Underweight patients at greater risk of postoperative adverse events following stand-alone ALIF than obese patients

Jonathan Grauer

Patients who are underweight are more likely to experience postoperative adverse events following stand-alone anterior lumbar interbody fusion (ALIF) than those who have either a normal, overweight or even obese body mass index (BMI), new research published by Jonathan Grauer (Yale School of Medicine, New Haven, USA) et al in The Spine Journal suggests.

The retrospective cohort study analysed how ALIF perioperative outcomes vary along the BMI spectrum. In this study, World Health Organisation categories of BMI were used.

According to the researchers, the study results highlight that underweight patients are an at-risk population that “should be given additional consideration by health systems and physicians, as is already done for those on the other side of the BMI spectrum”.

Patients undergoing stand-alone one or two-level ALIF found in the 2005 –2018 American College of Surgeons National Surgical Quality Improvement Program (NSQIP) databases were included. Posterior cases and those primary diagnoses of trauma, tumour, infection, or emergency presentation were excluded.

The key outcome measures were 30-day adverse events, hospital readmissions, postoperative infections, and mortality. In total, 13,710 ALIF patients were included in the study.

The data reveal that incidence of adverse events was elevated in both the underweight (BMI <18.5 kg/m3) and super morbidly obese (>50 kg/m3). However, multivariate risks for adverse events and postoperative infection were elevated for underweight patients beyond those found in any other BMI category.

No effect was noted in these identical variables between normal, overweight, obese class 1, or even obese class 2 patients. Multivariate analysis also found overweight patients showed a slightly protective trend against mortality while the super morbidly obese had elevated odds.

Speaking to Spinal News International, Grauer said: “Surgeons often only consider the high end of the BMI spectrum as a significant risk factor for postoperative infections, however this study highlights increased risks for the underweight patients undergoing anterior lumbar interbody fusion that bear consideration.”


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