Bariatric Times

JUN 2017

A peer-reviewed, evidence-based journal that promotes clinical development and metabolic insights in total bariatric patient care for the healthcare professional

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24 Journal Watch Bariatric Times • June 2017 Assessing the causal relationship between obesity and venous t hromboembolism through a Mendelian Randomization study. Lindström S, Germain M, Crous-Bou M, et al. Hum Genet. 2017 May 20. [Epub ahead of print] Synopsis: Observational studies have shown an association between obesity and venous thromboembolism (VTE) but it is not known if observed associations are causal, due to reverse causation or confounding bias. The authors conducted a Mendelian Randomization study of body mass index (BMI) and VTE. They identified 95 single nucleotide polymorphisms (SNPs) that have been previously associated with BMI and assessed the association between genetically predicted high BMI and VTE leveraging data from a previously conducted GWAS within the INVENT consortium comprising a total of 7507 VTE cases and 52,632 controls of European ancestry. Five BMI SNPs were associated with VTE at P < 0.05, with the strongest association seen for the FTO SNP rs1558902 (OR 1.07, 95% CI 1.02- 1.12, P = 0.005). In addition, we observed a significant association between genetically predicted BMI and VTE (OR = 1.59, 95% CI 1.30- 1.93 per standard deviation increase in BMI, P = 5.8 × 10-6). They concluded that their study provides evidence for a causal relationship between high BMI and risk of VTE. Reducing obesity levels will likely result in lower incidence in VTE. PMID: 28528403 Assessment of the relationship between body mass index and incidence of venous thromboembolism in hospitalized overweight and obese patients. Samuel S, Gomez L, Savarraj JP, Bajgur S, Choi HA. Pharmacotherapy. 2017 May 18. [Epub ahead of print] Synopsis: To assess whether a positive linear association exists between body mass index (BMI) and i ncidence of venous thromboembolism (VTE) in overweight and obese hospitalized patients, researchers conducted a single-center, retrospective, observational cohort study. The study included a total of 1,452 adults hospitalized between January 1, 2013, and December 31, 2014, who weighed more than 100kg and had a BMI of 25 kg/m 2 or greater on admission, and received heparin subcutaneously for VTE prophylaxis. The patients were categorized into four subgroups based on World Health Organization BMI classification: overweight (141 patients), obese class I (305 patients), obese class II (324 patients), and obese class III (682 patients). The primary outcome was occurrence of VTE in each subgroup; all-cause mortality and length of hospital stay were secondary outcomes. A linear trend test did not show an association between occurrence of VTE and BMI ≥ 25 kg/m 2 . VTE occurred in seven (5%) of 141 patients in the overweight group, five (2%) of 305 in the obese class I group, eight (3%) of 324 in the class II group and 18 (3%) of 682 in the class III group (p=0.573). In addition, no linear association was noted between all-cause mortality or length of hospital stay and BMI ≥ 25 kg/m2 . Overall mortality was 10% (146/1452 patients). Ten deaths (7%) occurred in the overweight group, 45 (15%) in the obese class I group, 38 (12%) in the obese class II group, and in 53(8%) the obese class III group (p=0.067). The median length of hospital stay was five (interquartile range 3-9) days (p=0.122) for all patients. The researchers concluded that in overweight and obese hospitalized patients who weighed more than 100kg and had a BMI of 25 kg/m 2 or greater, the incidence of VTE did not increase incrementally with increasing severity of obesity. P MID: 28520085 Evaluation of an unfractionated heparin pharmacy dosing protocol for the treatment of venous thromboembolism in nonobese, obese, and severely obese patients. Hosch LM, Breedlove EY, Scono LE, Knoderer CA. Ann Pharmacother. 2017 May 1:1060028017709819. [Epub ahead of print] Synopsis: The objective of this study was to evaluate the time and dose required to achieve a therapeutic activated partial thromboplastin time (aPTT) in nonobese, obese, and severely obese patients using a pharmacist-directed heparin dosing protocol. This was a retrospective cohort study in a single-center community hospital inpatient setting. Adult patients receiving heparin for venous thromboembolism (VTE) treatment from July 1, 2013, to July 31, 2015, were evaluated. Patients were categorized into three groups: nonobese (BMI < 30kg/m 2 ), obese (BMI = 30–39.9kg/m 2 ), and severely obese (BMI ≥ 40kg/m 2 ). Data on height, weight, initial bolus dose, initial infusion rate, time to therapeutic aPTT, and therapeutic infusion rate were collected. Dosing body weight (DBW) was utilized for patients 20 percent over their ideal body weight (IBW). The primary outcome was time to therapeutic aPTT. Analysis included 298 patients. Median times to therapeutic aPTT (hours:minutes) in the nonobese, obese, and severely obese were 15:00 (interquartile range [IQR] = 8:05- 23:21), 15:40 (IQR = 9:22-25:10), and 15:22 (IQR = 7.54-23:40), respectively (P = 0.506). There was no difference in bleeding among the nonobese (14%), obese (13.9%), or severely obese groups (7.9%; P = 0.453). No adverse thrombotic events occurred during hospitalization. T he authors concluded that using a DBW for heparin dosing in patients 20 percent over their IBW resulted in similar times to therapeutic aPTT and adverse events in the nonobese, obese, and severely obese. PMID: 28511582 Who should get extended thromboprophylaxis after bariatric surgery?: A risk assessment tool to guide indications for post-discharge pharmacoprophylaxis. Aminian A, Andalib A, Khorgami Z, et al. Ann Surg. 2017;265(1):143–150. Synopsis: The researchers sought to determine the risk factors for 30- day postdischarge venous thromboembolism (VTE) after bariatric surgery and to identify potential indications for extended pharmacoprophylaxis. From American College of Surgeons-National Surgical Quality Improvement Program, the authors identified 91,963 patients, who underwent elective primary and revisional bariatric surgery between 2007 and 2012. Regression-based techniques were used to create a risk assessment tool to predict risk of postdischarge VTE. The model was validated using the 2013 American College of Surgeons-National Surgical Quality Improvement Program dataset (N = 20,575). Significant risk factors were used to create a user-friendly online risk calculator. The overall 30-day incidence of postdischarge VTE was 0.29 percent (N = 269). In those experiencing a postdischarge VTE, mortality increased about 28-fold (2.60% vs 0.09%; P < 0.001). Among 45 examined variables, the final risk- assessment model contained 10 categorical variables including congestive heart failure, paraplegia, reoperation, dyspnea at rest, A q u i c k l o o k a t t h e n o t e w o r t h y a r t i c l e s i n b a r i a t r i c a n d m e t a b o l i c r e s e a rc h THIS MONTH'S TOPIC: VENOUS THROMBOEMBOLISM AND PORTAL VEIN THROMBOSIS Journal Watch

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