Table 1. Characteristics of validated readmission risk prediction models.
| Study | Population | Setting | No. of patients, derivation cohort | No. of patients, validation cohort* | Utilization outcome† | Actual readmission rate (% of patients) | Range of readmission rates according to predicted risk (validation cohort) | Model discrimination (c-statistic‡ unless specified otherwise) | |
|---|---|---|---|---|---|---|---|---|---|
| Derivation cohort | Validation cohort | ||||||||
| Models relying on retrospective administrative data | |||||||||
| Anderson, 198522 | Medicare patients(excluded ESRD pts), 1974-1977 | US, general population | 21043 | 10522 | 60-day readmissions | NR | NR | 4 – 40 (lowest to highest decile)§ | NR |
| Bottle, 200612 | Inpatients, 2000-2001 | England, general population | ∼1373755║ | ∼1373754║ | 12-month readmissions | 9.80 overall | --- | All patients: 0.72 Patients with ambulatory care sensitive conditions¶: 0.75 All patients (12 month deaths excluded): 0.70 |
|
| CMS model, AMI Krumholz 200816 | Medicare AMI patients ≥ 65 yr, 2005-2006 | US, general population | 100465 | 100285 | 30-day readmissions | 18.9 | 19.2 | 8. 0 – 33.0 (lowest to highest decile) | 0.63 |
| CMS model, CHF Krumholz, 200815 | Medicare CHF patients ≥ 65 yr, 2003-2004 | US, general population | 283919 | 283528 | 30-day readmissions | 23.6 | 23.7 | 15.0 - 37.0 (lowest to highest decile | 0.6 |
| CMS model, Pneumonia Krumholz, 200817 | Medicare pneumonia patients ≥ 65 yr, 2005-2006 | US, general population | 226545 | 226706 | 30-day readmissions | 17.4 | 17.5 | 9.0 – 31.0 (lowest to highest decile) | 0.63 |
| Halfon, 200613 | All hospitalizations in year 2000 | Switzerland, general population | 65740 | 66069 | 30-day potentially avoidable readmissions | 5.1 | 5.2 | --- | Nonclinical: 0.67 Charleson based: 0.69 SQLape: 0.72 |
| Hammill, 201118 | CHF registry patients ≥ 65 yr, 2004-2006 | US. general population | 24163# | 30-day readmissions | 21.9 overall | Claims-only: 14.4 – 32.7 (lowest to highest decile) Claims-clinical: 13.5 – 33.9 | Claims-only: 0.59 Claims-clinical: 0.60 |
||
| Holloway, 199053 | Medical, neurologic, surgical, and geriatric inpatients, 1981-1982 | US, single VA hospital | 2970 | unclear | 30-day readmissions | 22.0 overall | --- | NR | |
| Holman, 200514 | Medical, surgical, psychiatric inpatients, 1989-1997 | Western Australia, general population | 326,456 | 5289 (asthma) 5265 (AMI) |
30-day readmissions | NR | NR | --- | Asthma 0.71 AMI 0.64 |
| Howell, 200954 | General medical inpatients with ambulatory care sensitive condition¶ 2005-2006 | Queensland, Australia, general population | 13207 | 4492 | 12-month readmissions | 45.5 | 45.1 | LR+ readmission for risk scores 50, 70, 80: 2.04, 3.11, 7.02 (overall range 0 – 100) | 0.65 |
| Naessens, 199223 | Inpatients ≥ 65 yr, 1980, 1985, and 1987 | US, general population in a single county | 5854 | randomly selected10% of derivation cohort | 60-day mortality/readmissions | 20.8 overall | 15.6 – 36.0 (lowest to highest quartile) | HCFA alone 0.59 (SE=0.01) HCFA + COMPLEX 0.61 (SE=0.01) |
|
| Philbin, 199919 | CHF inpatients, 1995 | US, multicenter in a single state | 21227 | 21504 | CHF readmissions within calendar year | 21.3 overall | 9.8 – 45.4 (lowest to highest ninth) | Simple scoring system: 0.60 Weighted scoring system: 0.61 |
|
| Silverstein, 200820 | Inpatients ≥ 65 yr, 2002-2004 | US, multicenter in a single city | 19528 | 9764 | 30-day readmissions | 11.7 overall | --- | 0.65 (same for both Elixhauser and HRDES methods) | |
| Thomas, 199621 | Medicare inpatients ≥ 65 yr, 1989-1991 | US, multicenter in a single state | 12 different cohorts based on diagnosis; range 1163-14590 | 15-, 30-, 60-, and 90-day readmissions | 3 - 40** overall | --- | among 8 medical conditions and 4 time periods, c statistic ranged from 0.55-0.61 | ||
| Models using administrative data in real time | |||||||||
| Amarasingham, 201024 | CHF patients, 2007-2008 | US, single center | 1029 | 343 | 30-day readmissions | 24.1 overall | 12.2 – 45.7 (lowest to highest quintile) | 0.72 (0.70-0.75) | |
| Billings, 200725 | Patients eligible for mandatory Medicaid managed care enrollment, 2000-2004 | US, general population in a single city | ∼35000║ | ∼35000║ | 12-month readmissions | NR | NR | NR (inpatient costs ranged 23,687 – 44,385 for risk scores 50-90, overall range 0 – 100) |
Risk scores range 0-100 Using risk score 50+, Sens 58%, Spec 74%, PPV 69.5%, LR+ 2.23 |
| PARR model Billings, 200626 | Inpatients with an ambulatory care sensitive reference condition¶ 2002-2003 | England, general population | 10% of hospital episodes for all England | A second 10% sample of hospital episodes for all England | 12-month readmissions | NR | NR | --- | 0.69 |
| Models using retrospective primary data collection | |||||||||
| Coleman, 200427 | Medicare inpatients ≥ 65 yr, 1997-1998 | US, general population | 700 | 704 | 30-day “complicated care transitions”†† | 21.9 | 25.0 | --- | administrative data model: 0.77colspan="11"administrative + self-report data: 0.83 |
| Krumholz, 200030 | Medicare CHF patients ≥ 65 yr, 1994-1995 | US, multicenter in a single state | 1129 | 1047 | 180-day readmissions | 50.0 | 47.0 | All-cause: 26.0 – 59.0 CHF: 9.0 – 31.0 (lowest to highest tertile) |
Number of risk factors associated with readmission risk (P<0.0001). 0 risk factors: 26% 3-4 risk factors: 59% |
| Morrissey, 200328 | Medical inpatients ≥ 65 yr, 1997-1998 | Ireland, single rural hospital | 487 | 732 | 12-month readmissions | 40.7 | 29.0 | --- | 0.70 |
| Smith Index (original) Smith, 198555 | Medical inpatients, 1979-1980 | US, single county hospital | 1007 | 499 | 90-day readmissions | 16.9 | NA | 7.3 – 38.0 (lowest to highest octile) | Sens 59.0%, Spec 69.3%, PPV 29.9% LR+ 1.92 |
| Smith Index validation Smith, 198856 | Medical inpatients, 1985 | US, single county hospital | 502 (control) 499 (intervention) | Readmissions/month/patient (mean 180 days f/u) | NA | 10.0 | 0.07 – 0.18 (lowest to highest tertile) | NR | |
| Smith Index validation Smith, 199657 | Medical inpatients ≥ 45 yr, 1988-1990 | US, single VA hospital | 662 (validation) | 90-day readmissions | NA | 20.1 | --- | 0.66 | |
| Van Walraven, 201029 | Medical and surgical inpatients | Canada, multicenter | 4812 patients — split derivation/internal validation | 1M patients from Discharge Abstract Database for external validation | 30-day readmissions | 7.3 | 7.3 | 0 – 42.9 (scores 0 – 17, footnote – corresponding to expected probability of readmission/death of 2.0 – 34.6%) | 0.68 (0.65-0.71) |
| Models using primary data collected in real time | |||||||||
| Burns, 199158 | Medical inpatients ≥ 65 yr, 1987 | US, single VA hospital | 134 | 34 | 60-day readmissions | 30.6 overall | --- | NR | |
| Evans, 198859 | Medical, neurologic, and surgical inpatients over a 6 week period | US, single VA hospital | 532 | 177 | Composite of 60-day readmission, nursing home placement, or LOS longer than expected per mean LOS of DRG | 21.0 overall (60-day readmissions) | % high-care users: 34.7 – 91.7 (lowest to highest eighth) | Risk score range 0-8Score >= 3: Sens 0.60, Spec 0.76, LR+ 2.5Score >= 4: Sens 0.42, Spec 0.93, LR+ 6 |
|
| Hasan, 200931 | Medical inpatients, 2001-2003 | US, multicenter | 7287 | 3659 | 30-day readmissions | 17.5 | 17.4 | 5.9 – 28.9 (lowest to highest quartile) | 0.61 |
| PRA (original) Boult, 199332 | Non-institutionalized Medicare patients ≥ 70 yr, 1984 | US, general population | 2942 | 2934 | 4 year readmissions | 28.4 | NA | 26.1 (score 0-3) – 41.8 (score 4+) | 0.61 (SE=0.01) |
| PRA validation Allaudeen, 201134 | Medical inpatients ≥ 65 yr, 5 week period in 2008 | US., single academic center | NA | 159 | 30-day readmissions | NA | 32.7 | --- | PRA 0.56 (0.44-0.67) Prediction by physician 0.58-0.59 (0.46-0.70) Prediction by non-physician provider 0.50-0.55 (0.38 – 0.67) |
| PRA validation Novotny, 200833 | Medical inpatients, 2005-2007 | US, single academic center | 1077 | 41-day readmissions | NA | 14.0 | --- | PRA score 0.53 cutpoint, LR+ 1.67 | |
Abbreviations: DRG denotes Diagnosis Related Group; LR+, Positive Likelihood Ratio; NA, Not Applicable; NR, Not Reported; PARR, Patients at Risk for Re-hospitalization algorithm; PRA, Probability of Repeated Admissions; SE, Standard Error.
*
The most recent validation cohort is listed if a study had multiple validation cohorts.
†
Unplanned, all-cause readmissions unless otherwise specified
‡
Validation cohort values for the c-statistic are listed if a study provided c-statistic values for both validation and derivation cohorts. 95% confidence interval is provided in parentheses, if reported.
§
Approximate values of data presented in a bar graph.
║
The total number of subjects was divided equally between the derivation and validation cohorts, but the exact numbers were not specified.
¶
Reference conditions such as congestive heart failure, chronic obstructive pulmonary disease, diabetes, and asthma, for which timely and effective case-management has the potential to reduce the risks of readmission.
#
Used bootstrap method for internal validation, no separate validation cohort
**
Reports 15-, 30-, 60-, and 90-day readmission rates for 12 different conditions
††
At least one transfer from lower to higher intensity care environment