Why do older people not get immunised against influenza?

Vaccine 21 (2003) 2421–2427

Why do older people not get immunised against influenza? A community survey Meirion R. Evans a,∗ , Phil A. Watson b a

Department of Epidemiology, Statistics and Public Health, University of Wales College of Medicine, Abton House, Wedal Road, Cardiff CF14 3QX, UK b Public Health Directorate, Bro Taf Health Authority, Cathays Park, Cardiff CF10 3NW, UK Received 19 August 2002; received in revised form 17 January 2003; accepted 17 January 2003

Abstract Many older people who would benefit from influenza vaccine do not get immunised. We carried out a postal questionnaire survey of people aged 65 years and over living in the community to explore views about influenza vaccine and identify ways of improving uptake. Completed questionnaires were returned by 1468/2553 (57.5%). Vaccine coverage for 1998–1999 season was 50.5% (95% confidence interval (CI) 47.9–53.1%). Important predictor variables for non-uptake included absence of medical risk factors, perceived good health, lack of advice from a doctor or nurse, and negative views on vaccine efficacy and safety. Most people had to request vaccination, only one in five got a reminder from their general practitioner. There is scope for improving influenza vaccine coverage in older people by placing more emphasis in patient information materials on vaccine efficacy and safety and by greater use of reminders. © 2003 Elsevier Science Ltd. All rights reserved. Keywords: Influenza vaccine; Aged; Patient acceptance of health care

1. Introduction Every year in the United Kingdom there are thousands of hospital admissions and between 5000 and 30,000 deaths due to influenza and its complications, most in people aged over 65 years [1,2]. Influenza vaccine is both effective and safe. It has a protective efficacy against infection of 50% when vaccine and circulating virus strains are closely matched [3], and reduces hospitalisation by about 40% and death by up to 60% in older people living in the community [4,5]. Minor side-effects occur in around 10% of older people, but systemic symptoms are no more likely in vaccinees than controls [6]. In 1998–1999, influenza immunisation policy in the United Kingdom was extended to include everyone aged 75 years and over, not just those with high-risk conditions [7,8]. In 1999–2000, this recommendation was extended further to include everyone aged 65 years and over [9]. In practice, vaccine uptake is sub-optimal both in high-risk groups and in older people generally. Influenza vaccine coverage rose to 65% in people aged 65 years and over in 2000–2001 from levels probably nearer 50% in the late 1990s [10]. Not much ∗ Corresponding author. Tel.: +44-29-2052-1997; fax: +44-29-2052-1987. E-mail address: [email protected] (M.R. Evans).

is known about what older people in Britain think of the influenza vaccine or how they would prefer to be offered it. Bro Taf Health Authority has promoted a local policy of influenza immunisation for everyone aged 65 years and over since 1997–1998. In 1999, we carried out a community survey to measure influenza vaccine uptake, to explore knowledge, attitudes and beliefs about influenza and influenza vaccine, and to obtain views and preferences of older people about a future offer of vaccine.

2. Methods 2.1. Setting and participants Bro Taf Health Authority has a population of 737,000 of whom 114,000 (15.5%) are aged 65 years and over. The district is a mixture of urban, old industrial and rural communities, including many areas of social deprivation. The vast majority of individuals in this age group will be from the indigenous white population. A computer generated, age-stratified random sample of 2600 people aged 65 years and over (520 people per 5-year age stratum) was drawn from the Authority’s family health (population) register in May 1999. Sample size was calculated to allow the true value of vaccine coverage to be estimated with 95% confidence

0264-410X/03/$ – see front matter © 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0264-410X(03)00059-8

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to within 2.5% overall and 5% within each stratum, assuming 30% vaccine uptake and a 50% survey response. People living in residential care were excluded. We sent everyone a letter, large print questionnaire, and reply paid envelope. A second mailshot was sent to non-responders. The local research ethics committee accepted the study. 2.2. Data collection The questionnaire asked about personal characteristics, knowledge of influenza symptoms, severity and risk of catching infection, views on safety and efficacy of influenza vaccine, and sources of information about it. People were also asked if they had ever been immunised, if immunised in each of 1998–1999, 1997–1998 and 1996–1997 seasons, how the vaccine had been offered, and whether they would wish to be offered vaccine in future. Finally, people were asked if they suffered from any chronic illnesses (asthma, chronic chest disease, chronic heart disease, chronic kidney disease, diabetes, cancer treatment), whether they had been a hospital inpatient or outpatient in the past 12 months and how they would describe their own health. We requested written consent to contact their general practitioner and subsequently validated data from a stratified, random sample of 5% of responders against their medical record. 2.3. Data analysis Data were analysed using Epi Info (Version 6.04) and Stata (Version 5.0). Rate of agreement between self-reported and medical record data was measured by the kappa statistic. We constructed logistic regression models to clarify the association between self-reported vaccine uptake in 1998/1999 and three groups of variables: personal characteristics (Model A); knowledge, beliefs and attitudes (Model B); and sources of health information (Model C). The core model (Model A) was based on characteristics associated with vaccine uptake identified in previous studies [11,12]. We tested model fit for potentially confounding variables using the likelihood ratio test, only retaining those that represented a significant component of the model (P < 0.05). The final model combined all significant variables from Models A–C. We also modelled the effects of these variables on future immunisation preferences. Confidence intervals (CI) for proportions were calculated with the exact binomial distribution, together with crude and adjusted odds ratios.

3. Results 3.1. Response rate Usable replies were received from 1468/2553 (57.5%), excluding 26 addressees who had died and 21 moved away. Response rate was higher in men (62.0%) than women (53.9%) (χ2 : 6.4, P < 0.0001) and declined with increasing age

(65–69 years, 63.4%; 70–74 years, 62.3%; 75–79 years, 58.6%; 80–84 years, 57.3%; 85 years and over, 45.7%; χ2 for linear trend: 33.7, P < 0.0001). There was no difference in speed of response between immunised and unimmunised respondents (median 4.2 weeks versus 4.6 weeks). Predictive value of self-report when compared with the medical record was 70% for immunisation status (κ: 0.52, P < 0.001) and 90% for chronic illness (κ: 0.87, P < 0.001). 3.2. Immunisation uptake The number of people ever immunised against influenza was 907 (61.8%), 322 (21.9%) had never been offered the vaccine, 161 (11.0%) had been offered vaccine but refused it, and 78 (5.3%) did not know. Reasons for refusing immunisation included: worried about side-effects (37/161, 23.0%), did not think it would work (26, 16.1%), and too unwell (6, 3.7%). Five hundred and ninety five people (40.5%) had been immunised in all three seasons 1998–1999, 1997–1998 and 1996–1997, but 110 (7.5%) defaulted in 1998–1999 in spite of being immunised in one of the two previous seasons. Defaulters were much more likely to report side-effects from the vaccine (19/110; 17.3%) than regularly immunised people (18/595; 3.0%) (relative risk 3.8, 95% confidence interval 2.6–5.4). Men (0.7, 0.5–0.9) and people with chronic illness (0.5, 0.3–0.8) were less likely to default. Table 1 shows details of influenza immunisation history for the 1998–1999 season. Vaccine coverage was Table 1 Immunisation details of people aged 65 years and over immunised against influenza during 1998–1999 season (n = 741) Variable

No. of people

How informed that immunisation was duea Sent an appointment Sent a letter or reminder Opportunistically during a visit to the GP surgery Asked after seeing leaflet or poster Asked after being prompted by someone else

81 149 164 383 58

(10.9) (20.1) (22.1) (51.7) (7.8)

Where immunised GP surgery Hospital clinic At home Other Do not know

645 3 63 6 24

(87.0) (0.4) (8.5) (0.8) (3.3)

By whom immunised General practitioner Practice nurse District nurse or health visitor Other Do not know

130 542 37 2 30

(17.5) (73.1) (5.0) (0.3) (4.0)

Suffered serious side-effects from the vaccine Yes No Do not know

25 (3.4) 679 (91.6) 37 (4.9)

Values are numbers (percentages) unless stated otherwise. a Respondents could answer more than one option.

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Table 2 Logistic regression model of the effects of personal characteristics and health status on reported influenza vaccine uptake in 1998–1999 season in people aged 65 years and over living in the community (n = 1468) Characteristic

No. of people Alla

Odds ratio (95% CI)

P-value

Immunised

Crude

Adjustedb

Gender Female Male

758 710

364 (48.0) 377 (53.1)

Reference 1.2 (1.0–1.5)

Reference 1.3 (1.0–1.6)

0.03

Age (years) 65–69 70–74 75–79 80–84 ≥85

326 320 301 290 231

131 162 168 161 118

(40.2) (50.6) (55.8) (55.5) (51.1)

Reference 1.5 (1.1–2.1) 1.9 (1.4–2.6) 1.9 (1.4–2.6) 1.6 (1.1–2.2)

Reference 1.5 (1.1–2.1) 2.0 (1.4–2.9) 2.0 (1.4–2.9) 1.6 (1.1–2.4)

0.01 <0.001 <0.001 0.01

Number of chronic illnesses None One Two Three or more

850 484 116 18

337 309 82 13

(39.6) (63.8) (70.7) (72.2)

Reference 2.7 (2.1–3.4) 3.7 (2.4–5.6) 4.0 (1.4–11.2)

Reference 2.5 (1.9–3.2) 3.2 (2.0–5.1) 4.0 (1.2–12.9)

<0.001 <0.001 0.02

Hospital outpatient in past 12 months No 713 Yes 662

322 (45.2) 375 (56.6)

Reference 1.6 (1.3–2.0)

Reference 1.3 (1.0–1.7)

0.06

Hospital inpatient in last 12 months No 1113 Yes 276

538 (48.3) 163 (59.1)

Reference 1.5 (1.2–2.0)

Reference 1.0 (0.7–1.4)

1.0

Self-reported health status Excellent Very good Good Fair Poor

17 136 240 253 78

Reference 1.8 (1.0–3.3) 2.3 (1.2–4.1) 3.0 (1.7–5.5) 3.9 (2.0–7.6)

Reference 2.0 (1.0–3.9) 2.0 (1.1–3.9) 2.1 (1.1–4.0) 2.1 (1.0–4.5)

0.04 0.03 0.03 0.05

56 308 483 446 124

(30.4) (44.2) (49.7) (56.7) (62.9)

Values are numbers (percentages) unless stated otherwise. a Not all respondents answered all questions. b Adjusted for effects of all other variables in the table.

50.5% overall (741/1468; 95% confidence interval (CI) 47.9–53.1%), 45.4% (41.5–49.3%) in the 65–74 year age group, 54.5% (51.0–57.9%) in people aged 75 years and over, and 65.4% (404/618; 61.5–69.1%) in people with self-reported chronic illness. Fewer than a third had been sent a letter or appointment. Twenty-five (3.4%) reported side-effects from the vaccine, mostly flu-like symptoms. Table 2 shows the relationship between personal characteristics, health status and vaccine uptake (Model A). On univariate analysis, vaccine coverage was significantly higher in people with one or more chronic illnesses (65.4%; 61.5–69.1%) than in healthy people (39.6%; 36.3–43.0%). People were more likely to be immunised the poorer they perceived their health status to be (χ2 for linear trend: 27.6, P < 0.0001). None of the variables of a priori interest were excluded from the core model by likelihood ratio testing. 3.3. Knowledge, beliefs and attitudes, and sources of health information People were more likely to be immunised the higher they considered the level of protection offered by the vaccine

(χ2 for linear trend: 167.9, P < 0.0001), if they expressed confidence in vaccine safety, and if they wanted to be offered vaccine in future. Perceived seriousness of influenza, believing that vaccine side-effects were more risky than the disease, or that immunisation weakened the immune system (P-values on likelihood ratio testing of 0.210, 0.169 and 0.151, respectively) did not contribute significantly to the second model (Model B). When sources of information were examined (Model C) only advice from a doctor or nurse or from friends contributed significantly, the latter having a negative influence on vaccine uptake. The remaining variables: advice from family members (P = 0.654), posters (P = 0.270), leaflets (P = 0.960), television or radio advertisements (P = 0.188), newspaper or magazine advertisements (P = 0.375), television or radio programmes (P = 0.182) and newspaper or magazine articles (P = 0.892) were eliminated from further analysis. Table 3 shows the final model which combines all variables in Model A (Table 2) together with those that contributed significantly to Models B or C. All these variables apart from gender (P = 0.908) make a significant contribution to the final model.

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Table 3 Logistic regression model of the effects of perceptions of influenza illness, influenza vaccine efficacy and safety, and sources of health advice on reported vaccine uptake in 1998–1999 season in people aged 65 years and over living in the community (n = 1468) Variable

No. of people Alla

Odds ratio (95% CI)

P-value

Immunised

Crude

Adjustedb

812 656

289 (35.6) 452 (68.9)

Reference 4.0 (3.2–5.0)

Reference 2.3 (1.6–3.4)

<0.001

Advice from friends No Yes

1258 210

684 (54.4) 57 (27.1)

Reference 0.3 (0.2–0.4)

Reference 0.4 (0.2–0.7)

0.001

Knowledge of influenza symptoms Poor Good Do not know

215 1198 29

114 (53.0) 607 (50.7) 11 (37.9)

Reference 0.9 (0.7–1.2) 0.5 (0.2–1.2)

Reference 1.0 (0.6–1.7) 4.6 (0.8–26.7)

0.9 0.09

458 984

223 (48.7) 508 (51.6)

Reference 1.1 (0.9–1.4)

Reference 0.9 (0.6–1.3)

0.5

‘How much protection does flu immunisation give?’ <70% 479 70–90% 298 91–100% 213 Do not know 411

221 222 179 102

(46.1) (74.5) (84.0) (24.8)

Reference 3.4 (2.5–4.7) 6.1 (4.1–9.2) 0.4 (0.3–0.5)

Reference 1.5 (0.9–2.4) 3.4 (1.8–6.8) 0.7 (0.4–1.3)

0.09 <0.001 0.3

‘How safe is flu immunisation?’ High risk/moderate risk Slight risk/no risk Do not know

95 (34.9) 526 (69.3) 108 (28.1)

Reference 0.4 (0.3–0.5) 0.7 (0.5–1.0)

Reference 1.6 (1.0–2.7) 0.8 (0.4–1.4)

0.07 0.4

Reference 1.1 (0.8–1.6) 2.0 (1.5–2.8) 0.3 (0.2–0.5)

Reference 1.6 (0.8–3.0) 1.3 (0.8–2.3) 0.6 (0.3–1.1)

0.2 0.3 0.08

‘I would recommend everyone over 65 years of age to be immunised against flu’ Disagree 92 5 (5.4) Reference Neutral 303 33 (10.9) 2.2 (0.8–5.6) Agree 882 672 (76.2) 55.7 (22.3–139.0) Do not know 125 10 (8.0) 1.5 (0.5–4.6)

Reference 1.2 (0.3–4.9) 7.2 (1.9–26.9) 0.9 (0.2–4.8)

0.8 0.004 0.9

‘In future, would you like to be offered immunisation against flu?’ No 276 6 (2.2) Yes 890 638 (71.7) Do not know 157 6 (3.8)

Reference 57.2 (15.4–23.0) 4.8 (1.0–23.0)

Advice from doctor or nurse No Yes

Likelihood of getting influenza Not very likely/not likely Likely/very likely

272 759 384

‘Doctors give sufficient information about the side-effects of immunisations’ Disagree 205 104 (50.7) Neutral 268 144 (53.7) Agree 534 362 (67.8) Do not know 369 97 (26.3)

Reference 113.9 (50.0–259.2) 1.8 (0.6–5.6)

<0.001 0.05

Values are numbers (percentages) unless stated otherwise. a Not all respondents answered all questions. b Adjusted for effects of all other variables in this table and for all variables in Table 2.

3.4. Future immunisation preferences Most people (890/1468; 60.6%) want to be offered influenza immunisation in future, including 174/483 (36.0%) of those never immunised. Apart from previous influenza immunisation, the most important predictors for accepting a future vaccine offer are younger age, a belief that everyone over 65 years of age should be immunised against influenza, and that vaccine side-effects are less risky than the disease (Table 4). Most people, regardless of immunisation status, would like a letter or written reminder from the surgery to let them know their influenza immunisation is due (440/863;

51.0%) (Table 5), particularly if they have never been immunised.

4. Discussion Using a community survey, we found influenza vaccine coverage in people aged 65 and over to be 50.5% in 1998–1999. One in five people had never been offered immunisation. People with chronic illness or in poorer health were more likely to be immunised, as were those advised by a doctor or nurse. However, fewer than a third of immunised

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Table 4 Logistic regression model to identify predictors of acceptance of a future offer of influenza vaccine in never immunised people aged 65 years and over living in the community (n = 483) Variable

No. of people Alla

Age (years) 65–69 70–74 75–79 80–84 ≥85

149 113 84 73 64

Hospital outpatient in past 12 months No 259 Yes 204

Odds ratio (95% CI)

P-value

Crude

Adjustedb

(40.3) (34.5) (25.0) (13.7) (20.3)

Reference 0.8 (0.5–1.3) 0.5 (0.3–0.9) 0.2 (0.1–0.5) 0.4 (0.2–0.8)

Reference 0.9 (0.4–1.8) 0.9 (0.4–2.1) 0.2 (0.0–0.6) 0.5 (0.2–1.4)

0.7 0.8 0.004 0.2

74 (18.6) 67 (32.8)

Reference 1.2 (0.8–1.8)

Reference 1.6 (0.9–3.1)

0.1

Wish to be immunised 60 39 21 10 13

Hospital inpatient in last 12 months No Yes

389 75

119 (30.6) 20 (26.7)

Reference 0.8 (0.5–1.4)

Reference 1.0 (0.4–2.5)

1.0

Likelihood of getting influenza Not very likely/not likely Likely/very likely

165 311

29 (17.6) 110 (35.4)

Reference 2.5 (1.6–4.1)

Reference 2.1 (1.1–4.0)

0.03

‘Doctors give sufficient information about the side-effects of immunisations’ Disagree 65 20 (30.8) Neutral 70 21 (30.0) Agree 101 41 (40.6) Do not know 214 57 (26.6)

Reference 1.0 (0.5–2.0) 1.5 (0.8–3.0) 0.8 (0.4–1.5)

Reference 1.2 (0.4–3.7) 1.3 (0.5–3.7) 1.3 (0.5–3.3)

0.7 0.6 0.6

‘The side-effects of flu immunisation are less risky than the disease itself’ Disagree 20 0 (0.0) Neutral 110 15 (13.6) Agree 190 98 (51.6) Do not know 153 30 (19.6)

Reference 6.7 (3.6–12.5) 1.5 (0.8–3.0)

Reference 4.9 (2.3–10.8) 1.4 (0.6–3.3)

<0.001 0.5

‘I would recommend everyone over 65 years of age to be immunised against flu’ Disagree 63 2 (3.2) Neutral 193 39 (20.2) Agree 113 90 (79.6) Do not know 91 11 (12.1)

Reference 8.0 (1.9–34.0) 123.3 (28.0–541.7) 4.3 (1.0–20.3)

Reference 7.4 (1.6–33.6) 76.5 (16.1–363.8) 3.5 (0.7–18.1)

0.01 <0.001 0.1

Values are numbers (percentages) unless stated otherwise. a Not all respondents answered all questions. b Adjusted for effects of all other variables in the table.

people got a written reminder from their doctor, most had to request the vaccine. Unimmunised people were more likely have negative views on vaccine efficacy and safety. Until the introduction of universal influenza immunisation for people aged 65 years and over in 1999–2000 no reliable vaccine coverage data existed in the United King-

dom. Our coverage figures are in line with levels of around 60 and 65% reported in 1999–2000 and 2000–2001, respectively [10]. It is possible that immunised people may have been more likely to return the questionnaire, but we were unable to investigate non-responders. However, there was no difference in immunisation status between early and late

Table 5 How people aged 65 years and over who want to be offered influenza vaccine (n = 863) would like to be informed that their immunisation is due How informed

Immunisation history Ever (n =

Sent an appointment Sent a letter or reminder Opportunistically during a visit to the GP surgery Ask after seeing leaflet or poster Ask after being prompted by someone else a

Not all respondents answered.

162 368 127 172 14

720)a

P-value Never (n = 54 72 25 12 0

143)a

Relative risk (95% CI) 1.7 1.0 1.0 0.4 0.0

(1.3–2.1) (0.8–1.2) (0.9–1.1) (0.2–0.6) (undefined)

<0.001 0.9 0.9 <0.0001 0.1

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responders. Self-reported immunisation status had a predictive value of 70% when validated against medical records, lower than values of around 90% found in some American studies [13,14]. This discrepancy could equally be explained by incomplete documentation of immunisation in the medical record, a view supported by the high level of agreement for self-report of chronic illness. Poor immunisation uptake is usually due to a combination of patient characteristics, beliefs and attitudes about immunisation, and barriers to access [15]. Two small British studies have highlighted the influence of lay beliefs about both risk from influenza and about the possibility that vaccine may cause illness [16,17]. A recent Dutch study in healthy older people found that anxiety about vaccine side-effects was the most important reason for non-compliance [11]. Similar findings have been reported in studies of older people in Italy [18], and North America [19–22]. People may also think the vaccine does not work if they suffer flu-like symptoms despite immunisation. It is therefore important that providers give patients a clear explanation of what to expect following immunisation. Our study did not explore the influence of provider attitudes to influenza immunisation but in other studies a clear provider recommendation has been shown to have a stronger effect than the patient’s own attitudes to immunisation [20,21]. A recent British study found that information given by a health professional was the only source that significantly influenced vaccine uptake [23]. Further studies of the interaction between provider attitudes and patient views are merited, and we are therefore currently undertaking a qualitative study of barriers to influenza immunisation in older people. Interventions that involve organisational change to clinical practice result in higher immunisation rates than those based on provider education alone [15,24–26]. Generally, our study respondents expressed a clear patient preference for a more proactive approach by primary care professionals, particularly the use of reminder systems. Several controlled trials have demonstrated the value of mail and telephone reminders in promoting influenza vaccine uptake, at least in North American settings [25,26]. In Britain, immunisation is largely opportunistic or fortuitous, relying on the memory of practice staff or self-referral by the patient [27]. Many eligible people may therefore miss immunisation. Experience in the United States shows that high influenza vaccine coverage among older people can be achieved nation-wide by active influenza immunisation programmes [28]. Written reminders and appointments for immunisation should be much more widely used. Health professionals need a greater appreciation of the influence of their advice on immunisation uptake, and information for patients needs to clearly address concerns about vaccine efficacy and safety. Our findings suggest that in all countries where the family practitioner plays a key role in delivering influenza immunisation, there is still likely to be considerable scope for improving vaccine coverage in older people through initiatives in primary care.

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