Impact of introducing quality control/quality assurance (QC/QA) guidelines in respiratory specimen processing

Abstract

To assess the impact of the introduction of a new quality control/quality assurance (QA/QC) protocol on the processing and reporting of respiratory specimens. After implementation of guidelines for processing respiratory specimens, an investigation was carried out over a six-month period on 200 specimens, 105 sputa, and 95 deep tracheal aspirates (DTAs), assessed blindly by two independent investigators. Data regarding disagreement were arranged into two subgroups. A minor disagreement was defined as a difference in the two assessments of < 10 or 10-25 for white blood cell (WBC) or squamous epithelial cell (SEC) counts. A major disagreement was defined as one assessor reporting < 10 and the other > 25 for either WBC count or SEC count, or one assessor reporting the specimen as non-assessable, or both assessors having a minor disagreement in both the WBC count and the SEC count. Agreement was obtained on 111 samples. For 45 specimens, a major disagreement was documented, and in 44 cases, a minor disagreement was recorded, WBC being the most common cause of divergence. Data for sputa and DTAs were examined separately: of 45 major disagreements, 64.4% were observed for DTAs, while minor disagreements were recorded mostly for sputa. The role of the settings in which samples were taken in affecting quality was studied. Among the 105 sputa, 27 were from Community Health Centers (CHCs) and 78 from hospitalized patients. Agreement between the two observers was obtained in 48.1% of CHC cases versus 60.2% of hospital samples. To investigate how many of the rejected samples presented WBC > 25 suggestive of infection, we looked at the 107 samples rejected during the six-month period, grouped according to the suspected diagnosis. The highest number of rejected samples falls in the category of unrelated (non-respiratory) diagnosis, and clinical suspicion is not helpful in Gram stain interpretation. The annual saving (not culturing, not testing, and not treating) derived from this simple QC procedure totals about 5000 Euro. Standardization in microscopic screening of respiratory samples is difficult to achieve. Criteria for rejection must be adapted to local conditions after discussion with clinicians to increase their compliance with the newly introduced guidelines and to avoid sending unnecessary specimens. The effects on patient management and cost control are significant.