Prevalence and predictors of postoperative thiamine deficiency after vertical sleeve gastrectomy.

Background: As the vertical sleeve gastrectomy (VSG) becomes increasingly popular, its effect on postoperative micronutrient levels, such as thiamine, becomes more important. We previously found a 1.8% prevalence of thiamine deficiency in bariatric patients before surgery.

Objective: The aims of this study were to determine the prevalence of thiamine deficiency at our center after VSG and to explore possible predictors of postoperative thiamine levels.

Setting: University hospital, United States.

Methods: A retrospective chart review was performed on 147 bariatric patients between 18- and 65-years old who underwent VSG between April 2011 and February 2015. Demographic characteristics, preoperative body mass index (BMI), obesity-associated co-morbidities, alcohol intake, smoking habits, insurance type, calendar year of the procedure, occurrence of postoperative complications, and compliance with postoperative nutrition and follow-up appointment guidelines were extracted from clinical charts. We defined thiamine deficiency as<78 nM on any lab draw within 1 year after the VSG. The χ, Fisher exact, and Mann-Whitney U tests, and multivariate logistic regression models were created to analyze the association of the above factors with thiamine deficiency after a VSG.

Results: Of 147 patients, 105 met inclusion criteria and were analyzed, of whom 27 (25.7%) had thiamine deficiency. Overall median age was 42 years (interquartile ratio: 36, 49). The majority of patients were either African Americans or Caucasian (47.6% and 44.8%, respectively), female (77.1%), and compliant with vitamins (81.0%). The overall mean preoperative BMI was 46.4 kg/m. Patients with thiamine deficiency were more likely to be African American (66.7%, P = .024), have a larger preoperative BMI (P = .026), and to report repetitive episodes of nausea (59.3%, P = .002) and vomiting (44.4%, P = .001) at any of their postoperative appointments within 1 year after surgery. Compliance with vitamins did not differ between those with or without thiamine deficiency (70.4%, 84.6%, P = .10). After controlling for all factors, African American race (odds ratio [OR] 3.9, P = .019), higher preoperative BMI (OR 1.13, P = .001), nausea (OR 3.81, P = .02), and vomiting (OR 3.49, P = .032) were independent risk factors for the development of thiamine deficiency.

Conclusions: We found an alarmingly high prevalence of thiamine deficiency in postoperative SG patients. This disorder may have serious consequences including Wernicke encephalopathy; hence, it is important to identify predictive demographic, postoperative, and behavioral factors so that appropriate measures can be taken to prevent thiamine deficiency in VSG patients.