Assessment of empiric body mass index-based thromboprophylactic dosing of enoxaparin after bariatric surgery: evidence for dosage adjustment using anti-factor Xa in high-risk patients.

BACKGROUND: Despite thromboprophylaxis, postoperative deep vein thrombosis and pulmonary embolism occur after bariatric surgery, perhaps because of failure to achieve optimal prophylactic levels in the obese population. OBJECTIVES: The aim of this study was to evaluate the adequacy of prophylactic dosing of enoxaparin in patients with severe obesity by performing an antifactor Xa (AFXa) assay. SETTING: An academic medical center METHODS: In this observational study, all bariatric surgery cases at an academic center between December 2016 and April 2017 who empirically received prophylactic enoxaparin (adjusted by body mass index [BMI] threshold of 50 kg/m2) were studied. The AFXa was measured 3-5 hours after the second dose of enoxaparin. RESULTS: A total of 105 patients were included; 85% were female with a median age of 47 years. In total, 16 patients (15.2%) had AFXa levels outside the prophylactic range: 4 (3.8%) cases were in the subprophylactic and 12 (11.4%) cases were in the supraprophylactic range. Seventy patients had a BMI <50 kg/m2 and empirically received enoxaparin 40 mg every 12 hours; AFXa was subprophylactic in 4 (5.7%) and supraprophylactic in 6 (8.6%) of these patients. Of the 35 patients with a BMI ≥50 who empirically received enoxaparin 60 mg q12h, no AFXa was subprophylactic and 6 (17.1%) were supraprophylactic. Five patients (4.8%) had major bleeding complications. One patient developed pulmonary embolism on postoperative day 35. CONCLUSION: BMI-based thromboprophylactic dosing of enoxaparin after bariatric surgery could be suboptimal in 15% of patients with obesity. Overdosing of prophylactic enoxaparin can occur more commonly than underdosing. AFXa testing can be a practical way to measure adequacy of pharmacologic thromboprophylaxis, especially in patients who are at higher risk for venous thromboembolism or bleeding.

The Outcome of Bariatric Surgery in Patients Aged 75 years and Older.

BACKGROUND: Bariatric surgery has been shown to be safe and effective in patients aged 60-75 years; however, outcomes in patients aged 75 or older are undocumented. METHODS: Patients aged 75 years and older who underwent bariatric procedures in two academic centers between 2006 and 2015 were studied. RESULTS: A total of 19 patients aged 75 years and above were identified. Eleven (58%) were male, the median age was 76 years old (range 75-81), and the median preoperative body mass index (BMI) was 41.4 kg/m2 (range 35.8-57.5). All of the bariatric procedures were primary procedures and performed laparoscopically: sleeve gastrectomy (SG) (n = 11, 58%), adjustable gastric band (AGB) (n = 4, 21%), Roux-en-Y gastric bypass (RYGB) (n = 2, 11%), banded gastric plication (n = 1, 5%), and gastric plication (n = 1, 5%). The median operative time was 120 min (range 75-240), and the median length of stay was 2 days (range 1-7). Three patients (16%) developed postoperative atrial fibrillation which completely resolved at discharge. At 1 year, the median percentage of total weight loss (%TWL) was 18.4% (range 7.4-22.0). The 1-year %TWL varied among the bariatric procedures performed: SG (21%), RYGB (22%), AGB (7%), and gastric plication (8%). There were no 30-day readmissions, reoperations, or mortalities. CONCLUSION: Our experience suggests that bariatric surgery in selected patients aged 75 years and older would be safe and effective despite being higher risk. Age alone should not be the limiting factor for selecting patients for bariatric surgery.