A person who is severely overweight pays nearly $200 more for asthma treatment in a year than the average patient.
A local study of polyclinic patients has found that the latter spends around $605 a year, while an obese person - defined as having a body mass index (BMI) of 27 and above - pays about $795. For those considered to be overweight, with a BMI ranging from 24 to 27, asthma treatment costs $675 a year. A healthy person should have a BMI of less than 24.
"Very few people actually understand how much they pay for their asthma treatment in a year," said Dr Tan Ngiap Chuan, director of research at SingHealth Polyclinics. "This could give (the overweight) some extra motivation to work on their weight."
The bulk of the cost, he added, goes to medication and doctors' consultation fees, although indirect costs such as loss of work days are also factored in.
The 10-year study of 939 polyclinic patients examined the factors influencing the cost of asthma treatment here. It was published in the European Respiratory Journal in December.
Unsurprisingly, doctors also found that smokers incurred higher costs, paying an average of $754 a year compared with $665 among non-smokers. Cigarette smoke can irritate the airways and trigger asthma attacks.
But the experts also found that those who had quit smoking ended up paying about the same amount for treatment as non-smokers. "This shows that it is never too late to quit," said Assistant Professor Nguyen Van Hai, who is from the Duke-NUS Medical School health services and systems research programme, and who collaborated on the study.
Dr Tan said his study is unable to pinpoint the relation between obesity and higher asthma costs, but surmised that it could be because those who are obese generally need more medication.
"Higher doses of medication are often needed to match the weight of the patient," he said. "Using the dose for a normal-weight individual may be inadequate for an obese patient."
The study also found that the use of combination drugs to treat asthma could start out more expensive, but pays off in the long run by resulting in better asthma control and fewer visits to the doctor.
Combination medication refers to drugs that help to soothe the inflamed airways as well as open them up over a period of hours. "For some patients, the cost of medication deters them from using it regularly," Dr Tan said. "But this is an example of how you pay more and actually benefit from it."