Have the experts got it wrong? According to the Global Asthma Network (GAN) Steering Group’s Global Asthma Report 2014, 330 million people worldwide suffer from bronchial asthma. The World Health Organisation and the Global initiative For Asthma mention figures of 230 and 300 million patients respectively. These figures could be much too high, Dr. Shawn Aaron, University of Ottawa, writes in a recent study.
Diagnoses put to the test
“We have recruited 701 adults who had been diagnosed with asthma during the last five years”, says Aaron. In the end, data from 613 people was able to be included. From among these, 86.6 percent took baseline asthma medication, such as inhalable corticosteroids and or leukotriene antagonists. “We brought all the participants into our laboratories and conducted extensive lung function tests”, explains the researcher. If the doctors found no evidence of the disease, they asked patients to discontinue their asthma medications. Provocation tests then followed, in order to confirm or disprove the presence of the condition.
Criteria for the presence of asthma were considered to be an improvement by 12 percent or more in (FEV1) (forced expiratory volume in one second) following administration of a bronchodilator; expiratory peak flow fluctuation of more than 10 percent; or that a methacholine-provocation test proved positive. Pulmonologists simultaneously searched for other causes of symptoms.
“Ultimately, we found out that 33 percent of participants were not suffering from asthma and therefore had no need for medication”, says Aaron. Even twelve months after their first examination, there was a lack of laboratory diagnostic or clinical evidence of the disease with 181 individuals.
“Physicians need to make the right tests”
Aaron doesn’t refrain from offering one particular explanation: “On the one hand, GPs wrongly diagnose asthma with some patients. On the other hand, some patients may have had asthma, but are now in remission”. And last but not least, there are many pathologies associated with cough or dyspnea. The spectrum here ranges from gastro-eosophageal reflux disease or allergic rhinitis to decompensated congestive heart failure or pulmonary embolism.
“We found that two percent of our randomly selected patients had severe heart or lung disease and had been misdiagnosed with asthma”, adds the scientist. Doctors found ischaemia, subglottic stenoses, interstitial lung disease, pulmonary hypertension and other diseases among the study participants.
One criticism remains: “Asthma is not so difficult to diagnose, but doctors have to do the right tests”, writes Shawn Aaron. He advocates first and foremost lung function tests – the aim here being to ascertain total volume of inhaled and exhaled air (vital capacity, VC) and forced exhaled volume in one second (FEV1).
If adults do not suffer – or are no longer suffering – from asthma, using medications no longer makes sense. Aaron points out the number of side effects that end up being tolerated without any necessity, as well as the high costs involved.
Misdiagnosis with children
Ingrid Looijmans-van den Akker from Utrecht has arrived at similar results with studies of children as well. She retrospectively scrutinised data from 4,960 Dutch children. All of the young patients were between six and eighteen years of age. GPs had diagnosed asthma for 546 of them. A further 106 children were included because of their medication, the end result being that the researcher had data from 652 people.
In only 16.1 per cent of all cases had asthma been confirmed via spirometry. With a further 23.2 percent, symptoms at least suggested the presence of the disease, without evidence for this being provided. And Looijmans-van den Akker considers asthma to be unlikely with 53.5 percent. As far as misdiagnosis is concerned, the researcher indicates a figure of 7.2 percent. She too criticises the fact that too few asthma diagnoses were confirmed by lung function tests.
No medical errors
Why it is that GPs and paediatricians do not send their patients to a specialist is unclear. Neither Shawn Aaron nor Ingrid Looijmans-van den Akker established contact with the treating fellow practitioners. Since their investigations were carried out in two different healthcare systems, one can assume that national specifics are not the crux of the matter.
There exist several additional other explanations. “There is no gold standard in diagnosing asthma”, experts write. Patients can be symptom free for a long time, then experience a threatening attack after contact with allergens. Studies involving specialists are of little benefit: “The methacholine-provocation test has poor specificity, if excellent sensitivity”, it was further stated. And last but not least, a reliable diagnosis of children younger than five or six years of age is practically impossible.
Their conclusion: “In most cases, therefore, these are not medical errors; the problem resides in the nature of asthma. The publications should be used as an opportunity to review every asthma patient from time to time as to the necessity (overdiagnosis?) to be taking current asthma medication, its dosage, and to reduce the amount of treatment used in managing asthma”.