EQA Interpretation Case Studies PDF
EQA Interpretation Case Studies PDF
EQA Interpretation Case Studies PDF
Samantha Jones
WeQas
Unit 6, Parc Tŷ Glas
Llanishen
Cardiff
Summary of Talk
Audience participation
Instrument A
Distribution P226
Same pool
distributed 3 times
Case Study 1 - answer
• Analyte: Creatinine
• Previous Dist / comments: P221 SDI <2, P224 SDI <1, several non returns, constant
poor SDI from P225. Inter assay precision poor. Negative bias to method mean,
compares well with instrument mean (n=2). N<8 in method group, SDI calculated
from overall mean value.
Instrument A
Instrument B
Case Study 2 - answer
• Analyte: Creatinine
Instrument C
Case Study 3 - answer
• Analyte: LDH
• SDI Score: Unacceptable, overall SDI 2.49, (All 4 SDI scores are >2 SDI)
• Accuracy: Linear regression shows 8% negative proportional bias and 11.3 IU/L
constant negative bias.
• Previous Dist / comments: Previous SDI graph shows SDI >3 at Dist PT, no
return, Dist PV shows good score (although still 6% bias) then increasing SDI
scores from that point. Negative bias compared to Method mean, Overall mean
and Reference values. Previous distribution graph shows long standing negative
bias.