Table 1.
Baseline characteristics of older patients receiving maintenance HD, ∼90 days after initiation, before and after matching on propensity score
| Variable | Full cohort |
Propensity score-matched cohort |
||||
|---|---|---|---|---|---|---|
| Recipients of heparin-free hemodialysis (n = 836) | Recipients of heparin with hemodialysis (n = 11 632) | Std. diff (%) | Recipients of heparin-free hemodialysis (n = 728) | Recipients of heparin with hemodialysis (n = 728) | Std. diff (%) | |
| Demographics | ||||||
| Age (year, mean ± SD) | 77 ± 6 | 76 ± 6 | 8.5 | 77 ± 6 | 77 ± 7 | 8.3 |
| Male sex, n (%) | 421 (50) | 6194 (53) | 5.7 | 374 (51) | 370 (51) | 1.1 |
| Race, n (%) | ||||||
| Black | 164 (20) | 2622 (23) | 7.2 | 143 (20) | 143 (20) | 0 |
| White | 630 (75) | 8484 (73) | 5.5 | 554 (76) | 546 (75) | 2.6 |
| Other | 42 (5) | 526 (5) | 2.3 | 31 (4) | 39 (5) | 5.1 |
| Hispanic ethnicity | 63 (8) | 997 (9) | 3.8 | 55 (8) | 57 (8) | 1 |
| Reported comorbidities, n (%) | ||||||
| Arrhythmia | 266 (32) | 3022 (26) | 12.9 | 228 (31) | 230 (32) | 0.6 |
| Cancer | 149 (18) | 1727 (15) | 8.1 | 130 (18) | 122 (17) | 2.9 |
| Coronary artery disease | 329 (39) | 4186 (36) | 7.0 | 283 (39) | 274 (38) | 2.5 |
| Deep vein thrombosis | 106 (13) | 873 (8) | 17.2 | 88 (12) | 79 (11) | 3.9 |
| Diabetes mellitus | 424 (51) | 6529 (56) | 10.9 | 373 (51) | 372 (51) | 0.3 |
| Gastrointestinal bleeding | 154 (18) | 1349 (12) | 19.2 | 129 (18) | 120 (16) | 3.3 |
| Heart failure | 499 (60) | 6392 (55) | 9.5 | 431 (59) | 415 (57) | 4.5 |
| Hemorrhagic stroke | 23 (3) | 105 (1) | 13.8 | 18 (2) | 21 (3) | 2.6 |
| Heparin-induced thrombocytopeniaa | −(<1) | −(<1) | 4.4 | −(<1) | −(<1) | 5.2 |
| Ischemic stroke | 164 (20) | 2076 (18) | 4.6 | 141 (19) | 140 (19) | 0.3 |
| Liver disease | 53 (6) | 452 (4) | 11.2 | 37 (5) | 37 (5) | 0 |
| Peripheral vascular disease | 247 (30) | 3592 (31) | 2.9 | 208 (29) | 211 (29) | 0.9 |
| Pulmonary disease | 224 (27) | 2836 (24) | 5.5 | 184 (25) | 166 (23) | 5.8 |
| Pulmonary embolism | 20 (2) | 193 (2) | 5.2 | 15 (2) | 17 (2) | 1.9 |
| Vital signs and laboratory measurements (mean ± SD) | ||||||
| Weight (kg) | 69 ± 16 | 74 ± 18 | 26.6 | 70 ± 16 | 70 ± 18 | 2.3 |
| Pre-dialysis systolic blood pressure (mmHg) | 139 ± 28 | 145 ± 27 | 23.0 | 140 ± 27 | 140 ± 27 | 0.7 |
| Hemoglobin (g/dL) | 11.6 ± 1.6 | 12.5 ± 1.5 | 57.6 | 11.7 ± 1.6 | 11.7 ± 1.6 | 3.6 |
| Platelet count (×103/µL) | 205 ± 101 | 240 ± 91 | 37.1 | 207 ± 97 | 215 ± 99 | 8.3 |
| Albumin (g/dL) | 3.4 ± 0.5 | 3.5 ± 0.5 | 21.5 | 3.4 ± 0.5 | 3.4 ± 0.5 | 1.9 |
| Dialysis characteristics | ||||||
| Kt/V | 1.6 ± 0.4 | 1.6 ± 0.4 | 0.3 | 1.6 ± 0.4 | 1.6 ± 0.4 | 0.9 |
| Vascular access, n (%) | ||||||
| Central venous catheter | 589 (70) | 8282 (71) | 1.6 | 504 (69) | 510 (70) | 1.8 |
| Fistula or graft | 239 (29) | 3255 (28) | 1.3 | 218 (30) | 213 (29) | 1.5 |
| Length of session (min, mean ± SD) | 205 ± 26 | 209 ± 25 | 15.1 | 206 ± 25 | 206 ± 24 | 0.1 |
| Reuse | 266 (32) | 6347 (55) | 47.1 | 251 (34) | 234 (32) | 5.0 |
| Facility characteristics | ||||||
| Number of outpatient hemodialysis patients (mean ± SD) | 88 ± 43 | 83 ± 44 | 11.2 | 87 ± 41 | 88 ± 42 | 1.9 |
| Rural, n (%) | 112 (13) | 2281 (20) | 16.4 | 101 (14) | 94 (13) | 2.8 |
| Census division, n (%)b | ||||||
| East North Central | 118 (14) | 1847 (16) | 4.9 | 108 (15) | 108 (15) | 0 |
| East South Central | 30 (4) | 663 (6) | 10.0 | 27 (4) | 27 (4) | 0 |
| Middle Atlantic | 144 (17) | 1172 (10) | 20.1 | 130 (18) | 130 (18) | 0 |
| Mountain | 35 (4) | 559 (5) | 3.0 | 31 (4) | 31 (4) | 0 |
| New England | 70 (8) | 452 (4) | 18.8 | 64 (9) | 64 (9) | 0 |
| Pacific | 102 (12) | 1656 (14) | 6.0 | 88 (12) | 88 (12) | 0 |
| South Atlantic | 232 (28) | 3092 (27) | 2.6 | 215 (30) | 215 (30) | 0 |
| West North Central | 22 (3) | 734 (6) | 17.9 | 18 (2) | 18 (2) | 0 |
| West South Central | 54 (6) | 1244 (11) | 15.1 | 47 (6) | 47 (6) | 0 |
SD, standard deviation; Std. diff, standardized difference.
Variables and the n (%) recipients of heparin-free HD versus n (%) recipients of heparin with HD missing data in the unmatched sample: weight: 34 (4) versus 323 (3); pre-dialysis systolic blood pressurea: −(1) versus 32 (<1); hemoglobin: 34 (4) versus 215 (2); platelet count: 38 (5) versus 271 (2); albumin: 38 (5) versus 236 (2); Kt/V: 62 (7) versus 480 (4); vascular accessa: −(1) versus 95 (1); length of sessiona: −(<1) versus −(<1); facility number of outpatient HD patients: 29 (3) versus 242 (2); facility rural status: 29 (3) versus 237 (2); facility census division: 29 (3) versus 213 (2).
aPer federal research regulations, any cell counts <10 must not be reported. This variable was not included in the estimation of the propensity score, but was exactly balanced in the propensity score-matched cohort.
bPairs were matched on propensity score within each Census division (standardized differences are zero by default).