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Table 1 Demographic and clinical characteristics of patients aged ≥16 years (all adults group)

From: Influenza vaccine effectiveness against influenza-related hospitalization during a season with mixed outbreaks of four influenza viruses: a test-negative case-control study in adults in Canada

  Cases
N = 528
Controls
N = 835
p-value
Age, years
 Mean (SD) 67.11 (20.05) 69.17 (16.94) 0.732
 Median (range) 70 (18–104) 73 (18–99)  
Age subgroups, n (%)
 16–49 years 107 (20.3) 107 (12.8) 0.118
 50–64 101 (19.1) 164 (19.6)  
 65–75 years 101 (31.6) 206 (36.5)  
 > 75 years 219 (68.4) 358 (63.5)  
Female, n (%) 288 (54.5) 469 (56.2) 0.580
BMI, kg/m2
 Mean (SD) 26.51 (6.74) 26.81 (7.07) 0.407
 Median (range) 25.39 (9.64–60.35) 25.73 (10.7–63.77)  
Obese (BMI ≥30 kg/m2), n (%) 103 (19.5) 229 (27.4) 0.016
≥1 co-morbidity, n (%)
 Cardiac disease 210 (39.8) 415 (49.7) 0.005
 Vascular disease 317 (60.0) 557 (66.7) 0.093
 Pulmonary disease 231 (43.8) 426 (51.0) 0.021
Smoking, n (%)
 Current 89 (16.9) 143 (17.1) 0.529
 Past 143 (27.1) 334 (40.0) <0.001
Children aged <5 years in household, n (%)    
 0 456 (86.3) 763 (91.4) 0.001
 1 or more 54 (10.2) 46 (5.5)  
Received 2011/12 seasonal influenza vaccine, n (%) 262 (49.6) 529 (63.4) <0.001
Received 2010/11 seasonal influenza vaccine, n (%) 248 (47.0) 515 (61.7) <0.001
  1. N number of patients, BMI body mass index, SD standard deviation
  2. Missing data: BMI: 40 cases (7.6%), 15 controls (1.8%); Obesity: 40 cases (7.6%), 15 controls (1.8%); Current smoking: 5 cases (0.9%), 7 controls (0.8%); Past smoking: 105 cases (19.9%), 156 controls (18.7%); Children aged <5 years in the household: 18 cases (3.4%), 26 controls (3.1%); Received 2010/11 seasonal influenza vaccine: 47 cases (8.9%), 42 controls (5.0%)