Table 4.
Reasons for Misclassification by Three-Step Algorithms
| Mammograms without Cancer Registry Linkage (N=191,865) |
Excluding mammograms for women with prevalent breast cancer (N=175,575) |
|||
|---|---|---|---|---|
| Type of Misclassification |
Reason for Misclassification | n (%) | Reason for Misclassification | n (%) |
| Misclassified as diagnostic |
Diagnostic HCPCS code Breast cancer diagnoses on claims in prior year* |
4,380(2.3) 426 (0.2) |
Diagnostic HCPCS code | 448 (0.3) |
| Misclassified as screening |
Prior history of breast cancer not detected by claims BCSC data indicating breast imaging within 9 mo Non-screening indication† |
6,802 (3.5) 947 (0.4) 793 (0.4) |
Non-screening indication† BCSC data indicating breast imaging within 9 mo |
3,350 (1.9) 979 (0.5) |
| Total misclassified | 13,348 (7.0) | 4,777 (2.7) | ||
Abbreviations: HCPCS=Healthcare Common Procedure Coding System; ICD-9-CM=International Classification of Disease, 9th Edition, Clinical Modification; BCSC=Breast Cancer Surveillance Consortium; mo=months
*
Breast cancer diagnosis codes can appear on claims of women without breast cancer (e.g., during evaluation to “rule-out” breast cancer).
†
Clinical indications for mammogram based upon BCSC mammogram data. Non-screening indications include evaluation of breast symptoms/signs and short interval follow-up.