From the onset of the COVID-19 pandemic, it has become clear that obesity is linked to an increased risk for complications. Among 438 adults hospitalized with COVID-19 from March 1 to May 31, 2020, nearly 90% had at least 1 underlying condition, and obesity was most commonly reported (73%; Table 1).1 Other underlying conditions, including hypertension, diabetes mellitus, and chronic lung disease, were considerably less prevalent.1

In March 2021, the World Obesity Federation reported that COVID-19 mortality rates were 10 times higher in countries where more than 50% of the population is overweight.2 Given that the current prevalence of obesity in the US is 42%, many patients whom nurse practitioners (NPs) and physician assistants (PAs) are managing are obese.3 This article will review the pathophysiology of obesity and COVID-19 and provide essential information for NPs and PAs supporting patients in the treatment and prevention of COVID-19.

Table 1. Underlying Conditions in Patients (N=438) With COVID-19 in US Hospitals1

Underlying ConditionPercentage of Hospital Admissions
for COVID-19, %
Obesity72.5
Hypertension40.6
Chronic metabolic disease36.7
Diabetes mellitus30.9
Chronic lung disease26.7

Epidemiologic Review of Patients With COVID-19 and Obesity

The increased risk for severe outcomes of COVID-19 for patients with obesity is evident in the literature.4,5 A hospital in Wuhan reported that nonsurvivors of COVID-19 were more likely to have a BMI greater than 25 kg/m2 compared with survivors (88.2% vs 18.9%; P<0.001).6

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In a study from the United Kingdom, 72% of patients admitted to the critical care unit for COVID-19 were overweight or obese, and mortality was 60.9% among patients with a BMI >30.7,8 Data from the United States show that obesity is linked to an increased risk of SARS-CoV2 infection and increased severity of COVID-19, including significantly higher rates of hospitalization, severe cases, intensive care unit admission, invasive mechanical ventilation, and mortality.9,10

Additionally, patients with obesity are more likely to have diabetes and hypertension, both of which are recognized as major risk factors for COVID-19 complications.11

Obesity appears to overcome protective factors associated with younger age with regard to COVID-19 severity (Table 2).12

Table 2. Risk for Admission to Acute or Critical Care for COVID-19 in Patients With Obesity Younger Than Age 60 Years12

BMIAdmission to Acute CareICU Admission
30 to 342× more likely1.8× more likely
≥352.2× more likely3.6× more likely
BMI, body mass index; ICU, intensive care unit

Pathophysiology of Severe COVID-19

It is pivotal for NPs and PAs managing patients with COVID-19 to understand the pathophysiology of the infection as it relates to the viral cascade that leads to a cytokine storm. Research shows that SARS-CoV-2 binds to angiotensin-converting enzyme 2 (ACE2) receptors, which are prevalent in the lung, heart, ileum, kidney, and bladder.13 In the lung, these receptors are mostly located on epithelial cells of the alveolar space. The virus often destroys these cells, causing distal lung damage in the early phases of infection.13 Thus, pneumonia is a feature of nearly all serious COVID-19 cases.14

Cytokine storm leading to acute respiratory distress syndrome (ARDS) is another common manifestation of severe infection. High levels of cytokines attract neutrophils and cytotoxic T cells, possibly causing lung damage.13 There is a positive correlation between interleukin 6 (IL-6) levels and severe disease in SARS-CoV-2 infections. Certain rare subsets of inflammatory monocytes further elevate IL-6 levels and accelerate inflammatory response in severe infection.13 In addition, central ACE2 receptors in the midbrain may be affected, resulting in sympathetic activation and vasoconstriction. This in turn leads to capillary leaking in the lungs, increasing the risk for ARDS.15 This level of endothelium involvement can cause hypercoagulability, leading to pulmonary and peripheral venous thromboembolic disease in multiple organs and possibly life-threatening respiratory failure.16

Obesity is associated with higher inflammatory cytokine levels, leading to a more severe disease course. Higher levels of the proinflammatory adipokine leptin and lower levels of anti-inflammatory adiponectin trigger subcutaneous adipose tissue to produce increased levels of inflammatory cytokines, which affect innate immunity.17,18

Interleukin-6, a proinflammatory cytokine shown to activate the inflammatory cytokine cascade for many days, is a cause of cytokine storm and a strong predictor of mortality.18,19 Thus, it is possible that adipose tissue acts as a significant source of IL-6 and potentially causes a cytokine storm in patients with obesity.18,19

Risk Factors Associated With Obesity and Worsening COVID-19 Outcomes

Adipocytes and related cells contribute to the pathogenicity and disease process in patients with obesity with COVID-19. Adipose tissue, particularly abdominal adipose tissue, exerts endocrine activity, effectively functioning as an endocrine organ that interacts with other endocrine organs and the immune system as well as influencing metabolic function.18

Angiotensin-converting enzyme 2 is upregulated in individuals with obesity and diabetes; thus, adipose tissue may provide a target for the virus and serve as a viral reservoir.17,18 SARS-CoV-2 affinity for ACE2 appears to be 10 to 20 times higher than that of severe acute respiratory syndrome coronavirus.17

Adiponectin level is a predictor of mortality in critically ill patients with COVID-19.18,19 This has led some researchers to suggest therapeutically targeting adipose tissue directly to manage COVID-19.7

Respiratory muscle strength is poor in patients with obesity despite the greater demand on respiratory muscles because of increased airway resistance and changes to chest wall mechanics.20 Quiet breathing accounts for 1% to 3% of oxygen consumption under normal conditions in individuals with a healthy weight but accounts for more than 14% of oxygen consumption in obese individuals.20 The stress of a respiratory infection further compounds the work required to breathe, putting these patients at increased risk for respiratory failure. Screening for respiratory muscle impairment in patients with obesity along with respiratory muscle training may help prevent serious complications.20

Because of these factors, patients with obesity are more likely to have decreased forced expiratory volume, forced vital capacity, functional capacity, and respiratory system compliance and increased respiratory dead space. Abdominal obesity impairs pulmonary function in the supine position. All these factors contribute to higher rates of invasive mechanical ventilation among patients with COVID-19 who are obese.21 This is compounded by the lack of clear guidelines for indication of invasive mechanical ventilation in SARS-CoV-221; therefore, various strategies are being implemented across hospitals.21 To prevent COVID-19 progression in patients with obesity with respiratory impairment, the monoclonal antibody tocilizumab — which binds to the IL-6 receptor and inhibits its activity — has been suggested.8

A case report from China involved a patient with obesity with COVID-19 who developed type 2 acute respiratory failure (hypoxia with hypercapnia).22 Although the patient recovered without progression to malignant obesity hypoventilation syndrome and the need for invasive mechanical ventilation, recovery was prolonged. Current guidelines for COVID-19 management fail to consider the increased risk for patients with obesity to develop type 2 respiratory failure and recommend earlier invasive ventilation therapy for these patients.22

Respiratory conditions, including asthma, obstructive sleep apnea, hypoventilation syndrome, and chronic obstructive bronchopathy, are common in obesity, causing increased susceptibility to infection, more rapid disease progression, greater rates of complications, and poorer outcomes.8

Vitamin D deficiency, which is common in obese individuals,8 impairs immune response and increases the infection risk. Vitamin D supplementation can normalize the balance of pro-inflammatory and anti-inflammatory cytokines, which prevents respiratory infections and reduces the complication risk in existing infections.8 Italy has among the highest rates of vitamin D deficiency in Europe, particularly in people with obesity, and it has been hypothesized that vitamin D deficiency may play a role in the link between obesity and higher rates of complications and mortality due to COVID-19.8

It is unknown whether diabetes increases COVID-19 complication risk independently of obesity and hypertension; however, diabetes is linked to increased morbidity and mortality in SARS-CoV.11 Mechanisms may include11:

  • Increased binding efficiency of the virus;
  • Decreased viral clearance;
  • Poor T cell function;
  • Increased susceptibility to hyper-inflammation, leading to cytokine storm; and
  • Presence of cardiovascular disease

Barriers to Diagnosis and Treatment of COVID-19 in Patients With Obesity

Early diagnosis of COVID-19 is key to effectively treating patients with obesity; however, barriers exist for diagnosing the virus in patients with obesity as well as in racial and ethnic minorities, populations that are also at greater risk for negative outcomes of COVID-19 (Table 3).23,24

Table 3. Risk Factors for Minorities With COVID-19

Racial and Ethnic Disparities23,24Risk Factors23,24
Inadequate nutritional educationObesity
Decreased access to healthy foodsPoor nutritional status
Decreased access to health careDiabetes
Living in a densely populated areaIncreased risk for exposure
Living in an area of lower socioeconomic statusLower testing rates; less access to health care

These disparities play out in COVID-19 hospitalization rates. Surveillance data from the Centers for Disease Control and Prevention show that, of hospitalizations in Michigan associated with laboratory-confirmed COVID-19 as of April 10, 2020, 33% were in Black patients whereas only 14% of this state’s population is Black.24 Changing the societal conditions that create these disparities can lessen infectious disease burden among minority communities and, by extension, the entire country.25

Certain factors of obesity hinder COVID-19 management:

  • Medical facilities not equipped to accommodate patients with severe obesity8
  • Obscured findings on pulmonary ultrasound because of excessive weight8
  • Obesity-related difficulties with intubation or catheterization procedures (eg, tracheal trauma from intubation attempts because of lack of glottis visibility, necessitating multiple attempts and the use of a bougie)26
  • Less effective influenza immunization in obese individuals, who show twice the risk for flu infections regardless of immunization status, could indicate less effective COVID-19 immunization for obese patients as well27

Chronic inflammation inhibits macrophage activity and is a causative factor behind poor vaccination success in obese individuals.19 Sedentary behavior also reduces macrophage activation and impairs feedback inhibition of proinflammatory cytokines.21

Implications for NPs and PAs

Obesity clearly worsens outcomes in COVID-19 and NPs and PAs must be aware of this risk to advise patients accordingly in health promotion. Understanding the implications of diet and socioeconomic risk can improve disease outcomes.

Careful screening of patients for BMI helps modify the risk for negative outcomes of COVID-19. When clinicians make patients aware of their high BMI and the associated risks, they can provide improved access to weight management and obesity reduction strategies. Patients who have a good rapport with their health care providers might be more amenable to adopting diet and lifestyle changes, such as eating healthy, balanced meals that will improve their BMI and reduce comorbid conditions of obesity.

Clinicians can explain to patients how they can incorporate more physical activity into their daily routines. Ask patients what small changes they can make to introduce exercise into their daily schedule. Taking the stairs instead of an elevator or escalator, finding ways to sit down less and move around more, or reducing screen time are some simple suggestions. Instead of merely recommending changes or providing resources for patients to follow up with on their own, NPs and PAs should include patients in the planning process so they feel more ownership of the changes.

Clinicians can refer patients to health coaches and dietitians or nutritionists to ensure that they follow through on the recommended changes. Practicing NPs and PAs should support all patients with lifestyle modifications for weight management to protect against physiological imbalances that favor inflammation, oxidative stress, endothelial dysfunction, and immune dysregulation. When clinically indicated, patients should be referred for weight-loss pharmacotherapy or bariatric surgery.

Although more studies are needed on this topic, safeguarding patients with obesity in this health risk is pivotal during the COVID-19 pandemic. Accurate information and education are key for patients with obesity to stay safe and healthy, and NPs and PAs play an important role in patient education. When clinicians communicate effectively with their patients and help them implement a plan for modifying unhealthy behaviors and lowering their BMI, they help reduce devastating COVID-19 complications.

Kristene Diggins, DNP, MBA, FAANP, CNE, NEA-BC, DCC, is a doctorate-prepared NP with 15 years of experience as a family NP, in both primary and geriatric care. In addition, Kristene is certified as nurse educator and administrator. She served as the National Manager of Professional Practice for 4 years with Minuteclinic, supporting nurse practitioners in their career development. Kristene works as adjunct faculty for University of Phoenix as well as Chamberlain University and Liberty University. Kristene and her husband live in Charlotte, NC.

References

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2. World Obesity Federation. COVID-19 and Obesity: The 2021 Atlas. March 20201. Accessed March 8, 2021. https://www.worldobesityday.org/assets/downloads/COVID-19-and-Obesity-The-2021-Atlas.pdf

3. Adult obesity facts. Centers for Disease Control and Prevention. Updated February 11, 2021. Accessed February 24, 2021. https://www.cdc.gov/obesity/data/adult.html

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This article originally appeared on Clinical Advisor

Topics:

COVID19 Health Disparity Infectious Disease Obesity