Assessing precision, bias, and sigma metrics of 22 measurands using Ricos and EFLM specifications and implementation...

The European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) biological variation (BV) database is currently the reference source for BV-based specifications, providing evidence-based and more stringent limits than the historical Ricos database.

This study aimed to assess the impact of the transition from old to updated BV goals on sigma metrics in our laboratory.

The study was conducted at the National Institute of Salah Azaiz medical biology laboratory over an 8-month period. It included 22 biological parameters for which coefficients of variation and biases were calculated using internal and external quality control materials. Sigma metrics were determined using Ricos and the EFLM desirable specifications.

Using Ricos desirable specifications, 27.3% of analytes (ALT, CK, iron, total bilirubin, triglycerides, and CA19-9) achieved sigma ≥ 6, 36.4% had sigma between 3 and 6 (AST, LDH, urea, uric acid, AFP, CEA, CA125, and CA15-3), and 36.4% had sigma < 3 (calcium, creatinine, glucose, magnesium, potassium, sodium, total cholesterol, total protein). With the stricter EFLM targets, 6 sigma performers decreased to 19.1% (CK, iron, total bilirubin, triglycerides). 28.5% of analytes had sigma between 3 and 6 (ALT, AST, urea, uric acid, CEA, CA19-9), and 52.4% had sigma < 3 (calcium, creatinine, glucose, LDH, magnesium, potassium, sodium, total cholesterol, total protein, AFP and CA125). The resulting internal quality control strategy hence differed. The quality goal index indicated that imprecision was the main limitation for most analytes.

Updating performance specifications from the historical Ricos database to the evidence-based EFLM resulted in more stringent BV goals that are challenging to achieve with current routine technologies. Intensified root-cause analysis, closer collaboration with manufacturers, and ongoing performance reassessment are necessary for poor performers.