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Table 1 Characteristics of the study population

From: Diagnosis-specific readmission risk prediction using electronic health data: a retrospective cohort study

  Derivation cohort N = 3572 Historical validation cohort N = 1756 Random sample combined cohort N = 396
Readmitted in 30 days 577 (16.2%) 311 (17.7%) 64 (16.2%)
Demographics    
Age, median (IQR) 61 (51–72) 62 (52–73) 61 (52–71)
Gender, Female (%) 1541 (43.1%) 759 (43.2%) 162 (40.9%)
Marital status, single* (%) 2023 (56.6%) 988 (56.3%) 203 (51.3%)
Race, Black† (%) 1090 (30.5%) 497 (28.3%) 130 (32.8%)
Distance from the zip code centroid to hospital, miles [median, (IQR)] 9.6 (4.6–46.2) 12 (4.6–53.6) 9.4 (4.6–46.2)
Comorbidities    
Charlson Score‡, median (IQR) 3 (1–4) 3 (2–5) 3 (2–4)
Solid tumor 192 (5.4%) 104 (5.9%) 27 (6.8%)
Other neurologic disease 185 (5.2%) 95 (5.4%) 18 (4.6%)
Hypertension 2,533 (70.9%) 1,239 (70.6%) 289 (73.0%)
Lymphoma 86 (2.4%) 46 (2.6%) 8 (2.0%)
Abnormal weight loss 231 (6.5%) 94 (5.4%) 34 (8.6%)
Obesity 550 (15.4%) 258 (14.7%) 67 (16.9%)
Liver disease 154 (4.3%) 61 (3.5%) 18 (4.6%)
Peripheral vascular disease 286 (8.0%) 184 (10.5%) 45 (11.4%)
Arrhythmia 1,149 (32.2%) 722 (41.1%) 145 (36.6%)
Metastatic cancer 106 (3.0%) 74 (4.2%) 15 (3.8%)
Details of hospital visit    
Length of stay, median (IQR) 4 (2–7) 4 (3–8) 4 (2–7)
Inpatient visit within the last 30 days 379 (10.6%) 181 (10.3%) 45 (11.4%)
ED visit within the prior 30 days 167 (4.7%) 94 (5.4%) 18 (4.6%)
Number of discharge medications 12 (8–16) 12 (8–16) 12 (8–16)
AMI 1047 (29.3%) 594 (33.8%) 119 (30.1%)
CHF 1354 (37.9%) 610 (34.7%) 148 (37.4%)
PNA 1171 (32.8%) 552 (31.4%) 129 (32.6%)
  1. Abbreviations: IQR interquartile range, ED emergency department, AMI acute myocardial infarction, CHF congestive heart failure, PNA pneumonia.
  2. *Single includes single, widowed, divorced and separated.
  3. †Versus not black.
  4. ‡Calculated only using ICD-9 data from the index encounter.