UK data shows rising age, rates of obesity and comorbidity in surgical patients requiring anesthesia

Snapshot survey data from the 7th National Audit Project of the Royal College of Anesthetists (NAP7) published in Anaesthesia reveals an extremely worrying picture of increasing age, rates of obesity, and complexity of surgical patients requiring anesthesia in the U.K.

The snapshot activity survey collected patient-level data from all cases under the care of an anesthetist in U.K. hospitals delivering anesthesia in November 2021. Anesthetists recorded details of all cases undertaken over four days at their institution through an online survey capturing anonymous patient characteristics and anesthetic details. Of 416 hospital sites invited to participate, 352 (85%) completed the activity survey. A total of 24,172 reports were included in the final dataset. This new research is the first set of results available from NAP7, with the full report due to be published in November 2023.

This paper has been produced by a team of authors across U.K. hospitals including; Dr. Andrew Kane, Fellow, Health Services Research Center, Royal College of Anesthetists, London, UK; and Dr. Jasmeet Soar, Consultant in Anesthesia and Intensive Care Medicine, Southmead Hospital, North Bristol NHS Trust, Bristol, U.K.; and Professor Tim Cook, Consultant in Anesthesia and Intensive Care Medicine, Royal United Hospitals Bath NHS Foundation Trust, Bath, U.K., and Honorary Professor, School of Medicine, University of Bristol.

Patients requiring anesthesia are older

While the authors found that working patterns in terms of day of the week, time of day and surgical specialties were similar to previous NAP reports, some worrying trends were evident. Between the NAP5 (2013) and NAP7 (2021) surveys and excluding those patients who were pregnant, the estimated median age of patients increased by 2.3 years (50.5 to 52.8 years).

Dr. Andrew Kane, lead author says, "The fact that the population requiring surgery with anesthesia is 2.3 years older than nine years ago has important implications. Although this may seem a modest increase in age, the all-cause mortality in the general population increases approximately 10% for each year of advancing age and doubles as age increases 6–7 years; and thus a 2.3-year increase in age equates to an approximately 27% increase in all-cause mortality. This increase in age is likely to interact with peri-operative risk, most notably for those patients who are elderly, meaning that morbidity, mortality and health care costs might all be expected to have risen."

A higher proportion of patients are living with overweight and obesity

The median BMI of patients increased from 24.9 kg/m² (the borderline of what is classified as normal weight and overweight) to 26.7 (overweight). On this, the authors say, "We are seeing an increase in both the proportion of patients who are living with obesity presenting for anesthesia and surgery and in the extent of the obesity. Just 10 years ago, the median BMI of the surgical population was at the top of the 'normal' BMI category, and now in NAP7 it is 'overweight'—such that it is hard to argue that normal weight is indeed still normal. While the proportion of overweight patients in this survey is consistent with the population as a whole, the proportion of patients living with obesity is higher: patients with a BMI over 30 kg/m² now represent one in three patients presenting to anesthetists. This increase is most marked in obstetric patients who require anesthetic care to assist childbirth."

Surgical cases are becoming more complex

Anesthetists and surgeons use the ASA (American Society of Anesthesiology physical status) scale to provide a measure of the complexity/comorbidity of surgical patients where 1 is the least complex and 5 the most complex. The proportion of patients scored as ASA 1 (least complex) decreased from 37% in NAP5 (2013) to 24% in NAP7 (2021). The proportion of patients with an ASA score of 2 (with controlled long term health issues such as high blood pressure or diabetes) increased from 39% in NAP5 to 45% in NAP7. The proportion of patients who scored ASA 3 (such as those who have had a previous heart attack or stroke) increased from 18% in NAP5 to 25% in NAP7, while the proportion of very high risk (ASA 4) patients was similar (3% in NAP 5 / 4% in NAP7). The authors believe these numbers represent actual changes in the patient mix presenting to NHS hospitals for surgery.

Anesthesia is reducing its carbon footprint

The survey also examined anesthetic techniques in use, and highlights a dramatic increase in the use of "greener" anesthetic techniques. Administering anesthesia with an intravenous infusion of drugs, is a more sustainable technique than traditional methods using anesthetic "gases" as it avoids use of volatile anesthetics and nitrous oxide all of which are potent greenhouse gases. Over the last decade the use of intravenous anesthesia has tripled from 8% to 26% delivering a more "climate friendly" anesthesia.

Implications for patient waiting lists and the health care workforce

The survey was taken as a snapshot of activity during a year in which surgical activity was still affected by COVID-19. The authors comment that this might alter extrapolations in terms of absolute case activity but does not alter the findings reported here.

Dr. Soar says, "These data show increasing age, obesity and comorbidity trends leading to an increasingly complex peri-operative workload. The extent to which these trends would have occurred without the COVID-19 pandemic is unclear, but they must be addressed in this new post-pandemic era."

Prof Cook adds, "This study shows important patient changes that all increase the workload of anesthetic, surgical and perioperative teams. Patients undergoing anesthesia and surgery in the U.K. have, over the last decade, become older, more likely to be living with obesity and more medically unwell. All these factors interact to make anesthetic and surgical care more complicated and higher risk. Safely managing patients with these characteristics requires more time in the operating theater and can lead to slower recovery and more complications after surgery, both of which can require a longer time spent in hospital.

"These trends are a threat to current efforts to reduce the huge surgical waiting list. Any increases in the trends we have seen in this report will add to pressures on hospital services and we need to make national efforts to get patients fitter for surgery."

Dr. Fiona Donald, president of the Royal College of Anesthetists said, "These results confirm that what we have observed in our day-to-day work caring for patients is a nationwide trend. It is a worrying picture, but there are things that we can do to better prepare many patients for their operation through greater emphasis on perioperative care. We can help patients by supporting them to improve their health while they are waiting, for example through access to smoking cessation services and providing practical advice on changes to diet and exercise that can make a big difference."