Genomic Analysis of an Obesity Paradox: A Microarray Study of the Aortas of Morbidly Obese Decedents With Mild and Severe Atherosclerosis

Complexities and complications of extreme obesity

Obesity is a common chronic disorder and has detrimental long-term consequences if left untreated. Herein, we report a case of a young lady who suffered from morbid obesity and many of its consequences, and we present a literature review of these complications. While the cause of obesity is multifactorial, the genetic component is particularly important in the pathophysiology of marked obesity. Resistance to Leptin is considered one of the main causes of obesity. There is a unique relationship between polycystic ovary syndrome and obesity, as observed in our case. Obesity is associated with cardiovascular and lung diseases such as heart failure, thromboembolic disease, sleep apnea, and pulmonary hypertension. Our patient had cardiomegaly (730 gm) with eccentric hypertrophy of left and right ventricles. The coronary arteries and aorta were free of atherosclerosis, which is a surprising finding that relates to the mysterious phenomenon of obesity paradox. The terminal event in our young woman was multiple segmental and subsegmental pulmonary arterial thrombi/thromboemboli superimposed on chronic cardiopulmonary stress due to massive obesity.

Obesity Paradox: Laboratory Findings in Uncomplicated Obesity. Is Bias a Plausible Explanation?

OBJECTIVES

Obesity predisposes to multiple diseases, such as heart disease, diabetes, stroke, arthritis, and malignancy. However, obese patients have better outcomes than normal-weight patients with some of these disorders, including those admitted to critical care units. We compared the results for common laboratory tests in patients with uncomplicated obesity against the findings in normal-weight patients.

METHODS

Patients who had a comprehensive metabolic profile test were identified. Patients with acute and/or chronic debilitating disorders were excluded, and the laboratory parameters were compared among 4 groups based on body mass index.

RESULTS

With the exception of elevated triglycerides and lower high-density lipoprotein in obese and morbidly obese patients, laboratory findings were not meaningfully different from those in normal-weight patients.

CONCLUSIONS

The obesity paradox of better outcomes in obese patients admitted to critical care units could not be explained on the basis of lower additional disease burden necessitating critical care admission due to abnormal laboratory values at the baseline. It is conceivable that unconscious bias against obese patients, with lower disease burden than normal-weight patients, triggers their admission to critical care, thus creating the appearance of better outcomes.

An unexpected paradox: wall shear stress in the aorta is less in patients with severe atherosclerosis regardless of obesity

BACKGROUND

Obesity is a widespread condition that is more prevalent in Western countries compared to others. Aortic atherosclerosis (AA) is a condition that frequently has been associated with obesity. An obesity paradox, where morbidly obese decedents had either no or minimal AA compared to nonobese decedents, recently has been described by some of us. The explanation for this almost counterintuitive paradox has yet to be determined, but a number of hypotheses were advanced, including hemodynamic factors producing aortic wall shear stress (WSS). The purpose of the present study was to determine if there was a relationship between AA and WSS, as determined by postmortem measurement of aortic wall diameters.

METHODS

Circumferences of the aorta at the levels of the ascending, thoracic and abdominal aorta were measured in 274 consecutive autopsies over 2-year period of time. AA was assessed using a previously described grading scale as either mild or severe. Circumferences were mathematically converted to diameters and WSS was calculated using the Hagen-Poiseuille formula. Two different methods to estimate cardiac output were used, both based on literature methods, one of which was body mass index (BMI) dependent, and the other BMI independent. Univariate and multivariable analyses of the relationship between WSS, age, BMI, gender, race and severity of AA were performed.

RESULTS

Of the 274 decedents, 140 had mild and 134 had moderate to severe AA. BMI <35 was associated with moderate to severe AA. WSS was inversely correlated with AA in all these segments of the aorta in each BMI subgroup with the exception of the ascending aorta for decedents with BMI ≤35 kg/m². Contrary to what we had hypothesized, WSS was not a determinant of the obesity paradox. However, among all the variables analyzed, a history of hypertension, diabetes mellitus and age were significant factors for developing AA (relative risk [RR] 0.35, P = .039; RR 1.51, P = .0006, RR 1.19, P = .0001, respectively).

CONCLUSIONS

Our data demonstrate that WSS was unexpectedly lower in decedents with moderate and severe AA as compared to those with mild AA. This observation, which requires further investigations, was seen in all BMI ranges and was confirmed by 2 methods to calculate WSS.

APOE - a genetic marker of comorbidity in subjects with morbid obesity

Background

In population-based studies, the genetic variability of the APOE E alleles have been associated with health outcomes. Health problems are common in subjects with obesity. This study explored associations between the APOE E alleles and comorbidity in subjects with morbid obesity.

Methods

The study included consecutive subjects referred for evaluation of bariatric surgery with morbid obesity (defined as BMI > 40 or > 35 kg/m² with complications related to obesity). The subjects followed a conservative weight loss program for 6 months before surgery and had a follow-up visit 12 months after surgery. Demographic data and a set psychosomatic scores (musculoskeletal pain, WHO-5 Well-Being Index, Rosenberg Self-Esteem Scale, Hopkins Symptom Check-list 10; Epworth Sleepiness Scale, and Fatigue Severity Scale) were collected, and blood samples were analysed for haematological and biochemical parameters and APOE alleles.

Results

One hundred and forty subjects (men/women: 32 (23%)/108 (77%) with mean age 43.0 (SD 8.7) years and BMI 42.1 (SD 3.8) kg/m² were included. One hundred and eight and 92 subjects had data after conservative treatment and 12 months after surgery, respectively. The prevalence of the APOE alleles were: E2E2: 1 (0.7%), E2E3: 13 (9.3%), E2E4: 4 (2.9%), E3E3: 71 (50.7%), E3E4: 47 (33.6%), and E4E4: 4 (2.9%). The prevalence rates were as anticipated in a Norwegian population. The weight loss during conservative treatment and after bariatric surgery was independent of E allele variability. E2 was associated with a significant or clear trend toward improvement of all psychosomatic disorders. There was a significant fall in CRP during the two treatment periods with weight loss. E2 and E4 were significantly associated with high and low CRP, respectively, but no associations were seen between CRP and comorbidity.

Conclusions

The most marked finding was the association between E2 and improvement of all psychosomatic disorders. The positive and negative associations between CRP and E2 and E4, respectively, could indicate effects on inflammation and immunological reactions.