Quality Assurance

 Quality assurance of gFOBT testing  

Whilst an immunochemical test is recommended, programmes that adopt a traditional guaiac test need to apply additional laboratory quality procedures. To minimise variability and error associated with visual test reading, including manual results input, the following procedures should be considered

o Use of appropriate temperature for artificial lighting and neutral-coloured walls in the reading laboratory; 

o Use of a national laboratory training programme to prosper consistency of interpretation; 

o A blinded internal QC check each day for each analyst prior to commencing testing;

o Adoption of a monitoring programme to identify operator related analytical performance (e.g. positivity variability and bias); and 

o Double entry of test results 

 Quality assurance of iFOBT testing  

Consistency in analytical performance must be assured by the adoption and application of rigorous quality assurance procedures. Manufacturer’s Instructions for Use must be followed. Laboratories should perform daily checks of analytical accuracy and precision across the measurement range with particular emphasis at the selected cut-off limit. Rigorous procedures need to be agreed and adopted on how internal quality control data is interpreted and how the laboratory responds to unsatisfactory results. Performance data, both internal quality control and external quality assessment data, should be shared and reviewed by a Quality Assurance team working across the programme. Sufficient instrumentation should be available to avoid delays in analysis due to instrument failure or maintenance procedures

External quality assessment  

A European external quality assessment scheme should be developed to facilitate Europe-wide quality assurance of occult blood testing and enhance the reproducibility of testing within and between countries providing population screening

 Outcome monitoring  

All aspects of laboratory performance in respect of the screening test should be part of a rigorous quality assurance system. Uptake, undelivered mail, time from collection to analysis, analytical performance (internal QC and external QA), positivity rates, lost & spoilt kits and technical failure rate, technician performance variability and bias should each be subject to rigorous monitoring

Quality of information 

 The proportion of unacceptable tests received for measurement is influenced by the ease of use of the test kit and the quality of the instructions for use. This proportion should not exceed 3% of all kits received; less than 1% is desirable