The validity of diagnostic support of an asthma/COPD service in primary care

Background To support GPs in diagnosing and monitoring their patients with asthma/chronic obstructive pulmonary disease (COPD), 'asthma/COPD services' have been developed. Within these services, pulmonologists perform structured diagnostic and therapeutic assessments based on the combination of written history data and spirometry. Aim This study determines the validity of the diagnosis and advice when assessed using only written information. Design of study The results of the diagnostic procedures of an asthma/COPD service were compared with the results of regular office consultations by pulmonologists. Setting From January until August 2004, two pulmonologists examined 80 randomly selected patients referred to an asthma/COPD service in Eindhoven, the Netherlands. Method Concordance was analysed between diagnosis and advice based on written spirometry and history data, with assessments based on live consultations with the same patients by pulmonologists. Results The validity of the assessed diagnosis was high (Cohen's kappa = 0.82). When the diagnosis was uncertain, the advice for medical treatment scored low in validity (Cohen's kappa = 0.39). The advice for additional diagnostic examinations had a high internal validity: in half of the patients, uncertainty in diagnosis turned into a definite diagnosis of asthma/COPD, or another cause for the complaints of the patient was revealed; in the other half, the diagnosis of asthma/COPD could be rejected. Conclusions A structured asthma/COPD service offering diagnosis and diagnostic advice assessed from written spirometry and history data is a new and valid facility that can support the GP who faces the complicated diagnostic procedures in a progressive number of patients with asthma/COPD.