Could Biased Medication Prescribing Explain Obesity Paradox in PCI?

The so-called “obesity paradox” that has confounded researchers for years may have a simpler explanation than previously thought.

Multiple studies over the years have provided support for the idea that patients who are overweight or obese are less likely to die from certain chronic health conditions, and that the obesity itself somehow confers protection. 

Now, a study from the Veterans Affairs Clinical Assessment, Reporting, and Tracking System Program offers a possible reason for better survival in overweight patients—they may get more preventive medications than patients of normal weight because their doctors may perceive more of an immediate concern about their health and mitigating risk factors.

“Our hypothesis was actually that despite the obesity paradox, we would see lower rates of guideline-recommended therapy in the obese, based on some of the stereotypes and things we have seen in the literature regarding these patients,” lead author Javier A. Valle, MD (VA Eastern Colorado Health Care System, Denver, CO), told TCTMD, pointing to the stigma associated with obesity in the healthcare profession. “That was not the case.”

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His study, published in the Journal of the American Heart Association, involved 17,037 patients with known CAD or its equivalent, prior MI, or heart failure who were referred for elective PCI in the VA system between 2007 to 2012. When they were stratified by BMI, 13.9% were normal weight (19 to 25 kg/m²), 35.3% were overweight (> 25 to 30 kg/m²), and 50.8% were obese (> 30 kg/m²). Compared with normal-weight patients, those who were overweight or obese were more likely to have a history of CAD, A-fib, sleep apnea, hypertension, or diabetes. Patients with normal weight were more likely to have a history of heart failure, be current tobacco users, have lung disease, and have prior cerebrovascular disease, MI, or cerebrovascular accident.

To assess medication prescribing differences, Valle and colleagues looked at all patients with a guideline indication for a statin drug, beta-blocker, ACE inhibitor/angiotensin receptor blocker (ACE/ARB), or anticoagulant. 

On average, more overweight and obese patients were prescribed statins, ACE/ARBs, and beta-blocker/statin combinations compared with normal-weight patients. Additionally, obese patients were more likely than either of the other two groups to receive beta-blockers and beta-blocker/ACE/ARB combinations. No differences were seen across groups for anticoagulant prescribing.

Guideline-Recommended Therapies by BMI

Valle said the results were “a little bit of a surprise” and suggest that medication prescribing may be a potential contributor to the obesity paradox. “There may be something about obese patients, about the way they interact with physicians and the way physicians view them that triggers something where the physician is more readily saying I need to put these men and women on guideline-recommended therapy.”

The study did not look at whether patients actually were taking the medications that were prescribed for them, however, focusing only on whether guideline-recommended therapy was initiated by a physician. It also did not look at outcomes, but Valle said the expectation would be that overweight and obese patients would do better than normal-weight or underweight patients, as other studies have shown.

“The thing we wonder but don’t really know is whether there is a higher level of vigilance that may not be fully captured in medication prescribing or adherence data,” Valle said. “[Obese and overweight patients] may be seeing their physicians more frequently and having closer follow up. That’s one of the things we need to get at, and we need to sort of evaluate this ‘culture of care’ and how it ties into how physicians think about the patient in front of them.”

• Valle JA, O’Donnell CI, Armstrong EJ, et al. Guideline recommended medical therapy for cardiovascular diseases in the obese: insights from the Veterans Affairs Clinical Assessment, Reporting, and Tracking (CART) program. J Am Heart Assoc. 2016;5:e003120.

Disclosures:

• Valle reports no relevant conflicts of interest.

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