1. Appendix 1. Criteria for Clinically Necessary 30-day Readmissions At rehospitalization, readmission included one or more of the following: Major Criteria ICU admission Unplanned return to the operating room Non-operating room invasive procedure* Peripherally inserted central catheter Minor Criteria Abnormal vital signs Temperature > 38.3 or < 36C Tachycardia (Heart rate > 100 bpm) Absolute Hypotension (Systolic blood pressure < 90 mmHg) Clinically documented orthostatic hypotension Acute renal failure defined as 0.3 mg/dL increase in serum creatinine from baseline of < 1.8 mg/dL 1.0 mg/dL increase in serum creatinine from baseline of 2-4mg/DL White blood cell count of > 12000, or < 4000 cells/mm3 Severe electrolyte imbalance or hypoglycemia requiring treatment Drop in hemoglobin count (<7.0) or requiring blood transfusion CT scan evidence of bowel obstruction or anastomotic leak * Percutaneous abdominal drain, endoscopy, bronchoscopy, cardiac catheterization Adapted from Hechenbleikner et al; Hospital readmission by method of data collection J Am Coll Surg, 216 (6); 1150-8

2. Appendix 2. The Patient health Questionnaire (PHQ9)* Over the last 2 weeks, how often have you been bothered by any of the following problems? (use "check mark" to indicate your answer) Not at all Several days More than half the days Nearly everyday 1. Little interest or pleasure in doing things0123 2. Feeling down, depressed or hopeless0123 3. Trouble falling or staying asleep, or sleeping too much0123 4. Feeling tired or having little energy0123 5. Poor appetite or overeating0123 6. Feeling bad about yourself - that you are failure, or have let yourself or your family down0123 7. Trouble concentrating on things, such as reading the newspaper or watching television0123 8. Moving or speaking so slowly that other people could have noticed.0123 Or the opposite - being so fidgety or restless that you have been moving around a lot more than usual0123 9. Thoughts that you would be better off dead, or hurting yourself0123 Interpreting PHQ-9 Scores DiagnosisScore Minimal depression≤ 4 Mild to moderate depression5-14 Moderate to severe depression> 14 *Adapted from: Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. Sep 2001;16(9):606-613.

3. Estimated Cardio Fitness (VO2 Max) Exercise Capacity (MHR) Preoperative Pulse (PP) Body Mass Index (BMI)METS Depression (PHQ9) VO2 max1 MHR0.28 (<0.0001)1 PP-0.02 (0.58)0.28 (<0.0001)1 BMI-0.17 (0.001)0.08 (0.04)0.06 (0.14)1 METS0.30 (<0.0001)0.98 (<0.0001)0.08 (0.05)0.10 (0.007)1 PHQ90.18 (0.001)0.09 (0.02)-0.01 (0.88)0.06 (0.12) 0.06 (0.14)1 Gray areas represent redundant repeat values, for example first value under column MHR is grayed out since the correlation coefficient between MHR and VO2 Max appears under column labeled Lomax, and row labeled MHR Appendix 3A. Correlations of physical function measures and depression symptom severity Appendix 3B. Correlations among covariates for 30-day readmissions risk models AgeMHR # of Chronic conditionsCCindexGait speedMETSDepression MHR -0.97 (<0.0001)1 # of Chronic conditions0.24 (0.001)-0.22 (0.001)1 CCIndex0.76 (<0.0001)-0.74 (<0.0001)0.73 (<0.0001)1 gait speed-0.26 (0.001)0.30 (0.001)-0.12 (0.006)-0.22 (0.001)1 METS -0.94 (<0.0001)0.98 (<0.0001)0.22 (0.001) -0.72 (<0.0001) 0.28 (0.00011 Depression-0.08 (0.04)0.01 (0.01)-0.01 (0.78)-0.02 (0.47)0.2 (0.01) 0.09 (0.02)1 Legend: CCIndex represents Charlson-Deyo Co-morbidity Index, METS represents metabolic Equivalent of tasks; Gray areas represent redundant repeat values; MHR represents maximal heart rate; PHQ9 represents patient-health questionnaire 9.

4. Appendix 4: Comparing 30-Day Readmissions to same center by principal diagnosis Principal Diagnosis* NSQIP Data (N=71) * University HealthCare System Data (N=129)* YNHH Data (N=107) Bleeding3 (4.3)4 (3.1)5 (4.7) Dehydration16 (22.5)30 (23.3)20 (18.7) Gastrointestinal27 (38.0)51 (39.5)26 (24.3) Infection16 (22.5)27 (20.9)18 (16.8) Other9 (12.7)17 (13.2)38 (35.5) Bleeding refers to gastrointestinal bleeding; gastrointestinal refers to constipation, diarrhea or ileus; Infection refers to urinary tract, skin or soft tissue infection;other refers to medication non-adherence, medication overdose, failure to thrive NSQIP: National Surgical Quality Improvement Program YNHH: Yale New Haven Hospital *Adapted from Hechenbleikner et al; Hospital readmission by method of data collection J Am Coll Surg, 216 (6); 1150-8