Pooled Sera as an Alternative to Commercial Internal Quality Control in Clinical Laboratories

Abstract

Introduction: Internal Quality Control (IQC) is run to assess the day-to-day performance of an analytical process, ensuring the reliability of patient results. However, commercial internal quality materials can be expensive and inaccessible for many laboratories. Therefore, there is a need for an effective and economical alternative to commercial IQC. Aim: To evaluate the effectiveness and stability of pooled sera as an IQC material. Materials and Methods: A laboratory study was conducted over a period of 50 days, from January 10 to February 28, 2023, in the Department of Biochemistry at Dr. Rajendra Prasad Government Medical College (DRPGMC), Kangra, Himachal Pradesh, India. Serum samples (150 μL) were collected from 100 leftover samples over a span of 10 days. The serum was thoroughly mixed and distributed into 75 aliquots. Commercial IQC was also reconstituted and distributed into 75 aliquots. Both the commercial and pooled sera IQC were stored at -20°C. One aliquot of pooled sera was analysed daily for 16 routine biochemistry parameters, along with the commercial IQC, for the entire 50-day period. The results from both materials were interpreted using L-J chart and Westgard multirule. The stability of pooled sera for these routine parameters was assessed by comparing the mean values of the biochemical parameters on day 1 and day 50. Data analysis was performed using Statistical Package for the Social Sciences (SPSS) version 20.0 software, and a paired t-test with a p-value <0.05 was considered statistically significant. The bias percentage for each pooled sera parameter was calculated and compared with the desirable bias for clinical significance. Results: Analytical errors were observed during the study period for Alkaline Phosphatase (ALP), urea, sodium, potassium, and chloride. The nature and number of analytical errors observed with both materials were the same, with Westgard rule 13s detecting random errors for ALP and rule 22s detecting systematic errors for urea and serum electrolytes (sodium, potassium, and chloride). Difference in the mean value of alanine transaminase, aspartate transaminase, and bilirubin, on day 1 and day 50 was statistically significant with p-values 0.035, 0.04, and 0.024, respectively. When these parameters were assessed for clinical bias, they were found to be clinically insignificant. Conclusion: Pooled serum is an effective and stable alternative IQC material for daily performance assessment of analytical processes. In-house IQC or pooled sera not only reduces the cost of quality control but also helps maintain continuity in the absence of commercial IQC, preventing any disruptions in the control system over an extended period.