Table S3. Successive logistic regression models predicting 30-day readmission risk for men (n=16,218 for derivation cohort; n=16,218 for internal validation cohort) discharged from inpatient psychiatric units in Ontario.

Variables / Model 1 / Model 2 / Model 3 / Model 4 / Model 4 Internal Validation
Sociodemographic
Age / 0.99 (0.99-1.00) / 0.99 (0.99-0.99) / 0.99 (0.99-1.00) / 0.99 (0.99-0.99) / 0.99 (0.99-0.99)
Unmarried vs. Married or with common-law partner / 1.34 (1.17-1.54) / 1.17 (1.02-1.35) / 1.11 (0.96-1.28)
Past Psychiatric and Medical History
Number of prior psychiatric admissions (lifetime): One to three vs. None / 1.34 (1.18-1.52) / 1.28 (1.12-1.46) / 1.25 (1.09-1.43) / 1.20 (1.05-1.37)
Four to five / 1.82 (1.52-2.18) / 1.64 (1.36-1.98) / 1.55 (1.27-1.89) / 1.34 (1.10-1.65)
Six or more / 2.31 (1.95-2.74) / 2.11 (1.76-2.52) / 1.96 (1.62-2.37) / 1.74 (1.44-2.10)
Outpatient physician mental health visits (past year): None vs. Two or more / 0.80 (0.69-0.92) / 0.74 (0.65-0.85) / 0.73 (0.63-0.84) / 0.88 (0.76-1.01)
One vs. Two or more / 0.81 (0.68-0.96) / 0.78 (0.65-0.92) / 0.73 (0.61-0.88) / 0.85 (0.71-1.01)
Emergency department mental health visits (past year): One or more vs. None / 1.33 (1.19-1.51) / 1.37 (1.22-1.54) / 1.35 (1.19-1.54) / 1.45 (1.27-1.64)
Number of ADGsa / 1.02 (1.01-1.04)
Admission Characteristics
Threat to others at admission / 1.12 (0.98-1.27)
Threat to self at admission / 1.14 (1.02-1.28) / 1.16 (1.03-1.30) / 1.14 (1.01-1.28)
Inability to care for self at admission / 1.29 (1.15-1.45) / 1.20 (1.06-1.36) / 1.19 (1.06-1.35)
Primary diagnosis: Bipolar vs. Psychotic Disorder / 1.02 (0.85-1.22) / 1.08 (0.89-1.30) / 1.12 (0.94-1.34)
Depressive vs. Psychotic Disorder / 0.90 (0.76-1.06) / 1.03 (0.86-1.22) / 0.84 (0.70-1.00)
Substance or Alcohol Use disorder vs. Psychotic Disorder / 0.70 (0.58-0.85) / 0.82 (0.68-0.99) / 0.65 (0.53-0.78)
Other vs. Psychotic Disorder / 0.89 (0.74-1.05) / 0.86 (0.71-1.05) / 0.82 (0.68-0.98)
Personality disorder diagnosis / 1.24 (1.04-1.47)
Substance/alcohol abuse / 1.12 (0.99-1.27)
Length of Stay: 15-28 vs. 29 or more days / 1.27 (1.07-1.50) / 1.27 (1.07-1.50) / 1.43 (1.20-1.70)
9-14 vs. 29 or more days / 1.52 (1.28-1.80) / 1.52 (1.28-1.80) / 1.77 (1.48-2.10)
8 or less vs. 29 or more days / 1.38 (1.17-1.63) / 1.33 (1.12-1.59) / 1.67 (1.40-1.99)
Planned discharge / 0.60 (0.51-0.72) / 0.66 (0.54-0.81) / 0.61 (0.50-0.74)
Clinical Rating Scales
Aggressive Behaviour Scale (Range 0-12): One or more vs. Zero / 1.40 (1.20-1.64) / 1.60 (1.37-1.85)
Depression Rating Scale (Range 0-15): Two vs. One or less / 1.11 (0.93-1.32) / 1.19 (1.01-1.40)
Three or more vs. One or less / 1.27 (1.07-1.52) / 1.27 (1.09-1.47)
Anxiety Rating Scale (Range 0-18) One vs. Zero / 1.30 (1.03-1.64)
Two or more vs. Zero / 1.13 (0.97-1.31)
Criminal Activity CAPb High risk vs. No risk / 1.13 (1.00-1.27) / 0.98 (0.87-1.11)
Self Care CAPb Low risk vs. No risk / 1.44 (1.26-1.64) / 1.28 (1.12-1.45)
High risk vs. No risk / 1.79 (1.17-2.74) / 1.14 (0.71-1.82)

aADG=John Hopkins Aggregated Diagnosis Groups which divides ICD coded diagnoses into 32 categories based on duration, etiology, severity, diagnostic certainty, and specialty care involvement (excluding psychosocial ADGs)(John Hopkins Bloomberg School of Public Health, 2009); bCAP=Clinical Assessment Protocol (high risk is a CAP of 2, except for criminality where high risk is a CAP of 1).

Model 1: Including sociodemographics only

Model 2: Model 1 variables + Past psychiatric and medical history

Model 3: Model 2 variables + Admission characteristics

Model 4: Model 3 + Clinical rating scales