Table 1. Baseline Characteristics for Matched and Unmatched Groups of Primary and Repeat Lung Recipients.
| Total Sample | 1:1 Matched Sample | |||||
|---|---|---|---|---|---|---|
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|
|
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| Variables | Primary (n = 9,270) | Repeat (n = 456) | p Valuea | Primary (n = 429) | Repeat (n = 429) | Stand. Diff.b |
| Continuous covariates | ||||||
| Donor age (years) | 32 (21–46) | 30 (21–45) | 0.156 | 28 (20–46) | 29 (21–45) | 0.01 |
| Donor BMI (kg/m2) | 25 (22–28) | 25 (22–28) | 0.700 | 25 (22–28) | 25 (22–28) | −0.02 |
| Recipient age (years) | 58 (49–64) | 51 (34–61) | <0.001c | 54 (31–62) | 51 (36–61) | −0.01 |
| Recipient BMI (kg/m2) | 25 (21–29) | 22 (19–26) | <0.001c | 24 (19–28) | 22 (19–26) | 0.05 |
| Wait list days | 73 (22–229) | 43 (12–125) | <0.001c | 52 (12–178) | 45 (12–129) | 0.01 |
| Lung allocation score | 39 (34–48) | 47 (40–70) | <0.001c | 47 (37–85) | 47 (40–67) | 0.13 |
| Ischemic time (hours) | 4.8 (3.8–6.0) | 4.8 (3.5–6.1) | 0.873 | 4.9 (3.8–6.0) | 4.8 (3.5–6.2) | 0.03 |
| Serum creatinine (mg/dL) | 0.8 (0.7–1.0) | 1.1 (0.8–1.3) | <0.001c | 0.8 (0.8–1.1) | 1.0 (0.8–1.3) | −0.02 |
| Days b/w transplants | NA | 1,056 (473–2,176) | NA | NA | 1056 (484–2171) | NA |
| Categoric covariates: | ||||||
| Donor race (Caucasian) | 5,771 (0.62) | 268 (0.59) | 0.267 | 261 (0.61) | 252 (0.59) | 0.04 |
| Donor sex (female) | 3,719 (0.40) | 197 (0.43) | 0.190 | 153 (0.36) | 183 (0.43) | −0.14 |
| Donor cause of death: | 0.039c | |||||
| CVA/stroke | 3,356 (0.36) | 158 (0.35) | 137 (0.32) | 148 (0.35) | −0.06 | |
| Head trauma | 4,432 (0.47) | 234 (0.51) | 216 (0.50) | 224 (0.52) | −0.04 | |
| Recipient race: (Caucasian) | 7,801 (0.84) | 398 (0.87) | 0.131 | 373 (0.87) | 374 (0.87) | 0.00 |
| Recipient sex (female) | 3,822 (0.41) | 203 (0.45) | 0.164 | 171 (0.40) | 190 (0.44) | −0.08 |
| Underlying diagnosis: | <0.001c | |||||
| Obstructive | 2,997 (0.32) | 120 (0.26) | 101 (0.23) | 114 (0.27) | −0.09 | |
| Restrictive | 4,045 (0.44) | 140 (0.31) | 141 (0.32) | 137 (0.32) | 0.00 | |
| CF/bronchiectasis | 1,295 (0.14) | 130 (0.29) | 120 (0.28) | 118 (0.28) | 0.00 | |
| PPH | 398 (0.04) | 26 (0.06) | 22 (0.05) | 25 (0.06) | −0.04 | |
| Other | 535 (0.06) | 40 (0.09) | 45 (0.10) | 35 (0.08) | 0.07 | |
| Retransplant diagnosis: | ||||||
| Obliterative bronchiolitis | NA | 241 (0.53) | NA | NA | 227 (0.53) | NA |
| PGD/acute rejection | 77 (0.17) | 72 (0.17) | ||||
| Other | 138 (0.30) | 130 (0.30) | ||||
| CMV (positive) | 5,056 (0.55) | 289 (0.63) | <0.001c | 267 (0.62) | 270 (0.63) | −0.02 |
| ABO match (level 1) | 8,517 (0.91) | 409 (0.90) | 0.098 | 403 (0.94) | 385 (0.90) | 0.15 |
| Medical condition: | ||||||
| Ventilator | 520 (0.06) | 96 (0.21) | <0.001c | 101 (0.24) | 83 (0.19) | 0.12 |
| ICU | 690 (0.07) | 118 (0.26) | <0.001c | 129 (0.30) | 101 (0.24) | 0.14 |
| Hospitalized | 1,407 (0.15) | 182 (0.40) | <0.001c | 177 (0.41) | 161 (0.38) | 0.06 |
| Procedure type (bilateral) | 6,106 (0.66) | 235 (0.52) | <0.001c | 245 (0.57) | 226 (0.53) | 0.08 |
| Diabetes (yes) | 1,628 (0.18) | 221 (0.48) | <0.001c | 203 (0.47) | 203 (0.47) | 0.00 |
| No limitation of ADLs | 3,041 (0.33) | 104 (0.23) | <0.001c | 94 (0.22) | 103 (0.24) | −0.05 |
| Employed (yes) | 856 (0.09) | 18 (0.04) | <0.001c | 22 (0.05) | 17 (0.04) | 0.05 |
| IV drug treated infect. (Yes) | 924 (0.10) | 130 (0.29) | <0.001c | 128 (0.30) | 119 (0.28) | 0.04 |
| Payer (Medicare/Medicaid) | 4,001 (0.43) | 208 (0.45) | 0.110 | 194 (0.45) | 196 (0.46) | −0.02 |
a
Student t test for continuous variables; χ2 for categoric variables.
b
Standardized differences displayed below are estimated as the difference in the mean between the 2 groups being compared, divided by the square root of the pooled variance, with modification to reflection proportions for categoric variables. Values < 0.2 indicate negligible differences in values for the 2 groups.
c
Significant difference at the 5% level.
ADLs = activities of daily living; BMI = body mass index; CF = cystic fibrosis; CMV = cytomegalovirus; CVA = cerebrovascular accident; NA = not applicable; PGD = primary graft dysfunction; PPH = primary pulmonary hypertension.