Sunday, July 31, 2016
Singapore - A double whammy: Lung disease patients at risk of active tuberculosis
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.