Proficiency panel testing--a reliable tool in external quality assessment of sputum smear microscopy services in...

To assess the proficiency of Senior TB Laboratory Supervisors (STLSs) and district level Laboratory Technicians (LTs) in sputum smear microscopy.

Intermediate Reference Laboratory (IRL), Ahmedabad had manufactured and validated Proficiency Panel Testing slides from sputum samples, made On Site Evaluation (OSE) visits of District TB Centres (DTCs) in two rounds, and conducted Proficiency Panel Testing of STLSs & DTC-LTs from January 2005 to June 2009.

High level of concordance in Z-N smear grading was found between Microbiologist and district laboratory staff. DTC readers reported overall consistency level of more than 98% in Z-N grade agreement during both the IRL, EQA, OSE visits. The tendency to over-grade the panel slides was much higher (more than 22%) as compared to under-grade (less than 2%) them in "correct slides". High False Positive (HFP) error was not observed in the present study.

Laboratory supervisor's proficiency can be quickly assessed by Proficiency Panel Testing, under multi-level quality assurance network system of sputum smear microscopy in public health programmes like the RNTCP. Proficiency Panel Testing is highly replicable and reproducible tool for quick and reliable assessment of proficiency of the staff and it can be made more effective by raising the proportion of lower grade positive slides in panel set of each reader. DTC readers' overall agreement level of more than 98% in Z-N grade suggests high level of precision and excellent consistency during both the IRL, EQA, OSE rounds. It is concluded that even for a large network of sputum smear microscopy centres under public health programmes like the RNTCP in order to take corrective action, Proficiency Panel Testing can be effectively used for quick identification of suboptimal- technical performance of the supervisory staff.