Effect of Body Mass Index on Outcomes After Surgery for Perforated Diverticulitis

Debunking the "Obesity Paradox": Obesity Is Associated With Adverse Outcomes in Emergency General Surgery

INTRODUCTION

Obesity is increasingly prevalent both nationwide and in the emergency general surgery (EGS) population. While previous studies have shown that obesity may be protective against mortality following EGS procedures, the association between body mass index (BMI) and postoperative outcomes, as well as intraoperative decision-making, remains understudied.

METHODS

The National Surgical Quality Improvement Program 2015-2019 database was used to identify all adult patients undergoing an open abdominal or abdominal wall procedure for EGS conditions. Our outcomes included 30-d postoperative mortality, composite 30-d morbidity, delayed fascial closure, reoperation, operative time, and hospital length of stay (LOS). Multivariable logistic regression models were used to explore the association between BMI and each outcome of interest while adjusting for patient demographics, comorbidities, laboratory tests, preoperative and intraoperative variables.

RESULTS

We identified 78,578 patients, of which 3121 (4%) were categorized as underweight, 23,661 (30.1%) as normal weight, 22,072 (28.1%) as overweight, 14,287 (18.2%) with class I obesity, 7370 (9.4%) with class II obesity, and 8067 (10.3%) with class III obesity. Class III obesity was identified as a risk factor for 30-d postoperative morbidity (adjusted odds ratio 1.14, 95% CI, 1.03-1.26, P < 0.01). An increase in obesity class was also associated with a stepwise increase in the risk of undergoing delayed fascial closure, experiencing a prolonged operative time, and having an extended LOS.

CONCLUSIONS

Obesity class was associated with an increase in delayed fascial closure, longer operative time, higher reoperation rates, and extended hospital LOS. Further studies are needed to explore how a patient's BMI impacts intraoperative factors, influences surgical decision-making, and contributes to hospital costs.

Associations between body mass index and all-cause mortality: A systematic review and meta-analysis

Fasting insulin and c-reactive protein confound the association between mortality and body mass index. An increase in fat mass may mediate the associations between hyperinsulinemia, hyperinflammation, and mortality. The objective of this study was to describe the "average" associations between body mass index and the risk of mortality and to explore how adjusting for fasting insulin and markers of inflammation might modify the association of BMI with mortality. MEDLINE and EMBASE were searched for studies published in 2020. Studies with adult participants where BMI and vital status was assessed were included. BMI was required to be categorized into groups or parametrized as non-first order polynomials or splines. All-cause mortality was regressed against mean BMI squared within seven broad clinical populations. Study was modeled as a random intercept. β coefficients and 95% confidence intervals are reported along with estimates of mortality risk by BMIs of 20, 30, and 40 kg/m2 . Bubble plots with regression lines are drawn, showing the associations between mortality and BMI. Splines results were summarized. There were 154 included studies with 6,685,979 participants. Only five (3.2%) studies adjusted for a marker of inflammation, and no studies adjusted for fasting insulin. There were significant associations between higher BMIs and lower mortality risk in cardiovascular (unadjusted β -0.829 [95% CI -1.313, -0.345] and adjusted β -0.746 [95% CI -1.471, -0.021]), Covid-19 (unadjusted β -0.333 [95% CI -0.650, -0.015]), critically ill (adjusted β -0.550 [95% CI -1.091, -0.010]), and surgical (unadjusted β -0.415 [95% CI -0.824, -0.006]) populations. The associations for general, cancer, and non-communicable disease populations were not significant. Heterogeneity was very large (I2  ≥ 97%). The role of obesity as a driver of excess mortality should be critically re-examined, in parallel with increased efforts to determine the harms of hyperinsulinemia and chronic inflammation.

Effect of obesity on perioperative outcomes following gastrointestinal surgery: meta-analysis

BACKGROUND

Obesity can pose perioperative challenges related to obesity-associated co-morbidities and technical factors. However, the true impact of obesity on postoperative outcomes is not well established and reports are conflicting. The aim was to perform a systematic review and meta-analysis to explore the effect of obesity on perioperative outcomes for general surgery procedures in distinct obesity subtypes.

METHODS

A systematic review was performed for studies reporting postoperative outcomes in relation to BMI in upper gastrointestinal, hepatobiliary and colorectal based on an electronic search using the Cochrane Library, Science Direct, PubMed and Embase up to January 2022. The primary outcome was the incidence of 30-day postoperative mortality among patients with obesity undergoing general surgical procedures in comparison to patients with normal range BMI.

RESULTS

Sixty-two studies, including 1 886 326 patients, were eligible for inclusion. Overall, patients with obesity (including class I/II/II) had lower 30-day mortality rates in comparison to patients with a normal BMI (odds ratio (OR) 0.75, 95 per cent c.i. 0.66 to 0.86, P < 0.0001, I2 = 71 per cent); this was also observed specifically in emergency general surgery (OR 0.83, 95 per cent c.i. 0.79 to 0.87, P < 0.0000001, I2 = 7 per cent). Compared with normal BMI, obesity was positively associated with an increased risk of 30-day postoperative morbidity (OR 1.11, 95 per cent c.i. 1.04 to 1.19, P = 0.002, I2 = 85 per cent). However, there was no significant difference in postoperative morbidity rates between the cohorts of patients with a normal BMI and class I/II obesity (OR 0.98, 95 per cent c.i. 0.92 to 1.04, P = 0.542, I2 = 92 per cent). Overall, the cohort with obesity had a higher rate of postoperative wound infections compared with the non-obese group (OR 1.40, 95 per cent c.i. 1.24 to 1.59, P < 0.0001, I2 = 82 per cent).

CONCLUSION

These data suggest a possible 'obesity paradox' and challenge the assumption that patients with obesity have higher postoperative mortality compared with patients with normal range BMI. Increased BMI alone is not associated with increased perioperative mortality in general surgery, highlighting the importance of more accurate body composition assessment, such as computed tomography anthropometrics, to support perioperative risk stratification and decision-making.

REGISTRATION NUMBER

CRD42022337442 (PROSPERO https://www.crd.york.ac.uk/prospero/).

Current Aspects on the Management of Perforated Acute Diverticulitis: A Narrative Review

Unhealthy nutritional habits and the current western lifestyle have led to an increased incidence of acute diverticulitis, which mainly affects older patients. However, the disease course in younger patients might be more severe. It has a continued increase in surgical practice, as it is the most common clinical condition encountered in the emergencies. Diagnosis and management have changed over the past decade. C-reactive protein > 170 mg/L represents the cut-off point between moderate and severe diverticulitis, and a CT scan is mandatory. It demands urgent surgical management and has high morbidity and mortality rate, especially in immunosuppressed patients, reaching up to 25%. According to the contemporary guidelines, there have been certain indications for conservative management and re-evaluation (administration of antibiotics, CT-guided drainage of the abscess, when it is > 4 cm). They include pericolic air bubbles or a small amount of fluid, absence of abscess within a distance of 5 cm from the affected bowel or abscess ≤4 cm. In other cases, Hartmann's sigmoidectomy is the procedure of choice. An alternative choice, nowadays, is resection and primary anastomosis with or without diverting stoma, especially in younger patients. Laparoscopic lavage only versus primary resection has been performed in severe cases of Hinchey III or IV. Damage control surgery, possible open abdomen, and reoperation are recommended in severe sepsis. Hinchey's classification may not be absolutely adequate, and several modifications have been proposed. Current classification criteria (CRP, qSOFA score) are more appropriate. The decision-making must be individualized depending on the hemodynamic status (septic shock), age, comorbidity, immune status, intraoperative findings, and MPI (Mannheim peritonitis index).

Excessive Body Weight and Diverticular Disease

BACKGROUND

The worldwide proportion of overweight adults almost doubled from 22% in 1975 to 39% in 2016. Comparably, for the USA and Germany in 2016, the proportion was 68 and 56.8%, respectively. In Olmsted County, Minnesota, the prevalence of diverticulitis also doubled between 1980 and 2007, from 19 to 40%. Obesity substantially increases the risk of multiple gastrointestinal (GI) diseases and non-GI diseases. In a narrative review, we examined the evidence on whether obesity also increases the risk for the development of diverticulosis or diverticular disease and its outcome.

SUMMARY

Evidence suggests that being overweight (body mass index ≥25 kg/m2) or obese (≥30 kg/m2), especially viscerally obese, is a risk factor for diverticulosis, diverticular disease and diverticulitis, diverticular bleeding, more severe or complicated disease, recurrent disease, and for worse outcomes after surgery.

KEY MESSAGES

There is a well-founded association between overweight and diverticular disease as well as diverticulosis. It is not clear whether overweight per se or confounders linked with it are responsible for the association. However, means to fight the overweight and obesity epidemic might also help to reduce the prevalence of morbidity and mortality from diverticular disease.

Impact of Excess Body Weight on Postsurgical Complications

BACKGROUND

Obesity is considered a risk factor for postoperative complications as it can limit exposure to the operation field, thereby significantly prolonging surgery time. Obesity-associated comorbidities, such as low-grade systemic inflammation, impaired functional status, and type 2 diabetes, are independent risk factors for impaired anastomotic wound healing and nonsurgical site infections. If obesity itself is an independent risk factor for surgical complications remains controversial, but the reason for this is largely unexplored.

SUMMARY

A MEDLINE literature search was performed using the terms: "obesity," "excess body weight," and "surgical complications." Out of 65,493 articles 432 meta-analyses were screened, of which 25 meta-analyses were on the subject. The vast majority of complex oncologic procedures in the field of visceral surgery have shown higher complication rates in obese patients. Meta-analyses from the last 10 to 15 years with high numbers of patients enrolled consistently have shown longer operation times, higher blood loss, longer hospital stay for colorectal procedures, oncologic upper gastrointestinal (GI) procedures, and pancreatic surgery. Interestingly, these negative effects seem not to affect the overall survival in oncologic patients, especially in esophageal resections. A selection bias in oncologic upper GI patients may have influenced the results with higher BMI in upper GI cancer to be a predictor for better nutritional and performance status.

KEY MESSAGES

Contrary to bariatric surgery, only limited evidence indicated that site and type of surgery, the approach to the abdominal cavity (laparoscopic vs. open), institutional factors, and the type of perioperative care such as ERAS protocols may play a role in determining postsurgical complications in obese patients. The initial question remains therefore partially unanswered. Large nationwide register-based studies are necessary to better understand which aspects of obesity and its related comorbidities define it as a risk factor for surgical complications.

Impact of overweight/obesity on clinical outcomes after reduction for intussusception in children

PURPOSE

Childhood obesity is a worsening epidemic. Little is known about the impact of overweight and obesity (OV-OB) on clinical outcomes after reduction for intussusception in children. The aim of this study was to compare clinical outcomes after primarily air enema reduction for intussusception in grouped OV-OB (body mass index-for-age percentile ≥ 85) pediatric patients compared with no OV-OB patients.

METHODS

A retrospective study of 564 children who had undergone intussusception reduction via pneumatic reduction (PR) from April 2018 to January 2020 was conducted with assessments of demographic data, clinical symptoms, pre-reduction examination, and reduction results. One-to-one propensity score matching (PSM) was performed to compare clinical outcomes between patients with and without OV-OB, and the risk factors affecting recurrence and surgical reduction were analyzed in the PSM population.

RESULTS

Of the 564 patients, 132 cases (23.4%) were OV-OB (overweight: 95 cases; obesity: 37 cases). In the propensity-matched analysis, the OV-OB group showed a significant increase in surgical reduction (10.2% versus 0.9%, P = 0.005) and recurrence (47.2% versus 10.2%, P < 0.001), excretion time of carbon powder after PR (median: 11.2 h versus 8.4 h, P < 0.001), higher maximum pressure of PR (median: 10.2 kPa versus 7.8 kPa, P < 0.001), and number of PR attempts (mean: 2.0 versus 1.4, P < 0.001). There were no significant differences in the reasons for surgery (PR failure or bowel perforation), time to recurrence (early or late), and the times of recurrences ≥ 2. After applying the multivariate logistic regression analysis, we found that OV-OB and white blood cell count ≥ 20 × 10⁹/L were risk factors for both surgical reduction and the recurrence of intussusception.

CONCLUSION

This study suggested that childhood OV-OB was associated with the failure of PR and recurrence of intussusception after reduction, which should be paid more attention in clinical practice.

Differential Perioperative Outcomes in Patients With Obstructive Sleep Apnea, Obesity, or a Combination of Both Undergoing Open Colectomy: A Population-Based Observational Study

BACKGROUND

An increasing body of evidence demonstrates an association between obstructive sleep apnea (OSA) and adverse perioperative outcomes. However, large-scale data on open colectomies are lacking. Moreover, the interaction of obesity with OSA is unknown. This study examines the impact of OSA, obesity, or a combination of both, on perioperative complications in patients undergoing open colectomy. We hypothesized that while both obesity and OSA individually increase the likelihood for perioperative complications, the overlap of the 2 conditions is associated with the highest risk.

METHODS

Patients undergoing open colectomies were identified using the national Premier Healthcare claims-based Database (2006-2016; n = 340,047). Multilevel multivariable models and relative excess risk due to interaction (RERI) analysis quantified the impact of OSA, obesity, or both on length and cost of hospitalization, respiratory and cardiac complications, intensive care unit (ICU) admission, mechanical ventilation, and inhospital mortality.

RESULTS

Nine thousand twenty-eight (2.7%) patients had both OSA and obesity diagnoses; 10,137 (3.0%) had OSA without obesity; and 33,692 (9.9%) had obesity without OSA. Although there were overlapping confidence intervals in the binary outcomes, the risk increase was found highest for OSA with obesity, intermediate for obesity without OSA, and lowest for OSA without obesity. The strongest effects were seen for respiratory complications: odds ratio (OR), 2.41 (2.28-2.56), OR, 1.40 (1.31-1.49), and OR, 1.50 (1.45-1.56), for OSA with obesity, OSA without obesity, and obesity without OSA, respectively (all P < .0001). RERI analysis revealed a supraadditive effect of 0.51 (95% confidence interval [CI], 0.34-0.68) for respiratory complications, 0.11 (-0.04 to 0.26) for cardiac complications, 0.30 (0.14-0.45) for ICU utilization, 0.34 (0.21-0.47) for mechanical ventilation utilization, and 0.26 (0.15-0.37) for mortality in patients with both OSA and obesity, compared to the sum of the conditions' individual risks. Inhospital mortality was significantly higher in patients with both OSA and obesity (OR [CI], 1.21 [1.07-1.38]) but not in the other groups.

CONCLUSIONS

Both OSA and obesity are individually associated with adverse perioperative outcomes, with a supraadditive effect if both OSA and obesity are present. Interventions, screening, and perioperative precautionary measures should be tailored to the respective risk profile. Moreover, both conditions appear to be underreported compared to the general population, highlighting the need for stringent perioperative screening, documentation, and reporting.

The impact of obesity and morbid obesity on urgent/emergency colorectal resections: a regional database analysis

BACKGROUND

The obesity rate is projected to reach 50% by 2030. Obesity may be modifiable prior to elective colorectal surgery, but there is no opportunity for weight loss when patients present for urgent/emergency operations. The impact of obesity focused on urgent/emergent colorectal operations has not been fully characterized. The study aim was to determine outcomes of obese patients who undergo urgent/emergency colorectal surgery and differences when compared with elective outcomes.

METHODS

This is a retrospective cohort study of 30-day outcomes for normal (BMI 18.5-25), obese (BMI 30-39.9), and morbidly obese (BMI > 40) patients in the Michigan Surgical Quality Collaborative between 1/1/2009 and 12/31/2018. Propensity score weighting was used to derive adjusted rates for overall morbidity, mortality, and specific complications. Primary outcome was postoperative complications (any morbidity).

RESULTS

The study included 5268 urgent/emergency and 10,414 elective colorectal surgery patients. Postoperative complications were significantly more common in morbidly obese and obese than the normal BMI group for both urgent/emergency (morbidly obese 42.76% vs 33.75%, p = 0.003; obese 36.46% vs 33.75%, p = 0.043) and elective (morbidly obese 18.17% vs 13.36%, p = 0.004; obese 15.45% vs 13.36%, p = 0.011) operations. Surgical site infections are were significantly more common in morbidly obese and obese BMI groups as compared to normal BMI for both urgent/emergency and elective cases. Mortality was significantly higher in the morbidly obese (14.93% vs 11.44%, p = 0.013) but not obese BMI groups as compared to the normal BMI group for urgent/emergency cases. Mortality for all groups undergoing elective operations was < 1% and with no significant differences.

CONCLUSIONS

Morbid obesity and obesity are associated with complications that are largely driven by surgical site infections after both urgent/emergency and elective colorectal surgery. Obesity is a risk factor difficult to modify prior to urgent/emergency surgery. Managing complications related to obesity after colorectal surgery will be a continued challenge with projected increasing obesity rates.