Underdiagnosis of asthma: is the doctor or the patient to blame? The DIMCAproject

Background-It is important to diagnose asthma at an early stage as early tr eatment may improve the prognosis in the long term. However, many patients do not present at an early stage of the condition so the physician may have difficulty with the diagnosis. A study was therefore undertaken to compare the proportion of patients who underpresented their respiratory symptoms w ith the proportion of underdiagnosed cases of asthma by the general practit ioner (GP). A secondary aim was to investigate whether bad perception of dy spnoea by the patient was a determining factor in the underpresentation of asthma symptoms to the GP. Methods-A random sample of 1155 adult subjects from the general population in the eastern part of the Netherlands was screened for respiratory symptom s and lung function and the results were compared with the numbers of asthm a related consultations registered in the medical files of the GP. In subje cts with reduced lung function the ability to perceive dyspnoea was investi gated during a histamine provocation test in subjects who did and did not r eport their symptoms to their GP. Results-Of the random sample of 1155 subjects 86 (7%) had objective airflow obstruction (forced expiratory volume in one second (FEV,) below the refer ence value corrected for age, length, and sex minus 1.64SD on two occasions ) and had symptoms suggestive of asthma. Of these 86 subjects only 29 (34%) consulted the GP, which indicates underpresentation by 66% of patients. Of all subjects with objective airflow obstruction who presented to their GP with respiratory symptoms, 23 (79%) were recorded in the medical files as h aving asthma, indicating underdiagnosis by the GP in 21% of cases. Of the s ubjects with objective airflow obstruction who visited the GP with respirat ory symptoms 6% had bad perception of dyspnoea compared with 26% of those w ho did not present to the GP in spite of airflow obstruction (chi(2) = 3.02 , p = 0.08) Conclusions-Underpresentation to GPs of respiratory symptoms by asthmatic p atients contributes significantly to the problem of underdiagnosis of asthm a. Underdiagnosis by the GP seems to play a smaller role. Furthermore, ther e are indications that underpresentation of symptoms by the patient is at l east partly explained by a worse perception of dyspnoea.