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Physicians’ immunization knowledge, attitudes, and practices
Physicians’ Immunization Knowledge, Attitudes, and Practices A Valid and Internally Consistent Measurement Tool Radmila Prislin, PhD, Philip R. Nader, MD, Michelle De Guire, MPH, MSW, Patricia L. Hoy, BS, Meredith A. Pung, BS, Sandy Ross, RN, Maureen J. Goerlitz, RN, Mark H. Sawyer, MD Medical Subject Headings (MeSH): physicians, knowledge, attitudes, practice, immunization (Am J Prev Med 1999;17(2):151–152) © 1999 American Journal of Preventive Medicine
Introduction
B
ecause physicians play a crucial role in immunizations,1–3 there is a need for reliable and valid assessments of physician-related determinants of immunizations. As part of a project aimed at improving immunization rates by targeting physicians,4 we developed measures of factors, which, according to theories of planned behavior5 and cognitive social learning,6 influence physicians’ immunization practices. Our measures include knowledge (understanding of the schedule, efficacy, and side effects of vaccines); attitudes (evaluative reactions toward immunizations); vested interest (perceptions of personal professional consequences of immunizations); self-efficacy (beliefs in personal capability to properly immunize); and perceived barriers (factors hindering proper immunizations). With few exceptions,7–9 studies measuring these variables either do not examine or do not report reliability and validity of their measures. Interventions based on potentially unreliable or invalid measures of needs may result in wasted resources or may not detect real improvements in immunization practices. Our measures should be of interest to those who plan interventions to improve physicians’ immunization practices or evaluate the effects of such interventions.
Methods Knowledge was measured on a 14-item, multiple-choice scale that covered a subset of the recommended immunization schedule, efficacy and adverse events, contraindications, and prevalence rates of vaccine-preventable diseases. Vested interest, self-efficacy, and attitudes From the San Diego State University (Prislin), San Diego, CA; Department of Pediatrics (Nader, De Guire, Hoy, Pung, Goerlitz, Sawyer), University of California, San Diego, San Diego, CA; and San Diego County Department of Public Health (Ross), San Diego, CA Address correspondence and reprint requests to: Philip R. Nader, MD, Chief, Division of Community Pediatrics, University of California, San Diego, 9500 Gilman Drive, Dept. 0927, La Jolla, CA 920930927. E-mail: [email protected].
Am J Prev Med 1999;17(2) © 1999 American Journal of Preventive Medicine
toward “having all children in your practice properly immunized at every health care visit” were measured on 3-, 2- and 4-item 5-point Likert scales, respectively. Perceived barriers were measured on a 16-item scale covering monetary, logistic, parental, medical, and physician-related factors. For instrument development, 4 groups answered the questionnaire: (1) the entire population of 34 entering pediatric and family medicine level-one residents, (2) 11 graduating pediatric level-three residents, (3) a convenience sample of 53 generalists in primary care practice either associated with the University or a large HMO or in group private practice, and (4) a convenience sample of 111 subspecialists recruited from the University and a local children’s hospital. More specialists were recruited because of the anticipated difficulty in getting questionnaires completed and returned. Internal consistency (the extent to which all items of each scale assess the same characteristic) was estimated using alpha coefficient. Construct validity (the extent to which each scale differentiates between people who do and do not have a certain characteristic) was tested using the known group method. Generalists, who practice immunizations daily, were expected to be knowledgeable, and to have stronger vested interest, selfefficacy, and more positive attitudes than subspecialists, for whom immunizations were not part of their daily work. The knowledge scale was additionally validated by testing whether third-year residents scored higher than first-year residents. These 2 groups were compared on other scales to examine whether vested interest, selfefficacy, and perceived barriers change with increased experience.
Results Response rate was 72% among general pediatricians, 49% among subspecialty pediatricians, 79% among third-year pediatric residents, and 97% among first-year
0749-3797/99/$–see front matter PII S0749-3797(99)00054-9
151
Table 1. Internal consistency (␣) and construct validity indices Generalists
Specialists
Scale
␣
M
SD
M
SD
t
P
Knowledge Vested interest Self-efficacy Attitudes Perceived barriers
.71 .81 .70 .97 .89
9.37 2.81 2.83 3.58 1.82
2.33 .67 .74 .55 .58
5.93 2.00 1.87 3.37 1.53
2.47 1.11 1.16 1.00 .94
6.50 3.81 4.29 1.12 1.60
.001 4.48–2.38 .001 1.23–.39 .001 1.40–.51 .27 .50–⫺.02 .10 .65–⫺.06
pediatric and family medicine residents, resulting in the overall response rate of 65%. Individual scores on the knowledge scale were computed as a sum of all correct answers and on all other scales as averages across the items comprising the scale. Table 1 presents alpha index of internal consistency and group comparisons as tests of each scale’s construct validity.
Discussion All scales proved internally consistent. All but the attitude scale possessed satisfactory construct validity as they differentiated between general and subspecialty pediatricians and the knowledge scale additionally differentiated between third and first-year residents. The mean knowledge score of general pediatricians indicates that even this most knowledgeable group could profit from additional immunization education. The mean vested interest and self-efficacy scores of general pediatricians indicate that although they consider proper immunizations important, they could improve their sense of control over immunization. They could be taught how to influence office and clinic practices to assure immunization of every child. Similar segments should be included in the resident curriculum because our results show that self-efficacy does not change from the first to the third year of residency. Need for boosting self-efficacy is further supported by our finding that although general pediatricians considered that barriers to immunizations are on average moderate, they inaccurately10 perceived those related to parents (e.g., parents forgetting, refusing, or being reluctant to have their children immunized) as the most serious. Our finding about uniformly positive attitudes toward immunizations may reflect social desirability. Nevertheless, it suggests that attitudes may serve as a good motivational basis, which should make physicians responsive to educational interventions. There are certain limitations to this study that should be noted. Generalizability of our findings could be
152
95% CI
3rd Year Residents
1st Year Residents
M
SD
M
SD
t
P
95% CI
8.45 2.73 2.91 3.57 2.22
2.30 .55 .74 .67 .57
5.18 2.80 2.73 3.66 1.88
1.94 .59 .53 .60 .60
4.62 ⫺.35 .89 ⫺.44 ⫺1.63
.001 .73 .38 .66 .11
4.70–1.84 ⫺.48–.34 ⫺.23–.59 ⫺.53–.34 ⫺.75–.08
easily tested by replication in other locales. Bias due to response rate, however, does not invalidate our findings because responding subspecialty pediatricians likely were more knowledgeable and motivated than those who did not respond. If anything, the nonresponding group would have made our results stronger. Finally, although some of the items in the knowledge scale may become out-of-date, our scale can either be easily revised or serve as a framework for development of new instruments. Supported by the NCDC Grant #U60/CCU 912985-01, Mark H. Sawyer, Principal Investigator. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of the Centers for Disease Control and Prevention.
References 1. Woodin KA, Rodewald LE, Humiston SG, Carges MS, Schaffer SJ, Szilagyi, PG. Physician and parent opinions: are children becoming pincushions from immunizations? Arch Pediatr Adolesc Med 1995; 149:845–9. 2. Grabowsky M, Orenstein WA, Marcuse EK. The critical role of provider practices in undervaccination. Pediatrics 1996; 97:735–7. 3. Campbell JR, Szilagyi PG, Rodewald LE, Winter NL, Humiston SG, Roghmann KJ. Intent to immunize among pediatric and family medicine residents. Arch Pediatr Adolesc Med 1994; 148:926 –9. 4. Sawyer M, Nader P, Fontanesi J. The UCSD Partnership of Immunization Providers: a collaborative demonstration project to improve immunization delivery. New Orleans: The Ambulatory Pediatric Association, Annual Meeting, May 1–5, 1998. 5. Ajzen I. From intentions to actions: a theory of planned behavior. In: Kuhland J and Beckman J, eds. Action-control: from cognitions to behavior. Heidelberg: Springer; 1985. 6. Bandura A. Self-efficacy: The exercise of control. New York: Springer:1997. 7. Wood D, Donald-Sherbourne C, Halfon N, et al. Factors related to immunization status among inner-city Latino and African-American preschoolers. Pediatrics 1995; 96:295–301. 8. Zimmerman RK, Barker WH, Strikas RA, et al. Developing curricula to promote preventive medicine skills: the teaching immunization for medical education (TIME) project. JAMA 1997; 278:705–11. 9. Prislin R, Dyer JA, Blakely CH, Johnson C. Immunization status and sociodemographic characteristics: the mediating role of beliefs, attitudes, and perceived control. Am J Public Health 1998; 88:1821– 6. 10. Halperin BA, Eastwook BJ, Halperin SA. Comparison of parental and health care professional preferences for the acellular or whole cell pertussis vaccine. Pediatr Infect Dis Journal 1998; 17:103–9.
American Journal of Preventive Medicine, Volume 17, Number 2
Introduction
B
ecause physicians play a crucial role in immunizations,1–3 there is a need for reliable and valid assessments of physician-related determinants of immunizations. As part of a project aimed at improving immunization rates by targeting physicians,4 we developed measures of factors, which, according to theories of planned behavior5 and cognitive social learning,6 influence physicians’ immunization practices. Our measures include knowledge (understanding of the schedule, efficacy, and side effects of vaccines); attitudes (evaluative reactions toward immunizations); vested interest (perceptions of personal professional consequences of immunizations); self-efficacy (beliefs in personal capability to properly immunize); and perceived barriers (factors hindering proper immunizations). With few exceptions,7–9 studies measuring these variables either do not examine or do not report reliability and validity of their measures. Interventions based on potentially unreliable or invalid measures of needs may result in wasted resources or may not detect real improvements in immunization practices. Our measures should be of interest to those who plan interventions to improve physicians’ immunization practices or evaluate the effects of such interventions.
Methods Knowledge was measured on a 14-item, multiple-choice scale that covered a subset of the recommended immunization schedule, efficacy and adverse events, contraindications, and prevalence rates of vaccine-preventable diseases. Vested interest, self-efficacy, and attitudes From the San Diego State University (Prislin), San Diego, CA; Department of Pediatrics (Nader, De Guire, Hoy, Pung, Goerlitz, Sawyer), University of California, San Diego, San Diego, CA; and San Diego County Department of Public Health (Ross), San Diego, CA Address correspondence and reprint requests to: Philip R. Nader, MD, Chief, Division of Community Pediatrics, University of California, San Diego, 9500 Gilman Drive, Dept. 0927, La Jolla, CA 920930927. E-mail: [email protected].
Am J Prev Med 1999;17(2) © 1999 American Journal of Preventive Medicine
toward “having all children in your practice properly immunized at every health care visit” were measured on 3-, 2- and 4-item 5-point Likert scales, respectively. Perceived barriers were measured on a 16-item scale covering monetary, logistic, parental, medical, and physician-related factors. For instrument development, 4 groups answered the questionnaire: (1) the entire population of 34 entering pediatric and family medicine level-one residents, (2) 11 graduating pediatric level-three residents, (3) a convenience sample of 53 generalists in primary care practice either associated with the University or a large HMO or in group private practice, and (4) a convenience sample of 111 subspecialists recruited from the University and a local children’s hospital. More specialists were recruited because of the anticipated difficulty in getting questionnaires completed and returned. Internal consistency (the extent to which all items of each scale assess the same characteristic) was estimated using alpha coefficient. Construct validity (the extent to which each scale differentiates between people who do and do not have a certain characteristic) was tested using the known group method. Generalists, who practice immunizations daily, were expected to be knowledgeable, and to have stronger vested interest, selfefficacy, and more positive attitudes than subspecialists, for whom immunizations were not part of their daily work. The knowledge scale was additionally validated by testing whether third-year residents scored higher than first-year residents. These 2 groups were compared on other scales to examine whether vested interest, selfefficacy, and perceived barriers change with increased experience.
Results Response rate was 72% among general pediatricians, 49% among subspecialty pediatricians, 79% among third-year pediatric residents, and 97% among first-year
0749-3797/99/$–see front matter PII S0749-3797(99)00054-9
151
Table 1. Internal consistency (␣) and construct validity indices Generalists
Specialists
Scale
␣
M
SD
M
SD
t
P
Knowledge Vested interest Self-efficacy Attitudes Perceived barriers
.71 .81 .70 .97 .89
9.37 2.81 2.83 3.58 1.82
2.33 .67 .74 .55 .58
5.93 2.00 1.87 3.37 1.53
2.47 1.11 1.16 1.00 .94
6.50 3.81 4.29 1.12 1.60
.001 4.48–2.38 .001 1.23–.39 .001 1.40–.51 .27 .50–⫺.02 .10 .65–⫺.06
pediatric and family medicine residents, resulting in the overall response rate of 65%. Individual scores on the knowledge scale were computed as a sum of all correct answers and on all other scales as averages across the items comprising the scale. Table 1 presents alpha index of internal consistency and group comparisons as tests of each scale’s construct validity.
Discussion All scales proved internally consistent. All but the attitude scale possessed satisfactory construct validity as they differentiated between general and subspecialty pediatricians and the knowledge scale additionally differentiated between third and first-year residents. The mean knowledge score of general pediatricians indicates that even this most knowledgeable group could profit from additional immunization education. The mean vested interest and self-efficacy scores of general pediatricians indicate that although they consider proper immunizations important, they could improve their sense of control over immunization. They could be taught how to influence office and clinic practices to assure immunization of every child. Similar segments should be included in the resident curriculum because our results show that self-efficacy does not change from the first to the third year of residency. Need for boosting self-efficacy is further supported by our finding that although general pediatricians considered that barriers to immunizations are on average moderate, they inaccurately10 perceived those related to parents (e.g., parents forgetting, refusing, or being reluctant to have their children immunized) as the most serious. Our finding about uniformly positive attitudes toward immunizations may reflect social desirability. Nevertheless, it suggests that attitudes may serve as a good motivational basis, which should make physicians responsive to educational interventions. There are certain limitations to this study that should be noted. Generalizability of our findings could be
152
95% CI
3rd Year Residents
1st Year Residents
M
SD
M
SD
t
P
95% CI
8.45 2.73 2.91 3.57 2.22
2.30 .55 .74 .67 .57
5.18 2.80 2.73 3.66 1.88
1.94 .59 .53 .60 .60
4.62 ⫺.35 .89 ⫺.44 ⫺1.63
.001 .73 .38 .66 .11
4.70–1.84 ⫺.48–.34 ⫺.23–.59 ⫺.53–.34 ⫺.75–.08
easily tested by replication in other locales. Bias due to response rate, however, does not invalidate our findings because responding subspecialty pediatricians likely were more knowledgeable and motivated than those who did not respond. If anything, the nonresponding group would have made our results stronger. Finally, although some of the items in the knowledge scale may become out-of-date, our scale can either be easily revised or serve as a framework for development of new instruments. Supported by the NCDC Grant #U60/CCU 912985-01, Mark H. Sawyer, Principal Investigator. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of the Centers for Disease Control and Prevention.
References 1. Woodin KA, Rodewald LE, Humiston SG, Carges MS, Schaffer SJ, Szilagyi, PG. Physician and parent opinions: are children becoming pincushions from immunizations? Arch Pediatr Adolesc Med 1995; 149:845–9. 2. Grabowsky M, Orenstein WA, Marcuse EK. The critical role of provider practices in undervaccination. Pediatrics 1996; 97:735–7. 3. Campbell JR, Szilagyi PG, Rodewald LE, Winter NL, Humiston SG, Roghmann KJ. Intent to immunize among pediatric and family medicine residents. Arch Pediatr Adolesc Med 1994; 148:926 –9. 4. Sawyer M, Nader P, Fontanesi J. The UCSD Partnership of Immunization Providers: a collaborative demonstration project to improve immunization delivery. New Orleans: The Ambulatory Pediatric Association, Annual Meeting, May 1–5, 1998. 5. Ajzen I. From intentions to actions: a theory of planned behavior. In: Kuhland J and Beckman J, eds. Action-control: from cognitions to behavior. Heidelberg: Springer; 1985. 6. Bandura A. Self-efficacy: The exercise of control. New York: Springer:1997. 7. Wood D, Donald-Sherbourne C, Halfon N, et al. Factors related to immunization status among inner-city Latino and African-American preschoolers. Pediatrics 1995; 96:295–301. 8. Zimmerman RK, Barker WH, Strikas RA, et al. Developing curricula to promote preventive medicine skills: the teaching immunization for medical education (TIME) project. JAMA 1997; 278:705–11. 9. Prislin R, Dyer JA, Blakely CH, Johnson C. Immunization status and sociodemographic characteristics: the mediating role of beliefs, attitudes, and perceived control. Am J Public Health 1998; 88:1821– 6. 10. Halperin BA, Eastwook BJ, Halperin SA. Comparison of parental and health care professional preferences for the acellular or whole cell pertussis vaccine. Pediatr Infect Dis Journal 1998; 17:103–9.
American Journal of Preventive Medicine, Volume 17, Number 2