Table 1.
Demographics of Study Population and Associations With Extreme Use of Disease-Monitoring Testing
| Total Population | Extreme Users | OR* | 95% CI | |||
|---|---|---|---|---|---|---|
| No. | % | No. | % | |||
| No. of patients | 2,460 | 100 | 924 | 37.6 | ||
| Age, years | ||||||
| 65-69 | 581 | 23.6 | 260 | 28.2 | 0.97 | 0.76 to 1.23 |
| 70-74 | 655 | 26.6 | 285 | 30.8 | Reference | |
| 75-79 | 550 | 22.4 | 205 | 22.2 | 0.85 | 0.68 to 1.12 |
| ≥ 80 | 674 | 27.4 | 174 | 18.8 | 0.58† | 0.45 to 0.75 |
| Diagnosis year | ||||||
| 2002-2004 | 649 | 26.4 | 241 | 26.1 | Reference | |
| 2005-2007 | 796 | 32.4 | 316 | 34.2 | 0.94 | 0.74 to 1.19 |
| 2008-2011 | 1,015 | 41.3 | 367 | 39.7 | 0.75† | 0.59 to 0.95 |
| Ethnicity | ||||||
| White | 2,200 | 85.4 | 791 | 85.6 | Reference | |
| Other/unknown | 360 | 14.6 | 133 | 14.4 | 1.02 | 0.79 to 1.33 |
| Marital status | ||||||
| Married | 870 | 35.4 | 380 | 41.1 | Reference | |
| Single | 1,483 | 60.3 | 500 | 54.1 | 0.77† | 0.63 to 0.93 |
| Geographic area | ||||||
| Large metropolitan | 1,460 | 59.3 | 526 | 56.9 | 0.83 | 0.69 to 1.00 |
| Other | 1,000 | 40.7 | 398 | 43.1 | Reference | |
| Charlson comorbidity score | ||||||
| 0 | 1,408 | 57.3 | 526 | 57.0 | Reference | |
| 1 | 632 | 25.7 | 232 | 25.1 | 1.15 | 0.93 to 1.43 |
| ≥ 2 | 417 | 17.0 | 165 | 17.9 | 1.43† | 1.12 to 1.84 |
| Region | ||||||
| East | 757 | 30.8 | 273 | 29.5 | Reference | |
| Midwest | 832 | 33.8 | 327 | 35.4 | 1.04 | 0.83 to 1.32 |
| West | 871 | 35.4 | 324 | 35.1 | 0.89 | 0.71 to 1.11 |
| Socioeconomic status | ||||||
| Low | 1,112 | 45.2 | 417 | 45.2 | Reference | |
| Medium | 620 | 25.2 | 216 | 23.4 | 0.92 | 0.73 to 1.16 |
| High | 726 | 29.6 | 289 | 31.4 | 1.15 | 0.92 to 1.45 |
| ER/PR status | ||||||
| Positive | 1,784 | 72.5 | 644 | 69.7 | Reference | |
| Negative | 335 | 13.6 | 170 | 18.4 | 1.63† | 1.27 to 2.08 |
| Unknown | 341 | 13.9 | 110 | 11.9 | 0.97 | 0.74 to 1.25 |
| PET use | ||||||
| No | 1,050 | 42.7 | 245 | 26.5 | Reference | |
| Yes | 1,410 | 57.3 | 679 | 73.5 | 2.92† | 2.40 to 3.55 |
| Maximum oncology office visit volume in any 1 year | ||||||
| Low | 792 | 32.2 | 205 | 22.2 | Reference | |
| Medium | 799 | 32.5 | 277 | 30.0 | 1.42† | 1.13 to 1.78 |
| High | 709 | 28.8 | 395 | 42.7 | 3.14† | 2.49 to 3.96 |
| Maximum No. of imaging tests in any 1 year | 1.31 | 0.88 to 1.95 | ||||
| ≤ 2 | 623 | 25.3 | ||||
| 3 | 546 | 22.2 | ||||
| 4 | 484 | 19.7 | ||||
| ≥ 5 | 807 | 32.8 | ||||
| More than 12 STM tests in any 1 year | ||||||
| Yes | 222 | 9.0 | ||||
| No | 2,238 | 91.0 | ||||
Abbreviations: ER/PR, estrogen receptor/progesterone receptor; OR, odds ratio; PET, positron emission tomography; STM, serum tumor marker.
*
ORs were derived from multivariable analysis, and models were adjusted for all other factors listed in the table.
†
P < .05.