Impact on clinical decision making of quality control standards applied to sputum analysis in COPD

doi:10.1016/j.rmed.2010.10.009

Respiratory Medicine

Volume 105, Issue 3, March 2011, Pages 371-376

https://doi.org/10.1016/j.rmed.2010.10.009 Get rights and content

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Summary

Purpose

Sputum analysis is important in COPD exacerbation management. We determined whether application of stringent quality control criteria for sputum samples had an impact on culture results.

Methods

We analyzed sputum samples of 108 patients during stable COPD and during exacerbations. To all samples quality control standards and culture interpretation rules according to the American Society of Microbiologists (ASM) were applied.

Results

In sputum exacerbation samples considered appropriate according to ASM quality standards, criteria for infection (40%) were met more often compared to inappropriate samples (13%) (p < 0.001). The same pattern was observed when applying these rules to sputum samples obtained during stable disease, (50% vs. 18%, p < 0.001). There was no difference in the percentage of infectious cultures obtained during the stable state and exacerbations.

Conclusions

Applying stringent quality control criteria to sputum samples can have a profound effect on the labeling of sputum samples as infectious, and therefore on clinical decision making.

Keywords

Sputum

COPD

Exacerbation

Quality

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Statement of originality and clinical relevance: This paper describes the importance of stringent quality control criteria on sputum samples in COPD patients. Since there is a high variability in the quality of sputum samples it is plausible that using samples of inadequate quality can have major consequences on the interpretation of culture results and therefore on clinical decisions.

Based on our results we concluded that applying stringent quality control criteria to sputum samples can have a profound effect on the number of positive sputum cultures and by inference on clinical decision making. It is therefore necessary that quality criteria are used and published in the literature on sputum outcomes in COPD. Furthermore, more longitudinal research is needed on the change in bacterial load from the stable state to exacerbations.