Table. Baseline Characteristics in Seasonal Influenza and COVID-19 Group Before and After Propensity Score Weighting.
| Before propensity score weighting | After propensity score weightinga | |||||
|---|---|---|---|---|---|---|
| Seasonal influenza (n = 2403) | COVID-19 (n = 8996) | SMDb | Seasonal influenza (n = 2403) | COVID-19 (n = 8996) | SMDb | |
| Age | ||||||
| Mean (SD), y | 70.52 (11.68) | 73.42 (12.25) | 0.24 | 73.81 (12.22) | 73.42 (12.25) | 0.03 |
| ≤65 y, No. (%) | 665 (27.67) | 1787 (19.86) | 0.18 | 481 (20.03) | 1787 (19.86) | 0.004 |
| >65 y, No. (%) | 1738 (72.33) | 7209 (80.14) | 0.18 | 1922 (79.98) | 7209 (80.14) | 0.004 |
| Race, No. (%)c | ||||||
| Black | 607 (25.26) | 2066 (22.97) | 0.05 | 562 (23.40) | 2066 (22.97) | 0.01 |
| White | 1694 (70.50) | 6421 (71.38) | 0.02 | 1713 (71.29) | 6421 (71.38) | 0.003 |
| Other | 102 (4.24) | 509 (5.66) | 0.07 | 128 (5.34) | 509 (5.66) | 0.01 |
| Sex, No. (%) | ||||||
| Male | 2245 (93.42) | 8580 (95.38) | 0.09 | 2295 (95.51) | 8580 (95.38) | 0.007 |
| Female | 158 (6.58) | 416 (4.62) | 0.09 | 108 (4.49) | 416 (4.62) | 0.007 |
| Smoking status, No. (%) | ||||||
| Never | 688 (28.63) | 3231 (35.92) | 0.16 | 890 (37.05) | 3231 (35.92) | 0.02 |
| Former | 906 (37.70) | 3658 (40.66) | 0.06 | 973 (40.50) | 3658 (40.66) | 0.003 |
| Current | 809 (33.67) | 2107 (23.42) | 0.23 | 540 (22.45) | 2107 (23.42) | 0.02 |
| Area Deprivation Index, mean (SD)d | 53.73 (19.06) | 53.01 (18.92) | 0.04 | 52.61 (18.93) | 53.01 (18.92) | 0.02 |
| BMI, mean (SD)e | 29.18 (6.97) | 28.43 (7.63) | 0.10 | 28.28 (6.85) | 28.43 (7.63) | 0.02 |
| eGFR, mean (SD), mL/min/1.73 m2 | 65.51 (26.36) | 65.02 (27.10) | 0.02 | 63.85 (27.43) | 65.02 (27.10) | 0.04 |
| Blood pressure, mean (SD), mm Hg | ||||||
| Systolic | 134.92 (12.43) | 134.39 (12.68) | 0.04 | 134.5 (12.57) | 134.39 (12.68) | 0.01 |
| Diastolic | 76.77 (7.47) | 75.29 (7.34) | 0.20 | 75.37 (7.34) | 75.29 (7.34) | 0.01 |
| COVID-19 vaccination status, No. (%) | ||||||
| Not vaccinated | 454 (18.89) | 1865 (20.73) | 0.05 | 429 (17.84) | 1865 (20.73) | 0.07 |
| 1 dose | 114 (4.74) | 384 (4.27) | 0.02 | 112 (4.68) | 384 (4.27) | 0.02 |
| 2 doses | 517 (21.51) | 1841 (20.46) | 0.03 | 530 (22.06) | 1841 (20.47) | 0.04 |
| Boosted | 1318 (54.85) | 4906 (54.54) | 0.01 | 1332 (55.43) | 4906 (54.54) | 0.02 |
| Influenza vaccine, No. (%) | 1487 (61.88) | 5743 (63.84) | 0.04 | 1524 (63.43) | 5743 (63.84) | 0.008 |
| SARS-CoV-2 infection, No. (%) | ||||||
| Primary infection | NA | 7111 (79.05) | NA | 7111 (79.05) | ||
| Reinfection | NA | 1885 (20.95) | NA | 1885 (20.95) | ||
| Treatment status, No. (%) | ||||||
| Outpatient nirmatrelvir-ritonavir, molnupiravir, or remdesivir | NA | 191 (2.12) | NA | 191 (2.12) | ||
| Inpatient remdesivir | NA | 2188 (24.32) | NA | 2188 (24.32) | ||
| Outpatient oseltamivir | 139 (5.78) | NA | 147 (6.13) | NA | ||
| Inpatient oseltamivir | 1982 (82.48) | NA | 1960 (81.58) | NA | ||
| Outcomes, No. (%) | ||||||
| Death within 30 d | 76 (3.16) | 538 (5.98) | 90 (3.74) | 538 (5.98) | ||
| In hospital death within 30 d | 47 (1.95) | 374 (4.16) | 56 (2.33) | 374 (4.16) | ||
Abbreviations: BMI, body mass index; eGFR, estimated glomerular filtration rate; NA, not applicable; SMD, standardized mean difference.
Propensity score weights were estimated based on age, self-reported race, sex, area deprivation index, body mass index, smoking status, prior history of SARS-CoV-2 infection, use of long-term care, eGFR, systolic and diastolic blood pressure, use of steroid, cancer, cardiovascular disease, chronic lung disease, coronary artery disease, dementia, diabetes, hyperlipidemia, HIV, immune dysfunction, liver diseases and peripheral artery diseases, number of outpatient visits and hospital admissions, number of blood panel tests, number of medications received and number of Medicare outpatient visits and hospital admissions, the calendar date of the admission, hospital bed capacity, and hospital bed occupancy at the participants’ health care facility within the week of the admission.
SMD less than 0.1 was considered evidence of good balance.
Self-reported race information was collected from electronic health records and used in the study in accordance with the requirement by the funding agency (US Department of Veterans Affairs) and the Office of Management and Budget, which defines minimum standards for maintaining, collecting, and presenting data on race and ethnicity for all federal reporting agencies. Other race included Alaska Native and American Indian, Asian, or Native Hawaiian and Other Pacific Islander. The categories in this classification are social-political constructs and should not be interpreted as being anthropological in nature.
A measure of socioeconomic disadvantage, with a range from low to high disadvantage of 0 to 100.
Calculated as weight in kilograms divided by square of height in meters.