Baseline characteristics by frequent hospital admission status
| All patients (n=25 244) | Frequent admitter (n=4322) | Non-frequent admitter (n=20 922) | p Value* | |
|---|---|---|---|---|
| Patient demographics | ||||
| Age, mean (SD) | 58.47 (17.96) | 65.06 (15.11) | 57.11 (18.2) | <0.001 |
| Gender, male (%) | 13 010 (51.5%) | 2294 (53.1%) | 10 716 (51.2%) | 0.027 |
| Ethnicity | <0.001 | |||
| Chinese (%) | 18 234 (72.2%) | 3231 (74.8%) | 15 003 (71.7%) | |
| Indian (%) | 2504 (9.9%) | 410 (9.5%) | 2094 (10%) | |
| Malay (%) | 3017 (12%) | 551 (12.7%) | 2466 (11.8%) | |
| Others (%) | 1489 (5.9%) | 130 (3%) | 1359 (6.5%) | |
| Social determinants of health | ||||
| Required financial assistance using Medifund (%) | 365 (1.4%) | 130 (3%) | 235 (1.1%) | <0.001 |
| Stayed in a subsidised ward during index admission (%) | 19 324 (76.5%) | 3860 (89.3%) | 15 464 (73.9%) | <0.001 |
| Past healthcare use | ||||
| ED visits (6 months before index admission), mean (SD) | 0.37 (0.92) | 0.67 (1.59) | 0.31 (0.69) | <0.001 |
| Specialist clinic visits (1 year before index admission), mean (SD) | 2.21 (5.52) | 4.27 (8.59) | 1.78 (4.52) | <0.001 |
| Hospital admissions (1 year before index admission), mean (SD) | 0.34 (1.09) | 0.99 (2.02) | 0.2 (0.69) | 0.022 |
| Markers of acute illness burden | ||||
| Index admission was urgent (%) | 19 320 (76.5%) | 3513 (81.3%) | 15 807 (75.6%) | <0.001 |
| Index admission was planned (%) | 4822 (19.1%) | 618 (14.3%) | 4204 (20.1%) | <0.001 |
| Required second line antibiotics during index admission (%) | 1252 (5%) | 297 (6.9%) | 955 (4.6%) | <0.001 |
| Required inpatient dialysis during index admission (%) | 841 (3.3%) | 406 (9.4%) | 435 (2.1%) | <0.001 |
| Required intravenous furosemide 40 mg and above during index admission (%) | 1485 (5.9%) | 521 (12.1%) | 964 (4.6%) | <0.001 |
| Required isolation during index admission (%) | 310 (1.2%) | 78 (1.8%) | 232 (1.1%) | <0.001 |
| Length of stay of index admission, mean (SD) | 5.59 (10.81) | 7.61 (11.59) | 5.17 (10.6) | <0.001 |
| Charlson Comorbidity Index,† mean (SD) | 1.5 (2.43) | 3.62 (3.01) | 1.06 (2.02) | <0.001 |
| Medical comorbidities‡ | ||||
| Stroke (%) | 397 (1.6%) | 67 (1.6%) | 330 (1.6%) | 0.95 |
| Metastatic disease (%) | 2752 (10.9%) | 482 (11.2%) | 2270 (10.8%) | 0.58 |
| Non-metastatic malignancy (%) | 4490 (17.8%) | 749 (17.3%) | 3741 (17.9%) | 0.401 |
| Peripheral vascular disease (%) | 1003 (4%) | 171 (4%) | 832 (4%) | 0.985 |
| Heart failure or fluid overload (%) | 3094 (12.3%) | 539 (12.5%) | 2555 (12.2%) | 0.655 |
| Pressure ulcer (%) | 804 (3.2%) | 142 (3.3%) | 662 (3.2%) | 0.714 |
| Thromboembolism (%) | 1606 (6.4%) | 313 (7.2%) | 1293 (6.2%) | 0.01 |
| Spine fracture (%) | 693 (2.7%) | 129 (3%) | 564 (2.7%) | 0.314 |
| Coronary heart disease or myocardial infarction (%) | 3794 (15%) | 703 (16.3%) | 3091 (14.8%) | 0.013 |
| Hip fracture (%) | 529 (2.1%) | 87 (2%) | 442 (2.1%) | 0.72 |
| Atrial fibrillation (%) | 1966 (7.8%) | 352 (8.1%) | 1614 (7.7%) | 0.353 |
| Epilepsy (%) | 266 (1.1%) | 47 (1.1%) | 219 (1%) | 0.875 |
| Parkinsonism (%) | 395 (1.6%) | 84 (1.9%) | 311 (1.5%) | 0.033 |
| Anxiety (%) | 247 (1%) | 40 (0.9%) | 207 (1%) | 0.761 |
| Bipolar disorder (%) | 76 (0.3%) | 17 (0.4%) | 59 (0.3%) | 0.287 |
| Collagen vascular disease (%) | 376 (1.5%) | 55 (1.3%) | 321 (1.5%) | 0.221 |
| Dementia (%) | 898 (3.6%) | 152 (3.5%) | 746 (3.6%) | 0.911 |
| Hypothyroidism (%) | 593 (2.3%) | 98 (2.3%) | 495 (2.4%) | 0.738 |
| Chronic kidney disease, stages 1–4 (%) | 4387 (17.4%) | 767 (17.7%) | 3620 (17.3%) | 0.497 |
| Chronic obstructive pulmonary disease (%) | 719 (2.8%) | 122 (2.8%) | 597 (2.9%) | 0.952 |
| Osteoarthritis (%) | 2152 (8.5%) | 376 (8.7%) | 1776 (8.5%) | 0.673 |
| Benign prostatic hypertrophy (%) | 1238 (4.9%) | 198 (4.6%) | 1040 (5%) | 0.298 |
| Asthma (%) | 781 (3.1%) | 145 (3.4%) | 636 (3%) | 0.298 |
| Hyperlipidaemia (%) | 7216 (28.6%) | 1284 (29.7%) | 5932 (28.4%) | 0.076 |
| Hypertension (%) | 10 136 (40.2%) | 1774 (41%) | 8362 (40%) | 0.194 |
| Chronic kidney disease stage 5 or end-stage renal failure (%) | 3423 (13.6%) | 611 (14.1%) | 2812 (13.4%) | 0.233 |
| Diabetes (%) | 6303 (25%) | 1098 (25.4%) | 5205 (24.9%) | 0.478 |
| History of alcoholism (%) | 431 (1.7%) | 103 (2.4%) | 328 (1.6%) | <0.001 |
| Treatment with antidepressants§ (%) | 2513 (10%) | 1048 (24.2%) | 1465 (7%) | <0.001 |
*Continuous variables were analysed using Student's t-test and categorical variables were analysed using χ2 test or Fisher's exact test when appropriate.
†Based on ICD codes of index admission.
‡Based on ICD codes in the preceding 7 years.
§Based on discharge and outpatient prescriptions in the preceding 1 year.
ED, emergency department; ICD, International Classification of Diseases.