Table 1.
Multilevel Model Variables: Description, Rationale, and Sample Statistics
| Variable (units of measure) |
Rationale for Inclusion | ||
|---|---|---|---|
|
Outcome whether cancer patient was diagnosed at a late stage (regional or distant =1, else=0) |
Late stage diagnosis is indicative of lack of knowledge regarding personal cancer risk, or the importance or availability of screening; lack of timely or proximate access to services, lack of funds to pay for, and cultural or other barriers related to utilization of timely cancer screening. |
Proport ion* |
Sdev |
| 0.543 | 0.498 | ||
| Person-level predictors (categorical variables coded into binary variables) | |||
| female | Both male and female are included in the CRC study, with male designated as the reference group. |
0.487 | 0.500 |
| African American | The national statistics cite African Americans as a disadvantaged group, with higher likelihood of late-stage CRC than whites, the reference group. |
0.112 | 0.315 |
| Hispanic | The national statistics cite Hispanics as a disadvantaged group, with higher likelihood of late-stage CRC than whites, the reference group. |
0.080 | 0.271 |
| Asian | The national statistics cite Asians as a disadvantaged group, with higher likelihood of late-stage CRC than whites, the reference group. |
0.031 | 0.172 |
| White (ref) | The reference group | 0.765 | 0.424 |
| Race all others | This group includes American Indians, Pacific Islanders, and others not defined above. We grouped them into a single indicator for the regressions. |
0.013 | 0.113 |
| age < 50 | CRC screening protocols recommend to start screening at age <50 for higher risk individuals |
0.111 | 0.275 |
| age 50–64 | CRC screening protocols recommend to start screening at age 50 for average risk individuals; this is the prime age bracket for screening |
0.314 | 0.464 |
| age 65–74 | Medicare insurance coverage begins at age 65 for people who are eligible for Social Security benefits |
0.250 | 0.433 |
| age 75+ (ref) | Screening is not needed or recommended as often for older individuals who have had regular screening at younger ages |
0.325 | 0.468 |
| County-level predictors (n = 2,471 counties in 40 states) | mean | sdev | min | max | |
|---|---|---|---|---|---|
| Isolation white | This index reflects the degree to which whites are proximate to other whites in their county of residence |
0.825 | 0.17 | 0.02 | 1.00 |
| Isolation African American |
This index reflects the degree to which African Americans are proximate to other African Americans in the county |
0.141 | 0.19 | 0.00 | 0.88 |
| Isolation Hispanic | This index reflects the degree to which Hispanics are proximate to other Hispanics in the county |
0.094 | 0.151 | 0.00 | 0.98 |
| Isolation Asian | This index reflects the degree to which Asians are proximate to other Asians in the county |
0.016 | 0.031 | 0.00 | 0.43 |
| Isolation Native American |
This index reflects the degree to which Native Americans are proximate to other Native Americans in the county (statistics exclude AK, not included in regressions) |
0.034 | 0.112 | 0.00 | 0.94 |
| Isolation Pacific Islander |
This index reflects the degree to which Pacific Islanders are proximate to other Pacific Islanders in the county (statistics exclude HI, not included in regressions) |
0.002 | 0.004 | 0.00 | 0.58 |
| Person-centered isolation construct |
This variable is constructed by retaining, for each individual, the specific isolation index (above) that reflects their race or ethnicity. This construct reflects the degree to which people are proximate to others of their same race or ethnicity in their county of residence. |
0.719 | 0.227 | 0.00 | 0.94 |
| Managed care penetration (%) |
Managed care has transformed the way medicine is practiced in highly-penetrated markets, with preventive care services more prevalent/utilized more intensively (2005). |
4.83 | 8.83 | 0.00 | 53.49 |
| Distance (miles) | Calculated as the average distance (miles) over all ZIP codes with centroid in the county to closest provider ZIP code. Greater distance to provider of CRC (endoscopy) screening suggests impeded access to preventive care services. Based on 100% FFS Medicare utilization of CRC screening endoscopy services (2006). |
12.10 | 9.74 | 0.00 | 72.45 |
| Screening rate (%) | Percent of the 100% FFS Medicare population residing in the county and alive all year that utilized CRC screening by endoscopy in 2006. |
10.32 | 1.78 | 1.15 | 18.18 |
| Percent uninsured | % of the under-age-65 population with no health insurance (2005) | 18.92 | 6.21 | 7.10 | 46.80 |
| Percent Rural | % of county population living in rural area (2005) | 59.88 | 30.59 | 0.00 | 100 |
| Percent Poverty | % of county population living in poverty (2005) | 15.96 | 6.71 | 2.50 | 51.00 |
(* mean of binary variable)