Table 5.
Risk factors included in readmission prediction models
| Risk factor | Studies (n, %) | Citations (see online supplemental appendix E) | |
| Overall (n=81) | General* (n=12) |
||
| Demographics | |||
| Age | 38 (47%) | 6 (50%) | 15–22 24 25 27 28 31 32 39 41 42 50 56 60–63 65–67 69 70 72 74 76 77 79 80 82 90 93 95 |
| Sex/gender | 30 (37%) | 5 (42%) | 15–21 25 27 28 31 41 50 53 56 60–63 65–67 69 76 77 79 83 85 90 93 |
| Race/ethnicity | 12 (15%) | 2 (17%) | 15 16 26 27 31 41 46 52 57 63 71 72 |
| Disease related | |||
| Comorbidities | 50 (62%) | 4 (33%) | |
| Cardiovascular (heart failure, infarction, etc) | 39 (48%) | 4 (33%) | 17–21 23 24 26 27 31–34 36 38 41 42 46 53 57 60–67 69 76–79 82 83 86 90 93 94 |
| Oncological (metastatic, leukaemia, etc) | 30 (37%) | 4 (33%) | 17–21 23 24 27 32 34 41 42 45 46 53 54 61–63 66 76–80 82 83 90 91 93 |
| Pulmonary (COPD, pneumonia, asthma, etc) | 29 (36%) | 3 (25%) | 17–21 23 24 26 27 31 38 42 53 57 60 61 63 65 66 76–79 82 83 86 90 91 93 |
| Endocrine (diabetes, etc) | 26 (32%) | 2 (17%) | 17–19 21 23 24 26 31–34 41 42 53 57 60 62–64 66 70 77 82 83 90 93 |
| Genitourinary (renal failure, etc) | 26 (32%) | 3 (25%) | 17–21 23 24 26 27 31 42 53 57 60 62–64 66 76 78–80 83 86 90 91 |
| Psychiatric (alcohol/drug use, psychosis, etc) | 21 (26%) | 1 (8%) | 18–21 23 24 29 31 39 46 52 53 61 62 76 77 82 90 93–95 |
| Haematological (fluid disorder, anaemia, etc) | 20 (25%) | 2 (17%) | 17–21 23 24 27 31 53 57 62–64 66 83 86 90 92 93 |
| Neurological (stroke, paralysis, etc) | 17 (21%) | 3 (25%) | 17–21 23 27 31 32 41 42 46 66 82 86 89 93 |
| Gastrointestinal (cirrhosis, obstruction, etc) | 16 (20%) | 3 (25%) | 18–21 23 24 27 42 46 53 77 83 86 88 90 93 |
| End of life (dementia, malnutrition, cachexia, etc) | 14 (17%) | 3 (25%) | 17–21 23 27 42 46 63 66 77 83 90 |
| Musculoskeletal-dermatological (injuries, etc) | 12 (15%) | 2 (17%) | 19–21 23 27 31 41 53 61 62 86 93 |
| Infectious (sepsis, shock, etc) | 10 (12%) | – | 17–19 21 23 53 63 66 70 90 |
| Obesity related (BMI, sleep apnoea, etc) | 4 (5%) | – | 62 63 78 90 |
| Obstetric-gynaecological (pregnancy, etc) | 3 (4%) | 1 (8%) | 20 23 53 |
| Severity scores | 29 (36%) | 8 (67%) | |
| Charlson Comorbidity Index | 14 (17%) | 7 (58%) | 16 20 32 37 40 46 50 51 55 56 61 74 92 95 |
| Other (Elixhauser, Tabak, SOI, PMC-RIS, etc) | 10 (12%) | 2 (17%) | 22 25 28 29 38 47 52 53 56 80 |
| Disease specific (GRACE, MELD, etc) | 6 (7%) | – | 70 84 85 90 91 93 |
| Laboratory values | 22 (27%) | 1 (8%) | 21 33 35 36 45 46 51 57 60 65 69–72 76 77 84–88 91 |
| Complications (post-procedure, etc) | 8 (10%) | – | 57 63 85 87 89 90 92 94 |
| Emergent admission (or acute admission) | 6 (7%) | 4 (33%) | 37 38 42 55 56 95 |
| Complexity (No of medical conditions) | 6 (7%) | – | 28 39 52 67 69 79 |
| Signs or symptoms (dyspnoea, ascites, etc) | 5 (6%) | – | 23 63 73 88 90 |
| Condition description (chronic, high risk, etc) | 4 (5%) | 1 (8%) | 16 25 68 |
| Functional ability | |||
| Functional status (or assistance with ADL) | 5 (6%) | – | 32 36 40 63 90 |
| Mental status (MMSE, etc) | 3 (4%) | 1 (8%) | 34 39 77 |
| Dependencies (ambulation, ventilator, etc) | 3 (4%) | – | 39 63 94 |
| Recent falls | 2 (2%) | – | 41 52 |
| Other (bedridden, incontinent, sedentary, etc) | 2 (2%) | – | 41 67 |
| Healthcare utilisation | |||
| Previous admissions | 32 (40%) | 7 (58%) | 15 20 24 29 31–34 39–42 45–47 49 50 52 56 61 62 64 71 76 78–80 82 84 87 93 95 |
| Length of stay | 26 (32%) | 6 (50%) | 28 37 40 45–47 50 51 53–56 61–63 68 69 74 76 78 79 83 86 91 92 95 |
| Previous emergency visits | 11 (14%) | 5 (42%) | 35 37 46 49 50 55 56 74 79 87 95 |
| Previous outpatient visits (specialist or primary care) | 7 (9%) | – | 29 41 54 75 78 86 95 |
| Previous procedures | 5 (6%) | – | 26 60 64 65 89 |
| Current admission | 25 (31%) | 3 (25%) | |
| Disposition (home, SNF, rehab, home health, etc) | 8 (10%) | – | 26 41 57 63 85 86 92 94 |
| Source (emergency, SNF, outpatient, transfer, etc) | 7 (9%) | 1 (8%) | 16 54 61 63 65 79 86 |
| Ward (medical, surgical, neurology, etc) | 3 (4%) | 1 (8%) | 22 27 54 |
| Reimbursement amount | 3 (4%) | 1 (8%) | 15 16 88 |
| Other (consultancies, timing, refusal, etc) | 9 (11%) | 2 (17%) | 16 29 31 45 47 62 69 71 75 |
| Current procedures | 15 (19%) | 2 (17%) | |
| Performed vs not (binary) | 9 (11%) | 2 (17%) | 15 20 22 45 46 51 53 60 77 |
| Type (arthroplasty, splenectomy, etc) | 6 (7%) | 1 (8%) | 26 46 51 57 60 77 |
| Characteristic (high risk, operation time, open, etc) | 6 (7%) | 1 (8%) | 20 57 63 64 90 92 |
| Status (urgent, emergent, elective, etc) | 4 (5%) | – | 57 60 63 90 |
| Medication related | |||
| Specific medications (in-hospital or home) | 19 (23%) | 1 (8%) | |
| Steroid | 5 (6%) | – | 46 57 62 63 90 |
| ACE inhibitor (or ARB) | 3 (4%) | – | 62 68 69 |
| Other cardiac (beta-blocker, nitrate, etc.) | 5 (6%) | 1 (8%) | 34 46 60 70 82 |
| Immunosuppressant | 3 (4%) | – | 60 76 77 |
| Antibiotic | 3 (4%) | – | 46 62 88 |
| Opioid | 3 (4%) | – | 80 82 86 |
| Other (statin, anticoagulant, insulin, etc) | 7 (9%) | – | 46 62 70 82 86 90 92 |
| No of medications (polypharmacy) | 7 (9%) | 2 (17%) | 34 46 50 52 80 82 85 |
| Social determinants of health | |||
| Zip code (or home address) | 11 (14%) | 2 (17%) | |
| Distance from hospital | 4 (5%) | – | 22 64 78 87 |
| Socioeconomic status (based on zip code) | 4 (5%) | 2 (17%) | 16 24 29 42 |
| Rurality (urban, suburban, rural, etc) | 3 (4%) | – | 24 64 69 |
| Insurance status | 10 (12%) | 2 (17%) | 15 26 27 29 32 40 50 65 84 87 |
| Living arrangement (alone, SNF, homeless, etc) | 7 (9%) | – | 39 41 67 69 76 77 87 |
| Marital status | 7 (9%) | 2 (17%) | 29 34 39 40 46 50 76 |
| Disability status | 6 (7%) | – | |
| Disabled vs not (binary) | 5 (6%) | – | 22 31 32 41 78 |
| Type (developmental, visual, cognitive, hearing, etc) | 3 (4%) | – | 31 32 41 |
| Patient-generated health data | 5 (6%) | – | 32 36 40 41 61 |
| Smoking status (current, former, etc) | 3 (4%) | 1 (8%) | 34 63 90 |
| Education level | 2 (2%) | – | 41 89 |
| Annual income | 2 (2%) | – | 41 76 |
| Institution related | |||
| Rurality (urban, suburban, rural, etc) | 2 (2%) | – | 15 26 |
| Standardised admission ratios | 2 (2%) | 1 (8%) | 16 31 |
| Identification code | 2 (2%) | 1 (8%) | 42 52 |
We could not extract factors from seven studies, either due to poor reporting or lack of feature selection.30 43 44 48 58 59 81 An extended version of table is available in online supplemental appendix D.
*'General' indicates models for the general hospitalised population, and is not restricted to any one target population.16 20 27 34 37 42 47 49–51 55 56
ACE, Angiotensin-converting enzyme; ADL, activities of daily living; ARB, Angiotensin receptor blocker; BMI, body mass index; COPD, chronic obstructive pulmonary disease; DNR, do not resuscitate; MMSE, Mini Mental State Exam; SNF, skilled nursing facility; SOI, severity of illness.