Weight loss outcomes and comparison with other weight management programmes programmes

To the best of our knowledge, this research is one of very few examples of an evaluation of the effectiveness of a lifestyle intervention made by a specialist weight management programme targeting subjects who are obese with BMI ≥30 kg/m². The research findings show that the NHS GCWMS achieved a 5 kg weight loss in 30.5% of participants following the lifestyle intervention. This equates with 25.5% of participants losing 5% of their initial body weight when a LOCF analysis is used, as the mean weight was greater than 100 kg at baseline. In total, 46% of participants who completed the programme achieved at least 5 kg weight loss and 39.5% of the individuals lost 5% of their weight.

In comparison with an earlier study by Morrison et al. (2011), which evaluated the lifestyle phase of all patients referred to the GCWMS between 2004 and 2006, 13.6% of patients who opted into the programme lost at least 5 kg compared with 30.5% in the current research. 35.5% of the patients completing the programme lost at least 5 kg, compared with 46% in this study. Additionally, a previous BMJ paper by Logue et al. (2014), which evaluated the GCWMS (2008-2009) over 12 months, reported that 26% of patients who opted in and 36% of those completing the programme had lost ≥5 kg at the end of the lifestyle phase. These results are better than the results obtained in the earlier two studies;

this might be attributable to the fact that as the patient figures spanned 6 years (2008-2014) the service may have improved over time. Another reason why the results are better might be that a higher threshold for completion than that used in previous studies was used in this study. As attendance is linked with successful weight loss, higher thresholds will selectively detect participants with higher weight losses. This will not affect all the patients included in the study; however, this research included participants who attended at least 2 sessions, whereas the other two papers included all the patients who attended ≥1 session.

In comparing the current results of the GCWMS with the other tier 3 weight management programme, the following table summarises the results of the three different weight management services (GCWMS, FWMS, and SLiM):

141

In comparison with the SLiM programme in Birmingham, a total of 828 participants with BMI ≥35 kg/m² with comorbidity or ≥40 kg/m² without comorbidity were enrolled between 2009 and 2013, within SLiM over 48 months duration (Brown et al., 2015). SLiM included monthly sessions over 6 months of lifestyle interventions and behavioural modification; and those who attended all 6 sessions were defined as completers. The mean weight change in the current study for all the participants (LOCF) was 3.58 kg (95% CI: -3.6 to -3.4 kg) over 4 months duration, compared with -4.1 kg (95% CI: --3.6 to -4.6 kg) for all the SLiM participants at 6 months duration. 25.5% by the end of the lifestyle phase of the current study, and 24.9% at the end of SLiM, achieved at least 5% weight loss, and this might be due to the higher mean weight (135 kg) and BMI (49.1 kg/m²) at baseline for the SLiM patients. In cases of completion, the mean weight change was -3.7 and -5.5 kg (95%

CI: -4.9 to -6.2 kg) at 3 and 6 months duration on the SLiM programme, compared to -5.09 kg (95% CI: -5.2 to -4.9 kg) for the GCWMS patients. Moreover, 44.4% and 32.3% of SLiM patients lost ≥5 kg and ≥5% of initial weight respectively, compared with 46% and 39.5% of GCWMS participants completing the programme. The completion rate for SLiM (56%) was very similar to that for the GCWMS; patients had a higher BMI at baseline

142

(49.1 kg/m²), and hence a lower percentage weight loss. In conclusion, SLiM achieved a lesser result than the GCWMS; this might be due to the fact that SLiM comprises a lower intensity lifestyle treatment and patients with a higher BMI than GCWMS.

Additionally, in comparison with other multidisciplinary FWMS in primary care (more details about the service are given in Chapter 1, page 70), the mean weight change at 3 months duration for 218 participants was -3.6 kg and 25.2% of the participants lost at least 5% of initial weight. There are some similarities in the outcomes between this programme and the results of the current research; in addition, the patients had almost the same characteristics as the GCWMS participants. The FWMS included participants with BMI

≥30 kg/m² with co-morbidity or ≥40 kg/m²; however, it provided monthly sessions and one-year outcomes were reported. Those included in the FWMS were heavier than the participants in the GCWMS (the mean weight at baseline was 124.4 kg vs. 115.2 kg).

Some limitations can be noticed as the percentage of 5 kg weight loss was not reported, in addition, the FWMS was evaluated from the initial set up in August 2011 to August 2012, and this relatively shorter period may not reflect its ultimate effectiveness (Jennings et al., 2014).

Comparisons with other weight management service (tier 2 services) outcomes are reasonable, with caution, as tier 2 is also a lifestyle weight management programme.

However, there were differences between the methods used and the duration of the studies, in addition to the higher BMIs of the GCWMS participants. The GCWMS participants had a mean BMI of 42.2 kg/m², which is higher than the Counterweight programme (BMI 37.1 kg/m²) or the Lighten Up trials (33.9 kg/m² in Weight Watchers, 33.8 kg/m² in Slimming World, 33.4 kg/m² in Rosemary Conley and 33.1 kg/m² in GP subgroup). For instance, the Lighten Up RCT reported that the proportions of patients achieving 5% loss in body weight at one year follow-up in Weight Watchers, Slimming World, and Rosemary Conley were 31%, 21% and 26%, respectively (Jolly et al., 2011). Additionally, there were differences in the data collection procedures between the current research and the Lighten Up study, as they used patient self-reporting for final weight; and the data were from RCTs where the mean BMIs were below 38 kg/m².

A previous study that evaluated a multicomponent lifestyle modification of the Live Life Better Service in the UK, from the period April 2010 to 30 April 2013, reported that 26%

of 242 participants had lost at least 5% of their initial weight after 12 weeks duration

143

(mean weight change was -4.9 kg). However, it recruited participants with BMI ≥35 kg/m² with a comorbidity or BMI >40 kg/m², which differ from the inclusion criteria for the current research. Unfortunately, this study did not report the proportion of patients who lost 5 kg and the outcomes for the completers to allow a comparison with the current data (Wallace et al., 2016).

Another recent study evaluated a tier 2 multi-component weight management programme on referral (WMOR) that was offered through NHS South Gloucestershire in the UK from October 2008 to November 2010 (Birnie et al., 2016). This programme included a 12 week course of sessions consisting of dietary advice, physical activity, and information on behavioural change. Participants were able to access group meetings of Weight Watchers as well as receiving vouchers for a 12 week course of supervised group sessions. The mean weight change for all participants (n =559) in the study was -3.7 kg (95% CI: -3.4 to 4.1 kg). This figure is higher than the current result, as 32% of all participants and 58% of patients who completed the WMOR programme lost ≥5% of their initial weight. The participants in the WMOR programme were lighter (BMI ≥28 kg/m² and co-morbidities) than the GCWMS participants, and the definition of course completion was higher than in the current research, which may explain the difference in the percentage weight loss.

Another study (n =29,326 from 2007 to 2009) evaluated the weight change among participants referred to Weight Watchers by the NHS in the UK. 33% of all patients, and 54% of those completed the programme and attended 12 sessions at Weight Watchers over 3 months lost ≥5% initial weight (Ahern et al., 2011). This might be due to the lower average BMI of the Weight Watchers’ patients at baseline, as the average BMI in the study was 35.1 kg/m² and 42.2 kg/m² in GCWMS. Therefore, the most successful programme is Weight Watchers, possibly a result of the higher attendance levels it commands (Dixon et al., 2012). Only 36% of participants attended Slimming World completed the programme of treatment compared with 44.8% for Rosemary Conley and 56% for Weight Watchers. In contrast with GCWMS, the Weight Watchers programme not only provides group support and dietary counselling, but also offers a variety of food products that can be purchased from supermarkets. Additionally, it provides support through technological media such as smart phones and computers.

Compared with the initial experience of the application of a Counterweight programme (1,256 participants) (more information about the programme is provided in Chapter 1, page

144

68), the current research shows the mean weight loss after 16 weeks’ duration was -3.58 kg; the mean weight change in the Counterweight programmes for patients at three months (n =599) was -3.4 kg (Laws, 2004). This equates to 25.5% and 25.3% of patients losing

≥5% of their initial weight in the GCWMS and Counterweight programmes respectively.

Of the 47.6% of those completing the Counterweight programme by attending 4 out of 6 sessions, 28% had lost ≥5% of weight. However, 55.1% completed the lifestyle programme in GCWMS, and of these, 39.5% lost 5% or more of their initial weight.

Therefore, when complete cases are considered, GCWMS is more successful than Counterweight programme in achieving 5% weight loss. The possible reasons may be due to the differences in completion rate, programme and methodological approach, and may be because the GCWMS patients were more motivated than Counterweight programme patients. It is relatively easy for Counterweight patients to attend appointments in a practice provided by practice nurses, whereas the GCWMS patients generally had to travel further to attend sessions, perhaps indicating higher motivation.