High BMI at Midlife Could Be a Predictor of Future Hospitalization for Heart Failure

Having a high body mass index (BMI) in midlife may lead to an increased risk of hospitalization for heart failure (HF), a new study has found.

Ambarish Pandey, MD, and a team of researchers from the University of Texas Southwestern Medical Center and The Cooper Institute in Dallas, Texas, studied 19,485 participants of the Cooper Center Longitudinal Study who received Medicare coverage from 1999 to 2009 in order to establish an association between BMI at midlife and cardiorespiratory fitness (CRF) as well as the risk of hospitalization for long-term HF after the age of 65.

The cohort was mostly Caucasian men who were relatively fit but had experienced HF. Patients of normal weight were defined as having a BMI <25.0 kg/m² (n = 8924); overweight patients, BMI 25.0 to 29.9 kg/m² (n = 8284); and obese patients, BMI <30.0 kg/m² (n = 2277).

After 127,110 person-years of Medicare follow-up, the researchers observed a total of 1038 HF events. They found that a high midlife BMI was significantly associated with a high risk of hospitalization for HF, with a 19% (95% confidence interval [CI], 1.12-1.26) increase in that risk for every 3 kg/m2 increase in BMI.

Participants who were considered obese with a low-fit CRF level experienced a HF hospitalization rate (per 1000 person years) of 22.4 (CI, 18.9-26.6) compared with participants who also had a low-fit CRF level but a normal BMI (13.6 [CI, 11.0-16.9]). In the moderately fit category, the hospitalization rate for obese participants was 12.8 (CI, 10.2-15.9) compared with normal-BMI participants, at 7.2 (CI, 6.2-8.4). Obese participants who were considered to have a high-fit CRF level experienced 5.7 hospitalizations (CI, 3.0-11.0) compared with those of normal BMI in this category, at 3.7 (CI, 3.1-4.5).

“HF risk increases with BMI even when metabolic health is present,” said Carl J. Lavie, MD, in an accompanying editorial in the same issue of JACC. “These data support the fact that fitness markedly alters the relationship between adiposity and subsequent prognosis.”

Without adjustment for CRF, the overall risk of HF that was attributable to BMI level was 12.5%. When adjusted for CRF, the increased risk of HF dropped to 8.4%.

As expected, the researchers observed an inverse association between midlife CRF levels and HF-event rate after age 65. They found that high-fit participants had a lower HF-event rate than individuals in the low-fit category.

Without adjusting for CRF levels, the overall risk of HF attributable to BMI was 12.5%; with adjustment for CRF levels, that risk dropped to 8.4%. In the low, moderate, and high CRF categories, the HF risk rates attributable to BMI were 14.5%, 7.2%, and 1.1%, respectively.

In reporting their observations, the authors concluded that the higher BMI-associated risk of hospitalization for HF was more pronounced among low- and moderate-fit individuals when compared with high-fit participants. “Mid-life CRF levels explained a large proportion of the HF risk associated with higher BMI levels,” they wrote, adding that, “…age related changes in CRF but not BMI was significantly associated with HF risk. Taken together, these findings highlight the important contributions that CRF plays on the observed association between BMI and risk of HF.”

The study, published in the May issue of JACC: Heart Failure, was titled, “Body Mass Index and Cardiorespiratory Fitness in Mid-life and Risk of Heart Failure Hospitalization in Older Age—Findings from the Cooper Center Longitudinal Study.”

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