Among 1242496 hospitalized patients between January 2015 and December 2020, 84389 cases were readmitted within 30 days from the patient’s discharge from the hospital. It included 74,494 planned readmission and 9,895 unplanned patients. There were significantly more women with planned readmissions versus unplanned readmissions at 67.0% and 51.3%, respectively. The age groups with the largest number of planned and unplanned readmissions were 40≤-<49 (21,653 cases, 29.1%) and 50≤ -<59 years (2,074 cases, 21.0%), respectively. The number of days of initial hospitalization for patients with planned and unplanned readmissions was predominantly in the 1≤-<4 day group, 67.0% (49,936 cases) and 46.5%(4,600 cases), respectively (Table 1). The age group with the lowest number of patients with planned and unplanned readmission was both ≥80 years old (0.9% vs 4.2%). Table 1 shows the demographic data and associated risk factors for planned and unplanned patient admissions.
Table 1 Characteristics of patients’ readmissions.
|
Planned readmission
n=74494
|
Unplanned readmission
n=9895
|
p
|
Gender
female
male
|
49938(67.0%)
24556(33.0%)
|
5073(51.3%)
4822(48.7%)
|
P<0.001
|
Marital status
Married/partner
Separated/divorced
single
Widowed/other
|
68879(92.4%)
1395(1.9%)
2959(4.0%)
1261(1.7%)
|
8236(83.2%)
224(2.3%)
1055(10.7%)
380(3.8%)
|
P<0.001
P<0.001
P<0.001
P<0.001
|
Age years
18≤-<30
30≤-<39
40≤-<49
50≤ -<59
60≤-<69
70≤ -<79
≥80
Mean±SD
|
3513(0.5%)
7631(10.2%)
21653(29.1%)
21346(28.7%)
15463(20.8%)
4213(5.7%)
675(0.9%)
52.61±12.35
|
1243(12.5%)
1213(12.3%)
1929(19.5%)
2074(21.0%)
1941(19.6%)
1079(10.9%)
416(4.2%)
51.64±16.72
|
P<0.001
P<0.001
P<0.001
P<0.001
P<0.001
P<0.001
P<0.001
|
Length of initial stay (days)
1≤-<4
4≤-<7
7≤-<14
14≤-<20
20≤-<30
≥30
Mean ± SD
|
49936(67.0%)
11397(15.3%)
9560(12.8%)
1612(2.2%)
1297(1.7%)
692(0.9%)
4.09±6.77
|
4600(46.5%)
1374(13.9%)
2173(22.0%)
737(7.4%)
644(6.5%)
367(3.7%)
8.02±12.17
|
P<0.001
P<0.001
P<0.001
P<0.001
P<0.001
P<0.001
|
Interval from discharge to readmission (days)
1 ≤-<3
3 ≤-<5
5≤<7
7 ≤ <10
10≤ <20
20≤ <30
Mean ± SD
|
1262(1.7%)
936(1.3%)
3485(4.7%)
10159(13.6%)
16980(22.8%)
41672(55.9%)
17.05±8.96
|
1093(11.0%)
364(3.7%)
1165(11.8%)
790(8.0%
1964(19.8%)
4519(45.7%)
16.79± 10.02
|
P<0.001
P<0.001
P<0.001
P<0.001
P<0.001
P<0.001
|
No stay in ICU
Stay in ICU
|
74394(99.9%)
100(0.1%)
|
9704(98.1%)
191(1.9%)
|
P<0.001
|
Surgery
No
Yes
|
47694(64.0%)
26800(36.0%)
|
4131(41.7%)
5764(58.3%)
|
P<0.001
|
Health insurance
Yes
No
Missing
|
67765(91.1%)
2322(3.1%)
4407(5.8%)
|
8395(84.8%)
525(5.3%)
975(9.9%)
|
P<0.001
|
Comparison of disease with planned and unplanned readmission
The disease with the highest number of planned readmissions was encounter for antineoplastic chemotherapy (62,756, 35.3%), followed by radiotherapy sessions for malignancy (919, 11.2%) and systemic lupus erythematosus (607, 13.1%). The disease with the highest number of unplanned readmissions was encounter for antineoplastic chemotherapy (2038, 1.1%), followed by age-related cataract (1,061, 5.0%) and unspecified disorder of refraction (544, 10.6%) (Table 2).
Table 2 Readmissions numbers and rates in Disease
|
Planned readmission
|
Unplanned readmission
|
|
Disease
|
N
|
Hospitalization
|
(%)
|
Disease
|
N
|
Hospitalization
|
(%)
|
Encounter for antineoplastic chemotherapy Z51.11
|
62756
|
177749
|
35.3
|
Encounter for antineoplastic chemotherapy
Z51.11
|
2038
|
177749
|
1.1
|
Radiotherapy session
Z51.0
|
919
|
8229
|
11.2
|
Age-related cataract
H25.900
|
1061
|
21255
|
5.0
|
Systemic lupus erythematosus
M32.0
|
607
|
4620
|
13.1
|
Unspecified disorder of refraction
H52.7
|
544
|
5134
|
10.6
|
Systemic lupus erythematosus with:
kidney involvement
M32.1+N085
|
296
|
1585
|
18.7
|
Radiotherapy session Z51.0
|
323
|
28108
|
1.1
|
Multiple myeloma
C90.0
|
290
|
616
|
47.1
|
Systemic lupus erythematosus
M32.0
|
188
|
4620
|
4.1
|
Unspecified disorder of refraction
H52.701
|
214
|
5134
|
4.2
|
Iridocyclitis
H20.9
|
69
|
7492
|
0.9
|
Age-related cataract
H25.9
|
213
|
21255
|
1.0
|
Chronic obstructive pulmonary disease with acute exacerbation J44.1
|
67
|
4457
|
1.5
|
Malignant neoplasm of bronchus and lung
C34
|
202
|
7763
|
2.6
|
Systemic lupus erythematosus with:
kidney involvement
M32.1+N085
|
64
|
1585
|
4.0
|
Encounter for other specified aftercare
Z51.89
|
111
|
2773
|
4.0
|
Hemiplegia, unspecified
G81.9
|
51
|
2063
|
2.5
|
Malignant neoplasm of rectum
C20.0
|
89
|
4588
|
1.9
|
Acute pancreatitis
K85.9
|
47
|
9350
|
0.5
|
Comparison of departments with planned and unplanned readmission
Planned readmissions were most frequent in the department of head and neck oncology both in terms of the total number (38461) and readmission rates (45.0%) followed by the department of hematology (9851, 29.9%). The highest number of unplanned readmissions was in the department of head and neck oncology (1172, 1.4%), followed by the department of nephrology (595, 1.5%) and hematology (547, 1.7%). The highest unplanned readmission rate was in the department of rheumatology (2.2%), followed by the department of ophthalmology (2.1%) and hematology (1.7%). The number and rate of planned and unplanned discharges in the department of internal medicine were much higher than the number and rate of planned and unplanned admissions in the department of surgery (Table 3).
Table 3. Hospital sections’ characteristics
|
Department
|
Planned
N
|
Hospitalization
N
|
(%)
|
Department
|
Unplanned N
|
Hospitalization
N
|
(%)
|
Internal medicine
|
Head & Neck Oncology
|
38461
|
85464
|
45.0
|
Head & Neck Oncology
|
1172
|
85464
|
1.4
|
Hematology
|
9851
|
32968
|
29.9
|
Nephrology
|
595
|
41130
|
1.5
|
Abdominal Oncology
|
9154
|
57504
|
15.9
|
Hematology
|
547
|
32968
|
1.7
|
Thoracic Oncology
|
6214
|
37192
|
16.7
|
Thoracic Oncology
|
417
|
37192
|
1.1
|
Lung Cancer Center
|
1986
|
16470
|
12.1
|
Rheumatology
|
416
|
18721
|
2.2
|
Surgery
|
Ophthalmology
|
659
|
89155
|
0.7
|
Ophthalmology
|
1749
|
84742
|
2.1
|
Gastrointestinal Surgery
|
465
|
39480
|
1.2
|
Urology
|
247
|
45287
|
0.6
|
Urology
|
158
|
46966
|
0.3
|
Liver Surgery
|
223
|
30413
|
0.7
|
Orthopedics
|
84
|
63487
|
0.1
|
Orthopedics
|
173
|
63487
|
0.3
|
Breast Surgery
|
73
|
28228
|
0.3
|
Gastrointestinal Surgery
|
172
|
39480
|
0.4
|
Annual distribution of planned and unplanned readmission
The number of planned readmissions and planned readmission rates increased incrementally with the number of inpatients except in 2020. The number of planned readmissions and readmission rate (15996, 6.7%) was the highest in 2019. The number and readmission rate of unplanned readmissions (2451, 1.2%) was highest in 2020 (Table 4).
Table 4 Chronological distribution of planned and unplanned readmission
Year
|
Hospitalizations
N
|
Planned
(N, %)
|
Unplanned
(N %)
|
2015
|
182116
|
8461( 4.7%)
|
1245 (0.7%)
|
2016
|
189949
|
10901 (5.7%)
|
1432 (0.8%)
|
2017
|
205893
|
12377 (6.0%)
|
1352 (0.7%)
|
2018
|
223952
|
14845 (6.6%)
|
1471 (0.7%)
|
2019
|
238141
|
15996 (6.7%)
|
1944 (0.8%)
|
2020
|
202445
|
11914 (5.9%)
|
2451 (1.2%)
|
Total
|
1242496
|
74494 (6.0%)
|
9895 (0.8%)
|
Monthly distribution of planned and unplanned readmission
Among the 12 months of the year, the highest number of patients planned readmission was in November (7,283, 9.8%), followed by September (7,201, 9.7%) and July (7,108, 9.5%). The highest number of unplanned admissions was in September (1,020, 10.3%), followed by November (1,008, 10.2%) and December (984, 9.9%). The month with the lowest number of planned and unplanned admissions was February (4,372, 6.6% vs. 437, 4.9%) (Table 5).
Table 5 Monthly distribution of planned and unplanned readmissions
Month
|
Planned
Male Female Total
|
Unplanned
Male Female Total
|
Hospitalization
Male Female Total
|
Jan
|
1546
|
3593
|
5139
|
359
|
354
|
713
|
53483
|
48955
|
102438
|
Feb
|
1194
|
3178
|
4372
|
218
|
217
|
435
|
37506
|
33086
|
70592
|
Mar
|
1713
|
3742
|
5455
|
297
|
306
|
603
|
53729
|
48498
|
102227
|
Apr
|
1861
|
3922
|
5783
|
351
|
385
|
736
|
54801
|
49572
|
104373
|
May
|
2217
|
4161
|
6378
|
397
|
390
|
787
|
55169
|
49986
|
105155
|
Jun
|
2022
|
4241
|
6263
|
415
|
391
|
806
|
54905
|
50276
|
105181
|
Jul
|
2315
|
4793
|
7108
|
462
|
520
|
982
|
58601
|
53224
|
111825
|
Aug
|
2274
|
4275
|
6549
|
437
|
431
|
868
|
56345
|
52236
|
108581
|
Sept
|
2457
|
4744
|
7201
|
481
|
539
|
1020
|
56962
|
53143
|
110105
|
Oct
|
2292
|
4473
|
6765
|
468
|
485
|
953
|
49296
|
45766
|
95062
|
Nov
|
2564
|
4719
|
7283
|
480
|
528
|
1008
|
57426
|
53626
|
111052
|
Dec
|
2101
|
4097
|
6198
|
457
|
527
|
984
|
60028
|
55874
|
115902
|
Total
|
|
|
74494
|
|
|
9895
|
648251
|
594242
|
|