Epidemiological characteristics and underlying risk factors for mortality during the Autumn 2009 pandemic wave in Mexico

G. Chowell, S. Echevarría-Zuno, C. Viboud, L. Simonsen, M.A. Miller, I. Fernández-Gárate, C. González-Bonilla, V.H. Borja-Aburto

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Background: Elucidating the role of the underlying risk factors for severe outcomes of the 2009 A/H1N1 influenza pandemic could be crucial to define priority risk groups in resource-limited settings in future pandemics.
Methods: We use individual-level clinical data on a large series of ARI (acute respiratory infection) hospitalizations from a prospective surveillance system of the Mexican Social Security medical system to analyze clinical features at presentation, admission delays, selected comorbidities and receipt of seasonal vaccine on the risk of A/H1N1-related death. We considered ARI hospitalizations and inpatient-deaths, and recorded demographic, geographic, and medical information on individual patients during August-December, 2009.
Results: Seasonal influenza vaccination was associated with a reduced risk of death among A/H1N1 inpatients (OR = 0.43 (95% CI: 0.25, 0.74)) after adjustment for age, gender, geography, antiviral treatment, admission delays, comorbidities and medical conditions. However, this result should be interpreted with caution as it could have been affected by factors not directly measured in our study. Moreover, the effect of antiviral treatment against A/H1N1 inpatient death did not reach statistical significance (OR = 0.56 (95% CI: 0.29, 1.10)) probably because only 8.9% of A/H1N1 inpatients received antiviral
treatment. Moreover, diabetes (OR = 1.6) and immune suppression (OR = 2.3) were statistically significant risk factors for death whereas asthmatic persons (OR = 0.3) or pregnant women (OR = 0.4) experienced a reduced fatality rate among A/ H1N1 inpatients. We also observed an increased risk of death among A/H1N1 inpatients with admission delays .2 days after symptom onset (OR = 2.7). Similar associations were also observed for A/H1N1-negative inpatients.
Conclusions: Geographical variation in identified medical risk factors including prevalence of diabetes and immune suppression may in part explain between-country differences in pandemic mortality burden. Furthermore, access to care
including hospitalization without delay and antiviral treatment and are also important factors, as well as vaccination coverage with the 2008–09 trivalent inactivated influenza vaccine.
OriginalsprogEngelsk
TidsskriftPLoS ONE
Vol/bind7
Udgave nummer7
ISSN1932-6203
DOI
StatusUdgivet - 2012
Udgivet eksterntJa

Citer dette

Chowell, G., Echevarría-Zuno, S., Viboud, C., Simonsen, L., Miller, M. A., Fernández-Gárate, I., ... Borja-Aburto, V. H. (2012). Epidemiological characteristics and underlying risk factors for mortality during the Autumn 2009 pandemic wave in Mexico. PLoS ONE, 7(7). https://doi.org/10.1371/journal.pone.0041069
Chowell, G. ; Echevarría-Zuno, S. ; Viboud, C. ; Simonsen, L. ; Miller, M.A. ; Fernández-Gárate, I. ; González-Bonilla, C. ; Borja-Aburto, V.H. / Epidemiological characteristics and underlying risk factors for mortality during the Autumn 2009 pandemic wave in Mexico. I: PLoS ONE. 2012 ; Bind 7, Nr. 7.
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title = "Epidemiological characteristics and underlying risk factors for mortality during the Autumn 2009 pandemic wave in Mexico",
abstract = "Background: Elucidating the role of the underlying risk factors for severe outcomes of the 2009 A/H1N1 influenza pandemic could be crucial to define priority risk groups in resource-limited settings in future pandemics.Methods: We use individual-level clinical data on a large series of ARI (acute respiratory infection) hospitalizations from a prospective surveillance system of the Mexican Social Security medical system to analyze clinical features at presentation, admission delays, selected comorbidities and receipt of seasonal vaccine on the risk of A/H1N1-related death. We considered ARI hospitalizations and inpatient-deaths, and recorded demographic, geographic, and medical information on individual patients during August-December, 2009.Results: Seasonal influenza vaccination was associated with a reduced risk of death among A/H1N1 inpatients (OR = 0.43 (95{\%} CI: 0.25, 0.74)) after adjustment for age, gender, geography, antiviral treatment, admission delays, comorbidities and medical conditions. However, this result should be interpreted with caution as it could have been affected by factors not directly measured in our study. Moreover, the effect of antiviral treatment against A/H1N1 inpatient death did not reach statistical significance (OR = 0.56 (95{\%} CI: 0.29, 1.10)) probably because only 8.9{\%} of A/H1N1 inpatients received antiviraltreatment. Moreover, diabetes (OR = 1.6) and immune suppression (OR = 2.3) were statistically significant risk factors for death whereas asthmatic persons (OR = 0.3) or pregnant women (OR = 0.4) experienced a reduced fatality rate among A/ H1N1 inpatients. We also observed an increased risk of death among A/H1N1 inpatients with admission delays .2 days after symptom onset (OR = 2.7). Similar associations were also observed for A/H1N1-negative inpatients.Conclusions: Geographical variation in identified medical risk factors including prevalence of diabetes and immune suppression may in part explain between-country differences in pandemic mortality burden. Furthermore, access to careincluding hospitalization without delay and antiviral treatment and are also important factors, as well as vaccination coverage with the 2008–09 trivalent inactivated influenza vaccine.",
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Chowell, G, Echevarría-Zuno, S, Viboud, C, Simonsen, L, Miller, MA, Fernández-Gárate, I, González-Bonilla, C & Borja-Aburto, VH 2012, 'Epidemiological characteristics and underlying risk factors for mortality during the Autumn 2009 pandemic wave in Mexico', PLoS ONE, bind 7, nr. 7. https://doi.org/10.1371/journal.pone.0041069

Epidemiological characteristics and underlying risk factors for mortality during the Autumn 2009 pandemic wave in Mexico. / Chowell, G.; Echevarría-Zuno, S.; Viboud, C.; Simonsen, L.; Miller, M.A.; Fernández-Gárate, I.; González-Bonilla, C.; Borja-Aburto, V.H.

I: PLoS ONE, Bind 7, Nr. 7, 2012.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Epidemiological characteristics and underlying risk factors for mortality during the Autumn 2009 pandemic wave in Mexico

AU - Chowell, G.

AU - Echevarría-Zuno, S.

AU - Viboud, C.

AU - Simonsen, L.

AU - Miller, M.A.

AU - Fernández-Gárate, I.

AU - González-Bonilla, C.

AU - Borja-Aburto, V.H.

PY - 2012

Y1 - 2012

N2 - Background: Elucidating the role of the underlying risk factors for severe outcomes of the 2009 A/H1N1 influenza pandemic could be crucial to define priority risk groups in resource-limited settings in future pandemics.Methods: We use individual-level clinical data on a large series of ARI (acute respiratory infection) hospitalizations from a prospective surveillance system of the Mexican Social Security medical system to analyze clinical features at presentation, admission delays, selected comorbidities and receipt of seasonal vaccine on the risk of A/H1N1-related death. We considered ARI hospitalizations and inpatient-deaths, and recorded demographic, geographic, and medical information on individual patients during August-December, 2009.Results: Seasonal influenza vaccination was associated with a reduced risk of death among A/H1N1 inpatients (OR = 0.43 (95% CI: 0.25, 0.74)) after adjustment for age, gender, geography, antiviral treatment, admission delays, comorbidities and medical conditions. However, this result should be interpreted with caution as it could have been affected by factors not directly measured in our study. Moreover, the effect of antiviral treatment against A/H1N1 inpatient death did not reach statistical significance (OR = 0.56 (95% CI: 0.29, 1.10)) probably because only 8.9% of A/H1N1 inpatients received antiviraltreatment. Moreover, diabetes (OR = 1.6) and immune suppression (OR = 2.3) were statistically significant risk factors for death whereas asthmatic persons (OR = 0.3) or pregnant women (OR = 0.4) experienced a reduced fatality rate among A/ H1N1 inpatients. We also observed an increased risk of death among A/H1N1 inpatients with admission delays .2 days after symptom onset (OR = 2.7). Similar associations were also observed for A/H1N1-negative inpatients.Conclusions: Geographical variation in identified medical risk factors including prevalence of diabetes and immune suppression may in part explain between-country differences in pandemic mortality burden. Furthermore, access to careincluding hospitalization without delay and antiviral treatment and are also important factors, as well as vaccination coverage with the 2008–09 trivalent inactivated influenza vaccine.

AB - Background: Elucidating the role of the underlying risk factors for severe outcomes of the 2009 A/H1N1 influenza pandemic could be crucial to define priority risk groups in resource-limited settings in future pandemics.Methods: We use individual-level clinical data on a large series of ARI (acute respiratory infection) hospitalizations from a prospective surveillance system of the Mexican Social Security medical system to analyze clinical features at presentation, admission delays, selected comorbidities and receipt of seasonal vaccine on the risk of A/H1N1-related death. We considered ARI hospitalizations and inpatient-deaths, and recorded demographic, geographic, and medical information on individual patients during August-December, 2009.Results: Seasonal influenza vaccination was associated with a reduced risk of death among A/H1N1 inpatients (OR = 0.43 (95% CI: 0.25, 0.74)) after adjustment for age, gender, geography, antiviral treatment, admission delays, comorbidities and medical conditions. However, this result should be interpreted with caution as it could have been affected by factors not directly measured in our study. Moreover, the effect of antiviral treatment against A/H1N1 inpatient death did not reach statistical significance (OR = 0.56 (95% CI: 0.29, 1.10)) probably because only 8.9% of A/H1N1 inpatients received antiviraltreatment. Moreover, diabetes (OR = 1.6) and immune suppression (OR = 2.3) were statistically significant risk factors for death whereas asthmatic persons (OR = 0.3) or pregnant women (OR = 0.4) experienced a reduced fatality rate among A/ H1N1 inpatients. We also observed an increased risk of death among A/H1N1 inpatients with admission delays .2 days after symptom onset (OR = 2.7). Similar associations were also observed for A/H1N1-negative inpatients.Conclusions: Geographical variation in identified medical risk factors including prevalence of diabetes and immune suppression may in part explain between-country differences in pandemic mortality burden. Furthermore, access to careincluding hospitalization without delay and antiviral treatment and are also important factors, as well as vaccination coverage with the 2008–09 trivalent inactivated influenza vaccine.

U2 - 10.1371/journal.pone.0041069

DO - 10.1371/journal.pone.0041069

M3 - Journal article

VL - 7

JO - P L o S One

JF - P L o S One

SN - 1932-6203

IS - 7

ER -