Table 1.
Demographic and Clinical Characteristics of Study Participants by Case Status
Cases vs Controls | |||||
---|---|---|---|---|---|
Characteristic | Total (N = 1024) | Cases (N = 512) | Controls (N = 512) | P Valuea | |
Demographics | |||||
Hospital | Hospital 1 | 523 (51.1) | 252 (49.2) | 271 (52.9) | .260 |
Hospital 2 | 501 (48.9) | 260 (50.8) | 241 (47.1) | ||
Age at presentation, y | Median | 5.9 | 5.8 | 6 | .981 |
IQR | 2.7–10.3 | 2.7–10.2 | 2.6–10.4 | ||
Age group, y | 0 to <5 | 438 (42.8) | 219 (42.8) | 219 (42.8) | .945 |
5 to <9 | 272 (26.6) | 138 (27.0) | 134 (26.2) | ||
9+ | 314 (30.7) | 155 (30.3) | 159 (31.1) | ||
Sex | Female | 497 (48.5) | 242 (47.3) | 255 (49.8) | .453 |
Male | 527 (51.5) | 270 (52.7) | 257 (50.2) | ||
Race/Ethnicity | Hispanic | 175 (17.1) | 92 (18.0) | 83 (16.2) | <.001 |
Non-Hispanic Black | 567 (55.4) | 311 (60.7) | 256 (50.0) | ||
Non-Hispanic White | 212 (20.7) | 78 (15.2) | 134 (26.2) | ||
Otherb | 70 (6.8) | 31 (6.1) | 39 (7.6) | ||
Season | 2012–2013 | 266 (26.0) | 133 (26.0) | 133 (26.0) | >.999 |
2013–2014 | 118 (11.5) | 59 (11.5) | 59 (11.5) | ||
2014–2015 | 252 (24.6) | 126 (24.6) | 126 (24.6) | ||
2015–2016 | 148 (14.5) | 74 (14.5) | 74 (14.5) | ||
2016–2017 | 240 (23.4) | 120 (23.4) | 120 (23.4) | ||
Vaccination | |||||
Type | Inactivated influenza vaccine | 347 (33.9) | 137 (26.8) | 210 (41.0) | <.001 |
Live attenuated influenza vaccine | 23 (2.2) | 12 (2.3) | 11 (2.1) | ||
None | 654 (63.9) | 363 (70.9) | 291 (56.8) | ||
Advisory Committee on Immunization Practices vaccination status | Complete | 145 (14.2) | 54 (10.5) | 91 (17.8) | <.001 |
Partial | 225 (22.0) | 95 (18.6) | 130 (25.4) | ||
None | 654 (63.9) | 363 (70.9) | 291 (56.8) | ||
Medical history | |||||
Blood disorder | Yes | 169 (16.5) | 94 (18.4) | 75 (14.6) | .130 |
Cardiac disorder | Yes | 85 (8.3) | 34 (6.6) | 51 (10.0) | .069 |
Endocrine disorder | Yes | 31 (3.0) | 14 (2.7) | 17 (3.3) | .716 |
Immunocompromised | Yes | 134 (13.1) | 69 (13.5) | 65 (12.7) | .781 |
Kidney disorder | Yes | 29 (2.8) | 17 (3.3) | 12 (2.3) | .452 |
Liver disorder | Yes | 19 (1.9) | 11 (2.1) | 8 (1.6) | .644 |
Hematologic malignancy | Yes | 31 (3.0) | 14 (2.7) | 17 (3.3) | .716 |
Solid organ malignancy | Yes | 21 (2.1) | 6 (1.2) | 15 (2.9) | .075 |
Metabolic disorder | Yes | 16 (1.6) | 6 (1.2) | 10 (2.0) | .451 |
Neurologic disorder | Yes | 243 (23.7) | 111 (21.7) | 132 (25.8) | .142 |
Prematurityc | Yes | 45 (22.1) | 15 (14.6) | 30 (29.7) | .011 |
Respiratory disorder | Yes | 463 (45.2) | 216 (42.2) | 247 (48.2) | .060 |
Rheumatologic disorder | Yes | 7 (0.7) | 1 (0.2) | 6 (1.2) | .124 |
Any medical history | Yes | 788 (77.0) | 393 (76.8) | 395 (77.1) | .941 |
Clinical presentation | |||||
Body mass index | Median | 16.6 | 16.8 | 16.5 | .168 |
IQR | 15.0–19.4 | 15.1–19.4 | 14.8–19.5 | ||
Days from vaccination to symptom onset | Median | 85 | 86 | 84 | .658 |
IQR | 54.0–125.0 | 56.0–132.0 | 53.0–124.0 | ||
Days of symptoms | Median | 3 | 3 | 3 | .496 |
IQR | 2.0–6.0 | 2.0–6.0 | 2.0–6.0 | ||
Fever | Yes | 832 (81.3) | 468 (91.4) | 364 (71.1) | <.001 |
Days of feverd | Median | 2 | 2 | 2 | .880 |
IQR | 1.0–4.0 | 1.0–4.0 | 1.0–4.0 | ||
Highest recorded temperature (ºC)d | Median | 39 | 39.1 | 38.9 | .002 |
IQR | 38.3–39.6 | 38.6–39.6 | 38.2–39.5 | ||
>3 symptomse | Yes | 677 (66.1) | 349 (68.2) | 328 (64.1) | .187 |
Microbiologyf | |||||
Influenza A | Positive | 370 (36.1) | 370 (72.3) | 0 (0.0) | <.001 |
Influenza B | Positive | 143 (14.0) | 143 (27.9) | 0 (0.0) | <.001 |
Human metapneumovirus | Positive | 58 (5.7) | 5 (1.0) | 53 (10.4) | <.001 |
Adenovirus | Positive | 20 (2.0) | 6 (1.2) | 14 (2.7) | .112 |
Chlamydophila pneumoniae | Positive | 1 (0.2) | 1 (0.3) | 0 (0.0) | >.999 |
Coronavirus Coronavirus 229E | Positive | 7 (1.1) | 4 (1.2) | 3 (0.9) | >.999 |
Coronavirus HKU1 | Positive | 2 (0.3) | 1 (0.3) | 1 (0.3) | >.999 |
Coronavirus NL63 | Positive | 17 (1.7) | 3 (0.6) | 14 (2.7) | .012 |
Coronavirus OC43 | Positive | 15 (2.3) | 4 (1.2) | 11 (3.4) | .114 |
Mycoplasma pneumoniae | Positive | 6 (0.8) | 2 (0.5) | 4 (1.1) | .686 |
Parainfluenza 1 | Positive | 2 (0.2) | 0 (0.0) | 2 (0.4) | .500 |
Parainfluenza 2 | Positive | 2 (0.2) | 0 (0.0) | 2 (0.4) | .500 |
Parainfluenza 3 | Positive | 6 (0.6) | 3 (0.6) | 3 (0.6) | >.999 |
Parainfluenza 4 | Positive | 3 (0.3) | 0 (0.0) | 3 (0.6) | .249 |
Rhinovirus/Enterovirus | Positive | 168 (16.4) | 25 (4.9) | 143 (27.9) | <.001 |
Respiratory syncytial virus | Positive | 99 (9.7) | 15 (2.9) | 84 (16.4) | <.001 |
Antiviral use while hospitalized | |||||
Oseltamivir | Yes | 452 (44.1) | 447 (87.3) | 5 (1.0) | <.001 |
Days of treatmentg | Median | 6 | 6 | 1 | <.001 |
IQR | 5.0–6.0 | 5.0–6.0 | 1.0–1.0 | ||
Outcome | |||||
Days of hospitalization | Median | 4 | 3 | 4 | <.001 |
IQR | 3–5 | 3–5 | 3–6 | ||
Intensive care unit admission | Yes | 340 (33.2) | 139 (27.1) | 201 (39.3) | <.001 |
Mechanical ventilation | Yes | 67 (6.5) | 28 (5.5) | 39 (7.6) | .206 |
Radiographic pneumoniah | Yes | 228 (22.3) | 123 (24.0) | 105 (20.5) | .202 |
Abbreviations: HMPV, human metapneumovirus; IQR, interquartile range.
aCases and controls compared using the Fisher exact test for categorical variables and Wilcoxon rank sum test for continuous variables.
bOther races included American Indian/Alaska Native, Asian, Native Hawaiian or Other Pacific Islander, multiple races, and unknown.
cPrematurity history unavailable for participants aged >2 years at admission.
dDays of fever and maximum temperature only defined for participants with fever.
eParticipants may be missing data for 1 or multiple symptoms.
fMicrobiology notes: One case coinfected with influenza A and B. A total of 101 participants were positive for multiple pathogens, with a maximum of 3 pathogens identified. Coronavirus Coronavirus 229E, coronavirus HKU1, and coronavirus OC43 results were missing in 378 participants (189 cases, 189 controls). Chlamydophila pneumoniae results were missing in 375 participants (187 cases, 188 controls), and Mycoplasma pneumoniae results were missing in 265 participants (133 cases, 132 controls).
gDays of treatment only defined for participants who received treatment.
hRadiographic pneumonia identified by presence of International Classification of Diseases, Ninth Revision, Clinical Modification and International Classification of Diseases, Tenth Revision, Clinical Modification, code.