Table 2. Multivariable Logistic Regression Results With Relative Risk Estimates for Microsatellite Instability Testing.
| Characteristics | MSI testing | ||
|---|---|---|---|
| OR (95% CI) | P value | RR (95% CI) | |
| Age group, y | |||
| 18-49 | 1 [Reference] | NA | NA |
| 50-59 | 0.68 (0.63-0.73) | <.001 | 0.84 (0.81-0.87) |
| 60-69 | 0.55 (0.50-0.59) | <.001 | 0.75 (0.72-0.78) |
| 70-79 | 0.50 (0.45-0.55) | <.001 | 0.70 (0.66-0.74) |
| Racea | |||
| White | 1 [Reference] | NA | NA |
| Black | 0.97 (0.90-1.04) | .35 | 0.98 (0.94-1.02) |
| Othera | 0.98 (0.87-1.10) | .73 | 1.00 (0.94-1.06) |
| Ethnicityb | |||
| Non-Hispanica | 1 [Reference] | NA | NA |
| Hispanicb | 0.97 (0.87-1.07) | .51 | 0.98 (0.93-1.04) |
| Sex | |||
| Male | 1 [Reference] | NA | NA |
| Female | 1.06 (1.01-1.12) | .02 | 1.04 (1.01-1.06) |
| Insurance type | |||
| Private | 1 [Reference] | NA | NA |
| No insurance | 0.88 (0.78-0.98) | .03 | 0.93 (0.86-1.00) |
| Medicaid | 0.89 (0.82-0.97) | .008 | 0.94 (0.90-0.99) |
| Medicare or otherc | 0.89 (0.83-0.95) | <.001 | 0.94 (0.90-0.97) |
| Unknown | 0.67 (0.53-0.87) | .002 | 0.80 (0.68-0.93) |
| Educational level in area of residence, %d | |||
| <6.3 | 1 [Reference] | NA | NA |
| 6.3-10.8 | 0.89 (0.83-0.96) | .003 | 0.94 (0.91-0.98) |
| 10.9-17.5 | 0.76 (0.69-0.82) | <.001 | 0.86 (0.82-0.90) |
| ≥17.6 | 0.72 (0.65-0.79) | <.001 | 0.84 (0.79-0.89) |
| Unknown | 1.35 (0.52-3.52) | .54 | 1.20 (0.66-2.18) |
| Facility type with CP | |||
| Academic | 1 [Reference] | NA | NA |
| Community | 0.59 (0.53-0.65) | <.001 | 0.74 (0.70-0.79) |
| Comprehensive | 0.67 (0.63-0.71) | <.001 | 0.81 (0.78-0.84) |
| Integrated network | 1.02 (0.95-1.10) | .007 | 1.01 (0.98-1.05) |
| Area of residence | |||
| Metropolitan | 1 [Reference] | NA | NA |
| Urban | 0.97 (0.88-1.05) | .42 | 0.98 (0.93-1.03) |
| Rural | 0.67 (0.54-0.84) | <.001 | 0.80 (0.69-0.92) |
| Facility locatione | |||
| New England | 1 [Reference] | NA | NA |
| Middle Atlantic | 0.65 (0.58-0.74) | <.001 | 0.81 (0.76-0.86) |
| South Atlantic | 0.55 (0.48-0.62) | <.001 | 0.73 (0.69-0.78) |
| East North Central | 0.55 (0.49-0.62) | <.001 | 0.74 (0.69-0.79) |
| East South Central | 0.46 (0.39-0.53) | <.001 | 0.67 (0.61-0.73) |
| West North Central | 0.53 (0.46-0.61) | <.001 | 0.72 (0.67-0.77) |
| West South Central | 0.50 (0.44-0.58) | <.001 | 0.70 (0.65-0.75) |
| Mountain | 0.77 (0.66-0.90) | .001 | 0.88 (0.82-0.95) |
| Pacific | 0.82 (0.72-0.93) | .002 | 0.90 (0.84-0.95) |
| Travel distance, miles | |||
| ≤5 | 1 [Reference] | NA | NA |
| 5.1-10 | 1.07 (1.00-1.15) | .04 | 1.04 (1.00-1.08) |
| 10.1-25 | 1.06 (0.99-1.14) | .09 | 1.02 (0.99-1.06) |
| >25 | 1.20 (1.10-1.30) | <.001 | 1.09 (1.05-1.14) |
| Year of diagnosis | |||
| 2010 | 1 [Reference] | NA | NA |
| 2011 | 1.47 (1.31-1.65) | <.001 | 1.32 (1.21-1.44) |
| 2012 | 1.80 (1.61-2.01) | <.001 | 1.51 (1.39-1.64) |
| 2013 | 2.04 (1.82-2.28) | <.001 | 1.67 (1.54-1.81) |
| 2014 | 2.59 (2.31-2.89) | <.001 | 1.94 (1.79-2.10) |
| 2015 | 3.84 (3.44-4.30) | <.001 | 2.41 (2.24-2.61) |
| 2016 | 5.78 (5.17-6.46) | <.001 | 2.94 (2.73-3.17) |
| 2017 | 9.95 (8.89-11.14) | <.001 | 3.71 (3.45-4.00) |
| Median household income, US$ | |||
| ≥63 333 | 1 [Reference] | NA | NA |
| 50 354-63 332 | 1.02 (0.95-1.10) | .64 | 1.01 (0.97-1.05) |
| 40 227-50 353 | 0.96 (0.88-1.04) | .28 | 0.97 (0.93-1.02) |
| <40 277 | 0.96 (0.87-1.06) | .44 | 0.97 (0.92-1.03) |
| Unknown | 0.62 (0.25-1.58) | .32 | 0.77 (0.43-1.37) |
| CCI | |||
| 0 | 1 [Reference] | NA | NA |
| 1 | 1.09 (1.02-1.16) | .01 | 1.04 (1.01-1.08) |
| ≥2 | 1.11 (1.01-1.22) | .03 | 1.05 (1.00-1.11) |
| Immunotherapy | |||
| Not administered | 1 [Reference] | NA | NA |
| Administered | 1.51 (1.42-1.62) | <.001 | 1.19 (1.15-1.23) |
| Unknown | 1.41 (0.89-2.23) | .15 | 1.19 (0.92-1.53) |
| Chemotherapy | |||
| Not administered | 1 [Reference] | NA | NA |
| Administered | 1.76 (1.65-1.88) | <.001 | 1.48 (1.42-1.55) |
| Unknown | 1.28 (1.09-1.50) | .002 | 1.23 (1.11-1.36) |
| Surgery primary site | |||
| No | 1 [Reference] | NA | NA |
| Yes | 5.34 (5.05-5.65) | <.001 | 2.80 (2.70-2.90) |
| Unknown | 1.20 (0.63-2.30) | .59 | 1.18 (0.75-1.85) |
| Surgery nonprimary site | |||
| No | 1 [Reference] | NA | NA |
| Yes | 1.23 (1.15-1.31) | <.001 | 1.08 (1.05-1.12) |
| Unknown | 0.58 (0.28-1.22) | .15 | 0.78 (0.49-1.22) |
Abbreviations: CCI, Charlson Comorbidity Index (range: 0-25, with the highest score indicating a higher number of comorbidities); CP, cancer program; MSI, microsatellite instability; NA, not applicable; OR, odds ratio; RR, relative risk.
Race data obtained from the National Cancer Database (NCDB) were self-identified in the patients’ medical records. Other races and non-Hispanic ethnicities include American Indian, Aleutian, or Eskimo; Asian Indian; Asian Indian or Pakistani; Chamorran; Chinese; Filipino; Fiji Islander; Guamanian; Hawaiian; Hmong; Japanese; Kampuchean; Korean; Laotian; Melanesian; Micronesian; New Guinean; Other; Other Asian; Pacific Islander; Polynesian; Samoan; Tahitian; Thai; Tongan; Unknown origin; and Vietnamese.
Ethnicity data obtained from the NCDB were self-identified in the patients’ medical records. Hispanic ethnicity includes Mexican, Puerto Rican, Cuban, South or Central American (except Brazil), Dominican Republic, or Spanish origin.
Other insurance type includes other governmental medical services, such as TRICARE, military, and Veterans Affairs.
Educational level was assessed at the zip code level based on the percentage of adult residents without a high school diploma.
US Census division.