2017/2018 Influenza Season 2017/2018 Influenza Season 2017/2018 Influenza Season 2017/2018 Influenza Season 2018/2019 Influenza Season 2018/2019 Influenza Season 2018/2019 Influenza Season
Cluster 1 (N=31) Cluster 2 (N=72) Cluster 3 (N=139)
P-Value
Cluster 1 (N=37) Cluster 2 (N=78)
P-Value
Demographics Demographics Demographics Demographics Demographics Demographics Demographics Demographics
Age 0.029c 0.704
18-49 6 (19.4) 15 (20.8) 44 (31.7) 14 (37.8) 24 (30.8)
50-64 14 (45.2) 18 (25.0) 48 (34.5) 10 (27.0) 26 (33.3)
≥65 11 (35.5) 39 (54.2) 47 (33.8) 13 (35.1) 28 (35.9)
Male Sex 10 (32.3) 35 (48.6) 54 (38.9) 0.226 14 (37.8) 40 (51.3) 0.177
Race
White 10 (32.3) 51 (70.8) 48 (34.5) <0.001ac 19 (51.4) 33 (42.3) 0.363
Black 18 (58.1) 20 (27.8) 79 (56.8) <0.001ac 18 (48.7) 42 (53.9) 0.602
Asian 2 (6.5) 0 (0.0) 1 (0.7) 0.018 0 (0.0) 1 (1.3) 0.489
Hispanic 1 (3.2) 0 (0.0) 7 (5.0) 0.152 0 (0.0) 5 (6.4) 0.105
Hospital <0.001ac 0.995
1 8 (25.8) 46 (63.9) 35 (25.2) 19 (51.4) 40 (51.3)
2 23 (74.2) 26 (36.1) 104 (74.8) 18 (48.7) 38 (48.7)
Flu Strain and Subtype/Lineage 0.852 0.744
Type A–H1 1 (3.2) 4 (5.6) 10 (7.2) 15 (40.5) 29 (37.2)
Type A–H3 22 (71.0) 41 (56.9) 86 (61.9) 14 (37.8) 33 (42.3)
Type B–Victoria 0 (0.0) 0 (0.0) 2 (1.4) 0 (0.0) 2 (2.6)
Type B–Yamagata 7 (22.6) 23 (31.9) 32 (23.0) 0 (0.0) 1 (1.3)
Unknown Subtype/Lineage 1 (3.2) 4 (5.6) 8 (5.8) 8 (21.6) 13 (16.7)
Unknown Type 0 (0.0) 0 (0.0) 1 (0.7) 0 (0.0) 0 (0.0)
Received Influenza Vaccine 17 (54.8) 48 (66.7) 82 (59.0) 0.429 24 (64.9) 49 (62.8) 0.832
Comorbidities Comorbidities Comorbidities Comorbidities Comorbidities Comorbidities Comorbidities Comorbidities
Charlson Comorbidity Index, mean (SD) 3.9 (2.8) 4.3 (3.1) 2.4 (2.3) <0.001bc 4.4 (2.7) 3.5 (3.0) 0.139
Charlson Comorbidity Index Group <0.001bc 0.031
0 1 (3.2) 8 (11.1) 25 (18.0) 0 (0.0) 13 (16.7)
1-2 11 (35.5) 16 (22.2) 64 (46.0) 13 (35.1) 22 (28.2)
≥3 19 (61.3) 48 (66.7) 50 (36.0) 24 (64.9) 43 (55.1)
BMI Category 0.353 0.177
Underweight (<18.5) 0 (0.0) 2 (2.8) 5 (3.6) 1 (2.7) 4 (5.1)
Normal/Healthy weight (18.5-24.9) 3 (9.7) 14 (19.4) 34 (24.5) 7 (18.9) 17 (21.8)
Overweight (25-29.9) 7 (22.6) 23 (31.9) 29 (20.9) 4 (10.8) 22 (28.2)
Obese (30-39.9) 17 (54.8) 26 (36.1) 53 (38.1) 17 (46.0) 23 (29.5)
Morbidly obese (≥40) 4 (12.9) 7 (9.7) 18 (13.0) 8 (21.6) 12 (15.4)
High-Risk Comorbidities
Heart Disease 14 (45.2) 45 (62.5) 50 (36.0) 0.001c 23 (62.2) 38 (48.7) 0.177
Heart Failure 6 (19.4) 25 (34.7) 27 (19.4) 0.039c 17 (46.0) 17 (21.8) 0.008
Asthma 9 (29.0) 17 (23.6) 46 (33.1) 0.359 10 (27.0) 17 (21.8) 0.536
COPD 11 (35.5) 23 (31.9) 49 (35.3) 0.881 16 (43.2) 28 (35.9) 0.449
Other Lung Conditions 14 (45.2) 24 (33.3) 44 (31.7) 0.354 21 (56.8) 35 (44.9) 0.234
Diabetes 24 (77.4) 24 (33.3) 38 (27.3) <0.001ab 29 (78.4) 25 (32.1) <0.001
Renal 13 (41.9) 42 (58.3) 36 (25.9) <0.001c 21 (56.8) 30 (38.5) 0.065
Blood Disorders 2 (6.5) 16 (22.2) 4 (2.9) <0.001c 6 (16.2) 9 (11.5) 0.557
Immunosuppression 5 (16.1) 24 (33.3) 31 (22.3) 0.104 10 (27.0) 25 (32.1) 0.584
Malignancy 8 (25.8) 25 (34.7) 13 (9.4) <0.001bc 7 (18.9) 22 (28.2) 0.284
Metabolic Disorders 20 (64.5) 39 (54.2) 49 (35.3) 0.002bc 20 (54.1) 43 (55.1) 0.914
Liver Disorders 3 (9.7) 11 (15.3) 14 (10.1) 0.501 5 (13.5) 5 (6.4) 0.288
Neurological/Musculoskeletal 11 (35.5) 20 (27.8) 30 (21.6) 0.228 11 (29.7) 26 (33.3) 0.699
Cerebrovascular Disorders 3 (9.7) 2 (2.8) 5 (3.6) 0.242 1 (2.7) 3 (3.9) 0.999
Endocrine 3 (9.7) 16 (22.2) 22 (15.8) 0.258 8 (21.6) 13 (16.7) 0.521
Long-term Medication 4 (12.9) 13 (18.1) 18 (13.0) 0.586 8 (21.6) 17 (21.8) 0.983
Morbid Obesity 5 (16.1) 11 (15.3) 18 (13.0) 0.844 12 (32.4) 12 (15.4) 0.036
Clustering Metrics Measured Within 24 Hours of Admission Clustering Metrics Measured Within 24 Hours of Admission Clustering Metrics Measured Within 24 Hours of Admission Clustering Metrics Measured Within 24 Hours of Admission Clustering Metrics Measured Within 24 Hours of Admission Clustering Metrics Measured Within 24 Hours of Admission Clustering Metrics Measured Within 24 Hours of Admission Clustering Metrics Measured Within 24 Hours of Admission
Time from symptom onset to admission (days), mean (SD) 2.6 (2.1) 2.2 (2.0) 2.5 (2.0) 0.597 2.6 (1.7) 2.6 (2.1) 0.886
Temperature
Min 97.8 (0.6) 97.9 (0.5) 97.9 (0.6) 0.691 97.9 (0.5) 98.1 (0.6) 0.036
Max 99.7 (1.5) 100.2 (1.5) 100.0 (1.5) 0.190 99.9 (1.4) 100.2 (1.5) 0.301
Heart Rate (Max), mean (SD) 109.1 (16.1) 101.3 (18.7) 109.5 (18.0) 0.006ac 110.5 (20.6) 110.7 (18.7) 0.966
Systolic Blood Pressure, mean (SD)
Min 117.0 (15.2) 111.2 (17.0) 110.3 (16.7) 0.134 104.4 (18.2) 105.4 (14.3) 0.732
Max 149.5 (30.3) 126.5 (29.2) 139.7 (29.4) 0.001ac 127.3 (38.9) 125.9 (28.9) 0.828
Glucose, mean (SD)
Min 210.4 (66.9) 90.5 (16.4) 110.0 (26.7) <0.001abc 157.2(82.2) 99.7 (21.4) <0.001
Max 311.6 (106.0) 139.4 (68.5) 136.0 (37.0) <0.001ab 292.0 (133.4) 119.5 (26.3) <0.001
Creatinine (Max), mean (SD) 1.2 (0.8) 1.8 (2.5) 1.2 (0.9) 0.018ac 1.9 (2.4) 1.6 (2.0) 0.502
Hematocrit (Min), mean (SD) 36.7 (4.7) 34.6 (5.6) 36.0 (5.4) 0.096 35.4 (6.2) 35.6 (6.2) 0.885
Sodium, mean (SD)
Min 134.4 (3.9) 136.0 (2.9) 135.9 (3.0) 0.034ab 134.0 (5.4) 135.9 (3.0) 0.015
Max 137.1 (4.1) 139.3 (3.4) 137.7 (3.0) 0.001ac 138.3 (4.7) 138.0 (3.5) 0.754
White Blood Cells, mean (SD)
Min 7.7 (3.4) 5.4 (5.0) 6.8 (2.7) 0.005ac 8.3 (4.2) 7.2 (9.8) 0.511
Max 9.4 (4.7) 8.9 (12.6) 8.3 (3.7) 0.710 12.0 (7.1) 9.4 (14.9) 0.317
Platelets (Min), mean (SD) 171.5 (44.7) 121.3 (39.8) 209.9 (62.5) <0.001abc 190.9 (76.3) 195.2 (135.5) 0.856
Respiratory Rate (Max), mean (SD) 25.9 (5.7) 23.8 (5.3) 24.0 (5.6) 0.176 27.5 (9.3) 25.6 (7.7) 0.243
Oxygen Saturation (Min), mean (SD) 90.7 (4.9) 91.1 (5.3) 92.0 (3.7) 0.182 88.5 (6.7) 91.6 (3.7) 0.002
Estimated glomerular filtration rate, mean (SD) 71.6 (26.2) 59.4 (28.2) 83.8 (44.7) <0.001ac 65.7 (40.8) 77.3 (40.6) 0.154
Outcomes Outcomes Outcomes Outcomes Outcomes Outcomes Outcomes Outcomes
ICU Admission 3 (9.7) 4 (5.6) 8 (5.8) 0.690 8 (21.6) 7 (9.0) 0.060
Mechanical Ventilator use 7 (22.6) 5 (6.9) 12 (8.6) 0.038a 12 (32.4) 7 (9.0) 0.002
Hospital LOS, mean (SD) 4.5 (4.4) 3.5 (2.9) 2.8 (2.4) 0.009b 5.3 (5.7) 2.8 (2.0) 0.001
Prolonged LOS (≥8 days) 4 (12.9) 4 (5.6) 7 (5.0) 0.250 6 (16.2) 3 (3.9) 0.021