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Table 3 Factors associated with at least one ILI episode (ILIECDC) during six influenza epidemic periods, GrippeNet.fr

From: Factors associated with influenza-like-illness: a crowdsourced cohort study from 2012/13 to 2017/18

  Na Casesb n (%) OR [CI 95%] Univariate analyses p-value OR [CI 95%] Multivariate analysis p-value
Season 2012/13 2943 866 (29%) Ref. <10−4 Ref. <10− 4
2013/14 4140 469 (11%) 0.31 [0.27;0.34] 0.30 [0.26;0.33]
2014/15 4428 886 (20%) 0.59 [0.54;0.66] 0.60 [0.54;0.67]
2015/16 4780 829 (17%) 0.50 [0.45;0.55] 0.50 [0.45;0.56]
2016/17 4204 787 (19%) 0.54 [0.49;0.60] 0.57 [0.51;0.63]
2017/18 4158 855 (21%) 0.61 [0.55;0.68] 0.64 [0.57;0.71]
Sociodemographic characteristics
 Gender Male 9742 1623 (17%) Ref. <10−4 Ref. <10−4
Female 14,911 3069 (21%) 1.30 [1.20;1.40] 1.29 [1.20;1.40]
 Age [45–65) 9940 1959 (20%) Ref. <10−4 Ref. <10− 4
[0–5) 306 111 (36%) 2.27 [1.78;2.89] 3.12 [2.05;4.68]
[5–15) 1133 279 (25%) 1.32 [1.12;1.55] 1.53 [1.17;2.00]
[15–45) 5948 1309 (22%) 1.15 [1.06;1.25] 1.13 [1.03;1.25]
[65–75) 6003 885 (15%) 0.71 [0.65;0.78] 0.88 [0.77;1.01]
≥75 1300 146 (11%) 0.54 [0.45;0.65] 0.70 [0.56;0.87]
 Household composition Living alone 3917 731 (19%) Ref. <10−4 NS NS
Living with ≥1 child 7712 1714 (22%) 1.25 [1.12;1.40]
Living with adults only 12,953 2234 (17%) 0.92 [0.83;1.02]
 Occupation Working 11,587 2432 (21%) Ref. <10−4 Ref. <10−2
Student 2162 543 (25%) 1.25 [1.11;1.41] 1.02 [0.83;1.26]
Unemployed 575 138 (24%) 1.18 [0.96;1.46] 1.18 [0.95;1.46]
Retired 8932 1299 (15%) 0.64 [0.59;0.70] 0.80 [0.70;0.91]
0.84 [0.70;1.02]
Stay at home/ Sick leave 993 191 (19%) 0.89 [0.74;1.07]
 Place of residency Rural 4840 906 (19%) Ref. 0.67
Urban 19,813 3786 (19%) 1.02 [0.93;1.12]
Lifestyle
 Use of public transport No 20,843 3855 (18%) Ref. <10−4 Ref. <10−2
Yes 3810 837 (22%) 1.22 [1.12;1.34] 1.17 [1.07;1.29]
 Pets at home None 13,492 2377 (17%) Ref. <10−4 Ref. <10− 4
At least one 11,118 2311 (20%) 1.21 [1.13;1.30] 1.18 [1.09;1.27]
 Contacts with patients No 22,163 4154 (19%) Ref. 0.01 NS NS
Yes 2490 538 (22%) 1.17 [1.04;1.30]
 Contacts with elderly No 22,153 4234 (19%) Ref. 0.41
Yes 2496 458 (18%) 0.96 [0.86;1.07]
 Contacts with a group of people No 16,795 3047 (18%) Ref. <10−4 NS NS
Yes 7858 1645 (21%) 1.17 [1.09;1.25]
 Contacts with children No 18,722 3342 (18%) Ref. <10−4 NS NS
Yes 5931 1350 (23%) 1.33 [1.23;1.43]
Health characteristics
 Influenza vaccination (current season) No 16,083 3240 (20%) Ref. <10−4 Ref. 0.04
Yes 8554 1450 (17%) 0.82 [0.76;0.88] 0.91 [0.84;0.99]
 Influenza vaccination (last season) No 15,190 3083 (20%) Ref. <10−4 NS NS
Yes 9305 1575 (17%) 0.81 [0.75;0.87]
 Smoking status Non smoker 21,995 4176 (19%) Ref. 0.55
Smoker 2630 514 (20%) 1.04 [0.92;1.16]
 Chronic treatment for at least one comorbidityc No comorbidity 19,425 3648 (19%) Ref.   Ref. <10−3
At least one comorbidity 5228 1044 (20%) 1.08 [0.99;1.17] 0.10 1.20 [1.09;1.32]
Asthma 1449 384 (27%) 1.53 [1.33;1.75] < 10−4
Diabetes 941 156 (17%) 0.85 [0.70;1.04] 0.12
Heart diseases 2473 420 (17%) 0.88 [0.78;0.99] 0.03
Kidney diseases 152 24 (16%) 0.77 [0.48;1.25] 0.29
Immunosuppression 655 140 (21%) 1.13 [0.91;1.39] 0.26
Pulmonary diseases 635 161 (25%) 1.40 [1.13;1.73] <10−2
 Respiratory allergy None 16,400 2887 (18%) Ref. <10−4 Ref. <10−4
At least one 8253 1805 (22%) 1.29 [1.20;1.39] 1.27 [1.18;1.37]
 BMI Normal weight [18.5;25[ 14,000 2563 (18%) Ref. <10−2 Ref. <10−4
Underweight < 18.5 1053 201 (19%) 1.04 [0.88;1.25] 0.92 [0.77;1.11]
Overweight [25;30[ 6571 1241 (19%) 1.04 [0.96;1.13] 1.18 [1.08;1.29]
Obese ≥30 2629 586 (22%) 1.26 [1.12;1.40] 1.28 [1.14;1.44]
  1. OR = Odd Ratio; CI95% = 95% confidence interval; NS = not significant; − = variable not tested in the multivariate analysis as the p-value was higher than 0.2 in univariate analysis
  2. aN = global number of individuals for the six GrippeNet.fr seasons (from 2012/13 to 2017/18), based on the 24,653 person-seasons. An individual may have participated up to six times (one time for each followed year)
  3. bThe ILI case definition used here is the ILIECDC definition
  4. cParticipants receiving a chronic treatment for at least one of the following diseases: asthma, diabetes, immunosuppression, heart, kidney, and pulmonary diseases. Inclusion of the gathered variable “At least one comorbidity” only in the analyses.