16
The Health | august-September, 2020
| Hot Topic |
Obesity
a serious risk
factor in Covid-19
It is advisable for high-risk individuals
to reduce weight by adapting a healthy
lifestyle
BY PROF DATUK
DR NIK RITZA KOSAI
NIK MAHMOOD
DR HARDIP SINGH
GENDEH and
DR MARDIANA
MARDAN
The need for recognition of risk
factors and high-risk population
is important to have a better
prevention and treatment approach
to treating Covid-19 patients.
Evidence has shown that the
factors contributing to the poor prognosis of
Covid-19 are advanced age and the presence
of other obesity-related comorbidities
such as diabetes mellitus, hypertension,
cardiovascular and pulmonary diseases.
It has been speculated that obesity acts
independently in increasing the risk and has
a worsening outcome. Reportedly, the rising
incidence of hospitalisation in the younger
population is correlated with obesity. This
poses a perturbation on its additional
impact to further aggravate the pandemic
due to the fact that obesity is already an
established growing prevalence worldwide.
Undeniably, there is very little available
data on Body Mass Index (BMI) for patients
with Covid-19 infections. Nevertheless, we
must not disregard the role of obesity in
Covid-19.
A descriptive study in the Seattle region
was among the first to report BMI data.
Although it involved a small sample size and
the numbers are too small for meaningful
statistical analyses, it was found that
a majority of the patients with obesity
required mechanical ventilation and a
significant percentage of these patients died.
Obesity can cause
respiratory dysfunction
The proportions are greater than those
without obesity. This is further justified by
the data from Shenzhen, China, New York,
USA and Lille, France. The risk of developing
severe pneumonia was higher in overweight
patients (86%) and even higher in those with
obesity (142%) compared to normal patients
from the 383 sample size in Shenzhen.
In New York, BMI of more than 40 kg/
m2 was the second strongest independent
predictor of hospitalization after advanced
age among 4,103 patients with Covid-19.
A small study of 124 infected patients in
Lille showed the need for mechanical
ventilation was associated with a BMI of
more than 35 kg/m2, independently of other
comorbidities.
In Korea, there are two studies that
reported on the first transmission case
outside China involving a Korean man who
was living in Wuhan before entering Korea
(index patient) and the first patient of Covid-
19. The similarity between these two cases
was that both of the patients were obese but
otherwise healthy.
To comprehend on how obesity plays an
important role in the pathogenesis of the
Covid-19 infection, we must compare the
anatomical, physiological and biochemical
disparity between an obese and a
normoweight person. Patients with obesity
Figure 1
Obesity
High fatality rate
Coronaviruses (CoV) are
enveloped, positive-sense,
single strand RNA viruses,
consisting of six species
known to affect animals
as well as humans. The
most fatal cases reported
in history were the severe
acute respiratory syndrome
coronavirus (SARS-CoV)
in 2002 and the Middle
East respiratory syndrome
coronavirus (Mers-CoV) in
2012.
In December 2019, a case
of unknown aetiology was
detected in Wuhan. It was
discovered that the disease
is caused by a new strain of
coronavirus, pre-defined as
the novel coronavirus (n-CoV)
that gives rise to an upper
respiratory tract infection.
Later, it was renamed SARS-
CoV-2 and the disease caused
by this virus is called the
coronavirus disease 2019
often have respiratory dysfunction.
It is characterized by the changes in
respiratory mechanism, increased airway
resistance, impaired gas exchange, low
lung volume and muscle strength that
results in impaired ventilation of the base
of the lungs and reduced oxygen saturation.
These individuals are predisposed to
hypoventilation-associated pneumonia,
pulmonary hypertension and cardiac stress.
Due to its lower and restricted baseline
lung functional capacity, obese patients tend
to be more susceptible to Covid-19 infection
and become vulnerable to the rapid severe
disease progression. It has been proven
that the reduced total lung capacity can be
Respiratory dysfunction
• Impaired respiratory
mechanisms
• Increased airway resistance
• Impaired gas exchange
• Low lung volume
• Low muscle strength
Comorbidities
• Cardiovascular disease
• Diabetes mellitus
• Kidney disease
Metabolic risk
• Hypertension
• Prediabetes
• Insulin resistance
• Dyslipidaemia
Severe course
of Covid-19
(Covid-19). The infected
patients can be seen to
exhibit a wide range
of symptoms such as
asymptomatic, having
undifferentiated mild fever
with vague symptoms or
respiratory compromise
such as shortness of breath
that could develop into acute
respiratory syndrome.
What we are most afraid of
is when these patients go into
septic shock that can lead to
refractory metabolic acidosis,
coagulation dysfunction
and eventually result in an
inevitable death. The World
Health Organisation (WHO)
had declared the viruses as
pandemic in March 2020 in
view of its rapid transmission,
progressivity and high fatality
rate. Ever since, Covid-19 has
had unprecedented impact on
social welfare and economy
globally.
improved by bariatric surgery.
Obesity is distinguished as a low-grade
state of inflammation and may impair
immune response. This in turn may
affect the lung parenchyma that leads to
an increased risk for inflammatory lung
diseases.
Recent research found that angiotensin
converting enzyme 2 (ACE2) is the reputed
receptor for the entry of SARS-CoV-2 into
host cells (Figure 2). There is a difference in
the tissue expression of ACE2 in heart, lungs
and kidneys between healthy individuals
and infected patients.
Moreover, the level of ACE2 expression
in adipose tissue is higher than that of
lung tissue, making it a major target and
vulnerable to the infection. Obese patients
have more adipose tissues leading to an
increase number of ACE2-expressing
cells and larger amount of ACE2.
Antihypertensive treatments such as
angiotensin-converting enzyme inhibitors
(ACEi) and angiotensin receptor blockers
(ARB) can also increase ACE2 expression and
increase susceptibility of the patient to viral
entry.
Previously, it has been established
that adipose tissue can act as a reservoir
to various pathogens including human
adenovirus (Ad-36), influenza A virus,
human immunodeficiency viruses (HIV),
cytomegalovirus, Trypanosoma gondii and
mycobacterium tuberculosis. By analogy,
SARS-CoV-2 might also infect adipose tissues
before propagating to other organs.
With regards to the influenza A virus,
obesity lengthens the period of virus
shading in which symptomatic obese
patients shed virus 42 per cent than
normoweight patients. It is indicated that
obesity is an independent risk factor for
hospitalization and death.
Adapting a healthy
lifestyle important
Obesity is also associated with an increased
risk of diabetes mellitus, hypertension,
cardiovascular, pulmonary and kidney
diseases. These comorbidities can result
in increased vulnerability to pneumoniaassociated
organ failures.
Hospitalized patients have shown
increased rates of both obesity and diabetes
for Covid-19 infection compared to nonhospitalized
cases in China, USA and Italy.
There are several potential mechanisms that
could offer explanation on the increased
susceptibility of Covid-19 infected patients
with diabetes.
This includes an increase in lung ACE2
expression, elevated circulating furin (a
protease involved in viral entry to cells) and
a decreased clearance of SARS-CoV-2 viral
particles due to impaired immunity.
There are more significant biological
abnormalities, including elevated