Validity and interpretation of spirometric recordings to diagnose COPD in UK primary care

Abstract

Background

The diagnosis of COPD is dependent upon clinical judgment and confirmation of the presence of airflow obstruction using spirometry. Spirometry is now routinely available; however, spirometry incorrectly performed or interpreted can lead to misdiagnosis. We aimed to determine whether spirometry undertaken in primary care for patients suspected to have COPD was of sufficient quality and whether their spirometry was correctly interpreted.

Methods

Two chest physicians re-read all spirometric readings for both quality of the procedure and interpretation, received as a part of COPD validation studies using data from the Clinical Practice Research Datalink (CPRD). We then used logistic regression to investigate predictors of correct interpretation.

Results

Spirometry traces were obtained for 306 patients, of which 221 (72.2%) were conducted in primary care. Of those conducted in primary care, 98.6% (n=218) of spirometry traces were of adequate quality. Of those traces that were of adequate quality and conducted in primary care, and in whom a general practitioner (GP) diagnosis of COPD had been made, 72.5% (n=218) were consistent with obstruction. Historical records for asthma diagnosis significantly decreased odds of correct interpretation.

Conclusion

The quality of the spirometry procedure undertaken in primary care is high. However, this was not reflected in the quality of interpretation, suggesting an unmet training in primary care. The quality of the spirometry procedure as demonstrated by spirometric tracings provides a re-assurance for the use of spirometric values available in the electronic health care record databases for research purposes.

Keywords:

• pulmonary disease
• chronic obstructive
• general practice
• respiratory function tests
• data accuracy
• electronic health records

Acknowledgments

We are very grateful to Dr John R Hurst for checking spirometry traces as part of the previous studies on COPD and AECOPD validation in CPRD. This study was supported by the Medical Research Council (G0902135) and GSK (WEUSKOP5893). The abstract of this paper was presented at the British Thoracic Society Winter Meeting 2015 as a poster presentation with interim findings. The poster’s abstract was published in “Poster Abstracts” Thorax.

Disclosure

HM is employed by GSK R&D and owns shares and stock options of GlaxoSmithKline Plc. The other authors report no conflicts of interest in this work.