Twenty-year review of the bariatric programme at Te Whatu Ora Waitematā

Obesity is a common disease with a considerable burden of cost on society. The World Health Organization describes the prevalence of obesity as an epidemic. A 2021 report by Hāpai Te Hauora has found that obesity-related healthcare costs are approximately NZ$2 billion per year, which is 8% of the Aotearoa New Zealand total health budget.¹ These costs continue to climb when compared with two previous estimates—in 1997, with an estimate of $135 million or 2.5% of healthcare costs,² and 2012, with an estimate of $624 million or 4.4% of healthcare expenditure.³ Obesity contributes to a wide variety of other health issues including type 2 diabetes mellitus (T2DM), cardiovascular disease, cancer, depression and mental health disorders, and osteoarthritis. As the rate of obesity rises in Aotearoa New Zealand, the cost of orthopaedic operations such as knee joint replacements will continue to exponentially climb, increasing the pressure on an already stretched healthcare system.⁴

Bariatric surgery is the most effective treatment of morbid obesity in carefully selected patients. It can result in long-term weight loss, remission of T2DM and improved oncological, cardiovascular, respiratory, reproductive and other physical outcomes. It also results in significant improvement of quality of life outcomes.⁵ Bariatric surgery decreases long-term mortality, morbidity and the use of healthcare resources in morbidly obese patients.⁶ Despite the large body of evidence demonstrating its benefits, only around 1% of eligible patients receive bariatric surgery.⁷ Although bariatric surgery is not a solution to the obesity epidemic that we are currently facing, it has transformative individual benefits, and is an effective tool that can be used in situations where few options are available.

The bariatric service at North Shore Hospital is a publicly funded service that is available to all eligible patients in the Waitematā catchment area. The Waitematā bariatric service was introduced in October 2001, and the first open gastric bypass was performed on 31 July 2002. The patient pathway begins with an electronic referral by their general practitioner (GP). Referral criteria include: a patient with a body mass index (BMI) of 40 or more; a patient with a BMI of 35 or more with one other obesity-related disease such as cardiovascular disease, T2DM or obstructive sleep apnoea (OSA); and a history of failed weight-loss attempts. Patients must have a clear understanding of what is involved, and a commitment to a permanent lifestyle change. These criteria are based on the National Institutes of Health (NIH) Consensus guidelines.⁸ The grading surgeon prioritises the patient according to clinical need and comorbidities. Bariatric referrals are generally graded as priority three (i.e., non-urgent).

The patient is waitlisted for an educational group seminar. At this seminar the patient is introduced to the multidisciplinary team. They are given education around the surgical options and a goal weight to reach prior to being considered eligible for surgery. This weight-loss target is calculated at 10% of excess body weight above a BMI of 25kg/m². When the patient meets their goal weight, this is communicated directly with the clinical nurse specialist (CNS). The patient is booked for a first specialist appointment (FSA) with an upper gastrointestinal surgeon, where operative options are discussed, and is waitlisted for surgery.

The patient undergoes surgery, and during their inpatient stay is reviewed by the CNS and dietician. Written dietary guidelines are given to the patient on discharge. Patients are usually seen 6 weeks after surgery, and depending on the operation, may be seen twice more within 1–2 years. There is ongoing outpatient support from the dietician service if required. Care is handed back to the GP once the bariatric service is satisfied that the patient has fully recovered and has no ongoing issues with dysphagia, pain, weight regain or nutrition.

Methods

We conducted a retrospective review using electronic records to identify all patients at North Shore Hospital who had bariatric surgery performed between 1 July 2002 and 30 September 2022. Demographic data including patient age, gender, smoking status, diabetes status, American Society of Anaesthesiologists (ASA) grade and date of death (if relevant) were anonymously collected. Operative data including date and type of operation, complications, intensive care unit/high dependency unit (ICU/HDU) admission, length of stay (LOS), return to theatre or readmission were recorded. As this was a retrospective review and clinical data were acquired anonymously and confidentially, patient consent was not required.

Results

Demographics

A total of 1,536 procedures on 1,449 patients were performed at North Shore Hospital from July 2002 to September 2022. The average patient age was 45.6 years at presentation (range 19–77 years). Of the patients, 1,104 (76.2%) were female and 345 (23.8%) were male. Fifty-five (3.8%) patients were smokers, 585 (40.4%) were ex-smokers, 692 (47.8%) were never smokers and 117 (8.1%) were status unknown. In total, 335 (23.1%) patients were diabetic. Seven (0.5%) patients were ASA 1, 681 (47.0%) patients were ASA 2, 747 (51.6%) patients were ASA 3, 14 (0.9%) patients were ASA 4 and zero patients were ASA 5. There was one death within 90 days in 20 years. This occurred in the community and the cause of death was unknown.

Primary ethnicity

A total of 1,035 (71.4%) of patients identified as European, 245 (16.9%) as Māori, 90 (6.2%) as Pacific peoples, 38 (2.6%) as Middle Eastern, Latin America or African (MELAA), 37 (2.5%) as Asian and four (0.25%) as Other (Figure 1). Figure 2 demonstrates the ethnicity breakdown of bariatric patients per year. As 2020 was affected by the COVID-19 pandemic, with nation-wide lockdowns having a far-reaching impact on the healthcare system, all patient numbers fell for 2020–2022.

View Figure 1–8.

LOS during the admission listed

The average patient LOS was 3.7 days. Figure 3 demonstrates how this has decreased over time as service provision and health provider education has improved. The service has developed bariatric protocols that have enabled patients to have a consistent care plan in the post-operative phase.

Complications

Fifty-three patients (3.7%) required ICU/HDU in the peri-operative phase. The average ICU/HDU LOS in this patient group was 0.66 days. Fifty-seven patients (3.9%) required a return to theatre during their index admission. A total of 217 patients (15.0%) required readmission within 30 days. Over a 20-year follow-up, 81 (5.6%) patients died following their operation. One patient (0.07%) died within 90 days and five further patients (0.35%) died within a year of their operation. The causes of death for these six patients were: metastatic duodenal adenocarcinoma (one), locally advanced pancreatic adenocarcinoma (one), metastatic oesophageal adenocarcinoma (one), sepsis (one), and unknown (one). Four deaths were in the community and two deaths were in hospital.

Procedures

Procedures offered include sleeve gastrectomy (SG), gastric bypass +/- silastic ring and biliopancreatic diversion with duodenal switch (BPD/DS). The total number of procedures excluding reversal, revision and trial patients was 1,349 (Figure 4).

A total of 522 SG procedures were performed: 519 were laparoscopic and three were open (Figure 5).

A total of 226 BPD/DS procedures were performed: 160 were laparoscopic and 66 were open (Figure 6).

A total of 580 gastric bypasses were performed: 523 were laparoscopic and 57 were open (Figure 7).

A total of 13 gastric band insertions were performed. No gastric bands were placed after 2007. A total of 123 gastric band removals were performed (Figure 8).

One hundred and ninety-four revision and reversal procedures were performed. Nineteen patients with a silastic ring underwent laparoscopic removal, and three had a laparoscopic revision. One BPD/DS patient had a laparoscopic reversal, and two patients had a laparoscopic revision. Two gastric bypass patients had a laparoscopic reversal, 18 had a laparoscopic revision, three had an open reversal and 14 had an open revision. Eight gastric band patients had a laparoscopic revision, 123 patients had a laparoscopic removal and one had an open removal.

Discussion

Bariatric surgery in the public sector

One-third of the population of Aotearoa New Zealand is obese, and we have the third highest adult obesity rate out of all Organisation for Economic Cooperation and Development (OECD) countries.¹ The New Zealand Health Survey 2020/2021 showed an increase in obesity in adults from 31.2% in 2019–2020 to 34.3% in 2020–2021.⁹ Bariatric surgery has been found to result in durable weight loss, and provide significant metabolic benefits to patients and their quality of life.⁵ It is widely known that obesity has a strong relationship with socio-economic status. In Aotearoa New Zealand, adults living in the most deprived areas are 1.6 times as likely to be obese as those living in the least deprived areas.⁹ Allowing increased public access to bariatric surgery will assist those economically disadvantaged patients who need it the most.

Despite this, there are ongoing limitations within the public sector for funding of metabolic surgery. The Aotearoa New Zealand national rate of publicly funded bariatric procedures in 2013–2014 was 2.7 per 1,000 morbidly obese patients, less than 5.2 per 1,000 in the United Kingdom and Ireland in 2011, and 8.0 per 1,000 in Australia in 2014–2015.^10,11 Research has shown that more than 90% of bariatric surgery is performed in the private health sector in Australia and over 70% in Aotearoa New Zealand.¹² A 2017 study suggested that only 15 public Australian hospitals out of a potential 700 institutions nation-wide offer a formalised bariatric-metabolic surgical service.¹³

Aotearoa New Zealand is not only limited by healthcare dollars, but by the availability of appropriately trained upper gastrointestinal surgeons, and operating theatre space and time. In 2013–2015, 11/19 district health boards (DHBs) provided 407 metabolic operations for morbidly obese patients.¹⁰ As training opportunities and the number of consultant surgeons increase, the availability of metabolic surgery may become available to larger numbers of patients across the regions. Health New Zealand – Te Whatu Ora was formed to replace the country’s 20 DHBs in July 2022. One of the aims of this public health agency is to eliminate geographic, socio-economic and ethnic inequity of healthcare delivery. However, it is uncertain as to how quickly and realistically these goals can be achieved.

The Waitematā bariatric service has undergone many developments since its inception. The era of laparoscopic surgery and the subsequent development of surgical skills among bariatric surgeons has expanded the landscape of operative options. The service has transitioned almost entirely to minimally invasive surgery over the past 20 years. Strengths of the bariatric service include a full range of restrictive and malabsorptive surgery, low mortality, minimal ICU/HDU requirements, skilled staff and competitive training opportunities.

The Australian and New Zealand Metabolic and Obesity Surgery Society (ANZMOSS) and Collective Public Bariatric Surgery Taskforce 2020 guidelines identified that bariatric surgery has limited clinical governance and structured training opportunities, and that a greater number of public training positions are required in this rapidly growing discipline to ensure better patient outcomes.¹² North Shore Hospital is an Australian and Aotearoa New Zealand Gastric and Oesophageal Surgery Association/ANZMOSS approved training unit and a competitive department for post-fellowship upper gastrointestinal training in Australasia. Eleven upper gastrointestinal and bariatric surgical fellowships have been completed. The unit has published the results of one randomised controlled trial comparing the 5- and 7-year outcomes of diabetes and obesity in SG versus Roux-en-Y gastric bypass (RYGB).^14,15 The 10-year outcomes are in the process of being published, and three more randomised controlled trials are underway. At least 27 further peer-reviewed articles have been published in relation to and by the Waitematā bariatric service since inception. The employment of surgeons trained in robotic, laparoscopic and endoscopic techniques allow patients access to a broad range of bariatric surgical options, including loop gastric bypass and BPD/DS.

Safety of bariatric surgery in public sector

Bariatric surgery can be safely and efficiently performed in publicly funded units across Australasia.^16,17,18 The morbidity and mortality of bariatric procedures is favourable when compared directly with other commonly performed abdominal procedures. The Australian Bariatric Surgery Registry data document a significant adverse event rate of 2.4% for primary metabolic surgery.¹² This is comparable to laparoscopic cholecystectomy, which has a significant complication rate of 0.6–3.4%.¹⁹ A 2021 bariatric surgery meta-analysis found that mortality rates were 0.03% for gastric band, 0.05% for SG, 0.09% for one-anastomosis gastric bypass, 0.09% for RYGB and 0.41% for BPD/DS.²⁰ In comparison, data from the Health Quality & Safety Commission found that between 2007–2017, 30-day mortality for patients undergoing an elective laparoscopic cholecystectomy was 0.15–0.22%, elective hip arthroplasty was 0.10–0.18% and elective colorectal resection was 1.67–2.03%.²¹ These results suggest that bariatric surgery is in fact safer than many commonly performed operations that occur in regional centres.

Other studies have shown that a public bariatric service is viable and can reduce health inequities for a high-needs population. Currently there are five Australian studies published that directly analyse public bariatric surgery.^{16,17,22,23,24} A 2014 pilot study in Australia of 65 patients found a significant reduction in BMI from a mean of 48.2kg/m2 to 35.7kg/m2 by 24 months, and significant resolution of T2DM, hypertension and OSA by 18 months, with continued improvements beyond 24 months.²² The success of a public bariatric service at the Alfred Hospital (Melbourne) was demonstrated in a 2016 study. Over a period of 6 years, 1,453 procedures were performed. Substantial weight loss was observed, and comorbidities and quality of life significantly improved.¹⁶

Clough et al. compared gastric banding, SG and RYGB at Box Hill Hospital (Melbourne) in 2016. They found that laparoscopic gastric band patients performed poorly, with an excess weight loss of 29.9%, but RYGB patients had an excess weight loss of 75.7% and SG patients of 52.7%.¹⁷ The Austin Hospital (Melbourne) recently published a 10-year retrospective review of their experience providing bariatric surgery in a public setting, with 995 patients and 1,086 bariatric procedures. There was a 26.2% total body weight loss for primary procedures, and 17.4% for revisional procedures. At 2 years’ follow-up, treatment was ceased or reduced in 65% of diabetics, 29% of hypertensive patients and 69% of OSA patients. They concluded that public bariatric programmes could deliver equivalent results with private.²⁴ In 2023, Chadwick et al. directly compared bariatric surgery in public versus private by comparing data from eight government-funded and 25 private Australian hospitals. The authors found that there were comparable metabolic and weight loss outcomes and safety.²⁵ There is an ongoing vested interest in increasing public access to bariatric surgery from healthcare providers. This trend is likely to continue as more literature reflects the multitude of benefits for patients.

The results of this study show that a publicly funded bariatric service is safe, can be performed on patients with multiple comorbidities and has a low mortality rate. A hospital that performs major abdominal surgery and has ICU/HDU facilities is capable of offering a bariatric service to its patients. This would allow rural communities and high-needs groups access to metabolic surgical options. Bariatric surgery decreases hospital costs for obese patients with high resource use.¹⁸ Increased public funding has the potential not only to positively benefit high-needs individuals, but also to provide significant cost savings over a long period to the public healthcare sector.

Barriers to accessing bariatric surgery

Bariatric surgery in Aotearoa New Zealand is a restricted resource and access to funded surgical options is limited to those who are considered the highest-needs group. National and region-specific criteria have been developed in an effort to assist with objective selection of patients in the resource-constrained environment of public healthcare. Despite improvements in this area of bariatric surgery, significant inequity remains. Māori and Pacific peoples have three to five times higher rates of obesity when compared with other ethnic groups in Aotearoa New Zealand.²⁶ Minority ethnic groups have high population needs for bariatric surgery, but are still under-represented in terms of publicly funded surgery.^26,27,28

Both Māori and Pacific peoples face significant disparities in accessing bariatric surgical treatments, and in having higher rates of obesity-related diseases and lower socio-economic status compared with New Zealand European patients.²⁶ Bennett et al. found that Māori and Pacific peoples were less likely to receive bariatric surgery than European patients, and that patients with increased deprivation and rurality were less likely to receive bariatric surgery.²⁹ Rahiri et al. found that the number of publicly funded bariatric procedures from 2010 to 2014 was three times lower in Māori and five times lower in Pacific peoples compared with New Zealand European/Other.²⁶

Some regions are performing better than others in terms of access of surgery for minority ethnic groups. A retrospective study conducted in the Waitematā district found that between 2010–2020, Māori received 19% of all bariatric procedures at Waitematā, surpassing population parity of 10% in the region.³⁰ However, equity is not achieved by proportional, equal care. In order to improve ethnic inequity, higher prioritisation must be placed on groups of patients who are under-served.

The root causes of racial inequity are complex and multifaceted, and include access to primary care, cultural competency and diversity of healthcare workers, patient engagement, institutionalised racism and unconscious bias. Racial discrimination is associated with a range of poorer health outcomes and reduced access to and quality of healthcare.³¹ Clinical environments with an under-representation of ethnically diverse staff are seen as barriers to developing emotional safety, trust and acceptance of the surgical process with patients undergoing bariatric surgery.²⁷

Inequitable access to bariatric surgery by geographical region is another major issue that needs to be addressed. Regional differences in allocation and provision of bariatric surgery are wide and do not align with the population prevalence of obesity. Murphy et al. found that there was a more than 16-fold difference in bariatric surgery intervention rates and in funding allocation for bariatric surgery between DHBs nationally.¹⁰ In this study, the Waitematā district performed the second highest number of bariatric surgeries in 2013/2014 and 2014/2015. Despite having a lower prevalence of BMI >/=40 patients at 2.7%, Waitematā outperformed the Ministry of Health target number of bariatric surgeries across 2013/2014 and 2014/2015. These results are likely reflective of a well-established bariatric service within a large district that receives more funding for metabolic procedures.

It is crucial that ongoing work is done to ensure that the highest-needs patients are served by the public health system, and that the distribution of this limited resource is fair and just. Public funding for bariatric surgery in Aotearoa New Zealand was established in 2008, but at this time there were no explicit targets set to ensure equitable access to Māori and Pacific peoples.³² The NIH guidelines are commonly used when it comes to determining a patient’s eligibility for bariatric surgery.⁸ These guidelines for the management of obesity and its associated comorbid conditions have recently been updated in 2023.³³ Ethnicity remains elusive as a contributing factor when it comes to deciding a patient’s eligibility.

Over time it has become evident that specific groups of patients are disadvantaged. Further efforts must be made to improve access to care. In February 2023, Te Whatu Ora Te Toka Tumai Auckland introduced an equity adjustor score, which seeks to reduce inequity by including a patient’s ethnicity among other factors. The goal of this score was to correct existing health inequity and access to care for Māori and Pacific peoples, who have high levels of deprivation and worse health outcomes when compared with other ethnicities across Aotearoa New Zealand. Public controversy surrounded the adoption of this score, resulting in a pause to further roll-out after its introduction.³⁴ Recently, it has been reported that Health New Zealand will stop using this tool after a review found it was “legally and ethically justifiable” but did not follow “best practice.”³⁵

In 2023, Srikumar et al. developed the first national prioritisation tool used for publicly funded bariatric surgery in Aotearoa New Zealand. This tool takes into account four major criteria (impact on life, likelihood of achieving maximum benefit with respect to control of diabetes, duration of benefit and surgical risk) to characterise the need and potential to benefit.³⁶ Further studies are planned to determine the external validity of this tool. If consistently used in all Aotearoa New Zealand hospitals, this tool may significantly improve equitable access for patients requiring metabolic surgery.

Challenges and limitations

Limitations of the Waitematā bariatric service include list cancellations, theatre time constraints, unprecedented national emergencies such as COVID-19, staffing and minimal online peri-operative support for patients. Other factors that may impact on the service include widespread adoption of glucagon-like peptide-1 receptor agonists, the development of endoscopic bariatric therapies, government changes to the healthcare system, improved urban design and unforeseen events that may have an impact on delivery of healthcare. Strong central regulation of the food environment is likely to make a significant difference, but is unlikely to be achieved due to the influence of advertising and an ongoing lack of governmental leadership on this issue.

Many of these factors may reduce the requirements for patients to receive bariatric surgery and lead to a healthier patient population. A combined approach for patients—including pharmacotherapy with surgery—may reduce the need for revisional surgery as well as reducing the burden on surgical services for patients who are amenable to a multi-tiered approach.³⁷ Opportunities to improve the service include the employment of a full-time health psychologist, funded online education and seminars, improved follow-up protocols, reduced LOS to less than 24 hours in selected patients, and ongoing clinical research and development.

The bariatric service was impacted greatly by COVID-19. During this period of uncertainty and both regional and nation-wide lockdowns, all elective bariatric operations were suspended to allow for the influx of patients with COVID-19. Many patients had their planned operation cancelled completely during this extended period. The impacts of COVID-19 continue, as currently the service is working through a significant backlog of those waiting for surgery. The service is vulnerable to other public health emergencies that may occur in the future. This is because bariatric surgery is elective and is widely considered to be of a lower priority when compared with cancer surgery and other emergency surgery.

Conclusion

This study demonstrates the feasibility and safety of a publicly run bariatric surgical programme in Aotearoa New Zealand. Even within the limitations of a constrained public healthcare system, a persistent increase in the number of patients operated on per year, a decrease in the average LOS, a low mortality rate and an ongoing commitment to improving surgical access to minority ethnic groups emphasise the importance of increased and ongoing public funding for bariatric surgery. Our data suggest ongoing prioritisation of patients with comorbidities, ensuring that surgical care is available to a high-needs population. This is likely to result in healthcare savings long term.

The Waitematā bariatric service endeavours to achieve equity among patients in terms of quality and access to care. Barriers remain throughout each stage of the process, and more research needs to be done to ensure that access is available to all comers. Engaging and retaining highly skilled bariatric and upper gastrointestinal surgeons within the Aotearoa New Zealand public healthcare system is essential to the ongoing delivery of quality care to this high-needs population.