The obesity paradox in patients with peripheral arterial disease.
BACKGROUND
Cardiac events are the predominant cause of late mortality in patients with peripheral arterial disease (PAD). In these patients, mortality decreases with increasing body mass index (BMI). COPD is identified as a cardiac risk factor, which preferentially affects underweight individuals. Whether or not COPD explains the obesity paradox in PAD patients is unknown.


METHODS
We studied 2,392 patients who underwent major vascular surgery at one teaching institution. Patients were classified according to COPD status and BMIs (ie, underweight, normal, overweight, and obese), and the relationship between these variables and all-cause mortality was determined using a Cox regression analysis. The median follow-up period was 4.37 years (interquartile range, 1.98 to 8.47 years).


RESULTS
The overall mortality rates among underweight, normal, overweight, and obese patients were 54%, 50%, 40%, and 31%, respectively (p < 0.001). The distribution of COPD severity classes showed an increased prevalence of moderate-to-severe COPD in underweight patients. In the entire population, BMI (continuous) was associated with increased mortality (hazard ratio [HR], 0.96; 95% confidence interval [CI], 0.94 to 0.98). In addition, patients who were classified as being underweight were at increased risk for mortality (HR, 1.42; 95% CI, 1.00 to 2.01). However, after adjusting for COPD severity the relationship was no longer significant (HR, 1.29; 95% CI, 0.91 to 1.93).


CONCLUSIONS
The excess mortality among underweight patients was largely explained by the overrepresentation of individuals with moderate-to-severe COPD. COPD may in part explain the "obesity paradox" in the PAD population.
Galal
Wael
W
Department of Anesthesiology, Erasmus Medical Center, Rotterdam, the Netherlands.
van Gestel
Yvette R B M
YRBM
Department of Anesthesiology, Erasmus Medical Center, Rotterdam, the Netherlands.
Hoeks
Sanne E
SE
Department of Anesthesiology, Erasmus Medical Center, Rotterdam, the Netherlands.
Sin
Don D
DD
James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research, St. Paul's Hospital & University of British Columbia, Vancouver, BC, Canada.
Winkel
Tamara A
TA
Department of Surgery, Erasmus Medical Center, Rotterdam, the Netherlands.
Bax
Jeroen J
JJ
Department of Cardiology, Leiden Medical Centre, Leiden, the Netherlands.
Verhagen
Hence
H
Department of Surgery, Erasmus Medical Center, Rotterdam, the Netherlands.
Awara
Adel M M
AMM
Department of Anesthesiology, Tanta Faculty of Medicine, Tanta, Egypt.
Klein
Jan
J
Department of Anesthesiology, Erasmus Medical Center, Rotterdam, the Netherlands.
van Domburg
Ron T
RT
Department of Cardiology, Erasmus Medical Center, Rotterdam, the Netherlands.
Poldermans
Don
D
Department of Anesthesiology, Erasmus Medical Center, Rotterdam, the Netherlands. Electronic address: d.poldermans@erasmusmc.nl.
D000368:Aged; D001157:Arterial Occlusive Diseases / Q000209:etiology / Q000401:mortality* / Q000503:physiopathology; D015992:Body Mass Index; D002423:Cause of Death / Q000639:trends; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D009765:Obesity / Q000150:complications* / Q000401:mortality / Q000503:physiopathology; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D015996:Survival Rate / Q000639:trends