Asthma and influenza vaccination in elderly hospitalized patients: Matched case-control study in Spain

ABSTRACT

Objectives: Influenza infection is an exacerbating factor for asthma, and its prevention is critical in managing asthmatic patients. We investigated the effect of influenza vaccination on asthmatic and non-asthmatic patients hospitalized with laboratory-confirmed influenza in Spain. Methods: We made a matched case-control study to assess the frequency of hospitalization for influenza in people aged ≥65 years. Hospitalized patients with unplanned hospital admissions were recruited from 20 hospitals representing seven Spanish regions. Cases were defined as those hospitalized due to a laboratory-confirmed influenza infection and controls were matched by age, sex, and hospital. Data were obtained from clinical records, and patients stratified by clinical asthma history. Vaccination status and asthma due to influenza infection were analyzed according to sociodemographic variables and medical risk conditions. Multivariable analysis was made using conditional logistic regression models. Results: 582 hospitalized patients with influenza (15.8% asthmatic) and 1,570 hospitalized patients without influenza (7.9% asthmatic) were included. In the multivariable conditional logistic regression using unvaccinated and non-asthmatic patients as the reference group, vaccination significantly prevented influenza in non-asthmatic patients (aOR = 0.63; 95% CI: 0.45, 0.88) and also showed a trend for a possibly protective effect in asthmatic patients (aOR = 0.79; 95% CI: 0.34, 1.81). Conclusion: Our results suggest that influenza vaccination could be a protective factor for asthmatic patients, although the results are inconclusive and further research is required. Practically, given the better clinical evolution of vaccinated asthma cases, and the lack of better evidence, the emphasis on vaccination of this group should continue.

KEYWORDS:

• Asthma
• asthma management
• elderly
• influenza
• influenza-related hospitalization
• laboratory-confirmed influenza
• multivariable conditional logistic regression
• prevention
• protective factor
• vaccination

Acknowledgements

The other members of the Working Group for Project FIS PI12/02079 ‘Effectiveness of influenza and pneumococcal polysaccharide 23-valent vaccines in elderly people’ are: J.M. Mayoral (Servicio de Vigilancia de Andalucía), J. Díaz-Borrego (Servicio Andaluz de Salud), A. Morillo (Hospital Universitario Virgen del Rocío), J. Gutiérrez (Hospital Universitario Puerta del Mar), M. Pérez-Ruiz, M.A. Fernández-Sierra (Hospital Universitario San Cecilio y Virgen de las Nieves), S. Tamames (Dir. General de Salud Pública, Investigación, Desarrollo e Innovación, Junta de Castilla y León), S. Rojo-Rello (Hospital Clínico Universitario de Valladolid), R. Ortiz de Lejarazu (Universidad de Valladolid), M.I. Fernández-Natal (Complejo Asistencial Universitario de León), T. Fernández-Villa (GIIGAS-Grupo de Investigación en Interacción Gen-Ambiente y Salud, Universidad de León), A. Pueyo (Hospital Universitario de Burgos), A. Vilella (Hospital Clínic), A. Antón (Hospital Universitari Vall d'Hebron; Universitat Autónoma de Barcelona), G. Navarro (Corporació Sanitària i Universitaria ParcTaulí), M. Riera (Hospital Universitari Mútua Terrassa), E. Espejo (Hospital de Terrassa), M.D. Mas, R. Pérez (ALTHAIA, Xarxa Hospitalaria de Manresa), J.A. Cayla, C. Rius (Agència de Salut Pública de Barcelona; CIBERESP), P. Godoy (Agència de Salut Pública de Catalunya; Institut de Recerca Biomèdica de Lleida, Universitat de Lleida; CIBERESP), N. Torner (Agència de Salut Pública de Catalunya; Universitat de Barcelona; CIBERESP), C. Izquierdo, R. Torra (Agència de Salut Pública de Catalunya), N. Soldevila, I. Crespo (Universitat de Barcelona; CIBERESP), M.F. Domínguez-Berjon, M.A. Gutiérrez, S. Jiménez, E. Gil, F. Martín, R.Génova-Maleras (Consejería de Sanidad), M.C. Prados, F. Enzzine de Blas (Hospital Universitario la Paz), J.C Galán, E. Navas, L. Rodríguez (Hospital Ramón y Cajal), C.J. Álvarez, E. Banderas (Hospital Universitario 12 de Octubre), J. Chamorro (Complejo Hospitalario de Navarra), I. Casado, J. Díaz (Instituto de Salud Pública de Navarra), M.J. López de Goicoechea (Hospital de Galdakao).

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding source

This study was funded by the National Plan of I + D + I 2008–2011 and ISCIII-Subdirección General de Evaluación y Fomento de la Investigación (Project PI12/02079), and was cofounded by Fondo Europeo de Desarrollo Regional (FEDER. Unión Europea. Una manera de hacer Europa), and the Catalan Agency for the Management of Grants for University Research (AGAUR Grant number 2014/SGR 1403). Funders played no role in the study design, data collection and analysis, the decision to publish, and manuscript preparation.