ITEM 22.  Report how indeterminate results, missing responses and outliers of the index tests were handled.

Uninterpretable, indeterminate, and intermediate test results pose a problem in the assessment of a diagnostic test.[1,2,3] By itself, the frequency of these test results is an important indicator of the overall usefulness of the test. Furthermore, ignoring such test results can produce biased estimates of diagnostic accuracy if these results occur more frequently in patients with the target condition than in those without it, or vice versa.

Uninterpretable, indeterminate and intermediate test results have many causes.[2] A test result may fail technically or from an insufficient sample, such as the absence of cells in a needle biopsy from a tumor (uninterpretable result).[4,5,6] A test result may be invalidated by a concomitant medical condition or therapy that affects the test, e.g. the effect of beta-adrenergic blockers on heart rate response during an exercise test (indeterminate result).[7]

The occurrence of uninterpretable, indeterminate, and intermediate test results varies from test to test, but frequencies up to 40% have been reported.[2] Intermediate test results (not clearly positive or negative) may have diagnostic value, as in the case of ventilation perfusion scans that are neither normal nor high probability for pulmonary embolism(s).[8] The incorporation of such test results into clinical decisions making varies.[3]

The table for Item 19 rightfully includes non-diagnostic test results.

 

 

References

1. Philbrick JT, Horwitz RI, Feinstein AR, Langou RA, Chandler JP. The limited spectrum of patients studied in exercise test research. Analyzing the tip of the iceberg. JAMA 1982;248:2467-70.
2. Begg CB, Greenes RA, Iglewicz B. The influence of uninterpretability on the assessment of diagnostic tests. J Chronic Dis 1986; 39:575-84.
3. Simel DL, Feussner JR, DeLong ER, Matchar DB. Intermediate, indeterminate, and uninterpretable diagnostic test results. Med Decis Making 1987; 7:107-14.
4. Ronco G, Montanari G, Aimone V, et al. Estimating the sensitivity of cervical cytology: errors of interpretation and test limitations. Cytopathology 1996; 7:151-8.
5. Pisano ED, Fajardo LL, Tsimikas J, et al. Rate of insufficient samples for fine-needle aspiration for nonpalpable breast lesions in a multicenter clinical trial: The Radiologic Diagnostic Oncology Group 5 Study. The RDOG5 investigators. Cancer 1998; 82:679-88.
6. Giard RW, Hermans J. The value of aspiration cytologic examination of the breast. A statistical review of the medical literature. Cancer 1992; 69:2104-10.
7. Detrano R, Gianrossi R, Froelicher V. The diagnostic accuracy of the exercise electrocardiogram: a meta-analysis of 22 years of research. Prog Cardiovasc Dis 1989; 32:173-206.
8. Value of the ventilation/perfusion scan in acute pulmonary embolism. Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED). The PIOPED Investigators. JAMA 1990;263:2753-9.