Pneumonia and respiratory causes were found to be the largest causes of long-term mortality after bariatric and metabolic surgery (BMS), according to a single-centre retrospective study by UK researchers. They also reported that the only factor to have a detrimental effect on all-cause mortality was age at the time of the operation which reduced survival with hypertension, ischaemic heart disease (IHD) and smoking noted as indirect factors that are associated with mortality.
The study’s authors explained that the percentage of adults in England who are classed as individuals with obesity rose by 13.1% from 1993 to 2019, whilst those classed as overweight or patients with obesity rose by 11.4%. The cost of treating these comorbidities is estimated to rise by £1.9–2 billion per year. Moreover, obesity has the second largest human-generated economic impact, at US$73 billion (3% of the UK’s GDP.). In 2019/20 there were over one million admissions where obesity was the primary or secondary diagnosis in the UK.
Bariatric and metabolic surgery (BMS) is the most effective tool to control the weight and its associated morbidity. A study in 2017, reported the in‐hospital death was 0.07% and the 30‐day mortality rate after discharge was 0.08%, making it safer than other common surgery procedures like knee or hip replacements.
Although bariatric studies focus on weight loss, comorbidities and 30-day mortality/morbidity, the authors stated there is less information about longer-term mortality. Therefore, the primary aim of their study was to find and examine the causes of death after bariatric metabolic surgery and identify the factors associated with the cause of death. The secondary aim is to find potential predictors for mortality after BMS.
Using data from one NHS trust, they collected data on all patients over the age of 18 who had undergone any surgical bariatric procedure (LAGB, one anastomosis gastric bypass (OAGB), Roux-en-Y gastric bypas (RYGB), or laparoscopic sleeve gastrectomy (LSG)) between June 2010 to September 2022. Those patients who had died since their operation were identified by searching each patient’s hospital identification number (or National Health Service number where their hospital number was not available) through trust records which provided a date of death.
Outcomes
In total, 891 patients were included in the study and 39 (4.38%) had died (the 30-day mortality rate was 0.11%.). The mean age at death was 57.33 years (95% CI: 53.78 to 60.88), with the mean number of days from operation to death being 2,317.31 days (6.34 years, 95%CI: 1921.21 to 2713.23 days). Of the 39 deceased patients, 66.7% were female and the whole of the deceased cohort had at least one of the recorded comorbidities, with the median number of comorbidities being three.
The most common comorbidities were hypertension, OSA and diabetes with 24 (61.5%), 21 (53.8%), and 20 (51.3%) cases, respectively. Five (12.8%) patients had their bariatric operation revised. The most common operation type was RYGB (n=19), followed by LAGB (n=11), LSG (n=6) and OAGB (n=3).
The researchers found that the largest cause of death was pneumonia and respiratory causes with 12 deaths, this included five deaths caused by COVID pneumonia. The next largest categories were infection/sepsis and liver failure, both with six deaths, followed by cardiac causes, malignancy, and multiple organ failure with five deaths. The smallest category was cerebrovascular accidents with two deaths.
Age at operation and age at death had a correlation coefficient of 0.952 and a p-value of <0.001, demonstrating that these two variables have a strong and significant association. The number of comorbidities also showed a positive correlation with age at death, with a correlation coefficient of 0.390 with a p-value of 0.014. A multiple linear regression of age at death by age at operation and number of comorbidities produced an adjusted R square value of 0.878 and the overall model was significant with p<0.001.
“Bariatric metabolic surgery has low mortality rates, with pneumonia and respiratory causes being the largest long-term cause of mortality, although this category may have been inflated by deaths from COVID-19,” the researchers concluded. “A history of asthma/COPD was significantly associated with all-cause mortality. The only potential predictor of mortality was age at operation which reduced survival in our patients.”
The findings were reported in the paper, ' Causes of Death After Bariatric Surgery: Long-Term Study of 10 Years', published in Obesity Surgery. To access this paper, please click here
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