Alcohol Consumption Patterns up to 10 years post Bariatric Surgery: Utilizing the Highly Specific Biomarker Phosphatidylethanol (PEth)

• 1,246 bariatric patients followed 10 yrs using PEth, a blood alcohol marker. • Alcohol use rose post-surgery, men at ∼8-fold higher risk. • Supports PEth screening in long-term follow-up. 1,246 bariatric patients followed 10 yrs using PEth, a blood alcohol marker. Alcohol use rose post-surgery, men at ∼8-fold higher risk. Supports PEth screening in long-term follow-up. The increasing prevalence of obesity has led to a rise in bariatric surgery as an effective intervention for weight loss and associated comorbidities. However, concerns persist regarding increased alcohol consumption following surgery. To objectively assess long-term changes in alcohol use following bariatric surgery we employed the use of the highly specific alcohol biomarker Phosphatidylethanol (PEth). Kalmar County Hospital, Sweden. This longitudinal cohort study included 1,238 patients who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) at Kalmar County Hospital from 2010 to 2020. Patients were divided into two cohorts based on preoperative PEth sampling (n=330 with, n=916 without). PEth levels were measured before surgery and at intervals up to 10 years post-op, using 0.30 μmol/L (∼210 ng/mL) as the threshold for heavy alcohol use. Mean PEth concentrations increased from 0.07 to 0.38 μmol/L (P<0.001)in men and from 0.06 to 0.11 μmol/L non significantly in women. The proportion of patients that postoperatively exceeded the heavy drinking threshold rose significantly over time. At five years, 37.5% of men and 4.8% of women had PEth values above 0.30 μmol/L (both p<0.001). Men were at significantly higher risk (OR 7.89, 95% CI 3.76–16.57; p<0.001). This pattern remained consistent at the 10-year follow-up. Alcohol consumption, as measured by PEth, increased significantly following bariatric surgery, particularly in men. These findings support routine postoperative alcohol screening and suggest incorporating PEth testing into long-term follow-up protocols.