Download Influenza risk factors and ethnic differences

Influenza risk factors and
ethnic differences
Michael Baker
Department of Public Health
University of Otago, Wellington
Outline
• Risk factors for what?
•
Infection vs. Progression
• Why identify risk factors?
•
Socio-demographic vs. Modifiable?
• Hospitalisations in Auckland
•
Seasonal, 2000-09
•
Pandemic influenza, 2009
• Conclusions & discussion points
Infection vs. Progression
Influenza
susceptibility:
Influenza progression cofactors:
Influenza
vaccination
Chronic illness, Pregnancy
Immune deficits
School & Work
exposure
Age
Obesity
Obesity, Smoking
Urban domicile
Immune
competence
Pneumococcal immunisation
Smoking
Antiviral treatment
Influenza
exposure:
Seasonal virus load
Household crowding
Children in house
Weather
Indoor air
Influenza
infection
Age, Sex, Ethnicity
Primary care access
Quality of hospital care
Influenza
illness
Serious
influenza
Influenza
death
Modifiable risk factors
Risk factors for infection and/or poor outcome
Evidence
Exposure factors
Household crowding
*
Poor indoor air quality in household
*
Susceptibility factors
Lack of influenza vaccination
***
Active & Passive smoke exposure
**
Immune deficiencies
**
Progression factors
Micronutrient deficiencies eg vitamin D deficiency
*
Obesity
*
Chronic illness, eg COPD, asthma, diabetes
**
Poor access to primary healthcare
*
Lack of antiviral treatments
**
Lack of pneumococcal vaccination
*
Broad determinants
Poverty
**
Risk factors
Influenza hospitalisations by year, Auckland
2000-10 (J09=474, J10=367, J11=569)
600
J09 Pandemic Influenza
500
J11 Clinical influenza
Number
400
J10 Confirmed Influenza
300
200
100
0
2000
2001
2002
2003
2004
2005
Year
2006
2007
2008
2009
2010
Risk factors
Numbers of Hospitalisations (2000-2008)
Influenza hospitalisations by month, Auckland
2000-08 (Ref = Summer)
180
160
J11 Clinical influenza
140
J10 Confirmed Influenza
120
100
Winter RR=12.5
80
60
Winter RR=59.0
40
20
0
Jan
Feb
Mar
Apr
May
Jun
Months
Jul
Aug
Sep
Oct
Nov
Dec
Risk factors
Influenza hospitalisation rate by age group,
Auckland 2000-08 (Ref = 30-39 years)
Average annual rate (cases / 100,000)
70
RR=4.6
Seasonal influenza (J10+J11)
60
Confirmed influenza (J10)
50
Pandemic influenza (J09)
40
RR=38.6
30
RR=6.7
20
RR=1.5
RR=4.3
10
RR=0.2
0
0-4
5-9
10-19
20-29
30-39
40-49
Age group (years)
50-59
60-69
70-79
80+
Risk factors
Average annual rate (cases / 100,000)
Influenza hospitalisation rate by ethnicity,
Auckland 2000-08 (Ref = European/Other)
70
Seasonal influenza (J10+J11)
60
50
RR=7.1
Confirmed influenza (J10)
Pandemic influenza (J09)
40
RR=3.6
30
RR=3.5
20
RR=1.6
RR=5.5
RR=1.7
10
RR=0.8
RR=2.2
RR=1.0
0
European/Other
Māori
Pacific
Ethnic group
Asian
Risk factors
Influenza hosp rate by deprivation, Auckland
2000-08 (Ref = NZDep 1-2)
Average annual rate (cases / 100,000)
35
30
RR=3.2
Seasonal influenza (J10+J11)
Confirmed influenza (J10)
25
Pandemic influenza (J09)
20
15
RR=3.3
10
RR=5.8
5
0
1-2
3-4
5-6
7-8
Deprivation quintile (NZDep 96) 9-10 = high deprivation
9-10
Risk factors
Pandemic influenza rate ratios for outcomes by
ethnic group, NZ 2009 (age & dep stand.)
Risk-adjusted event rate ratio to European/Other
rate
9
Consultations
Other flu hospitalisations
J09 hospitalisations
ICU cases
Deaths
8
7
6
5
4
3
2
1
1.00 1.00 1.00 1.00 1.00
0.88 1.74 2.44 2.01 1.14
0.90 2.21 4.16 5.03 3.28
0.72 0.60 0.98 0.77 0.76
European/Other
Māori
Pacific
Asian
0
Ethnicity
Risk factors
Pandemic influenza rate ratios for outcomes by
deprivation, NZ 2009 (age & ethnicity stand.)
Consultations
Other flu hospitalisations
J09 hospitalisations
ICU cases
Deaths
Risk-adjusted rate ratio to quintile NZDep 1-2
8
7
6
5
4
3
2
1
1.001.001.001.001.00
0.590.670.470.240.34
0.921.461.261.552.60
0.581.131.140.650.73
0.561.421.371.422.22
1-2
3-4
5-6
7-8
9-10
0
NZDep quintile
Respiratory infections, NZ
Hosp. rates for IDs vs. Non-IDs, 1989-2008
Hospitalisations per 100,000 people
per year
8000
All-cause hospitalisations
Non-infectious diseases
7000
6000
5000
4000
3000
2000
1000
0
Year
Source: Baker et al 2012, Lancet in press
Infectious diseases
Respiratory infections, NZ
Hospitalisations per 100,000 people per
year
Hospitalisation rates for ID categories, 2009
600
1989-1993
1994-1998
1999-2003
2004-2008
500
400
300
200
100
0
Blood Neurological Bone, Heart Neoplasms STIs
Lower Skin and Enteric Digestive Genito- URTIs, Postrespiratory soft
tract, urinary includingprocedure stream and eye joint,
and
from
and
ear
and circulationinfection HIV
tract
tissue
including
liver
connective
tissues
Infectious disease category
Source: Baker et al 2012, Lancet in press
Other
Respiratory infections, NZ
Hosp. SRR for IDs, by ethnicity, 1989-2008
Hospitalisation rate ratio to European
& Other
2.50
European & Other (reference)
2.02
2.00
Māori
2.33
1.93
2.06
1.92
Pacific
2.35
2.15
1.77
1.50
1.00
0.50
0.00
1989-1993
1994-1998
1999-2003
Five-year period
Source: Baker et al 2012, Lancet in press
2004-2008
Conclusions
• Large differences in occurrence of serious
influenza (hospitalised) across population
groups ⇒ differences in risk factors
• Relatively high rates of hospitalisation &
serious outcomes for Māori and Pacific
• Risk factors include: Exposure factors;
Susceptibility factors; Progression factors
• Some risk factors are modifiable ⇒ important
to identify these
• Small existing research base for seasonal
influenza, some studies for pandemic influenza
2009
Discussion Points
• What are ‘modifiable’ risk factors for influenza?
• Do modifiable risk factors matter vs. increasing
vaccine coverage?
Acknowledgements
• University of Otago: Jane Zhang, Lucy Telfar
Barnard, James Stanley, Nick Wilson, and
others
• ESR: Sue Huang, Don Bandaranayake, Graham
Mackereth and others
• NZ Ministry of Health
• US Centers for Disease Control and Prevention
and NZ Health Research Council for funding
support