Quality assurance of spirometry in a population-based study -predictors of good outcome in spirometry testing

The assurance of high-quality spirometry testing remains a challenge.

Spirometry training consisted of standardized coaching followed by certification for 35 spirometry-naïve and 9 spirometry-experienced research assistants. Spirometry was performed before and after bronchodilator (BD) in random population samples of 5176 people aged 40 years and older from 9 sites in Canada. using the hand-held EasyOne spirometer (ndd Medical Technologies Inc., Andover, MA, USA). Pulmonary function quality assurance with over reading was conducted centrally in Vancouver: spirograms were reviewed and graded according to ATS/ERS standards with prompt feedback to the technician at each site. Descriptive statistics were calculated for manoeuvre acceptability and repeatability variables. A logistic regression model was constructed for the predictors of spirometry quality success.

95% of test sessions achieved pre-determined quality standards for back extrapolated volume (BEV), time to peak flow (PEFT) and end of test volume (EOTV). The mean forced expiratory time (FET) was 11.2 seconds. Then, 90% and 95% of all manoeuvres had FEV1 and FVC that were repeatable within 150 ml and 200 ml respectively. Test quality was slightly better for post-BD test sessions compared with pre-BD for both groups of research assistants. Independent predictors of acceptable test quality included participant characteristics: female sex, younger age, greater BD responsiveness; but not study site or prior experience in completing spirometry by the technologist.

Good quality spirometry tests are attainable in large multicenter epidemiological studies by trained research assistants, irrespective of their prior experience in spirometry.