits in the consultations and the lack of use in association with the BCT ‘goal setting’ could have limited weight loss here.

Specific dietary or physical activity recommendations and BCTs were used infrequently and variably in this small group of GPN-led weight management consultations. Further analysis in larger and representative samples is warranted. Future studies could usefully examine if additional training can increase the quality and effectiveness of consultations.