Predictors of influenza among older adults in the emergency department

BMC Infectious Diseases

Table 2 Results of final logistic regression model for influenza, Ontario, Canada, 2011/12 and 2012/13

Predictors^a	Unadjusted OR (95 % CI)		Adjusted OR^†(95 % CI)
	n = 1313	p-value	n = 1313	p-value
Presenting symptoms^‡
Cough (self-report and/or chart)	12.4 (6.3, 24.6)	<.001	6.4 (3.2, 13.0)	<.001
Wheeze (chart)	3.7 (2.4, 5.7)	<.001	2.1 (1.3, 3.3)	.003
Any one or more of: sore throat, runny/stuffy nose, or sneezing	3.5 (2.4, 5.1)	<.001	–
Feverishness and/or triage temperature ≥37.2 °C	4.8 (3.2, 7.1)	<.001	3.0 (2.0, 4.7)	<.001
Number of systemic symptom(s)^₴	1.5 (1.3, 1.7)	<.001	–
Confused (self-report and/or chart)	1.6 (1.1, 2.3)	.02	–
Time to ED from symptom onset (2–5 days)^¶	3.1 (2.2, 4.5)	<.001	2.2 (1.5, 3.2)	<.001
Medical history
Influenza vaccine, current season	1.1 (0.8, 1.6)	.59	–
Antibiotics prescribed/taken prior to visit	1.9 (1.3, 2.8)	.001	–
General symptom relief medications prior to visit	2.4 (1.5, 4.0)	<.001	–
Frail (≥5 on Clinical Frailty Score)	0.78 (0.52, 1.2)	.24	–
Other factors
Age, per 10 year increase^ǁ	1. 1 (0.9, 1.3)	.51	1.2 (1.0, 1.5)	.03
Children (<16 years) in household	1.4 (0.8, 2.4)	.21	–
Recent transportation use	1.1 (0.7, 1.8)	.58	–
Exposed to person with ILI ≤7 days before onset	2.5 (1.7, 3.5)	<.001	1.9 (1.3, 2.8)	.002
Material deprivation index^b	1.2 (1.1, 1.4)	.002	–
Caucasian/White	0.67 (0.46, 0.98)	.04	–
Enrolled week when ≥10 % of influenza tests positive	7.7 (1.9, 31.3)	.005	5.1 (1.2, 21.7)	.03

OR Odds ratio, CI Confidence interval, ED emergency department, ILI influenza-like illness
^aParticipants with missing data on included predictors were excluded from the analysis. The proportion of participants with missing data for any given predictor did not exceed 3 %
^bMaterial deprivation index ranks from 1 (most privileged neighborhood) to 5 quintiles (most deprived neighborhood). The index is modeled as a continuous variable with one unit increase equivalent to an increase in quintile
^†Adjusted model also includes hospital site
^‡Symptoms were based on self-reported data unless indicated otherwise
^₴Systemic symptoms were headache, myalgia, chills, weakness, fatigue, and loss of appetite. Predictor modeled as a continuous variable with one unit increase per addition of one symptom
^¶Reference group: 0–1 days and >5 days for time to ED from symptom onset
^ǁAge was modeled as a continuous variable per 10 years increase

ISSN: 1471-2334