title: Relation of body mass index to late survival after valvular heart surgery.
abstract: Limited data have suggested that an "obesity paradox" exists for mortality and cardiovascular outcomes in patients undergoing coronary artery bypass grafting. Much less is known about the role of the preoperative body mass index (BMI) in patients undergoing valve surgery. We evaluated 2,640 consecutive patients who underwent valve surgery between April 2004 and March 2011. The patients were classified by the World Health Organization standards as "underweight" (BMI 11.5 to 18.4 kg/m(2), n = 61), "normal weight" (BMI 18.5 to 24.9 kg/m(2), n = 865), "overweight" (BMI 25 to 29.9 kg/m(2), n = 1,020), and "obese" (BMI 30 to 60.5 kg/m(2), n = 694). Mortality was ascertained using the Social Security Death Index. Hazard ratios (HRs), adjusted for known preoperative risk factors, were obtained using Cox regression models. The mean follow-up was 31.9 ± 20.5 months. The long-term mortality rate was 1.21, 0.52, 0.32, and 0.44 per 10 years of person-time for underweight, normal, overweight, and obese patients, respectively. Compared to the normal BMI category, overweight patients (adjusted HR 0.60, 95% confidence interval 0.46 to 0.79, p <0.001) and obese patients (adjusted HR 0.67, 95% confidence interval 0.50 to 0.91, p = 0.009) were at a lower hazard of long-term all-cause mortality. Underweight patients remained at a greater adjusted risk of long-term mortality than normal weight patients (adjusted HR 1.69, 95% confidence interval 1.01 to 2.85, p = 0.048). Similar patterns of mortality outcomes were noted in the subset of patients undergoing isolated valve surgery. In conclusion, overweight and obese patients had greater survival after valve surgery than patients with a normal BMI. Very lean patients undergoing valve surgery are at a greater hazard for mortality and might require more rigorous preoperative candidate screening and closer postoperative monitoring.
authors.affiliation: Divisions of Cardiac Surgery and Cardiology, Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
authors.forename: Muthiah
authors.initials: M
authors.lastname: Vaduganathan
authors.forename: Richard
authors.initials: R
authors.lastname: Lee
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Beckham
authors.forename: Adin-Cristian
authors.initials: AC
authors.lastname: Andrei
authors.forename: Brittany
authors.initials: B
authors.lastname: Lapin
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Stone
authors.forename: Edwin C
authors.initials: EC
authors.lastname: McGee
authors.forename: S Chris
authors.initials: SC
authors.lastname: Malaisrie
authors.forename: Preeti
authors.initials: P
authors.lastname: Kansal
authors.forename: Robert A
authors.initials: RA
authors.lastname: Silverberg
authors.forename: Donald M
authors.initials: DM
authors.lastname: Lloyd-Jones
authors.forename: Patrick M
authors.initials: PM
authors.lastname: McCarthy
mesh_terms: D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000150:complications / Q000401:mortality / Q000601:surgery*; D019918:Heart Valve Prosthesis Implantation / Q000401:mortality*; D017052:Hospital Mortality / Q000639:trends; D006801:Humans; D007087:Illinois / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000150:complications* / Q000401:mortality; D011183:Postoperative Complications / Q000209:etiology / Q000401:mortality; D012189:Retrospective Studies; D016019:Survival Analysis; D015996:Survival Rate / Q000639:trends; D013997:Time Factors