Obesity may appear to confer a survival benefit in patients with existing CVD, but this advantage is not observed in patients with newly diagnosed CVD, according to data published in PLOS ONE.
“When you look at people who have existing CVD, the people who are more sick are more likely to have lost weight over time,” Virginia W. Chang, MD, PhD, associate professor of social and behavioral sciences and interim chair of social and behavioral sciences at New York University College of Global Public Health, told Cardiology Today. “That can make obesity look protective. It could also be the case that in the obese population, those with more severe CVD died earlier, so you’re left with a more selective population that’s healthier. All of these factors can make obesity look protective relative to being normal weight, but do not suggest a causal influence of obesity on survival.”
Researchers analyzed data from 30,529 patients (mean age, 62 years; 56% women) from the Health and Retirement Study. Interviews every 2 years on MI, congestive heart HF and stroke were reviewed from 1992 to 2010 in addition to mortality follow-up through 2012. Data were linked to Medicare claims, and although patients were not Medicare-eligible at baseline, they were eligible over time.
Patients either had incident or prevalent diagnoses (n = 5,870; mean age, 69 years; 49% women) of CVD. Data from patients with an incident diagnosis were also categorized by their prediagnosis BMI: underweight (< 18.5 kg/m2), normal (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), class I obese (30-34.9 kg/m2) and class II or III obese (≥ 35 kg/m2).
Patients with prevalent CVD and class I obesity had a hazard reduction of 36% for congestive HF (95% CI, 15-51), 29% for MI (95% CI, 14-42), 20% for stroke (95% CI, 3-34) and 18% for general heart disease (95% CI, 8-27) vs. those of normal weight.
“We did see the ‘obesity paradox’ in prevalent cases, which is what we expected,” Chang said.
In patients with incident CVD, however, the protective HR for stroke, congestive HF, MI and general heart disease in patients with incident CVD and class I obesity was substantially weakened and no longer statistically significant. Patients who were overweight had a lower risk for mortality from heart disease and MI, whereas those with class II or III obesity had an increased risk for mortality from heart disease.
Similar observations were seen in Medicare claims for patients with either prevalent or incident CVD.
“Our findings do not offer support for re-evaluating current clinical and public health guidelines in pursuit of a potential obesity paradox,” Chang and colleagues wrote. – by Darlene Dobkowski
For more information:
Virginia W. Chang, MD, PhD, can be reached at New York University, 715-719 Broadway, New York, NY 10003; email: firstname.lastname@example.org.
Disclosure: Chang reports no relevant financial disclosures.