QConnect Limits provide users robust, validated control limits. Traditional QC approaches used to determine QC limits have been derived or modified from clinical chemistry, typically quantitative, and may not be applicable to serology or nucleic acid testing (NAT) qualitative data.

Developed by NRL1, utilise historical data to determine expected upper and lower values of results for each QC sample/assay combination. These statistically validated QConnect limits flag red when your system is not running to specification.

1.  Dimech W, Vincini G, Karakaltsas M. Determination of quality control limits for serological infectious disease testing using historical data. Clin Chem Lab Med. 2014 Aug 12.

All QConnect participants using the same QC sample/assay combination submit results to EDCNet. Over time, multiple lots of QC samples tested by many laboratories, operators and instruments across numerous lots of reagents are collected. These results reflect the expected variation for that QC sample/assay combination and is used to determine an upper and lower limit for each QC sample/assay combination.

These limits allow for the identification of unacceptable variation, and aid in investigation of the source of variation including reagent lot numbers, instrument or equipment calibration and maintenance, operator errors, assay and QC sample storage, and transport or environmental conditions.


How to use QConnect Limits

When entering data into EDCNet, results outside the QConnect Limits for that QC sample/assay combination are flagged immediately red indicating further investigation is required. All results outside the QConnect Limits are held in quarantine until they are validated by an NRL staff member. Participants can overlay the QConnect Limits on Levey-Jennings and other EDCNet charts in conjunction with laboratory-specific and peer group limits. NRL also provides a suggested approach, including a check list, for the investigation and troubleshooting of unexpected results.

Note: QConnect QC samples are used in addition to the manufacturers’ controls and as such, the manufacturers’ instructions for validating an assay should be adhered to.

QConnect Limits is the differentiator of NRL’s QConnect concept and all other statistical methods used in the marketplace. Traditional QC limits (pass/fail) rely on establishment of standard curves based on smaller data sets, which has proven quite successful and reliable within many fields of pathology testing, particularly clinical chemistry.

NRL are the experts in the Science of Quality of infectious disease testing for serology and NAT. We understand that biological immune indicators such as antibodies don’t all express the same way biologically. The immune response to antibody production is not constant like organic and inorganic clinical chemistry analytes.

Only by adopting a statistical model based on QC limits setting based on thousands of data points, not dozens, can a true set of limits be expressed. This is the QConnect advantage, and it is backed up by significant data.

QConnect Limits ultimately is the statistical method that provides robust and accurate QC performance, ensuring the lowest risk of false positive and false negatives in your precious samples.