The issue of whether or not obesity directly affects cardiovascular morbidity and mortality is unresolved. Obesity certainly is associated with risk factors for cardiovascular disease (CVD), but it is unclear whether it is a risk factor itself. For example, obesity is not included as an independent risk factor in the Framingham Risk Score. It is also unclear whether a patient with normal blood pressure or cholesterol levels should lose weight. Yan and colleagues studied the effect of body mass index (BMI) earlier in life on cardiac mortality within already established cardiac risk categories for older persons.
Researchers collected data on participants, including height, weight, blood pressure, total cholesterol, electrocardiography results, smoking status, medication use, and demographic information. The mean follow-up time was 32 years. The follow-up data were obtained from Medicare claims. Outcome measures included hospitalization for coronary heart disease (CHD), CVD, and diabetes. Diabetes was included only if it was listed on an inpatient record or listed at least twice on an outpatient claim. Older-age mortality was an additional outcome measure. Patients with preexisting cardiovascular conditions at baseline were excluded from the study. The final cohort included 17,643 participants 31 to 64 years of age. At baseline, patients were classified as having low, moderate, intermediate, elevated, or high cardiovascular risk. Each category was further divided by placing participants into normal weight, overweight, and obese groups.
At baseline, persons who were overweight and obese had higher blood pressure measures and were less likely to smoke than persons of normal weight. Cholesterol levels were similar across weight groups. CHD mortality risk was consistently higher among overweight and obese persons across all risk groups. However, morbidity risk was higher for obese persons in the low-risk group compared with the higher risk groups. The overweight and obese groups also were strongly associated with diabetes morbidity and mortality risk across each category.
The authors conclude that in the study cohort of persons 65 years and older, those who were overweight and those who were obese when they were 31 to 64 years of age had higher risks of hospitalization and mortality later in life when compared with peers of normal weight, regardless of concurrent risk factors. This study also shows that among persons living to be 65 years and older, having a normal BMI in young adulthood and middle age provides health benefits at all levels of conventional risk factors.