Evaluating the Cause of Death in Obese Individuals: A Ten-Year Medical Autopsy Study

Background: Obesity is a growing public health problem associated with increased morbidity and rate of death. Postmortem examination is imperative to determine the cause of death, to detect clinically unsuspected disease entities, and consequently to determine the actual impact of obesity on patient mortality. 

Methods: A total of 849 adult autopsies were retrospectively reviewed. Obese (BMI ≥ 30 kg/m2) and nonobese patients were separately studied. The primary cause of death in each group was categorized into malignancy, infection, stroke, ischemic and nonischemic heart disease, pulmonary embolism, hemorrhage, and primary nonneoplastic diseases of different organ systems. 

Results: Of 849 autopsies, 32.3% were obese. The leading causes of death in the obese population were malignancy (31.4%), infection (25.9%), ischemic heart disease (12.8%), and pulmonary embolism (6.2%). Obese individuals were statistically more likely to die from pulmonary embolism and liver disease and less likely to die from neurologic diseases and nonischemic heart disease. 

Conclusion: Autopsies on obese individuals constitute a third of all adult medical autopsies in our center. Increased death rates in the obese due to pulmonary embolism and liver disease should receive special clinical attention. Autopsy findings in the obese population should contribute to overall premortem disease detection, prevention, and management.

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Alex’s Notes: Have you ever wondered what exactly kills obese people? In the Prospective Studies Collaboration analysis, every 5 kg/m2 increase in BMI over 25 kg/m2 was associated with about a 30% higher overall mortality, 40% for vascular mortality, 60–120% for diabetic, renal, and hepatic mortality, 10% for neoplastic mortality, and 20% for respiratory and all other mortalities. These results become impressive when we consider that the analysis included 57 prospective cohort studies totaling 894,576 persons.

So basically, obese persons walk around with an increased risk of death from various chronic diseases. However, this doesn’t necessarily mean that they die from them. The current study thus reviewed the postmortem findings of 849 consecutive adult autopsies from 2003 until 2013 performed at NewYork-Presbyterian Hospital/Weill Cornell Medical College and compared the cause of death in obese and nonobese persons.

In addition to the post-mortem findings, all the subjects’ medical history, lab tests, radiographic images, etc. were reviewed. Similar to the US’s obesity rate, 32% of the patients were classified as obese. Of these, 25% were class II (BMI 35-40 kg/m2) and 25% were class III (BMI > 40 kg/m2). For the normal subjects, the BMI ranged from 11.3 to 29.9 kg/m2. I am very curious to know what that 11.3 person died from. Medical histories revealed the information in the table below.

  Obese Nonobese
Hypertension 60.9% 44.5%
Diabetes 35.4% 17%
Hypertriglyceridemia 18.2% 12.7%
Metabolic Syndrome 29% 3.3%

Evidently, the cause of death between the two groups was not really that different. Malignancy was the most common, representing 31.4% of obese deaths and 32.5% of nonobese deaths. Specifically, carcinoma was the most common form of malignancy. However, there were no significant differences between the groups in type of cancerous death. The second most common form of death in both groups was infection(25.9% obese versus 23.8% nonobese) with pneumonia accounting for 59.2% and 66.4% of the deaths, respectively.

Finally, ischemic heart disease (IHD) came in third, representing 12.8% of obese deaths and 10.4% of nonobese deaths. And again, there was no significant difference between the groups, nor was there a significant difference in the extent of coronary artery disease. That said, obese individuals were significantly more likely to have had a history of symptomatic IHD and myocardial infarction (MI), and a history of coronary artery revascularization procedure. So perhaps the more vigilant physicians helped prevent heart-related deaths.

In the end, the only significant differences for causes of death were pulmonary embolism, liver complications, neurologic, and hematologic. The first two were more prevalent in the obese, whereas the latter two were more prevalent in the nonobese.

Bottom line

Just because you have a disease or health risk doesn’t mean that is what will kill you. So continue to look both ways before crossing the street.

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