Publication in the International Journal of COPD
Induced sputum is a noninvasive method to assess airway inflammation and is therefore frequently used in clinical trials for asthma and COPD. The quality of sputum cell preparations depends on multiple factors, including inter-individual differences in the ability to produce sputum, the proper selection of sputum plugs and the processing of samples.
The level of contamination with mouth and throat-derived squamous cells is most often used as a criterion for sputum quality. In this study we evaluated a more comprehensive quality score that also takes into account the more relevant inflammatory cell morphology and the amount of debris on sputum cell preparations.
The data shows that with respect to the major sputum cell types, this score is more closely related to the variability between sputum slide evaluators as compared to squamous cell contamination alone.
The score will help to avoid the unnecessary exclusion of samples from analysis (sufficient inflammatory cell morphology despite high levels of squamous cells) and to define a better cut-off for the exclusion of samples (bad inflammatory cell morphology despite low levels of squamous cells).
Overall, the score will support the definition of more appropriate cut-off levels and result in higher quality data for sputum cell analysis in clinical trials.
This research work is a cooperation of the German Center for Lung Research (DZL) and Fraunhofer ITEM.
Authors: Frauke Pedersen, Ulrich M. Zissler, Henrik Watz, Klaus F. Rabe, Jens M. Hohlfeld*, Olaf Holz*
*Fraunhofer ITEM
Fraunhofer Institute for Toxicology and Experimental Medicine