Dec 26, 1984 - Dr. Fulton is with the Department of Community Medicine at the hospital, and the. Department of Community Healthat the university; Dr. Kramer ...
Acceptance of Hepatitis B Vaccine among Hospital Workers HENRY C. BODENHEIMER, JR., MD, JOHN P. FULTON, PHD,
AND
PETER D. KRAMER, MD
Abstract: Data on sociodemographic status, health beliefs, knowledge of hepatitis B, experience with prior vaccinations, health locus of control, and desire to receive hepatitis B vaccine were assessed in 1,500 hospital employees. Twenty per cent of the variance of the decision to accept vaccine could be explained; beliefs about the safety and efficacy of vaccine influenced acceptance most. Beliefs concerning the likelihood of contracting hepatitis B and the chance of becoming severely ill were less important determinants of
vaccine acceptance. Additional factors studied, including knowledge, experience with vaccinations, and sociodemographic status, were important independent determinants of health beliefs. We conclude that the beliefs of health care providers, particularly regarding the safety and efficacy of hepatitis B vaccine, have a major impact on their decision to accept or reject vaccine. Health education interventions may be most effective when addressing beliefs about vaccine safety and efficacy. (Am J Public Health 1986; 76:252-255.)
Introduction
tenance, clerical, and administrative departments, where the risk of contracting hepatitis B was uniformly low. Subjects who consented to participate were approached for face-to-face interviews lasting approximately 30 minutes. Eighty-four per cent of the study sample completed interviews. Information obtained included age, sex, job description, years of employment, highest grade completed in school, knowledge of hepatitis B, desire to be vaccinated, perception of likelihood of subject contracting hepatitis B, and the perception of severity of HBV infection for subject (Table 1). Three health locus of control scales ("powerful others", "internal", and "chance") were also assessed.10 The interviews were conducted at the Rhode Island Hospital, using a 62-item questionnaire. The responses to individual questions were combined to form eight scales (Table 2). Questions measuring a subject's knowledge about hepatitis B assessed information concerning natural history, mode of transmission, and methods of treatment and prevention. Coefficient alpha ranged from 0.49 for " susceptibility to hepatitis B," to 0.82 for " discomfort of vaccine." The reliability of the locus of control scales closely matched results reported in the literature.11 The values of alpha calculated for the susceptibility to hepatitis B (0.49) and for knowledge of hepatitis B (0.52) scales are lower than we desired, and indicated that correlations between these scales and other variables might be attenuated. However, since this effect biases results conservatively, both scales were used in the analysis. Stepwise multiple regression was used to test the efficacy of HBM variables in explaining an employee's stated intention of receiving hepatitis B vaccine. The independent effect of each independent variable (identified in Table 1) on the dependent variable, acceptance of vaccine, was assessed. A set of primary independent variables which best explained acceptance was thereby identified. A probability level of p 5 0.001 was chosen to guide the regression analyses.
In the United States, the incidence of acute type B hepatitis is increasing. It has been estimated that 400,000 to 800,000 persons are now chronic carriers of this virus1 and vaccination of health care personnel is recommended.2'3 A marked variation in the rate of acceptance of vaccine among health care personnel has been reported ranging from 58 per cent3 to as low as 27 per cent.4 We wished to define and quantify the importance of factors instrumental in an individual's decision to be vaccinated using the Health Belief Model (HBM) as a construct. Although the HBM was designed to predict preventive health behavior,5 it has since been modified to explain other health behaviors as well.6 The HBM has particular applicability in predicting behavior directed at disease prevention, including participation in immunization programs.7 We applied the HBM in a survey of health care workers and evaluated the relative importance of different health beliefs as determinants of the acceptance of hepatitis B virus (HBV) vaccine.
Methods We obtained our data from a sample of employees at the Rhode Island Hospital, a 720-bed university-affiliated hospital with 4,740 employees. Subjects were stratified according to their risk of contracting hepatitis B on the basis of published reports8'9 as well as an assessment of the degree of an employee's exposure to patient blood. A total of 1,500 subjects were stratified into risk groups labeled: I) Low risk; II) Moderate risk; III) High risk; and IV) Very high risk. Hospital employees at risk were to be offered HBV vaccine free of charge, independent of participation in this study. Data collection was completed in 1983, prior to employee vaccination. All full-time day shift employees in groups II through IV were selected for interview, and a sample of 365 day shift employees in Group I was also studied. Forty-one per cent of Group I subjects included those personnel at low risk who work in high-risk areas of the hospital. Fifty-nine per cent of Group I subjects were sampled from dietary, mainAddress reprint requests to Henry C. Bodenheimer, Jr., MD, Division of Gastroenterology, Department of Medicine, Rhode Island Hospital and Brown University, 593 Eddy Street, APC 421, Providence, RI 02902. Dr. Fulton is
with the Department of Community Medicine at the hospital, and the Department of Community Health at the university; Dr. Kramer is with the Department of Psychiatry at the hospital. This paper, submitted to the Journal December 26, 1984, was revised and accepted for publication August 19, 1985. C 1986 American Journal of Public Health 0090-0036/86$1.50
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Results
Acceptance, defined as the stated intention of receiving hepatitis B vaccine, was the dependent variable chosen as the focus of the first regression (Table 3). The three scales central to the HBM contribute most to the explanation of vaccine acceptance: safety and effectiveness, susceptibility, and severity. Beliefs about vaccine safety and effectiveness had the greatest effect upon acceptance. Susceptibility and severity also had substantial effects on the determination of vaccine acceptance. The "powerful others" locus of control scale and level of education also contributed minor predictive AJPH March 1986, Vol. 76, No. 3
ACCEPTANCE OF HEPATITIS B VACCINE TABLE 1-Major Variables Investigated among Hospital Employ"s Relative to Hepatitis B Vaccination
Description
Variables Dependent Acceptance Independent Safety and effectiveness Susceptibility Severity Antecedent Sex Year of birth Education Occupation (dummy variable) Risk group Knowledge Discomfort Experience with vaccine side effects Experience with HBV Powerful others locus of control Internal locus of control Chance locus of control
Stated intention of receiving HBV vaccine
Perceived safety and effectiveness of HBV vaccine Perceived risk of contracting HBV infection Perceived risk of serious illness after contracting HBV infection
Highest grade completed in school MD, nurse, technician or therapist, others Risk of contracting HBV Knowledge of HBV Perceived discomfort of HBV vaccination Previous side effects from vaccine HBV in immediate family of respondent Belief in the power of others in the control of disease Belief in the power of self in the control of disease Belief in the power of chance in the control of disease
TABLE 2-Number of Items and Coefficient Alphas of Scales Used In Regression Analyses
Scale
Number of Items
Coefficient Alpha
Susceptibility to Hepatitis B Severity of Hepatitis B Safety and Effectiveness of Vaccine Discomfort of Vaccine Internal Locus of Control Powerful Others Locus of Control Chance Locus of Control Knowledge of Hepatitis B
2 4 4 2
0.49 0.77 0.69 0.82 0.70 0.75 0.72 0.52
6 6 6 15
TABLE 3-Results of Regression Analyses Variables
Acceptance* Safety and Effectiveness
Susceptibility Severity Safety and Effectiveness* Education Discomfort MD Experience with Vaccine Side Effects Year of Birth Knowledge of Hepatitis B Susceptibility* Knowledge of Hepatitis B Risk Group Education Nurse Vulnerability* Susceptibility Powerful Others Locus of Control
B
SE
0.20 0.23 0.05
0.02 0.02 0.01
0.83 -0.36 1.19 -0.65 0.24 0.12
0.11 0.03 0.26 0.14 0.06 0.03
0.19 0.33 -0.36 0.42
0.02 0.04 0.07
0.28 0.08
0.06 0.02
0.11
*Dependent variable.
value to this regression equation. Overall, 20 per cent of the variance of stated vaccine acceptance was explained. Three additional regressions were performed, each using one of the major independent variables from the first regression equation as the dependent variable (Table 3). All other variables (Table 1), excluding acceptance, were considered in this stepwise multiple regression process. Twenty-six per cent of the variance of safety and effectiveness was exAJPH March 1986, Vol. 76, No. 3
plained. Education and discomfort were its most important determinants with Betas of 0.83 (Standard Error 0.11) and -0.36 (SE 0.03), respectively. Occupation (represented by the dummy variable "MD"), experience with vaccines, year of birth, and knowledge of hepatitis B had small independent effects. Very small effects were also contributed by severity, internal locus of control, and chance locus of control. In sum, employees with higher education, those who perceived lesser potential discomfort from hepatitis B vaccination, and physicians were more likely than others to consider the vaccine safe and effective. Sixteen per cent of the variance of susceptibility was explained by the measures used (Table 3). The knowledge of hepatitis B index and risk group were the most important predictors of susceptibility. Education had a less substantial negative effect, which was independent of knowledge of hepatitis B. Occupation (represented by the dummy variable "nurse"), had a small independent effect. Very small effects were also contributed by discomfort, year of birth, powerful others locus of control, chance locus of control, and sex. Thus, employees with more knowledge of hepatitis B, those in high-risk groups, and those with less education were more likely than others to consider themselves relatively susceptible to infection by HBV. Nurses felt more susceptible than others, even when controlling for knowledge of hepatitis B, risk group, and education, although the independent effect of occupation was small. Nine per cent of the variance of severity was explained when investigated as the focus of the fourth regression analysis (Table 3). Susceptibility and the powerful others locus of control were its most important determinants. Discomfort, occupation, safety and effectiveness, knowledge of hepatitis B, internal locus of control, and year of birth also contributed small predictive effects. In sum, employees who felt more susceptible to hepatitis B infection, and those who believed more strongly in the importance of powerful others in the outcome of disease, were more likely to consider themselves vulnerable to serious illness by infection with hepatitis B. Stated desire to be vaccinated was a good indicator of actual vaccination (r = 0.6; 95% C.I. = 0.498, 0.686). Sixty-one per cent of those wanting vaccine were vaccinated, while only 4 per cent who rejected vaccination initially were vaccinated. Vaccination behavior was determined over a 253
BODENHEIMER, ET AL. TABLE 4-Acceptance of Hepatitis B Vaccine by Hospital Workers* Stated Probability of Vaccination
Low
II Moderate
liI High
Very High
Very low Low Medium High Very high Undecided Total (%) (n)
22 15 18 18 24 3 100 365
18 13 27 18 22 3 100 439
15 10 13 24 35 4 100 136
14 15 18 13 36 4 100 328
IV
*Data are expressed as per cent of each nsk group distributed according to their stated probability of receiving vaccine.
six-month period while a random sample of 199 subjects from Groups II through IV were offered an educational exchange and vaccination. Our study uses behavioral intention as its focus because this information was obtained at the time health beliefs were assessed. Although intention to be vaccinated correlated well with behavior, the discrepancy which exists is likely attributable to events during the vaccination period, and the educational intervention. The correlation between the risk of contracting hepatitis B and acceptance of vaccine is illustrated in Table 4. These data show that although probability of vaccination generally increased with risk group, only 49 per cent of persons in the very high-risk group felt their probability of accepting vaccine was high or very high. Subjects who declined vaccination were asked to express their reason for doing so. Concerns which focused on vaccine safety and efficacy were listed by 44 per cent of those responding. Lack of perceived risk of contracting hepatitis B was expressed by 20 per cent of respondents. The concern of transmission of the Acquired Immunodeficiency Syndrome (AIDS) by vaccine was specifically expressed by only 3 per cent of respondents. Discussion Our investigation has defined those factors which independently influence a health professional's intention to be vaccinated against hepatitis B. Employees who thought the vaccine was safe and effective, those who felt susceptible to infection, and those who felt vulnerable to serious illness or death following infection were more likely than others to receive free hepatitis B vaccine at the hospital in which they were employed. Of these three beliefs, concern regarding vaccine safety and efficacy was of paramount importance. The results of these analyses support the choice of the Health Belief Model (HBM) as a construct to predict behavior of persons involved in an immunization program. Studying a swine influenza vaccine program, Larson, et al,12 found that persons who received vaccine believe influenza to be more serious, believe they are more susceptible to influenza, and believe the vaccine is more efficacious than did persons not vaccinated. Rives and Mooney"3 and others'4 found that people refusing vaccine believe they are not susceptible to influenza, or that the vaccine is not reliable. Cummings, et al,'5 demonstrated that the influence of the HBM variables on behavior is mediated through behavioral intention. Ahol6 concluded that the finding of HBM variables as primary determinants of vaccine acceptance suggests that many of the beliefs influencing non-participation in a vaccination program are amenable to change with specific refer254
ence to beliefs about the effectiveness and safety of inoculation. HBM variables have been found to be predictive of the utilization of an HBV vaccination program offered to hospital employees.17 As in our study, those who chose not to be vaccinated tended to believe that the vaccine itself was unsafe, or that their jobs did not make them especially susceptible to HBV infection. These data are consistent with the findings of a retrospective study of Veterans Administration personnel.'8 In a review of the HBM literature, Becker and Maiman also report a similar finding: "Evidence indicates that, no matter how concerned the individual is with poliomyelitis, he or she will not accept vaccination if the vaccine's safety is in question."'9 Indeed, doubts about the safety and effectiveness of swine influenza vaccine prompted many individuals to avoid vaccination.13 Initial media coverage portrayed lack of unanimous support for this immunization program, largely based on doubts of vaccine safety. This information may have helped formulate health beliefs adverse to vaccine acceptance. Our data demonstrate that factual knowledge is but one factor responsible for decisions regarding health care. It is striking that knowledge of hepatitis B was not identified as an independent variable in relation to acceptance of vaccine. Because of the discrepancy between factual knowledge and behavioral intention, health care planning must accommodate motivational factors other than "measurable knowledge" in predicting health behavior. Only 3 per cent of persons identified a link with AIDS as being the reason for refusing HBV vaccination. Many more persons expressed concern regarding the "newness" of this vaccine. These data suggest that concern about the spread of AIDS by vaccine was only one of a number of concerns about the vaccine's newness. Our finding of the predictive value of HBM variables in hepatitis B vaccine acceptance may help to address the failure to vaccinate a large proportion of health care workers at risk of contracting hepatitis B. Programs to vaccinate health care workers against hepatitis B should focus on forming or reforming beliefs about the safety and efficacy of the vaccine. Level of education and knowledge of hepatitis B are determinants of these health beliefs which may be subject to modification. Further research is needed to ascertain whether education about HBV infection and vaccination is effective in modifying acceptance of the vaccine. Educational sessions incorporated as part of vaccine programs should ensure that persons who are candidates for vaccination have access to complete and accurate information. However, the proper formation of beliefs regarding the safety and efficacy of vaccine may be the most important factor in determining vaccine acceptance.
ACKNOWLEDGMENTS
This research was supported by a grant from Merck Sharp & Dohme, West Point, PA, and was presented in part at the 1984 International Symposium on Viral Hepatitis, San Francisco, CA.
REFERENCES
1. Centers for Disease Control: Inactivated hepatitis B virus vaccine. MMWR 1982; 31:317-322, 327-328. 2. Centers for Disease Control: General recommendations on immunization. Ann Intern Med 1983; 98:615-622. 3. Tong MJ, Kronborg AM, Schatz GC, Kane MA: Hepatitis B virus vaccine demonstration program in a large urban hospital. In Program of the International Symposium on Viral Hepatitis, San Francisco, CA, 1984.
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ACCEPTANCE OF HEPATITIS B VACCINE 4. Fulton JP, Bodenheimer HC, Kramer PD: Effect of education on hepatitis B vaccine acceptance. Clin Res 1985; 33:207A. 5. Aho WR: Smoking, dieting, and exercise: age differences in attitudes and behavior relevant to selected health belief model variables. RI Med J 1979; 62:85-92. 6. Mikhail B: The health belief model: a review and critical evaluation of the model, research, and practice. Adv Nursing Sci 1981; 4:65-82. 7. Janz NK, Becker MH: The health belief model: a decade later. Health Educ Q 1984; 11:1-47. 8. Denes AE, Smith JL, Maynard JE, Doto IL, Berquist KR, Finkel AJ: Hepatitis B infection in physicians: results of a nationwide seroepidemiologic survey. JAMA 1978; 239:210-212. 9. Dienstag JL, Ryan DM: Occupational exposure to hepatitis B virus in hospital personnel: infection or immunization? Am J Epidemiol 1982; 115:26-39. 10. Wallston KA, Wallston BS, De Vellis R: Development of the multidimensional health locus of control (MHLC) scales. Health Educ Monogr 1978; 6:160-170. 11. Wallston KA, Wallston BS: Health locus of control scales. In: Lefcourt HM (ed): Research with the Locus of Control Construct (Vol. 1). New York: Academic Press, 1981; 189-243.
12. Larson EB, Olsen E, Cole W, Shortell S: The relationship of health beliefs and a postcard reminder to influenza vaccination. J Fam Pract 1979; 8: 1207-1211. 13. Rives NW, Mooney A: Attitudes of nonparticipation toward the swine influenza immunization program in southern Delaware. Del Med J 1978; 50:533-549. 14. Rundall TG, Wheeler JRC: Factors associated with utilization of the swine flu vaccination program among senior citizens in Tompkins County. Med Care 1979; 17:191-200. 15. Cummings KM, Jette AM, Brock BM, Haefner DP: Psychosocial determinants of immunization behavior in a swine influenza campaign. Med Care 1979; 17:639-649. 16. Aho WR: Participation of senior citizens in the swine flu inoculation program: an analysis of health belief model variables in preventive health behavior. J Gerontol 1979; 34:201-208. 17. Palmer DL, King R: Attitude toward hepatitis vaccination among high-risk hospital employees. J Infect Dis 1983; 147:1120-1121. 18. Anderson AC, Hodges GR: Acceptance of hepatitis B vaccine among high risk health care workers. Am J Infect Control 1983; 11:207-211. 19. Becker MH, Maiman LA: Sociobehavioral determinants of compliance with health and medical care recommendations. Med Care 1975; 13:10-24.
May Conference in Canada to Focus on Menopause Health professionals and the women they treat are demanding more information about menopause. In response to this need, a conference entitled "Menopause: Myth, Medicine, Mirth" will take place in Ottawa, Canada, May 2-4, 1986. Experts from various disciplines will present the most up-to-date information on all aspects of menopause including hormone replacement therapy, osteoporosis, psychological aspects, and wellbeing. The conference is sponsored by JABARDO Programs Inc., a consortium of professionals located in Montreal. Professional accreditation applied for. For further information, contact: Joan Graham, Conference Coordinator, P.O. Box 73, Station Victoria, Westmount, Quebec, Canada, H3Z 2V4. Telephone (514) 481-9886.
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