Attaining a correct diagnosis of COPD in general practice

Chronic obstructive pulmonary disease (COPD) is common. Diagnosis should include objective evidence of airways obstruction and spirometry is recommended in guidelines and the general medical services contract in the UK. We assessed the impact of spirometry in general practice.

We determined by questionnaire the availability, staff training, use and the interpretation results of spirometry in 72% of general practices in Wales. We reviewed the diagnosis of COPD previously made in two general practices without spirometry.

Most practices had a spirometer (82.4%) and used it (85.6%). Confidence in use and interpretation of results varied widely: 58.1% were confident in use and 33.8% confident in interpretation. Spirometry was performed more often if confident in use and interpretation (both P<0.001) and was related to greater training periods (P<0.001). Spirometric confirmation of COPD varied widely (0-100%, median 37%). Of the 125 patients previously diagnosed with COPD 61 had spirometric confirmation, while 25 had reversible obstruction (range 210-800 mls), 34 had normal and 5 had restrictive spirometry.

Despite incentives to perform spirometry in general practice, lack of adequate training in use and interpretation suggests use is confounded and the diagnosis of COPD is likely to be made on imprecise clinical grounds.