Clinical diagnosis of current asthma: predictive value of respiratory symptoms in the SAPALDIA study

Bronchial asthma is a very common disease which often remains underdiagnose d. The aim of this study was to determine the predictive value of the most common respiratory symptoms and to explore the best symptom combinations to predict diagnosis of asthma, A questionnaire comprising common respiratory symptoms was submitted to 9,6 51 subjects aged 18-60 Srs, randomly selected from the Swiss population, of whom 225 subjects (2.3%) had current asthma as confirmed by their general practitioner, Based on these data the authors calculated the predictive val ues of single symptoms and symptom combinations to diagnose asthma, Wheezing was the most sensitive single symptom (sensitivity 75%). Simple sy mptoms such as wheezing with dyspnoea, chronic phlegm or chronic cough had specificity greater than 95%. Wheezing with dyspnoea (WD) or nocturnal dysp noea (ND) had the best positive predictive value (PPT) as isolated symptoms (24% and 21%, respectively). When combining symptoms, wheezing associated with daily dyspnoea at rest or nocturnal dyspnoea showed the best PPV (42% and 39%, respectively), almost double single symptoms such as WD or ND. Whe ezing associated with at least two of the three nocturnal symptoms (nocturn al dyspnoea, nocturnal cough or nocturnal chest tightness) had a sensitivit y of 80% to diagnose asthma, In conclusion, respiratory symptoms obtained by medical history are reliabl e predictors of asthma, The findings suggest that particular combinations o f symptoms are clinically useful in the differential diagnosis of asthma.