Hinal Pankajkumar Shah1, Shilpa Jain2
BACKGROUND
As a part of Internal Quality Assessment, it is a usual practice in Clinical Biochemistry Laboratories to run Internal Quality Control (IQC) sera and check the results for any violation of Westgard rules. A mean and standard deviation (SD) of minimum 20 values of IQC results is taken for plotting Levey-Jennings (LJ) chart, but results of extended period (60 or 90 days) can also be used to calculate mean and SD.
AIMS
ï?· To derive mean and SD of IQC results for a period of 20 days and 90 days.
ï?· To monitor daily IQC results for violation of Westgard rules using mean and SD of 20 days and 90 days.
ï?· To compare frequency of violation of Westgard rules and EQAS performance while using these two means and SDs.
METHODOLOGY
This study was conducted in the Clinical Biochemistry Laboratory of S.S.G. Hospital and Medical College, Vadodara, where two levels of IQC sera are run twice daily. When a new lot of IQC sera was put into use, means and SDs were derived using 20 days (Protocol-I) and 90 days (Protocol-II) results. Both were used for daily monitoring of IQC for 3 months. We compared frequency of violation of Westgard rules (13s, 22s, R4s, 10x) and EQAS Standard Deviation Index (SDI) for 10 different biochemical parameters while using these two protocols.
RESULTS
The Westgard rules were violated for a total of 48 times while using Protocol-I as compared to only 5 times while Protocol-II was used. No significant difference was found in EQAS results in terms of SDI.
CONCLUSION
From the current study, it is concluded that for IQC daily monitoring, if mean and SD are derived from longer period (90 days) results of IQC sera, there are fewer incidences of violations of Westgard rules without any compromising effect on EQAS results. Hence, by using more number of values over a longer period, one can reduce unnecessary rejections of run, re-run of IQC and repeated calibration of test parameters, thereby reducing the overall cost of testing and improving the turn-around time (TAT).
