Table 2. Accuracy of registry coding compared to Medicare claims in the SEER-Medicare cohort*.
| Under- ascertainment |
Kappa | Specificity | NPV | PPV | ||
|---|---|---|---|---|---|---|
| All patients | 18.7% | 96.5% | 97.1% | 97.1% | 84.2% | |
|
| ||||||
| Age | ||||||
| 66-69 | 19.4% | 72.2% | 93.9% | 77.2% | 95.0% | |
| 70-74 | 18.9% | 75.7% | 96.5% | 79.5% | 96.9% | |
| 75+ | 18.1% | 81.8%− | 98.2% | 88.2% | 97.0% | |
| Race | ||||||
| White | 18.7% | 78.6% | 97.2% | 84.0% | 96.7% | |
| Black | 20.4% | 76.6% | 95.8% | 85.5% | 93.8% | |
| Other/Unknown | 17.1% | 79.8% | 96.3% | 86.5% | 95.1% | |
| Year of Diagnosis | ||||||
| 2001 | 18.1% | 80.4% | 98.0% | 85.3% | 97.5% | |
| 2002 | 20.2% | 77.7% | 97.7% | 83.3% | 97.1% | |
| 2003 | 17.1% | 79.4% | 96.8% | 84.5% | 96.4% | |
| 2004 | 18.3% | 78.5% | 96.9% | 84.0% | 96.3% | |
| 2005 | 17.7% | 79.2% | 96.6% | 85.2% | 95.8% | |
| 2006 | 18.6% | 78.0% | 96.4% | 84.4% | 95.6% | |
| 2007 | 21.1% | 76.4% | 97.2% | 82.8% | 96.4% | |
| Registry† | ||||||
| SEER-9 | 14.1% | 91.4% | 97.0% | 87.1% | 96.6% | |
| SEER-Other | 21.8% | 87.9% | 97.2% | 82.4% | 96.3% | |
| County of residence | ||||||
| Urban | 18.4% | 78.4% | 96.9% | 83.8% | 96.3% | |
| Rural | 22.5% | 79.7% | 99.1% | 87.5% | 98.1% | |
| Stage | ||||||
| I | 15.8% | 81.0% | 97.0% | 85.6% | 96.7% | |
| II | 22.2% | 76.5% | 97.5% | 83.9% | 96.4% | |
| III | 29.1% | 67.2% | 96.2% | 76.8% | 94.9% | |
| Surgery | ||||||
| Biopsy only | 18.2% | 64.0% | 84.5% | 90.5% | 72.0% | |
| BCS | 17.3% | 69.3% | 95.4% | 67.7% | 98.0% | |
| Mastectomy | 27.8% | 79.2% | 99.3% | 94.6% | 95.6% | |
| Chemotherapy receipt | ||||||
| Yes | 29.0% | 62.2% | 95.9% | 67.8% | 96.5% | |
| No | 15.7% | 82.2% | 97.3% | 87.6% | 96.4% | |
| Interval from diagnosis to start of radiation therapy (days) | ||||||
| 0-120 | 14.8% | NA | NA | NA | NA | |
| 121-365 | 30.0% | NA | NA | NA | NA | |
Abbreviations: SEER, Surveillance, Epidemiology and End Results; BCS, breast-conserving surgery; NPV, negative predictive value; PPV, positive predictive value; NA, not available
Specificity, positive predictive value, negative predictive value, and cohen’s kappa statistic were calculated for radiation therapy (RT) receipt coded by registries compared to the gold standard of Medicare billing claims. Underascertainment of RT receipt was defined as the number of cases where Medicare claims indicated that the patient received RT but registry data indicated that the patient did not receive RT, divided by the total number of cases where Medicare claims indicated that the patient received RT (1-sensitivity).
The original SEER 9 registries include Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, San Francisco-Oakland, Seattle-Puget Sound, and Utah. The SEER-other registries include those added in 1992 and later (San Jose, Los Angeles, Rural Georgia, Greater California, Kentucky, Louisiana, and New Jersey).