Influenza vaccination among persons with chronic respiratory diseases: Coverage, related factors and time-trend, 1993–2001

ARTICLE IN PRESS Public Health (2007) 121, 113–121

www.elsevierhealth.com/journals/pubh

Original Research

Influenza vaccination among persons with chronic respiratory diseases: Coverage, related factors and time-trend, 1993–2001 Elga Mayo Montero, Valentı´n Herna ´ndez-Barrera, Pilar Carrasco-Garrido, ´ Angel Gil de Miguel, Rodrigo Jime ´nez-Garcı´a Preventive Medicine and Public Health Teaching and Research Unit, Health Sciences Faculty, Rey Juan Carlos University, Avda. de Atenas s/n, 28922 Alcorco ´n, Spain Received 20 December 2005; received in revised form 6 July 2006; accepted 18 September 2006 Available online 10 January 2007

KEYWORDS Vaccine; Influenza; Asthma; Chronic bronchitis; Survey

Summary Background: Influenza vaccination has shown itself to be effective in reducing morbidity and mortality in patients with underlying chronic respiratory diseases. This study sought to: (1) estimate influenza vaccination coverage among asthma and chronic bronchitis sufferers; (2) ascertain which variables were associated with vaccination; and (3) analyse the time-trend in coverage between 1993 and 2001. Methods: This was a descriptive study covering the 2611 subjects included in the 1993, 1995, 1997 and 2001 Spanish National Health Surveys who reported suffering from asthma or chronic bronchitis. Vaccination coverage was calculated for each year and the influence of socio-demographic and health-related variables analysed. Using logistic regression, we assessed which of the variables had an independent effect on vaccination, and analysed the time-trend. Results: The proportions of vaccinated subjects in 1993, 1995–1997 and 2001 were 44.7%, 45.6% and 44.4%, respectively. Variables that increased the likelihood of having been vaccinated were: higher age, presence of another concomitant chronic disease, poor perception of health, non-smoker status, and being married. There was no significant variation in coverage over the study period. Conclusion: Influenza vaccination coverage among Spanish asthma and/or chronic bronchitis sufferers is below desirable levels and showed no improvement over the period 1993–2001. Implementation of strategies to improve coverage is necessary. & 2006 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved.

Corresponding author. Tel.: +34 91 4888853; fax: +34 91 4888848.

´nez-Garcı´a). E-mail address: [email protected] (R. Jime 0033-3506/$ - see front matter & 2006 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.puhe.2006.09.009

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Introduction Influenza is an acute viral respiratory disease, which leads to excessive morbidity and mortality among subjects who are at special risk by reason of their age or presence of concomitant chronic diseases.1,2 With regard to the latter, chronic respiratory diseases have been associated with an increase in the number of hospitalizations and deaths during influenza outbreaks, regardless of subjects’ age or degree of morbidity.3,4 Within the group of chronic respiratory diseases, asthma and bronchitis are of great importance due to their high prevalence.5,6 A number of studies have linked secondary exacerbations of these two diseases to virus-induced respiratory infections, such as influenza, which are responsible for a great number of hospital admissions and deaths.1–4 The annual influenza vaccination has shown itself to be a safe, effective and efficient method for the prevention of influenza both among the healthy general population of all ages and among respiratory patients with different degrees of disease severity.1,7–11 In non-institutionalized persons aged X60 years this vaccine has been estimated to have an efficacy of approximately 58% against respiratory diseases.12,13 Influenza vaccine efficacy has been assessed by different authors in terms of the reduction in hospitalizations (21–52%) and secondary deaths (12–70%) due to acute respiratory infections in subjects at high risk of suffering influenza-related complications.1,13–16 In addition, it is highly effective (76%) in preventing such infections in patients with chronic obstructive pulmonary disease (COPD), irrespective of the severity of their disease.10 A Spanish study has reported a significant reduction in pneumonia-related hospital admissions of non-institutionalized sexagenarians, thanks to the influenza vaccination.17 In Spain, the responsibility for laying down guidelines for the use of the influenza vaccine lies with the Ministry for Health and Consumer Affairs working in liaison with the Autonomous Regions and, as in other countries, this vaccine is universally indicated for adults aged X65 years and for individuals of any age with chronic respiratory tract, cardiovascular or metabolic diseases and disorders.18–20 Public health campaigns in Spain have targeted all risk groups for influenza-related complications included in the Spanish Influenza Vaccine Recommendations. To our knowledge, no nationwide campaigns exclusively targeting persons with chronic respiratory diseases were conducted in Spain by either public or private institutions across the study period.

E. Mayo Montero et al. Despite the many studies that have demonstrated the benefit of annual influenza vaccination in chronic disease-sufferers, vaccination coverage in these at-risk groups fails to rise above 60% in the X65-year age group and is lower still (o40%) in younger subjects with chronic diseases.21–25 No specific studies have been conducted in Spain on influenza vaccination including those suffering respiratory tract diseases. Health surveys have been used by various authors as a tool for calculating influenza vaccination coverage and related factors.21–23,26,27 Based on data drawn from the 1993, 1995, 1997 and 2001 Spanish National Health Surveys (NHS) (Encuesta Nacional de Salud), this study sought to: 1. ascertain influenza vaccination coverage among Spanish subjects with asthma and chronic bronchitis in 1993, 1995–1997 and 2001; 2. analyse which socio-demographic and healthrelated variables were associated with the likelihood of such subjects being vaccinated in each of these years; and 3. analyse the time-trend in influenza vaccination coverage for the period 1993–2001, controlling for any socio-demographic and health-related variables that might influence the likelihood of being vaccinated.

Methods A descriptive cross-sectional study was conducted into influenza vaccination coverage nationwide, using data drawn from the 1993, 1995, 1997 and 2001 Spanish National Health Surveys (NHS) undertaken by the Ministry of Health and Consumer Affairs. These surveys cover a representative sample of the non-institutionalized Spanish adult population aged over 15 years. The NHS used multi-stage, stratified cluster sampling, with proportional random selection of primary and secondary sampling units (towns and sections, respectively), and selection of the final units (individuals) by means of random routes and sexand age-based quotas. Whereas the 1993 and 2001 surveys included 21 091 and 21 066 adults, respectively, the equivalent numbers in the 1995 and 1997 surveys were 6440 and 6447, respectively. Hence, owing to their smaller sample size and short intervening time, the databases of the latter two NHS were pooled and analysed as a single survey (1995–1997), an approach already used by other authors.28 Using all three NHS, we identified those individuals who had reported suffering from respiratory

ARTICLE IN PRESS Influenza vaccination among persons with chronic respiratory diseases diseases (asthma and/or chronic bronchitis), i.e., those that answered ‘yes’ to the question, ‘Has your doctor told you that you are currently suffering from asthma or chronic bronchitis?’. We used the answer (‘yes’ or ‘no’) to the question, ‘We’d like to know whether you had a ‘flu shot in the latest campaign’ as the dependent variable, and as independent variables, we analysed a further series of questions addressing: socio-demographic variables: age, sex, marital status, size of town or city, and educational level. The lifestyle- and health-related variables were: perception of health status, smoking habit, alcohol consumption, sedentariness, body mass index (BMI), and presence of any other related chronic diseases (e.g. diabetes and/or heart disease). Year of survey was also dependent variable. The variables used for study purposes were recorded identically in all the surveys sourced. Unfortunately information about ‘socio-economic status’ was not collected by the NHS until the 1995 edition and was therefore excluded from the analysis. We estimated the prevalence of asthma and/or chronic bronchitis in each NHS and calculated influenza vaccine coverage—defined as the percentage of individuals that reported having been vaccinated against influenza in the most recent campaign—for subjects with and without the target respiratory diseases. A bivariate analysis was performed for each year, duly cross-referencing the independent variables with the ‘influenza vaccination’ variable in subjects with respiratory diseases. The Chi-squared statistical method was used for bivariate comparison of proportions, and statistical significance was set at two-tailed ao0.05. Using multivariate logistic regression models, adjusted odds ratios were obtained for the purpose

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of estimating the independent effect on administration of influenza vaccine of those variables that had shown a significant association in the bivariate analysis and assessing the time-trend in vaccination coverage for the period 1993–2001. Estimates were made using the survey commands functions of the STATA 8.0 program, which enabled us to incorporate the complex sampling design and weighting factors into all our statistical calculations (descriptive, confidence intervals, Chi-squared, logistic regression).

Results We analysed a total of 55 368 records pertaining to individual adult participants in the 1993, 1995–1997 and 2001 NHS. The percentage of subjects that answered the question on influenza vaccination exceeded 99% in all the surveys used. Based on self-reported data in the 1993, 1995–1997 and 2001 NHS, asthma and/or chronic bronchitis prevalence was 4.7%, 4.9% and 4.8%, respectively, with the variation in prevalence not proving statistically significant. Table 1 shows influenza vaccination coverage in the 1993, 1995–1997 and 2001 NHS among subjects with and without respiratory diseases (asthma and/ or chronic bronchitis). Of those surveyed who presented with asthma and/or chronic bronchitis in each of the survey years, 44.7%, 45.6% and 44.4%, respectively, reported having received the influenza vaccine in the previous season. There was no statistically significant variation across the study period. Yet, significantly higher coverage was nevertheless found in each of the 3 years studied among patients with versus those without asthma and/or chronic bronchitis.

Table 1 Influenza vaccination coverage in the 1993, 1995–1997 and 2001 Spanish National Health Surveys (NHS) (Encuesta Nacional de Salud) among subjects with and without respiratory diseases (asthma and/or chronic bronchitis). Respiratory disease

Asthma and/or chronic bronchitis

Year of NHS

Yes

No

Total

Number of participants Number of vaccinated subjects Coverage (%) Number of participants Number of vaccinated subjects Coverage (%) Number of participants Number of vaccinated subjects Coverage (%)

Total

1993

1995–1997

2001

974 435 44.7 19 905 3301 16.6 20 879 3736 17.9

630 287 45.6 12 257 1981 16.2 12 887 2303 17.6

1007 447 44.4 20 026 3614 18.0 21 033 4062 19.3

2611 1169 44.8 52 188 8896 17.0 54 799 10 101 18.4

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E. Mayo Montero et al.

Influenza vaccination distribution and coverage among Spanish respiratory disease sufferers in the 1993, 1995–997 and 2001 NHS are shown in Table 2, with a breakdown by socio-demographic variables. When these variables were analysed vis-a ` -vis coverage, the latter were observed to rise significantly with age, a finding that was in evidence in all three NHS. Significantly more men than women were vaccinated in 1995–997 and 2001. Furthermore, the three surveys revealed a greater coverage among subjects who had reported being married than those that had not. Similarly, vaccination was significantly higher in all 3 years among subjects with a lower educational level (education until age 16 years). Table 3 shows influenza vaccination distribution and coverage for patients who reported suffering asthma and/or chronic bronchitis in the 1993, 1995–1997 and 2001 NHS, according to healthrelated variables. Vaccination coverage was significantly higher over the 3 years studied among patients who perceived their health as fair, poor or very poor compared to those who perceived it as excellent or good. Likewise, among patients who reported being ex- and never-smokers, a greater percentage had been vaccinated than among those who reported being smokers. In 1993, persons who

stated that they had consumed no alcohol in the preceding 2 weeks registered higher vaccination coverage. Similarly, we observed a greater proportion of vaccinated subjects among those with BMIX27 versus BMIo27 in the three NHS. Frequency of vaccination tended to be higher across all the years studied among subjects who, in addition to asthma or chronic bronchitis, suffered from a concomitant disease, such as diabetes and/ or heart disease, than among those who did not present with comorbidity. In all the NHS, after adjusting for potential confounders (age, gender and comorbidity), the likelihood of being vaccinated was significantly higher among asthma and/or chronic bronchitis sufferers than among non-sufferers. Table 4 shows the predictors of influenza vaccination in Spanish subjects with asthma and/or chronic bronchitis included in all three NHS. Age acted as a significant predictor of vaccination. Subjects aged 50–64 years were 2.73 times more likely to be vaccinated than subjects aged 16–49 years, and this rise in coverage was greater still (OR ¼ 5.66) among the oldest (X65 years) versus the youngest subjects. Vaccination among patients who suffered from pathologies associated with the target respiratory diseases was 21% higher

Table 2 Influenza vaccination distribution and coverage for subjects with asthma and/or chronic bronchitis in the 1993, 1995–1997 and 2001 Spanish National Health Surveys (NHS) (Encuesta Nacional de Salud), according to sociodemographic variables. Variable

Category

1993

1995–1997

2001

Number of Coverage Number of Coverage Number of Coverage participants (%) participants (%) participants (%) Agea

Sexb Matrimonial status

16–49 years 50–64 years X65 years Women Men Unmarried

Married Size of town or o10 000 inhabitants cityc 10 001–100 000 inhabitants 4100 001 inhabitants Until age 16 years Educational levela Education age 416 years a

277 285 399 411 563 351

18.1 45.3 63.4 46.2 43.5 34.2

199 185 245 281 349 231

18.1 44.9 68.6 37.7 51.9 35.5

378 205 422 478 529 404

16.7 47.8 67.5 40.0 48.4 33.9

623 242

50.6 47.1

399 156

51.6 53.8

602 244

51.5 56.1

300

46.0

209

45.5

355

38.9

431 781

42.5 49.3

265 446

40.8 51.3

408 719

42.2 51.2

191

25.7

125

22.4

285

27.4

Statistically significant association (Po0.05) for the 1993,1995–1997 and 2001 NHS. Statistically significant association (Po0.05) for the 1995–1997 and 2001 NHS. c Statistically significant association (Po0.05) for the 2001 NHS. b

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Table 3 Influenza vaccination distribution and coverage for subjects with asthma and/or chronic bronchitis in the 1993, 1995–1997 and 2001 Spanish National Health Surveys (NHS) (Encuesta Nacional de Salud), according to healthrelated variables. Variable

Category

1993

1995–1997

2001

Number of Coverage Number of Coverage Number of Coverage participants (%) participants (%) participants (%) Perception of Excellent or good health statusa Fair, poor or very poor Tobacco usea Smoker Ex-smoker Never-smoker Alcohol Abstainer consumptionb Drinker Sedentariness Non-sedentary Sedentary Body mass BMIo27 indexa BMIX27 Comorbiditya No Yes a b

278

29.9

179

25.1

342

31.3

692 280 255 430 566

50.4 24.6 55.3 51.6 50.7

448 161 170 290 355

54.0 21.7 65.9 46.2 48.2

665 283 269 455 554

51.1 23.7 63.9 45.7 46.2

393 365 600 431

35.1 40.5 46.7 36.7

272 280 348 277

42.3 42.5 48.0 35.4

450 455 545 434

42.0 46.4 42.8 33.9

298 802 173

53.0 41.1 60.7

205 492 138

55.1 40.7 63.0

368 779 228

52.4 39.5 61.0

Statistically significant association (Po0.05) for the 1993, 1995–1997 and 2001 NHS. Statistically significant association (Po0.05) for the 1993 NHS.

Table 4 Factors associated with influenza vaccination of subjects with asthma and/or chronic bronchitis included in the 1993,1995–1997 and 2001 Spanish National Health Surveys (NHS) (Encuesta Nacional de Salud).a Variables

Category

Adjusted OR

95% CI

Age groups

16–49 years 50–64 years X65 years No Yes Excellent or good Fair, poor or very poor Smoker Ex-smoker Never-smoker Unmarried Married

1 2.73 5.66 1 1.21 1 1.40 1 2.62 1.97 1 1.47

— 2.11–3.52 4.43–7.22 — 1.03–1.50 — 1.14–1.72 — 2.04–3.37 1.57–2.47 — 1.21–1.79

Comorbidity Perception of health status Tobacco use

Matrimonial status

OR, odds ratio; CI, confidence interval. Multivariate adjustment with logistic regression.

a

(OR ¼ 1.21, 95% CI 1.03–1.50) than it was among those who presented with no related comorbidity. Perception of health, smoking, and matrimonial status all maintained their significance in the multivariate model. As in the crude analysis, the coverage time-trend across the three NHS periods displayed no significant change following multivariate adjustment.

Discussion An overall prevalence of less than 5% was obtained for self-reported asthma and/or chronic bronchitis among non-institutionalized subjects aged X16 years over the period 1993–2001. These data are comparable to those reported by other Spanish studies in which prevalence was calculated

ARTICLE IN PRESS 118 separately for each disease,29,30 an example being the multicentre 2000 IBEREPOC study that calculated a COPD prevalence ranging from 4.9% to 18% according to the area.29 In the case of asthma, a study conducted in Europe in 1996 used self-report data to calculate a mean prevalence of this disorder in Spain of approximately 4%.30 In the NHS, the presence of asthma and/or chronic bronchitis is addressed in a single question, and consequently, the fact that one of the two diseases is self-reported without clinical diagnosis could lead to the result being underestimated. Nevertheless, we feel that all those who report suffering from either of these diseases must necessarily be candidates for receiving vaccination by virtue of suffering from a chronic respiratory disease.31 Another possible limitation that underestimates ascertainment of coverage levels in respiratory patients is the existence of other, far less prevalent disorders which, though equally susceptible to vaccination, are not addressed by this survey (e.g. emphysema, cystic fibrosis, etc.). Based on our analysis of the NHS, influenza vaccine coverage among subjects who reported suffering from asthma or chronic bronchitis was less than 50% during the study period. In the USA, coverage for asthma and chronic bronchitis sufferers is calculated separately.12,24,32 The US National Health Interview Surveys (NHIS) calculated that 35.1%, 36.7% and 33.3% of asthma sufferers (age X18 years) had been vaccinated against influenza in 1999, 2000 and 2001, respectively, while the Behavioral Risk Factor Surveillance System (BRFSS) for the year 2000 estimated that 41% of diagnosed asthma sufferers had reported having been vaccinated.24,25 Insofar as patients with bronchitis are concerned, the 1999 NHIS calculated a coverage of 43%.32 The proportions of estimated vaccinated subjects appear to be similar for both diseases, even though these are analysed separately in most studies. In Holland, 60% of subjects of all ages with pulmonary diseases had been vaccinated in 2000–2001, with the percentages being somewhat lower (54%) for those under the age of 65 years with these diseases.33,34 In Spain, a 1997 NHS-based study calculated a selfreported coverage of 45.4% among adults suffering from any chronic disease indicating vaccination, a figure similar to that calculated solely for asthma and/or bronchitis patients.21 In our study, as in most studies published both here and abroad, age was confirmed as the principal predictor of vaccination among subjects with or without respiratory disease.21,23,33–35 The greatest increase in the likelihood of being vaccinated takes place after the age of 65. This suggests

E. Mayo Montero et al. to us that, as from this age, a greater proportion of subjects receive the vaccine as a result of having entered the age group of universal indication, rather than because of their patient status, a finding in line with studies that analyse strategies for increasing vaccination coverage.36 These studies report the greater effectiveness of strategies that select patients by age group and stress the limitation of those that are based on selection of patients by related disease or disorder.36 In the year 2000, the Advisory Committee of Immunization Practices (ACIP) amended the influenza vaccination guidelines, by reducing the universal vaccination age from 65 to 50 years, with the intention of improving coverage in this age bracket among chronic disease sufferers.18 Our results appear to point to a higher proportion of vaccinated subjects among individuals who, aside from their respiratory disorder, suffer from some other chronic disease and also perceive their health more negatively. These data are similar to those detected by other studies, in which subjects who had related comorbidity and perceived their health as poor, registered higher vaccination coverage.21,22,24,25,32,34,37 We observed a statistically significant association between vaccination and smoking, comparable to that reported in other general population vaccination-coverage studies.21,22,38 No improvement in coverage among subjects with asthma and/or chronic bronchitis was in evidence over the course of the 1993, 1995–1997 and 2001 NHS. As already stated, in Spain influenza vaccine is universally indicated for adults aged X65 years and for individuals of any age with chronic respiratory tract, cardiovascular or metabolic diseases and disorders. These recommendations have not changed over the last 15 years. The Spanish National Health Service has been administering the vaccine free of charge to all those included in the recommendations groups, regardless of their age, and did so over the entire study period. It should also be noted that, here in Spain, the distribution and administration of influenza vaccine is through the general practitioner; specialists can recommend the vaccine but the administration is conducted at the primary care centre. To our knowledge, no nationwide campaigns exclusively targeting persons with chronic respiratory diseases were conducted in Spain by either public or private institutions across the study period. The campaigns targeting all persons at high risk of suffering influenza-related complications have used television, radio and newspaper advertising as well as notices at healthcare centres. Similarly, campaigns have also targeted health

ARTICLE IN PRESS Influenza vaccination among persons with chronic respiratory diseases professionals with the aim of enhancing their knowledge about the influenza vaccine recommendations and effectiveness. An increase in vaccination rates in all high-risk groups could thus be expected as a result of the additive effect on the patients of repeated campaigns and progressively greater awareness and collaboration on the part of professional health workers. Unfortunately it seems that this hypothesis has to be rejected. Among the reasons cited by different authors for high-risk subjects refusing the vaccine, the following should be noted, namely: perception of good health; not feeling susceptible to influenza; never having received the vaccine previously; having had a prior bad experience with the vaccine; perception of the vaccine as being of little or no use; and fear of the possible adverse effects of the vaccine on the subject’s own disease, notwithstanding the numerous studies that have demonstrated the vaccine’s safety in such patients.9,11,37,39,40 One of the most important factors in any strategy is adequate information regarding the vaccine’s benefits, its efficacy and safety.9,11,37,39,40 Improvements in vaccination coverage have been reported in chronic disease sufferers, even among the under-64 age group, as a result of intensive vaccination programs implemented in the USA.41 Timely vaccination information and reminders, whether given via telephone calls, computerized systems or during the medical visits that these patients make at least once a year for examination and monitoring of their condition, have proved effective in improving vaccination levels.42,43 As previously noted, lowering the age for universal vaccination is another possible strategy to increase vaccination uptake specifically among high-risk patients.18,36 All such strategies mentioned would enable vaccination outreach to be extended to a greater number of high-risk patients who would otherwise not make use of the vaccine, either because they do not perceive themselves as patients or because they do not come within the vaccine-indicated age group. Public health authorities should consider the many options open, options that should be urgently implemented and evaluated. The use of the NHS as a tool for studies seeking to estimate vaccination coverage has a series of limitations. The first of these consists of reliance on data obtained via self-report of influenza vaccination. However, comparison between this type of direct testimony and medical vaccine records has shown that the former is highly sensitive and moderately specific, and further-

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more, that there is good concordance between the two sources.44,45 Another possible limitation lies in the fact that the results obtained are solely applicable to the non-institutionalized adult population. This means that they cannot be generalized to the population aged over 65 years who live in residential homes, who would probably register coverage higher than our estimates. Finally, we have not included in the analysis variables that may have a confounding effect. One of these variables is ‘socio-economic status’ that has been described as an independent predictor for influenza vaccination in other studies and that could explain in part the associations found.21,22,46–50 Social class has been assessed in three studies conducted in Spain showing different results. Pen ˜a-Rey et al. found that women living in Galicia with higher incomes had a higher prevalence of vaccination (adjusted OR 1.39, CI 95% 1.01–1.9).46 On the other hand Jime´nez-Garcı´a et al. found that for subjects aged 50–64 years, monthly income showed a statistically significant association with frequency of influenza vaccination, in that the smaller the income of the individual, the greater the vaccination coverage, a trend that remained in evidence after adjusting for possible confounders. Finally another study conducted among the elderly found no association.21,22 A recent population-based survey conducted in five European countries, including Spain, showed that those with a low household income (less than 1000 Euro per month) had a higher vaccination rate (29.9%) than those with an income over 2000 Euro per month (21.0%).47 Mangtani et al. assessed factors influencing vaccine uptake in over 74 years in Britain and concluded that there are indications that people whose personal socio-economic circumstances are better than others are more likely to be vaccinated, although the differentials were modest; other studies among European elderly subjects obtained similar results.48–50 These discordant results may be explained by the fact that socioeconomic position is multi-dimensional and may vary with context.48

Conclusions Influenza vaccination coverage among Spanish asthma and/or chronic bronchitis sufferers is below desirable levels and showed no improvement over the period 1993–2001. Accordingly, effective strategies to increase influenza vaccine coverage levels among the at-risk population must be drawn up.

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Acknowledgements This study forms part of a research project funded by FIS (Fondo de Investigaciones Sanitarias–Health Research Fund) grant PI041662 from the Carlos III Institute of Public Health.

References 1. Nichol KL, Baken L, Nelson A. Relation between influenza vaccination and outpatient visits, hospitalization, and mortality in elderly persons with chronic lung disease. Ann Intern Med 1999;130:397–403. 2. Glezen WP, Greenberg SB, Atmar RL, Piedra PA, Couch RB. Impact of respiratory virus infections on persons with chronic underlying conditions. JAMA 2000;283:499–505. 3. Thompson WW, Shay DK, Weintraub E, Brammer L, Bridges CB, Cox NJ, et al. Influenza-associated hospitalizations in the United States. JAMA 2004;292:1333–40. 4. Thompson WW, Shay DK, Weintraub E, Brammer L, Cox N, Anderson LJ, et al. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA 2003; 289:179–86. 5. Sobradillo V, Miravitlles M, Jimenez CA, Gabriel R, Viejo JL, Masa JF, et al. [Epidemiological study of chronic obstructive pulmonary disease in Spain (IBERPOC): prevalence of chronic respiratory symptoms and airflow limitation.]. Arch Bronconeumol 1999;35:159–66. 6. Basagan ˜a X, Sunyer J, Zock J, Kogevinas M, Urrutia I, Maldonado JA, et al. Spanish Working Group of the European Community Respiratory Health Survey. Incidence of asthma and its determinants among adults in Spain. Am J Respir Crit Care Med 2001;164:1133–7. 7. Beyer WE, de Bruijn IA, Palache AM, Westendorp RG, Osterhaus AD. Protection against influenza after annually repeated vaccination: a meta-analysis of serologic and field studies. Arch Intern Med 1999;159:182–8. 8. Bridges CB, Thompson WW, Meltzer MI, Reeve GR, Talamonti WJ, Cox NJ, et al. Effectiveness and cost–benefit of influenza vaccination of healthy working adults: a randomized controlled trial. JAMA 2000;284:1655–63. 9. The safety of inactivated influenza vaccine in adults and children with asthma. N Engl J Med 2001;345:1529–36. 10. Wongsurakiat P, Maranetra KN, Wasi C, Kositanont U, Dejsomritrutai W, Charoenratanakul S. Acute respiratory illness in patients with COPD and the effectiveness of influenza vaccination: a randomized controlled study. Chest 2004;125:2011–20. 11. Nichol KL. The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines. Vaccine 2003;21: 1769–75. 12. Govaert TM, Thijs CT, Masurel N, Sprenger MJ, Dinant GJ, Knottnerus JA. The efficacy of influenza vaccination in elderly individuals. A randomized double-blind placebocontrolled trial. JAMA 1994;272:1661–5. 13. Gross PA, Hermogenes AW, Sacks HS, Lau J, Levandowski RA. The efficacy of influenza vaccine in elderly persons. A metaanalysis and review of the literature. Ann Intern Med 1995;123:518–27. 14. Mangtani P, Cumberland P, Hodgson CR, Roberts JA, Cutts FT, Hall AJ. A cohort study of the effectiveness of influenza vaccine in older people, performed using the United Kingdom general practice research database. J Infect Dis 2004;190:1–10.

E. Mayo Montero et al. 15. Hak E, Nordin J, Wei F, Mullooly J, Poblete S, Strikas R, et al. Influence of high-risk medical conditions on the effectiveness of influenza vaccination among elderly members of 3 large managed-care organizations. Clin Infect Dis 2002;35:370–7. 16. Nichol KL, Baken L, Wuorenma J, Nelson A. The health and economic benefits associated with pneumococcal vaccination of elderly persons with chronic lung disease. Arch Intern Med 1999;159:2437–42. 17. Puig-Barbera J, Marquez-Calderon S, Masoliver-Fores A, Lloria-Paes F, Ortega-Dicha A, Gil-Martin M, et al. Reduction in hospital admissions for pneumonia in non-institutionalised elderly people as a result of influenza vaccination: a case–control study in Spain. J Epidemiol Community Health 1997;51:526–30. 18. Harper SA, Fukuda K, Uyeki TM, Cox NJ, Bridges CB. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2004;53:1–40. 19. van Essen GA, Palache AM, Forleo E, Fedson DS. Influenza vaccination in 2000: recommendations and vaccine use in 50 developed and rapidly developing countries. Vaccine 2003;21:1780–5. 20. Barbera JA, Peces-Barba G, Agusti AG, Izquierdo JL, Monso E, Montemayor T, et al. Sociedad Espanola de Neumologia y Cirugia Toracica (SEPAR). [Clinical guidelines for the diagnosis and treatment of chronic obstructive pulmonary disease.]. Arch Bronconeumol 2001;37:297–316. 21. Jimenez R, Larrauri A, Carrasco P, Esteban J, Gomez-Lopez LI, Gil A. Influenza coverages in Spain and vaccinationrelated factors in the subgroup aged 50–64 years. Vaccine 2003;21:3550–5. 22. Sarria A, Timoner J. [Determination of influenza vaccination in persons 65 years of age and older.]. Rev Esp Salud Publica 2002;76:17–26. 23. Mayo Montero E, Hernandez Barrera V, Sierra Moros MJ, Pachon del Amo I, Carrasco Garrido P, Gil de Miguel A, et al. [Evolution of the degrees of influenza vaccine (flu shot) coverage in Spain throughout the 1993–2001 period. Analysis by Autonomous Communities.]. Rev Esp Salud Publica 2004;78:481–92. 24. Ford ES, Williams SG, Mannino DM, Redd SC. Influenza vaccination coverage among adults with asthma: findings from the 2000 Behavioral Risk Factor Surveillance System. Am J Med 2004;116:555–8. 25. Ford ES, Mannino DM, Williams SG. Asthma and influenza vaccination: findings from the 1999–2001 National Health Interview Surveys. Chest 2003;124:783–9. 26. Pleis JR, Gentleman JF. Using the National Health Interview Survey: time trends in influenza vaccinations among targeted adults. Eff Clin Pract 2002;5:E3. 27. Nelson DE, Powell-Griner E, Town M, Kovar MG. A comparison of national estimates from the National Health Interview Survey and the Behavioral Risk Factor Surveillance System. Am J Public Health 2003;93:1335–41. 28. Rodriguez Artalejo F, Lopez Garcia E, Gutierrez-Fisac JL, Banegas Banegas JR, Lafuente Urdinguio PJ, Dominguez Rojas V. Changes in the prevalence of overweight and obesity and their risk factors in Spain, 1987–1997. Prev Med 2002;34:72–81. 29. Pena VS, Miravitlles M, Gabriel R, Jimenez-Ruiz CA, Villasante C, Masa JF, Viejo JL, et al. Geographic variations in prevalence and underdiagnosis of COPD: results of the IBERPOC multicentre epidemiological study. Chest 2000; 118:981–9. 30. Variations in the prevalence of respiratory symptoms, selfreported asthma attacks, and use of asthma medication in

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39.

40.

the European Community Respiratory Health Survey (ECRHS). Eur Respir J 1996;9:687–95. Toren K, Brisman J, Jarvholm B. Asthma and asthma-like symptoms in adults assessed by questionnaires. A literature review. Chest 1993;104:600–8. Egede LE, Zheng D. Racial/ethnic differences in influenza vaccination coverage in high-risk adults. Am J Public Health 2003;93:2074–8. Kroneman M, Paget WJ, van Essen GA. Influenza vaccination in Europe: an inventory of strategies to reach target populations and optimise vaccination uptake. Euro Surveill 2003;8:130–8. Kroneman MW, van Essen GA, Tacken MA, Paget WJ, Verheij R. Does a population survey provide reliable influenza vaccine uptake rates among high-risk groups? A case-study of The Netherlands. Vaccine 2004;22:2163–70. Domı´nguez A, Junca ´ R, Tresserres J, Batalla J, Salleras L. Influenza vaccination: the prevalence of risk factors in persons aged 60 years and more in Catalonia. Vacunas 2003;4:114–8. Honkanen PO, Keistinen T, Kivela SL. The impact of vaccination strategy and methods of information on influenza and pneumococcal vaccination coverage in the elderly population. Vaccine 1997;15:317–20. Kamal KM, Madhavan SS, Amonkar MM. Determinants of adult influenza and pneumonia immunization rates. J Am Pharm Assoc (Washington DC) 2003;43:403–11. Nicholson KG, Kent J, Hammersley V. Influenza A among community-dwelling elderly persons in Leicestershire during winter 1993–4; cigarette smoking as a risk factor and the efficacy of influenza vaccination. Epidemiol Infect 1999;123:103–8. Dannetun E, Tegnell A, Normann B, Garpenholt O, Giesecke J. Influenza vaccine coverage and reasons for non-vaccination in a sample of people above 65 years of age, in Sweden, 1998–2000. Scand J Infect Dis 2003;35:389–93. Evans MR, Watson PA. Why do older people not get immunised against influenza? A community survey. Vaccine 2003;21:2421–7.

121

41. Nichol KL. Ten-year durability and success of an organized program to increase influenza and pneumococcal vaccination rates among high-risk adults. Am J Med 1998;105: 385–92. 42. Recommendations regarding interventions to improve vaccination coverage in children, adolescents, and adults. Task Force on Community Preventive Services. Am J Prev Med 2000;18:92–6. 43. Dexter PR, Perkins SM, Maharry KS, Jones K, McDonald CJ. Inpatient computer-based standing orders vs physician reminders to increase influenza and pneumococcal vaccination rates: a randomized trial. JAMA 2004;292: 2366–71. 44. Mac DR, Baken L, Nelson A, Nichol KL. Validation of selfreport of influenza and pneumococcal vaccination status in elderly outpatients. Am J Prev Med 1999;16:173–7. 45. Zimmerman RK, Raymund M, Janosky JE, Nowalk MP, Fine MJ. Sensitivity and specificity of patient self-report of influenza and pneumococcal polysaccharide vaccinations among elderly outpatients in diverse patient care strata. Vaccine 2003;21:1486–91. 46. Pen ˜a-Rey I, Perez-Farinos N, Sarria-Santamera A. Factors associated with influenza vaccination among elderly Spanish women. Public Health 2004;118:582–7. 47. Szucs TD, Mu ¨ller D. Influenza vaccination coverage rates in five European countries—a population-based cross-sectional analysis of two consecutive influenza seasons. Vaccine 2005;23:5055–63. 48. Mangtani P, Breeze E, Kovats S, Ng ES, Roberts JA, Fletcher A. Inequalities in influenza vaccine uptake among people aged over 74 years in Britain. Prev Med 2005;41: 545–53. 49. Landi F, Onder G, Carpenter I, Garms-Homolova V, Bernabei R. Prevalence and predictors of influenza vaccination among frail, community-living elderly patients: an international observational study. Vaccine 2005;23:3896–901. 50. Burns VE, Ring C, Carroll D. Factors influencing influenza vaccination uptake in an elderly, community-based sample. Vaccine 2005;23:3604–8.