Risk of infection following a visit to the emergency department: a cohort study

Caroline Quach; Margaret McArthur; Allison McGeer; Lynne Li; Andrew Simor; Marc Dionne; Edith Lévesque; Lucie Tremblay

doi:10.1503/cmaj.110372

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Figure 1:
Matched, univariable and multivariable analysis* of the risk of infection after a visit to the emergency department. Note: CI = confidence interval, ED = emergency department, OR = odds ratio. *Determined by conditional logistic regression.

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Table 1:

Baseline characteristics of patients who did and did not visit the emergency department during the study period

Characteristics	No. (%) of patients^*		p value
Characteristics	No visit to the emergency department n = 845	Visited the emergency department n = 424	p value
Age, yr, mean (SD)	85.8 (6.0)	85.2 (10.7)	^†
Age range, yr	69.6–104.9	65.5–105.2
Male	268 (31.7)	147 (34.7)	^†
Dining room on unit	681 (81.5)	322 (79.3)	0.06
Dined in room	26 (3.1)	34 (8.3)	< 0.001
Had roommate(s)	384 (45.4)	188 (44.3)	0.7
No. of roommates, mean (SD)	1.10 (2.1)	1.1 (2.3)
Ill roommate	61 (7.2)	27 (6.4)	0.6
Roommate with a respiratory infection	26 (3.0)	14 (3.3)	0.8
Smoker	34 (4.0)	22 (5.2)	0.3
Influenza vaccine received^‡	576 (68.2)	280 (66.0)	0.4
Pneumococcal vaccine received^§	507 (60.0)	254 (59.9)	0.97
Had visitors	331 (39.2)	199 (46.9)	0.01
Katz Index
A: independent	40 (4.9)	9 (2.2)	0.02
B: independent in all but one function	68 (8.3)	20 (4.8)	0.02
C: Katz B + dependent in bathing	56 (6.8)	34 (8.1)	0.4
D: Katz C + dependent in dressing	44 (5.3)	31 (7.4)	0.2
E: Katz D + dependent in going to toilet	106 (12.9)	72 (17.2)	0.04
F: Katz E + dependent in transferring	229 (27.8)	95 (22.7)	0.05
G: dependent	280 (34.0)	156 (37.2)	0.3
O: dependent in two or more functions but not classifiable as C, D, E or F	1 (0.1)	2 (0.5)	0.3
Charlson Comorbidity Index score, mean (SD)	5.5 (2.7)	6.1 (2.5)	< 0.001
Underlying medical condition	n = 704	n = 360
Neurologic disorders (overall)	556 (79.0)	265 (73.6)	0.05
Parkinson	49 (7.0)	18 (5.0)	0.2
Seizures	34 (4.8)	18 (5.0)	0.9
Previous cerebrovascular accident	97 (13.8)	61 (17.0)	0.2
Cardiovascular disease (overall)	224 (31.8)	140 (39.0)	0.02
Previous myocardial infarction	55 (7.8)	27 (7.5)	0.9
Coronary artery disease	116 (16.5)	76 (21.1)	0.06
Congestive heart failure	80 (11.4)	65 (18.1)	0.003
Pulmonary disease (overall)	95 (13.5)	58 (16.1)	0.3
Asthma	25 (3.6)	23 (6.4)	0.04
Chronic obstructive pulmonary disease	74 (10.5)	43 (11.9)	0.5
Diabetes	158 (22.4)	100 (27.8)	0.06

Note: SD = standard deviation
↵* Unless stated otherwise.
↵† Matching variables.
↵‡ Residents who had a record of influenza vaccination for the current season.
↵§ Residents who had a record of prior pneumococcal vaccination.

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Table 2:

Reasons for visits to the emergency department and the proportion of residents who subsequently developed an infection

Reason for visit	No. of residents	Developed an infection,^* no. (%) of residents
Mobility impairment	75	5 (6.7)
Neurologic issue	51	1 (2.0)
Gastrointestinal issue (noninfectious)	46	2 (4.4)
Skin and soft tissue	30	1 (3.3)
Cardiovascular	29	3 (10.3)
Urinary tract infection	18	2 (11.1)
Renal	5	0 (0)
Psychiatric	2	0 (0)
Other	70	2 (2.9)
Data missing	98	5 (5.1)

↵* The proportion of patients who developed an infection did not differ significantly according to the reason for the emergency department visit (p = 0.65 by the χ² test)

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Table 3:

Univariable, unmatched analysis^* of the risk of infection associated with a visit to the emergency department

Outcome	No. (%) of residents^†		Relative risk (95%CI)	p value
Outcome	No visit to the emergency department n = 845	Visited the emergency department n = 424	Relative risk (95%CI)	p value
Any infection	17 (2.0)	21 (5.0)	2.5 (1.3–4.6)	0.004
Any infection per 1000 patient-days	3.4	8.3		0.007
Respiratory tract infection	8 (1.0)	10 (2.4)	2.5 (1.0–6.3)	0.04
Gastroenteritis	9 (1.1)	11 (2.6)	2.4 (1.0–5.8)	0.04