Table 2.
Baseline characteristics for validation dataset (before imputation)
| Variables | Cases (n ═ 451) | Random controls (n ═ 3000) | P value* | ID-controls (n ═ 1990) | P value** |
|---|---|---|---|---|---|
| Age, years, median (IQR) | 62 (49, 71) | 65 (48, 76) | <0.001 | 76 (66, 85) | <0.001 |
| Sex, no. (%) | <0.001 | <0.001 | |||
| Female | 168 (37.4) | 1527 (50.9) | 942 (47.3) | ||
| Male | 281 (62.6) | 1472 (49.1) | 1048 (52.7) | ||
| Race, no. (%) | 0.010 | <0.001 | |||
| African American | 31 (6.9) | 122 (4.1) | 21 (1.1) | ||
| Asian | 19 (4.2) | 79 (2.6) | 7 (0.4) | ||
| White | 379 (84) | 2655 (88.5) | 1920 (96.5) | ||
| Others | 22 (4.9) | 144 (4.8) | 42 (2.1) | ||
| Ethnicity, no. (%) | 0.557 | <0.001 | |||
| Hispanic or Latino | 21 (4.7) | 151 (5) | 22 (1.1) | ||
| Not Hispanic or Latino | 416 (92.2) | 2778 (92.7) | 1936 (97.3) | ||
| Others, unknown, or not applicable | 14 (3.1) | 69 (2.3) | 32 (1.6) | ||
| Quarter of admission, no. (%) | <0.001 | <0.001 | |||
| January–March | 127 (28.2) | 604 (20.1) | 439 (22.1) | ||
| April–June | 100 (22.2) | 677 (22.6) | 703 (35.3) | ||
| July–September | 111 (24.6) | 852 (28.4) | 471 (23.7) | ||
| October–December | 113 (25.1) | 867 (28.9) | 377 (18.9) | ||
| Admission location, no. (%) | <0.001 | <0.001 | |||
| Arizona | 76 (16.9) | 526 (17.5) | 115 (5.8) | ||
| Florida | 75 (16.6) | 417 (13.9) | 60 (3) | ||
| MCHS | 46 (10.2) | 1086 (36.2) | 619 (31.1) | ||
| Rochester | 254 (56.3) | 971 (32.4) | 1196 (60.1) | ||
| Admission source, no. (%) | <0.001 | <0.001 | |||
| Another hospital or care facility | 122 (27.1) | 665 (22.2) | 482 (24.2) | ||
| Outpatient or emergency department | 148 (32.8) | 241 (8) | 171 (8.6) | ||
| Others or unknown | 181 (40.1) | 2094 (69.8) | 1337 (67.2) | ||
| Pre-hospital location home | 364 (80.7) | 2137 (71.2) | 1253 (63) | ||
| Transferred patient | 31 (6.9) | 528 (21.8) | <0.001 | 253 (12.7) | <0.001 |
| Country of residence, no. (%) | 0.142 | 0.014 | |||
| United States or Canada | 445 (98.9) | 2984 (99.5) | 1986 (99.8) | ||
| Others | 5 (1.1) | 16 (0.5) | 4 (0.2) | ||
| ***African Region | 0 | 1 (6.3) | 0 | ||
| *** Eastern Mediterranean Region | 5 (100) | 7 (43.8) | 4 (100) | ||
| *** Region of the Americas, other than the US and Canada | 0 | 7 (43.8) | 0 | ||
| *** South-East Asian Region | 0 | 1 (6.3) | 0 | ||
| RUCA codes, no. (%) | 0.001 | <0.001 | |||
| Metropolitan area | 264 (58.8) | 1974 (65.9) | 1250 (62.8) | ||
| Micropolitan area | 64 (14.3) | 411 (13.7) | 346 (17.4) | ||
| Small town | 58 (12.9) | 340 (11.3) | 208 (10.5) | ||
| Rural areas | 58 (12.9) | 259 (8.6) | 182 (9.1) | ||
| Not coded | 5 (1.1) | 12 (0.4) | 3 (0.2) | ||
| Body mass index, kg/m2, median (IQR) | 26 (22.8, 30.1) | 28.1 (24.2, 33.1) | <0.001 | 28.1 (23.9, 33.3) | <0.001 |
| Smoking, no. (%) | <0.001 | 0.097 | |||
| Active smoker | 146 (32.4) | 1233 (41.1) | 566 (28.4) | ||
| Never or ex-smoker | 305 (67.6) | 1767 (58.9) | 1424 (71.6) | ||
| Alcohol use disorder | 38 (8.4) | 391 (13.0) | <0.001 | 290 (14.6) | <0.001 |
| Comorbidities, no. (%) | |||||
| AIDS | 31 (6.9) | 24 (0.8) | <0.001 | 33 (1.7) | <0.001 |
| Asthma | 78 (17.3) | 783 (26.1) | <0.001 | 758 (38.1) | <0.001 |
| Cancer | 217 (48.2) | 969 (32.3) | <0.001 | 1012 (50.9) | 0.294 |
| Cardiovascular disorders | 83 (18.4) | 802 (26.7) | <0.001 | 856 (43) | <0.001 |
| Chronic heart failure | 96 (21.3) | 793 (26.4) | 0.003 | 914 (45.9 | <0.001 |
| Chronic kidney diseases | 149 (33) | 908 (30.3) | 0.234 | 1009 (50.7) | <0.001 |
| Chronic obstructive pulmonary disease | 93 (20.7) | 620 (20.7) | 1.00 | 766 (38.5) | <0.001 |
| Connective tissue disease | 31 (6.9) | 180 (6) | 0.463 | 241 (12.1) | <0.001 |
| Dementia | 28 (6.2) | 344 (11.5) | <0.001 | 545 (27.4) | <0.001 |
| Diabetes | 181 (40.2) | 1196 (39.9) | 0.886 | 1236 (62.1) | <0.001 |
| Dialysis | 36 (8) | 152 (5.1) | 0.011 | 94 (4.7) | 0.005 |
| Hypertension | 266 (59.1) | 1975 (65.8) | 0.005 | 1708 (85.9) | <0.001 |
| Immunodeficiency | 105 (23.3) | 224 (7.5) | <0.001 | 160 (8) | <0.001 |
| Interstitial lung disease | 160 (35.6) | 825 (27.5) | <0.001 | 1048 (52.7) | <0.001 |
| Leukemia | 68 (15.1) | 78 (2.6) | <0.001 | 64 (3.2) | <0.001 |
| Liver failure | 105 (23.3) | 838 (27.9) | 0.041 | 217 (10.9) | <0.001 |
| Lymphoma | 72 (16) | 97 (3.2) | <0.001 | 93 (4.7) | <0.001 |
| Myocardial infarction | 66 (14.7) | 560 (18.7) | 0.040 | 565 (28.4) | <0.001 |
| Peptic ulcer disease | 49 (10.9) | 288 (9.6) | 0.399 | 398 (20) | <0.001 |
| Peripheral vascular disease | 112 (24.9) | 929 (31) | 0.009 | 1225 (61.6) | <0.001 |
| Valvular dysfunction | 140 (31) | 946 (31.5) | 0.834 | 991 (49.8) | <0.001 |
| Laboratory variables at the time of admission, median (IQR) | |||||
| Hemoglobin, g/dL | 10.4 (9, 12) | 12.5 (10.7, 13.9) | <0.001 | 11.7 (10.1, 13.1) | <0.001 |
| Hematocrit, % | 32.2 (28.2, 36.9) | 38.2 (33.6, 42.3) | <0.001 | 36.5 (32.2, 40.4) | <0.001 |
| Platelets, ×10(9)/L | |||||
| Highest | 180 (104, 260) | 229 (178, 290) | <0.001 | 206 (155, 274) | <0.001 |
| Lowest | 176 (94, 254) | 227 (174, 286) | <0.001 | 202 (150, 269) | <0.001 |
| Leukocytes, ×10(9)/L | |||||
| Highest | 7.7 (4.3, 11.5) | 8.9 (6.7, 12.2) | <0.001 | 11.8 (8.1, 16.4) | <0.001 |
| Lowest | 7.4 (4.1, 11.1) | 8.8 (6.6, 11.8) | <0.001 | 11.4 (7.8, 15.9) | <0.001 |
| Lymphocytes, ×10(9)/L | |||||
| Highest | 0.76 (0.42, 1.3) | 1.25 (0.8, 1.83) | <0.001 | 0.94 (0.59, 1.39) | <0.001 |
| Lowest | 0.74 (0.4, 1.28) | 1.22 (0.78, 1.8) | <0.001 | 0.91 (0.57, 1.36) | <0.001 |
| Neutrophils, ×10(9)/L | |||||
| Highest | 5.36 (2.83, 9.03) | 6.32 (4.32, 9.42) | <0.001 | 9.47 (6.02, 13.94) | <0.001 |
| Lowest | 5.2 (2.69, 8.82) | 6.2 (4.27, 9.22) | <0.001 | 8.82 (5.41, 13.15) | <0.001 |
| Monocytes, ×10(9)/L | |||||
| Highest | 0.48 (0.26, 0.78) | 0.68 (0.49, 0.94) | <0.001 | 0.8 (0.51, 1.17) | <0.001 |
| Lowest | 0.46 (0.24, 0.74) | 0.66 (0.48, 0.93) | <0.001 | 0.78 (0.48, 1.14) | <0.001 |
| Eosinophil, ×10(9)/L | |||||
| Highest | 0.03 (0, 0.12) | 0.08 (0.02, 0.18) | <0.001 | 0.03 (0, 0.1) | 0.003 |
| Lowest | 0.03 (0, 0.11) | 0.08 (0.02, 0.17) | <0.001 | 0.02 (0, 0.09) | 0.006 |
| Glucose, mg/dL | |||||
| Highest | 124 (103, 174) | 123 (104, 161) | 0.620 | 141 (115, 188) | <0.001 |
| Lowest | 119 (100, 163) | 123 (104, 161) | 0.060 | 141 (115, 188) | <0.001 |
| Lactate, mmol/L | 1.6 (1.18, 2.6) | 1.6 (1.1, 2.4) | 0.428 | 1.9 (1.3, 2.9) | <0.001 |
| Creatinine, mg/dL | 1 (0.78, 1.4) | 0.95 (0.76, 1.26) | 0.249 | 1.15 (0.86, 1.62) | <0.001 |
| Blood urea nitrogen, mg/dL | 20 (13, 31) | 17.9 (12, 26) | <0.001 | 23 (16, 33) | <0.001 |
| Potassium, mmol/L | |||||
| Highest | 4.2 (3.8, 4.5) | 4.1 (3.8, 4.5) | 0.791 | 4.2 (3.8, 4.6) | 0.150 |
| Lowest | 4.1 (3.7, 4.4) | 4.1 (3.7, 4.4) | 0.184 | 4.1 (3.7, 4.4) | 0.545 |
| Sodium, mmol/L | |||||
| Highest | 136 (133, 139) | 138 (135, 140) | <0.001 | 137 (134, 140) | 0.002 |
| Lowest | 136 (132, 139) | 138 (135, 140) | <0.001 | 136 (133, 139) | 0.032 |
| Calcium, mmol/L | |||||
| Highest | 8.8 (8.3, 9.3) | 9.2 (8.8, 9.5) | <0.001 | 9 (8.6, 9.4) | 0.002 |
| Lowest | 8.7 (8.2, 9.2) | 9.1 (8.7, 9.5) | <0.001 | 8.9 (8.4, 9.3) | 0.032 |
| Bicarbonate, mmol/L | 23 (21, 26) | 24 (22, 26) | 0.013 | 23 (21, 26) | 0.880 |
| Chloride, mmol/L | |||||
| Highest | 100 (97, 103) | 101 (98, 104) | <0.001 | 99 (96, 103) | 0.068 |
| Lowest | 99 (96, 102) | 101 (97, 104) | <0.001 | 99 (95, 102) | 0.052 |
| AST, U/L | 35 (22, 60) | 27 (20, 43) | <0.001 | 29 (22, 48) | 0.021 |
| ALT, U/L | 27 (17, 53) | 23 (15, 38) | <0.001 | 23 (15, 38) | <0.001 |
| ALP, U/L | 99 (73, 155) | 88 (68, 118) | <0.001 | 96 (74, 142) | 0.525 |
| Total bilirubin, mg/dL | 0.5 (0.4, 0.9) | 0.5 (0.3, 0.9) | 0.262 | 0.7 (0.4, 1.1) | <0.001 |
| Albumin, g/dL | 3.2 (2.9, 3.6) | 3.8 (3.4, 4.2) | <0.001 | 3.5 (3.1, 3.9) | <0.001 |
Bold indicates statistical significance. *Cases vs controls, **Cases vs ID-controls, ***Among those who reside outside of the United States or Canada, ****Outside of the United States or unknown. AIDS: Acquired immunodeficiency syndrome; ALP: Alkaline phosphatase; ALT: Alanine transaminase; AST: Aspartate aminotransferase; CHF: Chronic heart failure; g/dL: Grams per deciliter; ID-controls: The control group that consisted of patients with community-acquired infectious diseases other than unusual infections; IQR: Interquartile range; MCHS: Mayo Clinic Health System; mg/dL: Milligrams per deciliter; mmol/L: Millimoles per liter; RUCA: Rural–urban commuting area; U/L: Units per liter.