Table 2.
Checklist B for “Interference” Studies: Identifying Weaknesses in Study Designs in Blood Glucose Interference Publications
| Yes | Partial | No | |
|---|---|---|---|
| Reference method | Well-characterized reference method, ideally that quoted by the manufacturer. Full details provided. Reference glucose measurements used to control the stability of the sample. | Full details of reference method not supplied. | Use of an inappropriate reference method. Reference method affected by interference. |
| Use of appropriate samples | Heparinized venous whole blood should be used, ideally fresh from a single donor. Serum or plasma samples are allowed. Effects should be determined at single, specific glucose concentrations. Paired difference testing consists of adding a potentially interfering substance to a sample and evaluating bias relative to a control portion of the same sample. Full details provided. | Incomplete details provided. | Use of an inappropriate sample. No details provided. |
| Investigation at different glucose concentrations | Interference investigated at a number of glucose concentrations (low, normal, high). Details of concentration and preparation provided. ISO/DIS 15197:20117 recommends two concentrations for general interferences and three for hematocrit studies. | Use of two or inappropriate glucose concentrations. | Investigation at a single glucose concentration. |
| Number of interference levels tested, rationale, and preparation | Interferent free, therapeutic/normal, and toxic/high levels should be ideally tested at concentrations recommended in guidance documents. The sample matrix should be diluted by no more than 5%. Control pool prepared exactly as the test except interferent is replaced with the same volume of solvent. | Incomplete details provided. | Inappropriate concentrations of interferents tested. Incorrect dilution of sample. |
| Details of BG meter system performance | Meter imprecision and quality control checks should be provided to help determine the number of replicates and confidence levels in interpreting interference responses and to verify the system is working correctly. Precision should be consistent with manufacturers' performance specifications. | Full details of meter performance not provided. | No details of meter performance provided. |
| Number of replicates | Assayed at least three times within one analytical run. Number of replicates should be appropriate for the imprecision and claim. Tables of the number of replicates needed to detect interference effects with 95% confidence and power and determined by the within-run imprecision standard deviation can be found in CLSI EP7.8 | Incomplete details provided. | No details provided. |
| Presentation of results | Appropriate table or graph of results with the observed effect on the y-axis and the interferent concentration on the x-axis. | Results explained but not presented appropriately. | No tabular or graphical presentation of results. |
| Interpretation of results | Use of appropriate, reasoned levels of deviation and statistics to classify difference or effects as interference. Clinical relevance determines whether an analytical effect is considered interference (CLSI EP78). | Use of partially reasoned deviations to determine interference. | Use of arbitrarily defined deviations to determine interference. Difference in results from BG meter system in presence and absence of interferences not used for interpretation. |
| Full details provided | Sufficient information provided to verify the study was carried out in accordance with CLSI EP78 and ISO/DIS 15197:2011,7 of appropriate design and conclusions justified and correct. | Basic relevant details supplied. | No or few relevant additional details provided. |
| Independency | Unbiased and independent; no potential manufacturer bias. | Not applicable | No clear information if the study was performed independently; no peer review. |
| Concordance CLSI EP78 and ISO/DIS 15197:20117 | Concordance with guidelines. | Partial concordance with guidelines. | Deviation from guidelines. |
BG, blood glucose.