Impact of age on postoperative complications following bariatric surgery

Background: The impact of age on complications following bariatric surgery remains unclear. Research is therefore warranted among previously unstudied populations of bariatric surgery patients. The aim of the current study was to assess the impact of age on postoperative complications following bariatric surgery in Saudi Arabia. Methods: This retrospective study included 301 patients who underwent bariatric surgery between January 2011 and July 2016. Patients were classified into three groups according to age: < 25 years; 25–36 years; and >36 years. Primary outcomes were determined by identifying the number of complications reported during a period of 180 days. The negative binomial model was used to assess the relationship between age and the high rate of postoperative complications following adjustment for confounding variables. Results: The incidence of overall complications was 10.1% in the < 25-year age group, 15% in the 25–36-year age group, and 24.2% in the >36-year age group. After adjusting for confounding variables, it was discovered that the risk of postoperative complications increases with age. The risk was higher in the >36-year age group than in the >25-year age group [adjusted relative rate (aRR) = 2.35; 95% confidence interval (CI) = 1.046–5.290; p = 0.039]. Diabetes (aRR = 3.27), adjustable gastric bands (aRR = 3.40), and a more lengthy hospital stay (aRR = 1.23) were associated with increased rates of postoperative complications. Conclusion: Age is independently associated with a high rate of postoperative complications following bariatric surgery. The results showed that patients with diabetes, those using adjustable gastric bands, and those with longer length of hospital stay had significantly higher incidence of postoperative complications. These findings indicate the need for risk stratification tools to evaluate patients as candidates for bariatric surgery and to use as a guide for identifying optimal preoperative factors.


INTRODUCTION
The prevalence of obesity is a growing global concern, 1 particularly in Saudi Arabia, where it remains a major public health issue. 2 In Saudi Arabia, the prevalence of obesity has increased from 22% in 1993 to 36% in 2005 2 and is projected to double by 2022. 2 Obesity has been noted in all age groups, and this trend appears to increase with age. 2 -5 Recently, bariatric surgery has been found to be the most effective intervention and long-term strategy for obtaining sustainable weight loss. 6 -8 Furthermore, two studies performed in Saudi Arabia revealed that laparoscopic gastric sleeve is effective for treating individuals with morbid obesity. 9,10 Several studies have assessed the risk factors contributing to complications in bariatric surgery patients. 10 -14 Although such complications may develop in any age group, 15 -18 the risk of postoperative complications tends to increase with age. 16 Some studies affirm that postoperative complications are observed more frequently in elderly people over the age of 65 years. 15,18 However, other reports conclude that bariatric procedures can be effective and safe for patients aged $60 years. 19 -21 Since there has been no conclusive evidence showing age as a risk factor for postoperative complications, 22,23 all published results regarding the link between age and complications after bariatric surgery remain debatable.
Although several studies support the effectiveness of bariatric surgery in various age groups, 19 -21 no data regarding the impact of age on postoperative complications are available in Saudi Arabia. The findings of such research could benefit surgeons who perform weight loss surgeries by helping them develop strategies to prevent or minimize postoperative complications in patients undergoing such surgeries. A wider range of research from various countries is warranted to understand the link between age and postoperative complications. Furthermore, these studies could be used to assess whether comparable results can be found to support findings that are reported in international bariatric surgery patients. This study reviewed the complications in a group of bariatric surgery patients. Patients were divided into three different age groups. The aim of the current study was to assess the impact of age on postoperative complications following bariatric surgery in Saudi Arabia. The hypothesis for this study stated that the rate of postoperative complications for bariatric procedures increases with age. This study also determined whether older age was an independent predictor for a high rate of postoperative complications in bariatric surgical patients.

METHODS
A cohort retrospective study was conducted on patients who underwent bariatric surgery at King Abdulaziz Medical City from January 2011 to July 2016. The study was approved by the Institutional Review Board of King Abdullah International Medical Research Center (Research Protocol #RSS/0001). The records of all patients who underwent bariatric surgery during the study period were used. A total of 301 bariatric surgery patients were identified. The patients were consecutively enrolled, and no patients were excluded from this population. Demographic data for all patients such as age, sex, and body mass index (BMI) was reviewed and recorded. For the purposes of analysis, patients were classified into three groups according to their age: ,25 years, 25 -36 years, and .36 years. BMI was divided into two groups: 1) overweight or class I obesity (BMI, 25 -34.9) and 2) class II or III obesity (BMI $35). Bariatric surgery and clinical data were also reviewed and recorded including: procedure type, number of procedures performed, procedure duration, length of hospital stay, history of prior bariatric surgery, hypertension, diabetes mellitus, asthma, kidney failure, dyslipidemia, heart disease, thyroid, obstructive sleep apnea, and gastroesophageal reflux disease.

Study outcome
The primary outcome of interest for this study was the number of bariatric surgery-related complications reported during a period of six months. Postoperative complications were recorded from the emergency department and hospital medical records following bariatric surgery. The postoperative complications included were as follows: surgical site infection, abdominal pain, nausea/vomiting, wound infection, fever, obstruction/ileus, port site infection, discharge, bleeding, site leak, general pain, chest pain, blockage, infection, headache\dizziness, diarrhea, pulmonary embolism, collection\pseudomonas infection, and other complications. The sum of all postoperative complications was calculated for each patient.

Statistical analysis
All data analyses were conducted using IBM SPSS, version 23 (Chicago, IL). Descriptive statistics were used to describe the sample studied (Table 1). Patient demographics and clinical characteristics across age groups were assessed using the chi-squared and Fisher's exact tests for nonnumerical variables, while the Kruskal -Wallis test was used to assess numerical variables ( Table 1). The negative binomial model was used to assess the relationship between age and the high rate of bariatric surgery-related complications after adjustment for confounders ( Table 2). An alpha (a) value of #0.05 was considered significant for all analyses. We evaluated whether the negative binomial regression model fit the data. The deviance for the

DISCUSSION
Currently, bariatric surgery is the most prevalent method for treating morbid obesity, and the number of Saudis with morbid obesity is increasing. As a result, there has been a widespread increase in the rate of postoperative complications. These complications were reported in a previous study based on a review of patients who visited the emergency department and/or were readmitted to the hospital. 10 In our study population, 75.7% of the bariatric surgeries performed during the study period were gastric sleeve surgeries, indicating that gastric sleeve surgery is the most popular procedure in Saudi Arabia. Furthermore, this is a procedure that has also become popular worldwide. 24 -26 The demographic characteristics of our study population are similar to those reported in other international bariatric surgery populations. 27

CONCLUSIONS
The unadjusted and adjusted rates demonstrated that postoperative complications were higher in bariatric surgery patients aged .36 years. This confirms the findings demonstrated in other international populations of bariatric surgery patients. Older patients may not be denied bariatric surgery, although other risk factors may have contributed to the higher rate of complications. The results suggest that diabetes, adjustable gastric band/removal, and longer length of hospital stay were significantly associated with higher incidence of postoperative complications. These findings indicate the need for risk stratification tools to assess patients as candidates for bariatric surgery and to identify optimal preoperative factors. The results may also offer useful information for surgeons and clinicians who handle postoperative care for bariatric surgery patients.
Abbreviations ED: emergency department; BMI: Body mass index; CI: Confidence interval; aRR: adjusted relative risk