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Table 2 Bivariate regression analysis of laboratory-confirmed influenza versus seven demographic and clinical variables of interest

From: Determination of clinical and demographic predictors of laboratory-confirmed influenza with subtype analysis

Variable Laboratory-confirmed influenza diagnosis
Total study population Subjects ages 3–5 years Subjects ages 6–49 years Subjects ages 50–80 years
(n = 789) (n = 65) (n = 523) (n = 201)
n/total (%)a OR (95% CI) n/total (%)a OR (95% CI) n/total (%)a OR (95% CI) n/total (%)a OR (95% CI)
Continuous variable         
Age (years)   1.00 (0.99–1.01)   0.47 (0.17–1.10)   0.99 (0.98–1.01)   1.01 (0.95–1.07)
Categorical variables  
Sex  
Female 141/494 (28.5) 1.09 (0.78–1.53) 5/30 (16.7) 0.80 (0.18–3.38) 109/357 (30.5) 1.08 (0.71–1.66) 27/107 (25.2) 0.98 (0.50–1.96)
Maleb 79/295 (26.8) 1.0 7/35 (20.0) 1.0 48/166 (28.9) 1.0 24/94 (25.5) 1.0
Acute onset
≤3 days 110/273 (40.3) 2.49 (1.78–3.48) 8/30 (26.7) 2.77 (0.65–14.21) 86/199 (43.2) 2.71 (1.81–4.06) 16/44 (36.4) 1.98 (0.90–4.31)
>3 daysb 110/516 (21.3) 1.0 4/35 (11.4) 1.0 71/324 (21.9) 1.0 35/157 (22.3) 1.0
Fever
> 38.0°C 65/126 (51.6) 3.49 (2.31–5.27) 1/11 (9.1) 0.40 (0.01–3.37) 51/91 (56.0) 3.91 (2.39–6.44) 13/24 (54.2) 4.28 (1.63–11.51)
≤ 38.0°Cb 155/663 (23.4) 1.0 11/54 (20.4) 1.0 106/432 (24.5) 1.0 38/177 (21.5) 1.0
Cough
Yes 219/736 (29.8) 22.99 (3.72–890.52) 12/63 (19.0) 0.55 (≥0.04) c 156/475 (32.8) 22.92 (3.84–932.74) 51/198 (25.8) 1.32 (≥0.14) c
Nob 1/53 (1.9) 1.0 0/2 (0.0) 1.0 1/48 (2.1) 1.0 0/3 (0.0) 1.0
Body achesd
Yes 177/581 (30.5) 1.67 (1.13–2.50) 8/27 (29.6) 3.40 (0.79–17.59) 127/388 (32.7) 1.70 (1.06–2.79) 42/166 (25.3) 0.98 (0.40–2.57)
Nob 43/207 (20.8) 1.0 4/37 (10.8) 1.0 30/135 (22.2) 1.0 9/35 (25.7) 1.0
Vaccinated
Yes 39/217 (18.0) 0.47 (0.31–0.71) 0/17 (0.0) 0.13 (≤0.89) c 16/112 (14.3) 0.32 (0.17–0.57) 23/88 (26.1) 1.07 (0.54–2.13)
Nob 181/572 (31.6) 1.0 12/48 (25.0) 1.0 141/411 (34.3) 1.0 28/113 (24.8) 1.0
  1. NOTE. Bivariate exact conditional logistic regression was performed in each age group. Bivariate results (OR, odds ratio; CI, confidence interval) are displayed here for all variables of interest (those that were retained in the final multivariate regression model in any age group) modeled against laboratory-confirmed influenza. aNumber of subjects meeting criteria at left who have laboratory-confirmed influenza/all subjects meeting criteria at left (percent). bReference category in regression model. cOR is a median unbiased estimate; one limit of CI is infinite or crosses zero due to cell size of zero. dData missing for 1 subject age 3–5 years.