Flu vaccine and the ED

Editorials / Commentaries

CJEM 2000;2(2):90-94

Abstract

Résumé

Background

Influenza causes substantial morbidity and mortality.¹Despite recent success with antiviral agents, immunization remains the most important relevant health care intervention. In high-risk populations, influenza vaccine reduces the risk of respiratory illness, pneumonia, hospitalization and death.²Several US studies have demonstrated that emergency department (ED) influenza vaccination is feasible and improves health outcomes in at-risk patients presenting to the ED.^4–7The US Centers for Disease Control recommends that emergency departments offer influenza vaccination to eligible patients.³

The British Columbia (BC) Ministry of Health has established a target influenza vaccination rate of 90% for vaccine-eligible persons.⁹Currently, patients meeting high-risk criteria receive influenza vaccine free of charge in vaccination clinics, at work and in family physician offices, but influenza vaccination in Canadian EDs is not the standard of care and has not been studied. Health Canada’s Laboratory Centre for Disease Control (LCDC) guidelines do not recommend ED influenza vaccination,⁸and it is not known whether ED vaccination is appropriate or necessary, given Canada’s emphasis on primary care and the absence of financial barriers to access.

Our primary objective was to assess the need for influenza vaccine in an ED patient sample and to determine the feasibility of providing influenza vaccine in a Canadian ED. Our secondary objective was to evaluate the community use of immunization callback systems (e.g., computer-generated reminders and callback lists), which have been shown to increase influenza vaccination rates.^10–12

Methods

Setting and patients

This survey was performed in the ED of the Prince George Regional Hospital between Nov. 6, 1997, and Dec. 10, 1997. All patients who arrived in the ED during designated shifts were eligible for the study. Patients with contraindications to vaccine (allergy to egg products, fever >38.5°C or indeterminate vaccine status) were included for data collection but ineligible for vaccine. Patients were excluded from the study if they were acutely ill and required immediate care, if they had an altered level of consciousness, were unable to provide informed consent, were under 3 years of age, or had been referred directly to a specialist. All patients provided informed consent, including consent for the investigators to contact their family physician (FP) to determine vaccination status. This study was approved by the Prince George Regional Hospital ethics committee.

Data collection

A research nurse interviewed all patients, collected demographic information, documented the patient’s FP and determined whether the patient met BC Department of Health (BCDOH) criteria for vaccination.¹³To determine whether our study sample was representative, we compared age and gender for the study group to the age and gender of all ED patients for 3 randomly chosen 24-hour days during the study period.

Intervention

Eligible patients who had not received vaccine that season and had no contraindications were given a fact sheet about the influenza vaccine, educated as to its usefulness, and given 2 options: immediate ED vaccination or follow-up vaccination at their FP’s office.

Follow-up

Local family physicians were not specifically notified that their patients received influenza vaccine, but as part of routine ED policy, a copy of the ED record containing a summary of treatment was sent to their office. FPs of study patients were contacted in January 1998, to determine whether they used a yearly callback system for influenza vaccine, whether the patient was on the FP’s influenza callback list, whether the patient received an influenza vaccine subsequent to their ED visit, and whether the patient had received an influenza vaccine during the previous (1996–97) influenza season.

Fig. 1. Vaccination status of 816 study-eligible patients

Table 1. Vaccination eligibility groups and prior vaccination status

Statistics

Student’s t-tests were used to determine the statistical significance of observed differences in continuous outcome variables. Chi²analysis was used to determine the statistical significance of observed differences in categorical outcomes. Univariate tests were performed to assess the level of association between potentially related variables, and odds ratios were used where appropriate to express differences between groups. Intervals of 95% confidence were calculated to illustrate the precision of specified study parameters.

Results

Patients

Of 935 patients screened during the study period, 49.1% were women and the mean age was 33.8 years. In the demographic comparison group (n = 301), 48.8% were women and the mean age was 31.8 years, suggesting that we enrolled a representative patient sample. Data on primary health care were available for 897 people. Of these, 822 (88%) were from the local primary health care catchment area and 818 (91.2%) reported having a family physician.

ED vaccination

In total, 816 patients met study eligibility criteria. Figure 1 shows that 225 (27.6%) of these fulfilled BCDOH criteria for influenza vaccination, that 11 were excluded because of uncertain vaccine status, and that 101 (47.2%) of 214 vaccine-eligible patients had already been immunized. Of 113 vaccine-eligible patients who had not yet been immunized, 53 (46.9%) agreed to ED vaccination and 49 received vaccine (4 had fever or allergy as a contraindication). Eight persons were later vaccinated by their FP, including one person who was inadvertently vaccinated twice. However, of the 60 patients who declined ED vaccination, only 4 were subsequently vaccinated. Table 1 shows the number of patients by influenza risk group and the proportion already vaccinated. Of note, patients who had an FP were more likely to have been previously vaccinated (odds ratio [OR] = 8.8; 95% confidence interval [CI], 1.1–18.9).

Community practice and callback lists

Of 225 vaccine eligible persons, 197 identified 57 local FPs as their primary care provider. These physicians were surveyed, and 54 (94.7%) responded, providing complete data on 140 (71.1%) of the 197 patients. Forty-six physicians reported using a callback list, but only 67 (49.3%) of the patients eligible for ED vaccination were found on their FP’s callback list. Table 2 shows that patients on callback lists were more likely than those not on callback lists to have been vaccinated prior to their ED visit (71.6% vs 17.6%; OR = 4.1; 95% CI, 2.4–6.9). Table 3 shows that patients over 65 were more likely to be on callback lists (70.2%) than patients with other vaccination criteria (70.2% vs 35.4%; OR 2.0; 95% CI, 1.4–2.8).

Previous-year vaccination

Information about previous-year vaccination was available for 203 vaccine-eligible patients. Of these, 51% of patients reported that they had not been vaccinated the previous season, but FP records suggested the figure was slightly higher, at 55%. In the subgroup who were vaccinated in the ED, 57% of patients reported that they had not been vaccinated the previous season, whereas FP records suggested that 66% had not.

Discussion

The value of influenza immunization for at-risk populations is well established. In the US, socioeconomic factors and poor access to primary care have been suggested as reasons for poor compliance with national guidelines.⁷Several US studies have examined organizational strategies, including ED-based immunization, but report widely variable success rates.^4–7One such study concluded that an ED immunization program could be implemented with minimal impact on staff workload.⁶

This is the first Canadian study to assess influenza vaccination rates in ED patients and to evaluate the potential for implementing an ED immunization program. The study showed that most vaccine-eligible patients had not been vaccinated prior to their ED visit; nor had most been immunized the previous season, suggesting that our findings are not specific to the 1997–1998 season. Non-vaccination rates in this study are similar to those (57%–63%) documented by US investigators,^4–6despite the fact that Canada has fewer social and financial barriers to immunization.

Our data showed that being on a family physician callback list increased the likelihood of appropriate vaccination, especially for patients over 65. Unfortunately, most of the eligible patients in this study were not on their FP’s list. We also found that half of eligible, unvaccinated patients accepted ED vaccination, and that eligible patients who left the ED without being vaccinated seldom received follow-up vaccination. Therefore, it seems clear that ED influenza

Table 3. Emergency department patients whose names were on a family physician flu vaccine callback list (and total number eligible* to be on a callback list), by risk group vaccination is an effective means to increase community coverage, and equally clear that many patients would benefit from ED vaccination programs.

Table 3. Emergency department patients whose names were on a family physician flu vaccine callback list (and total number eligible* to be on a callback list), by risk group vaccination is an effective means to increase community coverage, and equally clear that many patients would benefit from ED vaccination programs.

The value of ED immunization is apparent in our study, where the median age was 33.8 years and 91.2% of patients had a primary care physician. It will be more apparent in departments that treat more elderly patients and in inner-city settings, where patients are more likely to have comorbid illness and less likely to have family physicians or adequate preventive care.

Limitations

This study was performed between November 6th and December 10th. These dates are 4 to 5 weeks after widespread influenza vaccination began. The dates chosen for the study allowed time for primary care providers to immunize their eligible patients. Despite this delay, it is possible that some of the people who were vaccinated within the study would have received vaccine from their FP independent of the study.

In addition, our study took place in a northern regional ED, and its results may not be representative of urban Canadian centres. Notably, the high prevalence of young patients with primary care providers enrolled in this study would lead us to underestimate the value of ED immunization. In addition, while we believe that such a program could be instituted with minimal impact on ED workload, we used trained research nurses to interview patients and provide vaccine during the study; therefore, we do not have data to demonstrate that this is the case.

Conclusion

The administration of influenza vaccine in the Canadian ED setting is a feasible and effective method of increasing vaccination coverage in the community.

References

1. Centers for Disease Control and Prevention. Pneumococcal and influenza vaccination levels among adults aged more than or equal to 65 years — United States, 1993. MMWR 1996;45:854-9.
2. 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.
3. Centers for Disease Control and Prevention. Prevention and control of influenza: recommendations of Advisory Committee on Immunization Practices (ACIP). MMWR 1996;45:1-24.
4. Rodriguez RM, Baraff LJ. Emergency department immunization of the elderly with pneumococcal and influenza vaccines. Ann Emerg Med 1993;22:1729-32.
5. Polis MA, Davey VJ, Collins ED, Smith JP, Rosenthal RE, Kaslow RA. The emergency department as part of a successful strategy for increasing adult immunization. Ann Emerg Med 1988;17:1016-8.
6. Wrenn K, Zeldin M, Miller O. Influenza and pneumococcal vaccination the emergency department: Is it feasible? J Gen Inter Med 1994;9:425-9.
7. Slobodkin D, Kitlas J, Zielske P. Opportunities not missed-systematic influenza and pneumococcal immunzation in a public inner-city emergency department. Vaccine 1998;16:1795-801.
8. Statement on influenza vaccination for the 1997–1998 season. CCDR 1997:23.
9. British Columbia Provincial Health Officer. A report on the health of British Columbians. Provincial Health Officer’s Annual Report 1998: feature report. Immunization 1999:E1.
10. McDonald CJ, Hui SL, Tierney WM. Effects of computer reminders for influenza vaccination on morbidity during influenza epidemics. MD Comput 1992;9:304-12.
11. 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.
12. Gerace TM, Sangster JF. Influenza vaccination: a comparison of two outreach strategies. Fam Med 1998;20:43-5.
13. Northern Interior Regional Health Board. Letter to physicians: influenza vaccine for the 1997–1998 season. 1997.
14. Hayden GF, Frayha H, Kattan H, Mogarri I. Structured guidelines for the use of influenza vaccine among children with chronic pulmonary disorders. Pediatr Infect Dis J 1995;14:895-9.
15. Hak E, van Essen GA, Stalman WAB, de Melker RA. Improving influenza vaccination coverage among high risk patients: A role for computer-supported prevention strategy? Fam Prac 1998; 15:138-42.