Table 1.
Baseline Characteristics of Heart Failure (HF) Patients by Age Groups and Serum Digoxin Concentration (SDC)
| < 65 Years (n = 2658) | ≥ 65 Years (n = 2890) | |||||||
|---|---|---|---|---|---|---|---|---|
| N (%) or Mean (±SD) | Placebo (N = 1852) | SDC 0.5–0.9 (N = 510) | SDC ≥1.0 (N = 296) | Overall p | Placebo (N = 2009) | SDC 0.5–0.9 (N = 472) | SDC ≥ 1.0 (N = 409) | Overall p |
| Age, y* | 55 (±8) | 55 (±8) | 56 (±8) | .289 | 72 (±5) | 71 (±5) | 72 (±5) | .005 |
| Women* | 399 (22%) | 103 (20%) | 78 (26%) | .109 | 556 (28%) | 114 (24%) | 116 (28%) | .256 |
| Nonwhites* | 336 (18%) | 77 (15%) | 53 (18%) | .325 | 227 (11%) | 49 (10%) | 33 (8%) | .152 |
| BMI, kg/m2* | 28.4 (±5.7) | 28.3 (±5.3) | 27.9 (±5.8) | <.0001 | 26.5 (±4.5) | 26.0 (±4.4) | 26.0 (±4.9) | .039 |
| Ejection fraction, %* | 31 (±12) | 31 (±11) | 30 (±12) | .637 | 33 (±13) | 33 (±13) | 327 (±13) | .093 |
| NYHA class III–IV* | 526 (28%) | 132 (28%) | 87 (29%) | .457 | 668 (33%) | 141 (30%) | 144 (35%) | .218 |
| HF duration, mo | 30 (±35) | 32 (±36) | 37 (±39) | .003 | 30 (±37) | 32 (±41) | 33 (±38) | .159 |
| Ischemic etiology* | 1201 (65%) | 337 (66%) | 194 (66%) | .866 | 1453 (73%) | 335 (71%) | 313 (77%) | .144 |
| Hypertension* | 827 (45%) | 214 (42%) | 145 (49%) | .154 | 999 (50%) | 219 (46%) | 189 (46%) | .239 |
| Diabetes | 513 (28%) | 139 (27%) | 96 (32%) | .215 | 596 (30%) | 126 (27%) | 119 (29%) | .441 |
| Chronic kidney disease* | 573 (31%) | 117 (23%) | 129 (44%) | <.0001 | 1222 (61%) | 251 (53%) | 286 (70%) | <.0001 |
| Prior digoxin use† | 836 (45%) | 251 (49%) | 148 (50%) | .114 | 838 (42%) | 206 (44%) | 192 (47%) | .137 |
| ACE inhibitor use† | 1765 (95%) | 480 (94%) | 277 (94%) | .314 | 1852 (92%) | 451 (96%) | 387 (95%) | .014 |
| Diuretic use* | 1382 (75%) | 357 (70%) | 247 (83%) | <.0001 | 1635 (81%) | 358 (76%) | 339 (83%) | .011 |
| Dose of study medication* | 0.27 (±0.1) | 0.27 (±0.1) | 0.27 (±0.1) | .120 | 0.22 (±0.1) | 0.22 (±0.1) | 0.23 (±0.1) | .043 |
| Pulmonary congestion | 243 (13%) | 57 (11%) | 51 (17%) | .049 | 292 (15%) | 57 (12%) | 83 (20%) | .002 |
| Cardiothoracic ratio > 0.5* | 1067 (57%) | 289 (57%) | 174 (59%) | .839 | 1257 (63%) | 269 (57%) | 267 (65%) | .028 |
| Serum creatinine, mg/dL* | 1.2 (±0.3) | 1.1 (±0.3) | 1.3 (±0.4) | <.0001 | 1.4 (±0.4) | 1.3 (±0.4) | 1.4 (±0.4) | <.0001 |
| eGFR, ml/min/1.73 m2* | 70 (±23) | 73 (±19) | 64 (±19) | <.0001 | 57 (±24) | 60 (±17) | 53 (±18) | <.0001 |
| Serum potassium, mEq/L | 4.3 (±0.4) | 4.3 (±0.5) | 4.3 (±0.4) | .863 | 4.4 (±0.4) | 4.4 (±0.4) | 4.4 (±0.4) | .817 |
Note: SD = standard deviation; ACE = angiotensin-converting enzyme; BMI = body mass index; eGFR = estimate glomerular filtration rate; NYHA = New York Heart Association.
*
p < .0001 and
†
p <. 05 for comparisons between patient < 65 and ≥ 65 years