Table 1.
Baseline characteristics of chronic heart failure patients with chronic kidney disease, by potassium levels, before and after propensity score matching
| Variable | Before matching | After matching | ||||
|---|---|---|---|---|---|---|
| Potassium 4–4.9 mEq/L (n = 2266) | Potassium <4 mEq/L (n = 527) | P value | Potassium 4–4.9 mEq/L (n = 522) | Potassium <4 mEq/L (n = 522) | P value | |
| Age, years | 68 ± 9 | 68 ± 10 | 0.405 | 68 ± 10 | 68 ± 10 | 0.718 |
| Female | 680 (30%) | 207 (39%) | <0.001 | 200 (38%) | 204 (39%) | 0.830 |
| Non-white | 180 (8%) | 52 (10%) | 0.150 | 54 (10%) | 51 (10%) | 0.830 |
| Body mass index, kg/m2 | 27 ± 5 | 27 ± 5 | 0.507 | 27 ± 5 | 27 ± 5 | 0.729 |
| Duration of heart failure, months | 30 ± 37 | 29 ± 37 | 0.684 | 28 ± 36 | 29 ± 37 | 0.379 |
| Ischaemic heart disease | 1674 (74%) | 353 (67%) | 0.001 | 340 (65%) | 350 (67%) | 0.513 |
| Prior myocardial infarction | 1508 (67%) | 318 (60%) | 0.007 | 300 (58%) | 315 (60%) | 0.361 |
| Hypertension | 1113 (49%) | 294 (56%) | 0.006 | 298 (57%) | 289 (55%) | 0.596 |
| Diabetes mellitus | 675 (30%) | 146 (28%) | 0.344 | 145 (28%) | 145 (28%) | 1.000 |
| Medications | ||||||
| Pre-trial digoxin use | 942 (42%) | 225 (43%) | 0.638 | 221 (50%) | 222 (50%) | 1.000 |
| Trial use of digoxin | 1133 (50%) | 254 (48%) | 0.456 | 238 (46%) | 252 (48%) | 0.409 |
| Angiotensin-converting enzyme inhibitors | 2096 (93%) | 475 (90%) | 0.071 | 484 (93%) | 475 (91%) | 0.362 |
| Diuretics | 1888 (83%) | 461 (88%) | 0.019 | 465 (89%) | 456 (87%) | 0.439 |
| Potassium-sparing diuretics | 189 (8%) | 50 (10%) | 0.397 | 53 (10%) | 50 (10%) | 0.838 |
| Potassium supplement | 721 (32%) | 247 (47%) | <0.001 | 233 (45%) | 242 (46%) | 0.504 |
| Symptoms and signs of heart failure | ||||||
| Dyspnea on exertion | 1751 (77%) | 403 (77%) | 0.693 | 395 (78%) | 398 (76%) | 0.882 |
| Jugular venous distension | 299 (13%) | 94 (18%) | 0.006 | 87 (17%) | 90 (17%) | 0.858 |
| Third heart sound | 549 (24%) | 155 (29%) | 0.014 | 173 (33%) | 152 (29%) | 0.182 |
| Pulmonary râles | 384 (17%) | 106 (20%) | 0.085 | 103 (20%) | 103 (20%) | 1.000 |
| Lower extremity edema | 507 (22%) | 148 (28%) | 0.005 | 146 (28%) | 144 (28%) | 0.942 |
| New York Heart Association class III–IV | 822 (36%) | 202 (38%) | 0.378 | 196 (38%) | 197 (38%) | 0.949 |
| Heart rate, beats per minute | 78 ± 13 | 80 ± 13 | 0.004 | 79 ± 13 | 80 ± 13 | 0.471 |
| Systolic blood pressure, mm Hg | 129 ± 21 | 129 ± 23 | 0.569 | 129 ± 23 | 129 ± 23 | 0.933 |
| Diastolic blood pressure, mm Hg | 74 ± 11 | 75 ± 12 | 0.206 | 75 ± 11 | 75 ± 12 | 0.715 |
| Chest radiograph findings | ||||||
| Pulmonary congestion | 327 (14%) | 98 (19%) | 0.016 | 99 (19%) | 95 (18%) | 0.793 |
| Cardiothoracic ratio >0.5 | 1400 (62%) | 374 (71%) | <0.001 | 358 (69%) | 369 (71%) | 0.472 |
| Serum creatinine, mg/dL | 1.53 ± 0.34 | 1.53 ± 0.40 | 0.703 | 1.52 ± 0.35 | 1.52 ± 0.39 | 0.963 |
| Estimated GFR, ml/min/1.73 m2 | 47 ± 9 | 47 ± 10 | 0.527 | 47 ± 9 | 47 ± 10 | 0.701 |
| Ejection fraction, % | 32 ± 13 | 32 ± 14 | 0.969 | 33 ± 14 | 32 ± 14 | 0.995 |
Values are presented as n (%) or mean ± standard deviation. GFR=glomerular filtration rate