Internal quality control for immunodiagnostic laboratories

Internal quality control (IQC) is highly important and burning need for all laboratory settings involved in clinical analysis, diagnostics, biochemical analysis and analytical laboratory, etc. External Quality Assurance Scheme and IQC form the foundation of quality assessment during the analytical phase and serve as a key pillar in the broader framework of a laboratory's Quality Management System. The International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) 17025 standard emphasizes that the laboratory shall have quality control procedures for monitoring the validity of tests undertaken. The obtaining data shall be recorded in such a way that trends are detectable and within the prescribed range. The monitoring shall include regular use of IQC. IQC performance is typically evaluated using tools such as Levey-Jennings (LJ) charts and Westgard rules (WRs). These tools help laboratories monitor the accuracy, reproducibility, and precision of their analytical methods, instruments, and reagents. LJ charts visualize whether results fall within the acceptable control limits, while WRs offer a statistical approach to detecting systematic and random errors. When results deviate from expected norms, these tools trigger corrective actions to prevent the reporting of inaccurate data. In the current study, plasma samples reactive for human immunodeficiency virus, hepatitis C virus, and hepatitis B virus were utilized as IQC materials. These were analysed continuously for 20-day period. The signal-to-cutoff (S/Co) ratios were calculated, recorded, and then plotted using LJ charts. WRs were subsequently applied to assess performance trends and identify any potential deviations. The primary objective of this study is to reinforce the importance and implementation of IQC in any laboratory involved in clinical, medical, biochemical, or analytical testing. Establishing a strong IQC practice is not only vital for regulatory compliance but also indispensable for ensuring the delivery of accurate, consistent, and high-quality test results.