Table 1.
Clinical and demographic characteristics of the cohort stratified by methotrexate and surgery, and multivariable analysis of use of methotrexate.
| Methotrexate | Surgery | P-value | Methotrexate aRR (95% CI) |
|||
|---|---|---|---|---|---|---|
| N | (%) | N | (%) | |||
| All | 13,498 | (21.6) | 49,090 | (78.4) | ||
| Age | 0.02 | |||||
| <20 | 611 | (22.1) | 2,150 | (77.9) | Referent | |
| 20–24 | 2,667 | (22.0) | 9,443 | (78.0) | 0.96 (0.89–1.04) | |
| 25–29 | 3,927 | (21.8) | 14,096 | (78.2) | 0.93 (0.87–1.01) | |
| 30–34 | 3,653 | (21.7) | 13,156 | (78.3) | 0.92 (0.85–0.99)* | |
| 35–39 | 2,048 | (20.4) | 7,977 | (79.6) | 0.88 (0.81–0.96)* | |
| 40–44 | 548 | (20.4) | 2,145 | (79.7) | 0.89 (0.80–1.00)* | |
| ≥45 | 44 | (26.4) | 123 | (73.7) | 1.20 (0.91–1.56) | |
| Year | <0.001 | |||||
| 2006 | 784 | (14.5) | 4,626 | (85.5) | Referent | |
| 2007 | 856 | (15.3) | 4,744 | (84.7) | 1.08 (0.97–1.19) | |
| 2008 | 1,034 | (17.6) | 4,837 | (82.4) | 1.24 (1.09–1.40)* | |
| 2009 | 1,252 | (20.7) | 4,805 | (79.3) | 1.46 (1.29–1.64)* | |
| 2010 | 1,405 | (21.0) | 5,291 | (79.0) | 1.48 (1.32–1.65)* | |
| 2011 | 1,749 | (22.5) | 6,034 | (77.5) | 1.57 (1.40–1.76)* | |
| 2012 | 2,110 | (24.8) | 6,383 | (75.2) | 1.73 (1.54–1.94)* | |
| 2013 | 1,974 | (24.7) | 6,030 | (75.3) | 1.72 (1.52–1.95)* | |
| 2014 | 1,932 | (26.8) | 5,271 | (73.2) | 1.89 (1.67–2.14)* | |
| 2015 | 402 | (27.3) | 1,069 | (72.7) | 1.97 (1.70–2.28)* | |
| Marital status | <0.001 | |||||
| Married | 5,292 | (22.7) | 18,060 | (77.3) | Referent | |
| Single | 6,665 | (21.4) | 24,471 | (78.6) | 0.98 (0.93–1.02) | |
| Other/unknown | 1,541 | (19.0) | 6,559 | (81.0) | 0.87 (0.77–0.99)* | |
| Race | <0.001 | |||||
| White | 6,445 | (22.2) | 22,615 | (77.8) | Referent | |
| Black | 3,369 | (21.3) | 12,448 | (78.7) | 0.96 (0.90–1.03) | |
| Hispanic | 729 | (19.4) | 3,024 | (80.6) | 1.00 (0.87–1.16) | |
| Other/unknown | 2,955 | (21.2) | 11,003 | (78.8) | 0.95 (0.88–1.03) | |
| Insurance status | <0.001 | |||||
| Commercial | 6,800 | (23.1) | 22,680 | (76.9) | Referent | |
| Medicare | 144 | (20.3) | 567 | (79.8) | 1.05 (0.90–1.22) | |
| Medicaid | 4,053 | (20.5) | 15,725 | (79.5) | 0.92 (0.87–0.98)* | |
| Uninsured | 2,044 | (19.9) | 8,245 | (80.1) | 0.87 (0.82–0.93)* | |
| Unknown | 457 | (19.6) | 1,873 | (80.4) | 0.87 (0.78–0.97)* | |
| Hospital location | <0.001 | |||||
| Urban | 12,324 | (21.8) | 44,293 | (78.2) | Referent | |
| Rural | 1,174 | (19.7) | 4,797 | (80.3) | 1.03 (0.88–1.22) | |
| Hospital teaching status | <0.001 | |||||
| Non-teaching | 8,130 | (20.8) | 31,042 | (79.3) | Referent | |
| Teaching | 5,368 | (22.9) | 18,048 | (77.1) | 1.16 (1.02–1.33)* | |
| Hospital bed size | 0.01 | |||||
| <400 | 7,450 | (21.1) | 27,798 | (78.9) | Referent | |
| 400–600 | 3,549 | (21.9) | 12,649 | (78.1) | 0.94 (0.81–1.08) | |
| >600 | 2,499 | (22.4) | 8,643 | (77.6) | 0.84 (0.70–1.01) | |
| Hospital region | <0.001 | |||||
| Northeastern | 1,817 | (20.6) | 7,011 | (79.4) | Referent | |
| Midwest | 2,258 | (21.5) | 8,254 | (78.5) | 1.11 (0.90–1.36) | |
| South | 7,024 | (22.3) | 24,488 | (77.7) | 1.06 (0.88–1.27) | |
| West | 2,399 | (20.4) | 9,337 | (79.6) | 1.01 (0.82–1.23) | |
| Comorbidity (Elixhauser) | <0.001 | |||||
| 0 | 12,322 | (24.6) | 37,802 | (75.4) | Referent | |
| 1 | 947 | (9.9) | 8,602 | (90.1) | 0.41 (0.38–0.44)* | |
| ≥2 | 229 | (7.9) | 2,686 | (92.1) | 0.32 (0.28–0.37)* | |
| Annualized hospital volume | ||||||
| Median (IQR) | 28 | (18–43) | 25 | (15–37) | <0.001 | 1.010 (1.007–1.013)* |
*
P-value <0.05
aRR: adjusted risk ratio.
Generalized estimating equations were fitted accounting for hospital-level clustering. The covariates included were age, year, marital status, race, insurance status, hospital location, teaching status, bed size, region, comorbidity and annualized hospital volume.