Obese 'over-diagnosed' with asthma

The obese are likely to be wrongly diagnosed

Scientists say too many obese - and too few underweight - people are being diagnosed as having asthma.

It has also been found children of heavy smokers are less likely to get the treatment they need for asthma, because parents do not take them to the doctor.

Research in Australia found overweight people did report more wheeziness and shortness of breath, but did not show what they called the 'true' signs of asthma.

However, underweight people who were not diagnosed as asthmatic did show the symptoms.

The Australian scientists investigated almost 2,000 adults aged between 17 and 73.

They recorded asthma diagnoses and weight measurements, but carried out their own asthma checks.

Adjustments were made for age, sex, smoking and family history.

Diagnosis 'twice as likely'

Once these factors had been accounted for, it was found obese people were twice as likely to be diagnosed with asthma.

But they were not twice as likely to have overly responsive airways, which is a sign of asthma.

The authors suggest breathlessness in the obese may be due to the increased effort required for breathing, which is being misdiagnosed as asthma.

In the second study, Scottish researchers looked at health records for 400 children aged two to 12, whose parents smoked

They tested the children's spit for levels of cotinine, a by-product of tobacco, to test the extent of their passive smoking.

It was found children with parents who were heavy smokers were had up to a third fewer visits to the doctor for asthma.

The frequency of visits also fell the more the parents smoked, a link which was especially evident when it was the mother who smoked.

The same link was not seen for other illnesses.

The researchers commented: "High levels of parental smoking in the home are associated with a reduction in health care contacts for asthma.

"This could be due to a lack of awareness of asthma symptoms among heavy smokers, or a reluctance to visit the GP."

They warned: "Children with asthma who have parents who smoke heavily may not be receiving adequate management."

'Overdiagnosis risk

Dr Martyn Partridge, National Asthma Campaign Chief Medical Adviser said: "Obesity as a cause for breathlessness is surprisingly under-recognised.

"This is an important study because it highlights the likelihood of over-diagnosis of asthma in the obese and the danger that these patients may be treated unnecessarily.

"Similarly it should be a warning to us to recognise the possibility of asthma in those who are underweight."

"This study highlights the difficulty of diagnosing asthma. People with asthma have the right to expect an early and accurate diagnosis of asthma so appropriate management can be started without delay."

The studies are published in Thorax, the journal of the British Thoracic Society (BTS).

Dr John Harvey, chairman of the BTS external relations committee said: " Although obesity has been linked with asthma, health professionals must treat all patients according to correct measurement of their lung function and symptoms."

Highlighting the research showing children of heavy smokers are taken to the doctors with symptoms of asthma less, he said: "Medical evidence clearly shows that passive smoking can affect the severity of asthma in children. Parents should take this into account.

"This research may have highlighted an important gap in understanding among this group about what asthma symptoms actually are - and how they are triggered.

"This gap must be plugged if we are to help these children to breathe more easily."