I read with great interest the recently published guidelines from the European Society of Anaesthesiology on preoperative evaluation of the adult patient undergoing noncardiac surgery.1 I wish to question what is written in the paragraph on predictors of adverse outcome where it reads ‘…several factors have been proposed as predictors for an adverse outcome in obese patients. Increasing BMI values are closely correlated with an increasing incidence of perioperative complications in patients undergoing spinal surgery (level of evidence: 2-)’.
While this makes sense, I believe the authors have made a statement that is not supported by enough evidence for several reasons. First, the quoted article was a retrospective review of consecutive patients that were treated by a single surgeon from one institution over a 36-month period and that identified variables restricted to a sample derived from a cohort of 332 patients that was eventually reduced to 97.2 Second, the same topic has been addressed by a more recent article.3 With a similar number of patients (n = 87), but prospectively collected through a special database, Yadla and colleagues did not find any relationship between patients’ BMI and the incidence of minor or major perioperative complications. Third, it is likely that complications depend more on the surgical approach (anterior or posterior or combined anterior and posterior).4 In a study by Campbell et al.4 it reads ‘anterior thoracic and lumbar procedures had an 83.3% (five of six) incidence of complications. Of those patients having solely a posterior thoracic and lumbar procedure, 37 of 75 (49.3%) experienced at least one complication. Combined anterior and posterior surgical procedure had a complication incidence of 34 of 47 (72.3%). The mean number of complications reached significance for the minor and overall complications groups (P = 0.0076 and 0.0172, respectively, Poisson regression). Comparing the incidence of complications reveals the overall complications in the posterior-alone group compared with the anterior/posterior-combined group was significantly lower (P = 0.0134). Those undergoing instrumented fusions were statistically more likely to encounter complications (P < 0.001)’.
From these conclusions, it is likely that surgical approach, technical skills, length of surgery, blood loss and so on might play a greater role on complications than BMI itself. The topic is even more complicated because a recent meta-analysis was unable to find a difference between minimal access surgery and open spine surgery, but underlined the poor quality of many of the studies published in the orthopaedic literature.5 Cohort studies originating from a single institution are certainly flawed by the authors’ bias (e.g., surgeons evaluating their own abilities), various definitions of complications and so on.
In conclusion, I believe that at least in spinal surgery it is debatable whether perioperative complications are increased in obese patients.
1. De Hert S, Imberger G, Carlisle J, et al. Preoperative evaluation of the adult patient undergoing noncardiac surgery: guidelines from the European Society of Anaesthesiology. The Task Force on Preoperative Evaluation of the Adult Noncardiac Surgery Patient of the European Society of Anaesthesiology. Eur J Anaesthesiol
2. Patel N, Bagan B, Vadera S, et al. Obesity and spine surgery: relation to perioperative complications. J Neurosurg Spine
3. Yadla S, Malone J, Campbell PG, et al. Obesity and spine surgery: reassessment based on a prospective evaluation of perioperative complications in elective degenerative thoracolumbar procedures. Spine J
4. Campbell PG, Malone J, Yadla S, et al. Early complications related to approach in thoracic and lumbar spine surgery: a single center prospective study. World Neurosurg
5. Fourney DR, Dettori JR, Norvell DC, Dekutoski MB. Does minimal access tubular assisted spine surgery increase or decrease complications in spinal decompression or fusion? Spine
2010; 35 (9 Suppl):S57–S65.