The obesity paradox appears alive and well in the treatment of peripheral arterial disease (PAD), according to the results of a 10-year, 5.6-million patient database study.
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The researchers found that coding for obesity is associated with lower in-hospital mortality in PAD patients relative to those who were normal weight or overweight. This obesity survival paradox was independent of age, sex, and comorbidities and was seen in all obesity classes, according to Karsten Keller, MD, of the University Medical Center Mainz (Germany), and his colleagues.
In total, 5,611,827 inpatients aged 18 years or older with PAD were treated between 2005 and 2015 in Germany, 5,611,484 of whom (64.8% men) were eligible for analysis. Among these, 500,027 (8.9%) were coded with obesity and 16,620 (0.3%) were coded as underweight; 5,094,837 (90.8%) were in neither classification (considered healthy/overweight) and served as the reference group for comparison, according to Dr. Keller and his colleagues.
Obese PAD patients were younger, more frequently women, and had less cancer but were diagnosed more often with cardiovascular disease risk factors such as diabetes and hypertension, compared with the reference group. In addition, there were higher levels of coronary artery disease, heart failure, renal insufficiency, and chronic obstructive pulmonary disease (COPD) in obese patients.
Obese patients had lower mortality (3.2% vs. 5.1%; P less than .001), compared with the reference group, and showed a reduced risk of in-hospital mortality (odds ratio, 0.617; P less than .001). Univariate logistic regression analyses showed the association of obesity and reduced in-hospital mortality was consistent and significant, even with adjustment for age, sex, and comorbidities.
In contrast, underweight patients were significantly more likely to die than those in the reference group (6% vs. 5.1%; P less than .001), according to the researchers. Underweight was associated with an increased risk for in-hospital mortality (OR, 1.18; P less than .001), and this was consistent throughout univariate analysis.
Underweight PAD patients also had significantly higher frequencies of cancer and COPD, but lower rates of diabetes mellitus, hypertension, coronary artery disease, and heart failure, compared with the reference group. Both obese and underweight PAD patients stayed longer in the hospital than the PAD patients who were not coded as underweight or obese.
Obese PAD patients had slight but significantly higher rates of MI (3.9% vs. 3.4%; P less than .001) and venous thromboembolic events, and more often had to undergo amputation surgery (8.3% vs. 8.1%; P less than .001), including a higher relative number of minor amputations (6.3% vs. 5.5%; P less than .001). However, major amputation rates were significantly lower in obese patients (2.6% vs. 3.2%; P less than .001), with univariate analysis showing a significant association between obesity and a lower risk of major amputation (OR, 0.82; P less than .001), which remained stable after multivariate adjustment.
Limitations of the study reported by the researchers included a lower than expected percent obesity in the 10-year database, compared with current rates, and the inability to follow tobacco use or to determine the socioeconomic status of the patients.
“Obesity is associated with lower in-hospital mortality in PAD patients relative to those with normal weight/overweight. ... Therefore, greater concern should be directed to the thinner patients with PAD who are particularly at increased risk of mortality,” the researchers concluded.
This study was supported by the German Federal Ministry of Education and Research; the authors reported that they had no disclosures.
SOURCE: Keller K et al. Clin Nutr. 2018 Oct 3. doi: 10.1016/j.clnu.2018.09.031.