Hospital admissions for lower respiratory tract infections among infants in the Canadian Arctic: a cohort study

Anna Banerji; Val Panzov; Michael Young; Joan Robinson; Bonita Lee; Theo Moraes; Muhammad Mamdani; B. Louise Giles; Depeng Jiang; Danny Bisson; Marguerite Dennis; Johanne Morel; Judith Hall; Charles Hui; Bosco Paes; James B. Mahony

doi:10.9778/cmajo.20150051

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Figure 1
Map of Inuit regions in Canada, showing typical referral pathways in 2009. CHC = Churchill Health Centre, CHEO = Children's Hospital of Eastern Ontario, CSI = Centre de santé Inuulitsivik, CSTI = Centre de santé Tulattavik, MCH = Montréal Children's Hospital, QGH =Qikiqtani General Hospital, SCH = Stollery Children's Hospital, STH = Stanton Territorial Hospital, WCH = Winnipeg Children's Hospital.Adapted from Inuit Tapiriit Kanatami, https://www.itk.ca.

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Table 1: Demographic characteristics of cases of lower respiratory tract infection in infants who resided in the Canadian Arctic and were admitted to hospital in 2009, by region

Characteristic	Region; subregion								p value for comparison between all regions*	p value for NWT v. KTR, KQR, QIR, NK*
	NWT	NU				NK	All regions	All regions excluding NWT
	NWT	Overall	KTR	KQR	QIR	NK	All regions	All regions excluding NWT
No. of births in 2009	711	877	123	263	491	250	1838	1127	-	-
No. of admissions for LRTI	28	206	41	73	92	114	348	320
Male sex, no. (%) of admissions	20 (71.4)	92 (44.7)	14 (34.1)	38 (52.0)	40 (43.5)	63 (55.3)	175 (50.3)	155 (48.4)	0.02	0.02
Age at admission, median (interquartile range), d	147 (84-168)	109.5 (53-202)	168 (65-197)	82 (44-168)	90.5 (44-223)	136 (69-222)	114.5 (55.8-208)	114.5 (53-208)	0.03	0.11
Underlying condition, no. (%) of admissions†
Any underlying condition	3 (10.7)	44 (21.4)	3 (7.3)	14 (19.2)	27 (29.3)	23 (20.2)	70 (20.1)	67 (20.9)	0.03	0.20
< 36 weeks' gestation	2 (7.1)	42 (20.4)	2 (4.9)	13 (17.8)	27 (29.3)	21 (18.4)	65 (18.7)	63 (19.7)	0.006	0.10
Cardiac, respiratory	0	7 (3.4)	1 (2.4)	1 (1.4)	5 (5.4)	7 (6.1)	14 (4.0)	14 (4.4)	0.50	0.65
Neurologic, congenital	1 (3.6)	2 (1.0)	0	1 (1.4)	1 (1.1)	0	3 (0.9)	2 (0.6)	0.40	0.22

Note: KQR = Kivalliq Region, KTR = Kitikmeot Region, LRTI = lower respiratory tract infection, NWT = Northwest Territories, NK = Nunavik, NU = Nunavut, QIR = Qikiqtaaluk Region.

*For comparison of proportions across regions, χ² test was used; for comparison of age, nonparametric test was used; for comparison of admission for lower respiratory tract infection, Poisson regression was used.

†Some infants had more than 1 underlying condition.

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Table 2: Outcomes by region

Variable	Region; subregion								p value for NWT v. all KTR, KQR, QIR, NK	p value for NWT v. KTR, KQR, QIR, NK
	NWT	NU				NK	All regions	All regions excluding NWT
	NWT	Overall	KTR	KQR	QIR	NK	All regions	All regions excluding NWT
No. of cases tested for RSV	26	168	41	59	68	104	298	272	-	-
No. of cases in which RSV detected	14 (53.8)	66 (39.3)	20 (48.8)	28 (47.4)	18 (26.5)	44 (42.3)	124 (41.6)	110 (40.4)	-	-
No. of admissions to tertiary hospital	4	49	3	29	17	13	66	62	-	-
No. of admissions for severe LRTI*	1	15	2	7	6	5	21	20	-	-
Admissions for LRTI among infants < 1 yr per 1000 live births/yr	39	235	407	243	187	456	189	284	< 0.001	< 0.001
Admissions for RSV infection among infants < 1 yr per 1000 live births/yr	19.7	75.3	195.1	91.2	36.7	176.0	66.9	97.6	< 0.001	< 0.001
Tertiary admissions per 1000 live births/yr	5.6	55.9	24.4	110.3	34.6	52.0	35.9	55.0	< 0.001	< 0.001
Severe LRTI per 1000 live births/yr	1.4	17.1	16.3	26.6	12.2	20.0	11.4	17.7	0.009	0.001

Note: KQR = Kivalliq Region, KTR = Kitikmeot Region, LRTI = lower respiratory tract infection, NWT = Northwest Territories, NK = Nunavik, NU = Nunavut, QIR = Qikiqtaaluk Region, RSV = respiratory syncytial virus.

*Respiratory failure, intubation and mechanical ventilation, and/or cardiopulmonary resuscitation.

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Table 3: Summary of infectious agents identified

Infectious agent	No. (%) of cases (n = 298)
Infectious agent	Alone	Coinfection	Total
Respiratory syncytial virus	73 (24.5)	51 (17.1)	124 (41.6)
Enterovirus/rhinovirus	51 (17.1)	60 (20.1)	111 (37.2)
Influenza all subtypes	36 (12.1)	12 (4.0)	48 (16.1)
Influenza A (H1N1)	17 (5.7)	19 (6.4)	36 (12.1)
Parainfluenza all subtypes	14 (4.7)	13 (4.4)	27 (9.1)
Human metapneumovirus	11 (3.7)	9 (3.0)	20 (6.7)
Adenovirus	4 (1.3)	9 (3.0)	13 (4.4)
Human coronavirus	2 (0.7)	7 (2.3)	9 (3.0)
Bordetella pertussis	1 (0.3)	7 (2.3)	8 (2.7)
Bocavirus	0 (0.0)	3 (1.0)	3 (1.0)
Cytomegalovirus	1 (0.3)	1 (0.3)	2 (0.7)

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Table 4: Clinical features of the 21 infants with severe lower respiratory tract infection

Patient no.	Region	Age, mo	< 36 weeks' gestational age	Underlying risk factor(s) for severe RSV infection	Length of hospital stay, d	Duration of mechanical ventilation, d	Complications during hospital stay	Infectious agents identified
1	Northwest Territories	3-6	Yes	No	57	12	Necrosis of lung necessitating pneumonectomy, bacterial sepsis	RSV, rhinovirus/enterovirus
2	Nunavut	< 3	No	No	25	17	Bacterial sepsis	RSV, Bordetella pertussis
3	Nunavut	< 3	No	No	32	9	Required inotropes	RSV, B. pertussis
4		< 12	No	No	1	1	Bilateral necrotizing pneumonia, bacterial sepsis, acute renal failure; died during transport	Staphylococcus aureus
5	Nunavut	< 3	No	No	2	1	-	RSV
6	Nunavut	< 3	No	No	5	1	Required cardiopulmonary resuscitation	Negative
7	Nunavut	3-6	Yes	No	19	9	-	Rhinovirus/enterovirus
8	Nunavut	< 3	No	No	31	30	Required HFVO	RSV, adenovirus
9	Nunavut	< 3	No	No	41	16	Required HFVO	RSV, rhinovirus/enterovirus
10	Nunavut	3-6	Yes	Yes	216	32	Required HFVO	RSV, rhinovirus/enterovirus, influenza A (H1N1)
11	Nunavut	< 3	Yes	No	14	3	-	Negative
12	Nunavut	< 3	No	No	15	3	-	RSV
13	Nunavut	3-6	Yes	Yes	15	4	Required inotropes	Negative
14	Nunavut	< 12	Yes	No	17	0	Chest tube, pneumothorax	Negative
15	Nunavut	< 3	Yes	No	86	29	-	Rhinovirus/enterovirus, human coronavirus OC43
16	Nunavut	< 12	Yes	No	156	31	HFVO, bacterial sepsis	RSV, adenovirus, S. aureus (blood)
17	Nunavik	< 3	No	No	10	6	-	RSV, rhinovirus/enterovirus
18	Nunavik	< 3	Yes	No	13	2	-	Rhinovirus/enterovirus
19	Nunavik	< 3	No	No	24	12	-	RSV
20	Nunavik	< 3	No	No	25	8	-	RSV
21	Nunavik	< 3	No	No	96	18	Bacterial sepsis	Influenza virus

Note: HFVO = high-frequency ventilation oscillation, RSV = respiratory syncytial virus.

*Includes preterm birth (< 36 weeks' gestational age), chronic lung disease, congenital heart disease, immunodeficiency, congenital or neurologic conditions affecting respiration.