A re-audit of pulmonary function laboratories in the West Midlands

Abstract

In 1991 the West Midlands Pulmonary Function Audit Group examined the consistency between pulmonary function laboratories in the West Midlands. Three healthy subjects visited 22 centres and performed a standard set of pulmonary function tests. Demographic data on nine hypothetical subjects was also supplied for the laboratories to produce predicted values. Equipment was checked for accuracy using standard methods. The 1991 audit revealed significant inter-laboratory variability. Sources of error were identified and after consultation, recommendations were made to improve consistency. In addition, national and regional training workshops were organized for laboratory staff. In 1995 the audit was repeated using the same three subjects. Significant differences continued for all predicted results except for residual volume (RV) and forced vital capacity (FVC) and for all measured results except for functional residual capacity (FRC). However, improvements in the coefficient of variation were seen compared with 1991 for predicted forced expiratory volume (FEV1), total lung capacity (TLC), gas transfer (TLCO), FVC, FRC and RV. Similar improvements were seen in measured results for FEV1 and FVC. Increased variation was seen for predicted corrected transfer factor (KCO) and actual RV. The majority of variables in the 1995 audit had a coefficient of variation of less than 5% between laboratories. Analysis of the predicted results from the hypothetical subjects continued to show unacceptable variation reflecting continuing computer algorithm inconsistency. The improvements seen are encouraging and suggest that a regular audit programme is worthwhile.

Adopting universal lung function reference equations

“…Many European centres used the equations derived for the European Community for Steel and Coal (ECSC) [4]. However, it was still evident that different hospitals in a given locality might use very different prediction equations [5], meaning a patient's outcome might vary depending on which hospital they were tested at.…”

“…Many European centres used the equations derived for the European Community for Steel and Coal (ECSC) [4]. However, it was still evident that different hospitals in a given locality might use very different prediction equations [5], meaning a patient's outcome might vary depending on which hospital they were tested at.The Global Lung Initiative (GLI) was set up by the European Respiratory Society in 2010 with the remit to produce spirometry prediction equations that spanned all ages and could be used globally. These equations (GLI 2012) have been successfully produced [6] to the benefit of patients worldwide.…”

Validity of spirometry performed online

“…In summary, both result in better quality criteria in the conventional spirometry. However, a difference of 5.9% is not crucial because variation in quality criteria between different respiratory function laboratories, or even between different technicians in conventional spirometry, exceeds this percentage [25,[33][34][35]. Conversely, although a greater number of spirometric manoeuvres and more time were needed for the online procedure in comparison with the conventional procedure, the mean differences were 0.5 additional manoeuvres and 0.7 min, which may be acceptable as well.…”

Prejudgement towards the quality of spirometry in primary care does not help our case

“…In contrast to our findings, the study reported recently by ENRIGHT et al [3] clearly demonstrates that the performance rate of technicians in a pulmonary function laboratory can indeed be very high. However, significant variation in spirometry test results between laboratories has previously been reported by DOWSON et al [4]. This should be kept in mind when judging the quality of spirometry in primary-care settings.…”