Influence of non-index hospital readmission on length of stay and mortality Online-only materials
1. eTable 1 – selection of overall sample
2. eTable 2 – patterns of readmission and mortality data for patients with multiple readmissions within 30 days
3. eTables 3-5 – Characteristics of hospital discharges in each of the 3 cohorts a. eTable 3 – Medicare cohort
b. eTable 4 – post-acute care cohort c. eTable 5 – readmission penalty cohort
4. eFigures 1-4 – Survival curves for hospital length of stay a. eFigure 1 – overall sample
b. eFigure 2 – Medicare cohort c. eFigure 3 – post-acute care cohort d. eFigure 4 – readmission penalty cohort
5. eTable 6 – Results of sensitivity analysis using only one record per patient
eTable 1 – Selection of overall sample according to study inclusion and exclusion criteria
UNWEIGHTED WEIGHTED
N (Prop) Total N N (Prop) Total N Full sample before inclusion/exclusion 14,325,17
2
35,580,34 8 Exclusions
Age < 18 1,152,904 (8.0) 5,643,937
(15.9)
Died during index stay 308,479 (2.2) 701,200 (2)
Unknown or non-home discharge location 308,023 (2.2) 712,050 (2)
Less than 30 days follow-up 1,180,695 (8.2) 2,931,542 (8.2)
Admission is counted as readmission elsewhere
1,559,406 (10.9)
3,631,196 (10.2)
Missing outcome data 404 (0) 704 (0)
N After Exclusions 10,263,48
0
23,353,29 0 Missing Data
Weekend admission 28 (0) 73 (0)
Death or disposition 3,236 (0) 7,719 (0)
Patient number of chronic conditions 1,856 (0) 5,452 (0)
Elective admission 14,700 (0.1) 38,787 (0.2)
Length of stay 333 (0) 624 (0)
Primary payer 12,066 (0.1) 34,055 (0.1)
Patient rurality 33,007 (0.3) 66,816 (0.3)
Patient Income 163,231 (1.6) 352,399 (1.5)
Admission Date 28 (0) 73 (0)
APR-DRG 2,832 (0) 8,108 (0)
Analysis N 10,052,04
8
22,884,50 5 Readmission Cohorts
Overall sample 1,196,907 2,722,821
Medicare patients 702,236 1,603,684
Post-acute care 362,157 822,688
Readmission penalty 135,431 313,438
Exclusions and missing data are not mutually exclusive, number of discharges and proportion are reported for each category separately. APR-DRG = All Payer Refined Diagnosis Related Group.
eTable 2 – Patterns and mortality rates of patients with multiple readmissions within 30 days of index discharge
Index hospital Non-index hosp 2 different hosp 3 or More Hosp 2 Admissions 5.7 (11192/194975) 5.6 (1998/35462) 5.8 (4411/75939)
3 Admissions 5.2 (812/15688) 4.8 (109/2253) 4.8 (520/10885) 2 (56/2755) 4 or More Admissions 4.3 (51/1180) 1.7 (3/179) 2.1 (28/1355) 0.6 (6/983)
The Table presents mortality data for patients with multiple readmissions within 30 days. The rows capture how many admissions the patient had in the 30-day period; the columns present whether these multiple readmissions all occurred at the index hospital (first column), at the same non-index hospital (second column), 2 different hospitals (third column) or 3 or more hospitals (fourth column).
eTable 3 – Patient, hospitalization, and hospital characteristics of the Medicare cohort
No Readmission N=8,854,980
Readmitted to index hospital N=1,248,914
Readmitted to non- index hospital
N=355,490 Patient characteristics %
Age – Mean (years) 72.9 72.4 70.4
18-44 3.8 4.6 6.6
45-64 14.7 16.8 20.0
65-79 47.4 43.7 43.1
80+ 34.1 34.8 30.4
Female 56.5 54.1 51.9
Median Household Income, dollars
1 - 37,999 28.5 30.0 32.7
38,000 – 47,999 28.0 27.5 28.0
48,000 – 63,999 23.9 23.3 21.9
64,000+ 19.7 19.1 17.5
Number of chronic conditions, mean 6.3 7.2 7.0
Rural residence 21.6 18.6 22.9
Hospitalization characteristics %
Elective Admission 21.7 13.9 15.0
Length of Stay – mean (days) 5.1 6.3 6.8
0-2 days 32.0 22.9 24.2
3-4 days 32.0 28.6 27.1
5-7 days 19.4 23.5 22.1
>7 days 16.6 24.9 26.5
APR-DRG Mortality Risk
Minor 34.0 19.7 24.4
Moderate 36.9 38.1 37.1
Major 23.6 33.7 30.1
Extreme 5.5 8.5 8.4
Weekend Admission 19.7 21.3 21.3
Discharge Diagnosis
Acute MI 2.3 2.5 2.6
CABG 0.7 0.6 0.6
CHF 4.1 6.4 5.7
COPD 3.2 4.2 3.2
Pneumonia 4.2 4.6 3.8
THA/TKA 6.2 2.0 2.2
Discharge Destination
Home 54.7 48.3 49.9
Skilled nursing facility 25.1 27.8 30.4
Home Health Care 20.2 23.8 19.6
Hospital Characteristics % Ownership
Government, nonfederal 10.9 10.6 12.1
eTable 3 (continued)
Private, non-profit 73.0 73.2 67.9
Private, for-profit 16.2 16.1 20.0
Hospital Size
Small 13.4 10.9 16.8
Medium 23.6 22.9 24.3
Large 62.9 66.2 58.9
Teaching Status
Metropolitan, teaching 46.2 48.5 44.8
Metropolitan, non-teaching 40.1 39.3 41.4
Non-metropolitan 1338 12.2 13.7
Content is percentages of patients with each characteristic unless specified. APR-DRG = All Patients Refined Diagnosis Related Groups. MI = myocardial infarction, CABG = coronary artery bypass grafting, CHF= congestive heart failure; COPD = chronic obstructive pulmonary disease; THA/TKA = total hip/knee arthroplasty.
eTable 4 – Patient, hospitalization, and hospital characteristics of the post-acute care cohort
No Readmission N=4,008,078
Readmitted to index hospital N=644,732
Readmitted to non- index hospital
N=177,956 Patient characteristics %
Age – Mean (years) 76.6 75.9 74.6
18-44 1.4 1.8 2.5
45-64 10.3 12.4 14.3
65-79 41.7 40.7 42.5
80+ 46.6 45.0 40.7
Female 60.8 57.1 54.9
Median Household Income, dollars
1 - 37,999 27.2 28.9 31.0
38,000 – 47,999 27.4 26.9 27.5
48,000 – 63,999 24.2 23.6 22.5
64,000+ 21.2 20.7 19.0
Number of chronic conditions, mean 6.8 7.7 7.6
Rural residence 19.6 16.9 20.8
Hospitalization characteristics %
Elective Admission 21.4 12.4 14.6
Length of Stay – mean (days) 6.7 8.8 8.8
0-2 days 15.2 11.4 11.3
3-4 days 34.3 26.4 25.1
5-7 days 24.6 26.8 25.4
>7 days 25.9 35.4 38.1
APR-DRG Mortality Risk
Minor 22.8 11.5 14.0
Moderate 36.9 35.1 34.9
Major 31.1 40.5 37.6
Extreme 9.2 12.9 13.5
Weekend Admission 19.9 22.0 21.4
Discharge Diagnosis
Acute MI 1.7 2.3 2.4
CABG 0.9 0.8 0.9
CHF 4.5 6.9 5.7
COPD 2.5 3.6 2.7
Pneumonia 4.4 4.9 4.1
THA/TKA 11.0 3.4 3.8
Hospital Characteristics % Ownership
Government, nonfederal 10.3 9.8 11.3
Private, non-profit 73.7 73.9 68.9
Private, for-profit 16.0 16.3 19.8
Hospital Size
Small 13.6 10.8 16.1
eTable 4 (continued)
Medium 23.9 23.4 24.3
Large 62.5 65.8 59.6
Teaching Status
Metropolitan, teaching 46.2 47.7 46.2
Metropolitan, non-teaching 40.9 40.6 42.1
Non-metropolitan 12.9 11.6 11.7
Content is percentages of patients with each characteristic unless specified; all patients have Medicare as payer. APR-DRG = All Patients Refined Diagnosis Related Groups. MI = myocardial infarction, CABG = coronary artery bypass grafting, CHF= congestive heart failure; COPD = chronic obstructive pulmonary disease; THA/TKA = total hip/knee arthroplasty.
eTable 5 – Patient, hospitalization, and hospital characteristics of the readmission penalty cohort
No Readmission N=1,815,360
Readmitted to index hospital N=249,820
Readmitted to non- index hospital
N=63,618 Patient characteristics %
Age – Mean (years) 74.6 75.3 74.0
18-44 1.0 1.3 1.7
45-64 11.4 13.2 15.1
65-79 52.6 44.8 47.8
80+ 35.0 40.7 35.4
Female 56.0 53.0 50.7
Median Household Income, dollars
1 - 37,999 27.9 30.7 33.5
38,000 – 47,999 28.7 28.6 28.6
48,000 – 63,999 24.1 23.0 21.0
64,000+ 19.3 17.7 16.9
Number of chronic conditions, mean 6.8 8.0 7.8
Rural residence 25.0 21.8 27.9
Hospitalization characteristics %
Elective Admission 31.0 12.2 15.7
Length of Stay – mean (days) 4.7 5.9 6.0
0-2 days 25.0 18.9 19.9
3-4 days 42.2 33.7 33.9
5-7 days 19.2 25.2 23.6
>7 days 13.5 22.1 22.6
APR-DRG Mortality Risk
Minor 33.5 14.4 17.2
Moderate 34.9 36.5 36.8
Major 25.9 39.8 36.5
Extreme 17.6 22.7 21.5
Weekend Admission 17.6 22.7 21.5
Discharge Diagnosis
Acute MI 11.1 12.4 14.5
CABG 3.3 2.9 3.4
CHF 20.0 31.9 31.6
COPD 15.5 20.8 18.1
Pneumonia 20.7 22.8 21.5
THA/TKA 30.3 10.1 12.0
Hospital Characteristics % Ownership
Government, nonfederal 10.8 10.8 12.1
Private, non-profit 73.1 72.1 67.4
Private, for-profit 16.0 17.1 20.4
Hospital Size
Small 16.5 12.8 20.9
eTable 5 (continued)
Medium 24.4 24.2 25.0
Large 59.1 63.0 54.1
Teaching Status
Metropolitan, teaching 41.4 41.5 37.7
Metropolitan, non-teaching 41.5 42.0 43.3
Non-metropolitan 17.2 16.5 19.1
Content is percentages of patients with each characteristic unless specified; all patients have Medicare as payer. Patients could have more than one discharge diagnosis if they had both a medical diagnosis and a surgical diagnosis (for example, a hip replacement and pneumonia). APR-DRG = All Patients Refined Diagnosis Related Groups. MI = myocardial infarction, CABG = coronary artery bypass grafting, CHF=
congestive heart failure; COPD = chronic obstructive pulmonary disease; THA/TKA = total hip/knee arthroplasty.
eFigure 1: Survival curve for hospital length of stay in overall sample
Legend: A higher “survival” connotes higher probability of remaining in the hospital (longer length of stay).
eFigure 2: Survival curve for hospital length of stay in Medicare cohort
Legend: A higher “survival” connotes higher probability of remaining in the hospital (longer length of stay).
eFigure 3: Survival curve for hospital length of stay in post-acute care cohort
Legend: A higher “survival” connotes higher probability of remaining in the hospital (longer length of stay).
eFigure 4: Survival curve for hospital length of stay in readmission penalty cohort
Legend: A higher “survival” connotes higher probability of remaining in the hospital (longer length of stay).
eTable 6: Results of sensitivity analysis using only one record per patient
Model All adjusted records
HR (95% CI)
Single Record HR (95% CI) Mortality
Full 1.21 (1.17, 1.25) 1.22 (1.18, 1.26)
Medicare 1.20 (1.16, 1.24) 1.21 (1.16, 1.25)
Post-acute care 1.18 (1.13, 1.23) 1.14 (1.09,1.19)
Readmission penalty 1.25 (1.17, 1.33) 1.26 (1.18, 1.34)
Length of stay
Full 0.87 (0.86, 0.88) 0.87 (0.86, 0.88)
Medicare 0.87 (0.86, 0.89) 0.87 (0.86, 0.88)
Post-acute care 0.88 (0.86, 0.89) 0.88 (0.87, 0.90)
Readmission penalty 0.85 (0.83, 0.86) 0.85 (0.83. 0.87)
