Table 2. Multilevel Mixed-Effect Logistic Regression Models for AS or WW Compared With Active Treatment .
| Variables | OR (95% CI) | ||
|---|---|---|---|
| Model 1 (region only) | Model 2 (model 1 + patient factors in fixed-effect term) | Model 3 (model 2 + county factors in fixed-effect term) | |
| Patient-level variables | |||
| Age, y | NA | ||
| ≤50 | 1 [Reference] | 1 [Reference] | |
| 51-60 | 1.33 (1.21-1.46) | 1.33 (1.21-1.46) | |
| 61-70 | 1.86 (1.70-2.04) | 1.86 (1.70-2.04) | |
| 71-80 | 2.26 (2.04-2.50) | 2.26 (2.05-2.50) | |
| Race/ethnicity | NA | ||
| Non-Hispanic White | 1 [Reference] | 1 [Reference] | |
| Non-Hispanic Black | 1.01 (0.95-1.07) | 1.01 (0.95-1.07) | |
| Hispanic | 0.79 (0.74-0.84) | 0.79 (0.74-0.85) | |
| Asian/Pacific Islander | 0.97 (0.88-1.07) | 0.97 (0.88-1.07) | |
| Other | 0.94 (0.88-1.07) | 0.94 (0.84-1.05) | |
| Health insurance | NA | ||
| Private and/or Medicare | 1 [Reference] | 1 [Reference] | |
| Medicaid | 0.73 (0.66-0.81) | 0.73 (0.66-0.81) | |
| Uninsured | 1.07 (0.91-1.25) | 1.07 (0.91-1.25) | |
| Marital status | NA | ||
| Married | 1 [Reference] | 1 [Reference] | |
| Single | 1.29 (1.23-1.34) | 1.29 (1.23-1.35) | |
| PSA, ng/mL | NA | 0.98 (0.96-0.99) | 0.98 (0.97-0.99) |
| Clinical T category | NA | ||
| T1c | 1 [Reference] | 1 [Reference] | |
| T2a | 0.79 (0.73-0.84) | 0.79 (0.73-0.84) | |
| % Biopsy-positive cores | NA | ||
| <33% | 1 [Reference] | 1 [Reference] | |
| ≥33%, <50% | 0.46 (0.43-0.49) | 0.46 (0.43-0.49) | |
| ≥50% | 0.29 (0.27-0.32) | 0.29 (0.27-0.32) | |
| Year of diagnosis | NA | ||
| 2010 | 1 [Reference] | 1 [Reference] | |
| 2011 | 1.31 (1.23-1.40) | 1.31 (1.23-1.40) | |
| 2012 | 1.89 (1.77-2.01) | 1.89 (1.77-2.01) | |
| 2013 | 2.87 (2.69-3.06) | 2.87 (2.69-3.06) | |
| 2014 | 3.24 (3.03-3.47) | 3.24 (3.03-3.47) | |
| 2015 | 3.58 (3.35-3.83) | 3.58 (3.35-3.83) | |
| County-level variables | |||
| City type, population | NA | NA | |
| Metropolitan, >1 million | 1 [Reference] | ||
| Metropolitan, 250k-1 million | 0.89 (0.71-1.11) | ||
| Metropolitan, <250k | 0.76 (0.59-0.98) | ||
| Urban, >20k | 0.89 (0.67-1.17) | ||
| Urban, 2500-19 999 | 0.82 (0.63-1.06) | ||
| Rural/urban, <2500 | 0.97 (0.68-1.37) | ||
| Median household income, $ | NA | NA | |
| <50k | 1 [Reference] | ||
| ≥50k, <75k | 1.11 (0.91-1.37) | ||
| ≥75k, <100k | 1.14 (1.14-1.14) | ||
| ≥100k | 1.09 (0.70-1.71) | ||
| Median No. of ≥ college education per 100k | NA | NA | |
| <15k | 1 [Reference] | ||
| ≥15k, <30k | 1.19 (0.96-1.48) | ||
| ≥30k, <45k | 1.27 (0.91-1.76) | ||
| ≥45k | 1.29 (0.76-2.18) | ||
| Median No. of urologists per 100k | NA | NA | |
| 0 | 1 [Reference] | ||
| >0, ≤2 | 0.98 (0.75-1.28) | ||
| >2, ≤4 | 0.99 (0.78-1.27) | ||
| >4 ≤6 | 0.84 (0.62-1.13) | ||
| >6 | 0.88 (0.62-1.27) | ||
| Median No. of radiation oncologists per 100k | NA | NA | |
| 0 | 1 [Reference] | ||
| >0, ≤1 | 0.93 (0.69-1.26) | ||
| >1, ≤2 | 1.07 (0.84-1.37) | ||
| >2 ≤3 | 1.04 (0.76-1.42) | ||
| >3 | 0.90 (0.64-1.27) | ||
| Median No. of PCPs per 100k | NA | NA | |
| 0 | 1 [Reference] | ||
| >0, ≤50 | 0.93 (0.49-1.76) | ||
| >50, ≤100 | 0.93 (0.48-1.80) | ||
| >100 | 1.07 (0.52-2.20) | ||
| Median No. of hospital beds per 100k | NA | NA | |
| 0 | 1 [Reference] | ||
| >0, ≤200 | 1.20 (0.93-1.56) | ||
| >200, ≤400 | 1.15 (0.87-1.51) | ||
| >400, ≤600 | 1.16 (0.83-1.63) | ||
| >600 | 1.05 (0.75-1.48) | ||
| Random-effects of regional variables (SEER registry/county) | |||
| Variance of random effect (SEER registry) | 0.40 | 0.47 | 0.34 |
| Variance of random effect (county) | 0.32 | 0.34 | 0.32 |
| Intraclass correlation | 0.18 | 0.19 | 0.17 |
| Median odds ratio | 2.25 | 2.37 | 2.17 |
Abbreviations: NA, not applicable; OR, odds ratio; PCP, primary care physician; PSA, prostate-specific antigen; SEER, Surveillance, Epidemiology, and End Results.