Monitoring of CBNAAT Quality Indicators

Monitoring of quality indicators is an essential component of quality assurance for the Cartridge-based Nucleic Acid Amplification Test (CBNAAT).

• Routine monitoring of quality (performance) indicators:
  1. Critical element of quality assurance for any diagnostic test 
  2. International Organisation of Standardisation (ISO) requirement
• Each testing site should collect and analyze quality indicators monthly.
• Document and investigate any unexplained change in quality indicators, such as:
  1. Increase in error rates
  2. Change in Mycobacterium tuberculosis (MTB) positivity rate or Rifampicin (Rif) resistance rate
  3. Significant change in volume of tests conducted
  4. Error rates > pre-determined threshold (>5%)
  5. Test turnaround time
• All unexpected trends should be reviewed by the laboratory manager and linked to corrective actions.
• Standard set of quality indicators should be used for all CBNAAT testing sites.
• System should be in place for centralized reporting of monthly quality indicators.
• Each instrument should be monitored monthly, using the following minimum set of indicators to evaluate proper use:
  1. Number of tests performed per month
  2. Number and proportion of MTB detected; Rif-resistance not detected
  3. Number and proportion of MTB detected; Rif-resistance detected
  4. Number and proportion of MTB detected, Rif-indeterminate
  5. Number and proportion of MTB not detected
  6. Number and proportion of errors
  7. Number and proportion of invalid results
  8. Number and proportion of no results
  9. Median time to result after receipt of the specimen

Figure: Monthly Quality Indicators for CBNAAT

Where possible, disaggregated data according to the tested population group (HIV positive, Multi-drug resistance (MDR) risk, extrapulmonary or paediatric TB) is collected.

Quality Indicator Monitoring: Troubleshooting Aid

Identifying the number and type of various errors can help with troubleshooting since certain errors may be associated with processing, instrumental or environmental conditions

The following analyses may be performed:

• The number of errors occurring by user
• The number of errors occurring by instrument module
• The number of tests lost due to power outages or surges
• The number, duration and causes of routine interruptions in the CBNAAT testing service

Video : Monitoring of CBNAAT Quality Indicators

Resources

• NTEP Monthly Quality Indicator Sheet