Some current medications for COPD may increase
TB vulnerability, says new research
When Mr
Peter Tan (not his real name), who suffers from chronic obstructive pulmonary
disease (COPD), complained about deteriorating symptoms, his doctor sensed that
something was amiss.
Apart
from a worsening chronic cough, the 68-year-old businessman was coughing out
copious amounts of phlegm and was persistently out of breath. This was despite
him taking his medication regularly and having quit his smoking habit for some
time, said Dr Ong Kian Chung, a specialist in respiratory medicine at Mount
Elizabeth Medical Centre, who is treating Mr Tan for the lung disease.
It turned
out that Mr Tan was battling more than just one serious lung condition; he had
also come down with tuberculosis (TB), a contagious air-borne bacterial
infection which made headlines last month when an unusual drug-resistant
cluster was identified in an Ang Mo Kio block.
Mr Tan’s
concurrent COPD and TB episode is no coincidence, as mounting evidence suggests
a close connection between the two conditions.
Studies
have found that COPD patients have a three-fold increased risk of developing
active TB compared to those without the lung condition, according to Dr Ong,
who sees up to three such cases each year.
A person
with active TB is infectious to others when he coughs out germs into the air.
And
patients with a previous history of TB have a similar significantly higher
chance of getting COPD, he added.
With COPD
on its way to becoming the world’s third leading cause of deaths by 2020 as
predicted by the World Health Organisation (WHO), Dr Ong, who is the
vice-president of COPD Association (Singapore), said more needs to be done to
raise awareness of the link between the two conditions.
In COPD,
patients experience breathing problems due to damaged air sacs in the lungs.
Symptoms such as cough, phlegm and breathlessness are often magnified when both
conditions attack the lungs at the same time.
The WHO
estimates that about 4.5 million people die from COPD and TB annually, the
former affecting approximately more than 60,000 people in Singapore and is
consistently one of the top 10 causes of death here. In 2014, TB overtook the
human immunodeficiency virus as the top infectious disease killer worldwide.
“Such
data has raised the worrying prospect that the growing global burden of COPD
could potentially lead to a higher incidence of active TB, and vice versa. Both
conditions pose heavy health burdens,” said Dr Ong.
In
Singapore, a COPD sufferer is typically male and an older adult. The majority
of the patients seen at Tan Tock Seng Hospital (TTSH), which admits an average
of 1,000 patients with the lung disease each year, are smokers or ex-smokers
above the age of 55.
Non-smokers,
younger patients and women are not spared either.
Dr Ong
said that respiratory specialists here are seeing more local patients from
these groups. He estimated a 20 to 25 per cent increase in younger patients in
their early 30s and 40s in the last decade, possibly due to the ill effects of
smoking which is the disease’s top risk factor.
Professor
Sonny Wang, emeritus consultant and director of Tuberculosis Control Unit at TTSH,
which treats about three-quarters of all TB cases in Singapore, said it is not
uncommon to find both conditions in the same patient as they typically affect
older men and have a shared risk factor of smoking. Conditions such as diabetes
and malnutrition which impair the immune system also increases one’s risk of
developing both COPD and TB, said Dr Ong.
STEROIDS
MAY RAISE TB RISK
Furthermore,
recent studies now suggest that existing steroid medications, administered
orally or inhaled from a canister, can increase a patient’s risk of TB. They
are currently used as one of the first-line treatments of COPD, especially
during periods of exacerbation (worsening symptoms), said Dr Ong.
Steroids
are known to reduce patients’ immunity, predisposing them to TB, said Adjunct
Associate Professor Augustine Tee, chief and senior consultant of Changi
General Hospital’s Department of Respiratory and Critical Care Medicine.
In a
South Korean study published in the journal Chest in 2013, the use of inhaled
steroids in COPD patients was found to raise the risk of pulmonary TB by nine
times. In patients with inactive TB or had suffered previous TB episodes, the
risk is 25 times.
While
there are situations whereby steroid use may be necessary, for instance during
an episode of exacerbation, these newer study findings may lead to changes in
the recommended guidelines for COPD treatment in the coming years, said Dr Ong.
“With
greater awareness of the risks of inhaled steroids, doctors may prescribe a
lower steroid dose or seek other alternatives, such as the newer combined dual
bronchodilators,” said Adjunct Assoc Prof Tee.
Bronchodilators,
which relax the airway muscles, are another medication commonly prescribed to
relieve COPD symptoms. This group of medication has not been shown to raise the
risk of lung infections significantly, said Dr Ong.
According
to him, newer-generation dual bronchodilators — a combination of two types of
medications in a single inhaler device — may be a more effective regular
treatment option for COPD. He stressed that patients should not stop their
steroid medication on their own without consulting their doctors.
While treatment
can reduce symptoms and improve quality of life, Dr Albert Lim, senior
consultant of TTSH’s Respiratory and Critical Care Medicine, said none of the
existing medications have been proven to reduce the progressive decline of lung
function in COPD patients in the long term.
In the
severe stages, patients require oxygen therapy at home and have an average
survival rate of two to three years, similar to that of some advanced cancer
patients, said Adjunct Assoc Prof Tee.
“For
cigarette smokers, smoking cessation is the most effective way of preventing
the development of COPD and reducing the worsening of the condition,” said Dr
Lim.
In
addition, patients are recommended to undergo influenza and pneumococcal
vaccinations, exercise regularly and ensure good nutrition to keep the disease
under control and reduce the risk of complications.
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