Economic Burden of West Nile Virus Disease

Quebec, Canada, 2012-2013

Najwa Ouhoummane; Eric Tchouaket; Anne-Marie Lowe; Ann Fortin; Dahlia Kairy; Anne Vibien; Jessica Kovitz-Lensch; Terry-Nan Tannenbaum; François Milord

Disclosures

Emerging Infectious Diseases. 2019;25(10):1943-1950.

Abstract and Introduction

Abstract

The economic burden of West Nile virus (WNV) infection is not known for Canada. We sought to describe the direct and indirect costs of WNV infection in the province of Quebec, Canada, up to 2 years after onset of signs and symptoms. We conducted a retrospective cohort study that included WNV cases reported during 2012 and 2013. For 90 persons infected with WNV, persons with encephalitis accounted for the largest proportion of total cost: a median cost of $21,332 per patient compared with $8,124 for West Nile meningitis (p = 0.0004) and $192 for West Nile fever (p<0.0001). When results were extrapolated to all reported WNV patients, the estimated total cost for 124 symptomatic cases was ≈$1.7 million for 2012 and that for 31 symptomatic cases was ≈$430,000 for 2013. Our study provides information for the government to make informed decisions regarding public health policies and infectious diseases prevention and control programs.

Introduction

West Nile virus (WNV) infection is endemic to North America. More than 41,000 cases of WNV-related illnesses and 2,000 deaths were reported in the United States between the introduction of the virus in 1999 and 2015.^[1] During the same period, 5,310 cases were reported in Canada.^[2] In Quebec, the first cases were documented in 2002. After a quiet period (2004–2010), this province experienced an outbreak in 2012 (124 symptomatic cases); since 2013, the number of cases has remained stable (average of 30 cases/year).^[3]

WNV causes an asymptomatic infection in 80% of cases, but in <1% of cases, a severe illness occurs with neurologic involvement, such as aseptic meningitis, encephalitis, or acute flaccid paralysis.^[4,5] WNV infection and particularly neurologic disease have been associated with mild to severe clinical manifestations, might require hospitalization, and lead to long-term sequelae and death.^[6]

To date, 3 studies in the United States have estimated the economic burden of WNV disease.^[7–9] These estimates can be used in assessing the cost-effectiveness of various interventions designed to decrease WNV disease risk.^[8] In the province of Quebec, Canada, a cost-effectiveness analysis was conducted during 2006.^[10] However, this study was based on a hypothetical simulation of 2 scenarios (high activity of the virus versus low-activity season); therefore, the cost estimations could be speculative. Thus, in Canada, no data are available on the actual costs of WNV disease, and results from the United States cannot be extrapolated because of differences in the organization of the heathcare systems and costs, WNV disease prevention programs, mean income, and standards of living. Furthermore, exchange rate differences do not accurately reflect real differences in purchasing power.^[11] The objective of this study was to estimate direct and indirect costs of WNV disease cases in the province of Quebec, Canada, up to 2 years after symptom onset.

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Next Section

Abstract and Introduction
Materials and Methods
Results
Discussion
References

Table 1. Principal diagnoses for 71 hospitalized case-patients with West Nile virus infection, Quebec, Canada*
Principal diagnosis	ICD-10 code	No. (%) patients
West Nile virus infection	A923	42 (59)
Viral meningitis, unspecified	A879	16 (23)
Viral infection, unspecified	B349	7 (10)
Unspecified viral encephalitis	A86	3 (4)
Guillain–Barré syndrome	G610	2 (3)
Headache	R51	1 (1)

*ICD-10, International Classification of Diseases, 10th Revision.

Table 2. Physician service claims billing codes and costs for outpatient paramedical services, Quebec, Canada, 2012–2013*
Medical/paramedical service	Régie de l'Assurance maladie du Québec billing code	Patient age, y: rate in 2014/visit
Primary care physician visit	08874	<60: $40.00
	00074	60–69: $42.05
	08879	70–79: $48.60
	08881	≥80: $50.80
Neurologist visit	09162: initial visit	$70.60
	09164: control visit	$40.00
Physiotherapy, occupational and speech therapy	None	$79.00
Home care	09171	$44.00

*Costs are in Canadian dollars.

Table 3. Demographic and clinical characteristics of 90 WNV patients by clinical syndrome, Quebec, Canada, 2012–2013*
Characteristic	WNF, n = 24	WNM, n = 18	WNE, n = 48†
Age group, y
<50	7 (29)	7 (39)	6 (12)
50–59	10 (42)	7 (39)	8 (17)
≥60	7 (29)	4 (22)	34 (71)
Sex
M	7 (29)	8 (44)	24 (50)
F	17 (71)	10 (56))	24 (50)
Hospitalization	5 (21)	17 (94)	47 (98)
Days hospitalized, median (range)	4 (2–12)	4 (1–36)	12 (3–663)
Intensive care	0	0	22/47 (47)
Complications	0	3/17(18)	21/47 (45)
Death in hospital	0	1/17 (6)	10/47 (21)

*Values are no. (%) or no. occurrences/no. hospitalized (%) unless otherwise indicated. WNE, West Nile encephalitis; WNF, West Nile fever; WNM, West Nile meningitis; WNV, West Nile virus.
†Includes WNE (n = 28), meningoencephalitis (n = 18), and acute flaccid paralysis (n = 2).

Table 4. Characteristics for 79 WNV patients needing medical and paramedical services and other expenses by clinical syndrome <2 y after the acute phase of infection Quebec, Canada, 2012–2013*
Characteristic	WNF, n = 24	WNM, n = 17	WNE, n = 38†
Inpatient rehabilitation
No. (%)	0	1 (6)	6(13)
No. days, median (range)	0	21	75 (30–120)
Physiotherapy
No. (%)	2 (8)	3 (18)	6 (16)
No. visits, median (range)	20‡	28 (8–48)‡	32 (24–48)
Occupational therapy
No. (%)	0	0	4 (11)
No. visits, median (range)	0	0	24 (3–32)
Speech therapy
No. (%)	0	0	3 (8)
No. visits, median (range)	0	0	3 (1–3)
Home care
No. (%)	1 (4)	0	2 (5)
No. hours, median (range)	1	0	2 (1–3)
Primary care physician visits
No. (%)	15 (63)	12 (71)	25 (66)
No. visits, median (range)	2 (1–12)	4 (2–18)	2 (1–12)
Neurologist visits
No. (%)	1 (4)	6 (35)	14 (37)
No. visits, median (range)	1	3 (2–4)	1 (1–4)
Medications
No. (%)	7 (29)	10 (59)	15 (39)
Medical equipment
No. (%)	1 (4)	1 (6)	6 (16)
No. using equipment, median (range)	3	2	2 (1–3)
Household chores
No. (%)	0	0	2 (5)
Absence from work among workers
No. (%)	6/8 (75)	15/15 (100)	16/16 (100)
No. days, median (range)	21 (5–60)	60 (7–180)	90 (30–365)§
Absence from work to care for a patient
No. (%)	1 (4)	8 (47)	10 (26)
No. days, median (range)	3	5 (2–14)	7 (1–60)
Other personal expenses
No. (%)	5 (21)	11 (65)	26 (68)

*WNE, West Nile encephalitis; WNF, West Nile fever; WNM, West Nile meningitis; WNV, West Nile virus.
†Includes WNE (n = 19), meningoencephalitis (n = 18), and acute flaccid paralysis (n = 1).‡Visits number missing for 1 participant.
§Excluding 1 participant who reported stopping work because of his WNV infection.

Table 5. Economic costs for 90 patients with WNV diseases by clinical syndrome, Quebec, Canada, 2012–2013*
Cost	WNF, n = 24	WNM, n = 18	WNE, n = 48†
Direct
Mean (SD)	1,113 (2,048)	5,794 (7,625)	26,085 (28,363)
Median (IQR)	151 (20–685)	2,699 (2,483–7 703)	15,963 (7,881–28,065)
Total	27,271	106,167	1,257,249
Hospital
Mean (SD)	892 (1,930)	4,221 (3,682)	19,259 (17,488)
Median (IQR)	0 (0–0)	2,333 (2,295–5,604)	15,839 (7,603–27,931)
Total	21,401	75,977	924,447
Emergency department visits
Mean (SD)	55 (110)	110 (110)	110 (110)
Median (IQR)	55 (0–110)	110 (110–110)	110 (110–110)
Total	1,319	1,978	5,275
Inpatient rehabilitation
Mean (SD)	0	1,019 (4,323)	6,004 (18,120)
Median (IQR)	0	0 (0–0)	0 (0–0)
Total	0	18,340	288,209
Outpatient readaptation‡
Mean (SD)	74 (323)	289 (1,052)	480 (1,320)
Median (IQR)	0 (0–0)	0 (0–0)	0 (0–0)
Total	1,780	5,194	23,068
Physician visits§
Mean (SD)	74 (106)	180 (185)	89 (124)
Median (IQR)	41 (0–93)	126 (0–277)	60 (0–136)
Total	1,781	3,242	4,279
Additional costs¶
Mean (SD)	41 (104)	80 (66)	250 (673)
Median (IQR)	0 (0–0)	100 (0–100)	100 (0–100)
Total	990	1,435	11,971
Indirect costs (absence from work)#
Mean (SD)	896 (2,198)	5,169 (6,116)	3,454 (9,101)
Median (IQR)	0 (0–556)	2,550 (650–9,000)	0 (0–3,374)
Total	21,506	93,042	165,772
Total costs
Mean (SD)	2,009 (2,904)	10,963 (9,072)	29,539 (31,067)
Median (IQR)	192 (20–5,359)	8,124 (4,025–13,631)	21,332 (12,131–28,101)
Total	48,777	199,209	1,423,021

*Costs are in Canadian dollars. Total costs are the sum of all category costs. Mean and median costs are expressed as per-patient cost for all participants (including patients with 0 costs). Total is the costs sum for all participants. IQR, interquartile range; WNE, West Nile encephalitis; WNF, West Nile fever; WNM, West Nile meningitis; WNV, West Nile virus.
†Includes WNE encephalitis (n = 28), meningoencephalitis (n = 18), and acute flaccid paralysis (n = 2).
‡Includes physiotherapy, occupational therapy, speech therapy, and home care costs.
§Includes primary care physician and neurologist consultations costs.
¶Includes medical equipment purchase, recruitment for household chores costs, and other personal expenses.
#Includes participants' and families' missed work costs.

Table 6. Total extrapolated costs for WNV cases by clinical syndrome, Quebec, Canada, 2012–2013*
Cost	2012, n = 124						2013, n = 31
	WNF		WNM		WNE		WNF		WNM		WNE
	No.	Cost	No.	Cost	No.	Cost	No.	Cost	No.	Cost	No.	Cost
Hospitalization	11	61,644	23	54,556	62	982,018	1	5,604	7	16,604	16	253,424
ED visit	19	2,090	24	2,640	62	6,820	4	385	7	770	17	1,870
Inpatient rehabilitation	0	0	1	24,453	8	304,583	0	0	0	0	2	83,515
Outpatient readaptation†	3	2,818	4	2,528	9	34,286	1	519	1	737	2	9,401
Physician visit‡	24	1,900	17	4,004	37	4,158	4	350	5	1,168	10	1,140
Additional§	8	792	16	1,600	45	4,521	1	146	5	467	12	1,240
Indirect¶	11	14,054	21	68,267	23	104,625	2	2,589	6	19,911	6	28,688
Total	38	83,298	24	158,048	62	1,441,010	7	9,593	7	39,657	17	379,277

*Costs are in Canadian dollars. Total costs are the sum of all category costs. ED, emergency department; WNE, West Nile encephalitis; WNF, West Nile fever; WNM, West Nile meningitis; WNV, West Nile virus.
†Includes physiotherapy, occupational therapy, speech therapy, and home care costs.
‡Includes primary care physician and neurologist consultations costs.
§Includes medical equipment purchase, recruitment for household chores costs, and other personal expenses.
¶Includes participants' and families' missed work costs.

Table 7. Median economic costs of WNV diseases per patient by clinical syndrome, Quebec, Canada, 2012–2013*
Cost	Disease, no. patients; cost (IQR)
Cost	WNF	WNM	WNE†
Hospitalization	5; 5,604 (2,295–5,604)	17; 2,372 (2,295–5,604)	47; 15,839 (7,603–27,931)
ED visit	12; 110 (110–110)	18; 110 (110–110)	48; 110 (110–110)
Inpatient rehabilitation	0, 0	1; 18,340 (18,340–18,340)	6; 39,301 (26,200–78,602)
Outpatient readaptation‡	2; 890 (200–1,580)	3; 632 (100–4,462)	7; 3,792 (2,540–4,661)
Physician visit§	15; 80 (42–160)	13; 231 (126–280)	29; 111 (71–152)
Additional¶	5; 100 (100–340)	12; 100 (100–125)	35; 100 (100–115)
Indirect (absence from work)#	7; 1,268 (961–5,434)	16; 3,200 (1,259–9,418)	18; 4,500 (3,000–8,653)

*Costs are in Canadian dollars. Median costs are expressed as per-patient cost on the basis of participants who incurred costs in each category (excluding patients with 0 costs). ED, emergency department; IQR, interquartile range; WNE, West Nile encephalitis; WNF, West Nile fever; WNM, West Nile meningitis; WNV, West Nile virus.
†Includes WNE (n = 28), meningoencephalitis (n = 18), and acute flaccid paralysis (n = 2).
‡Includes physiotherapy, occupational therapy, speech therapy, and home care costs.
§Includes primary care physician and neurologist consultations costs.
¶Includes medical equipment purchase, recruitment for household chores costs, and other personal expenses.
#Includes participants, and families, missed work costs.