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Use of a New Combined Vaccine in Pediatric Practices

^a Child Health Evaluation and Research Unit
^b Division of General Pediatrics
^c Department of Health Management and Policy, University of Michigan, Ann Arbor, Michigan
^d Centers for Disease Control and Prevention, Atlanta, Georgia
^e Premier Medical Group, Nashville, Tennessee

	ABSTRACT

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
OBJECTIVE. On December 13, 2002, Pediarix, a combination vaccine that contains diphtheria, tetanus, acellular pertussis; hepatitis B; and inactivated polio vaccines, was licensed by the Food and Drug Administration for use in the primary immunization series. Use of this vaccine decreases the number of injections that children receive when completing their primary immunization series at the 2-, 4-, and 6-month well-child visits. The objective of this study was to determine the factors that influence the use of this combined vaccine in private pediatric practices, with particular attention to the perceived economic impact of Pediarix and actions taken to address this impact within the private pediatric setting.

METHODS. A mail survey study was conducted of a random sample of 565 practicing pediatricians that was obtained from the American Medical Association Masterfile. Frequency distributions were developed for all responses, and the vaccine financing policies of the state of practice for each respondent were determined. ² analysis was performed to assess any associations of the predictor variables with the outcome variables of interest, use or consideration of use of the Pediarix vaccine. Logistic regression was used to determine the independent association of the predictor variables with use or consideration of use of Pediarix. Regression models that did and did not include practice ownership as a predictor variable were developed.

RESULTS. Response rate was 63% (N = 355). A total of 39% (n = 123) of the respondents' practices were purchasing Pediarix for use with their private patients. An additional 18% (n = 55) were considering purchasing the vaccine. Those who were in practices that were owned by hospitals or health systems were more likely than those who were in solo or group practices to purchase Pediarix for their private patients. Approximately half of the remaining respondents order Pediarix through their state immunization program. Among the 52% of respondents who did not, 23% reported that the vaccine was not yet available through their state program, and 47% stated that they did not want to use different vaccines for their public and private patients. Only 11% believed that Pediarix was not compatible with their other vaccine products. Physicians that currently were purchasing or considering purchasing Pediarix were more likely to be influenced by both parental and provider desire to decrease the number of injections at a single visit and the reduced time for immunization delivery. Fewer than 1% of respondents reported either having experienced or expecting to experience a significant decrease in practice revenue as a result of the use of Pediarix.

CONCLUSIONS. Although use of the vaccine results in fewer administration fees for most physicians, the magnitude of the change seemed not to be significant for the majority of respondents or was outweighed by other factors. It also is possible that larger practices or buying cooperatives were able to negotiate discounted rates for Pediarix relative to the constituent products. This may have been a strategy of manufacturers and/or distributors to provide incentive for practices to switch to the combination product. Of note was the appreciation of respondents for the preferences of patients for fewer vaccines and, to a lesser degree, for the decrease in office staff time required to provide vaccination with multiple antigens when using Pediarix. Also, the role of the availability of a given vaccine through the Vaccines for Children program is important in its adoption into practice.

Key Words: vaccine • Pediarix • combined • immunization utilization

Abbreviations: VFC—Vaccines for Children

On December 13, 2002, Pediarix (GlaxoSmithKline, Brentford, Middlesex, United Kingdom), a combination vaccine that contains diphtheria, tetanus, acellular pertussis; hepatitis B; and inactivated polio vaccines was licensed by the Food and Drug Administration for use in the primary immunization series for children.¹ Use of this vaccine decreases the number of injections that children receive when completing their primary immunization series at the 2-, 4-, and 6-month well-child visits. Pediarix is the third of the "new" combination vaccines that have been licensed for use in the United States during the past decade. The first 2 such products were a hepatitis B–Haemophilus influenzae type B combination product produced by Merck (Whitehouse Station, NJ) and licensed as Comvax in 1996,² and a hepatitis A–hepatitis B combination product produced by SmithKline Beecham Biologicals (Brentford, Middlesex, United Kingdom) and licensed as Twinrix in 2001.³ More recently, a measles-mumps-rubella-varicella combination product (ProQuad) was licensed by Merck in September 2005,⁴ and additional combination products are anticipated in the next several years.

The use of combination products such as Pediarix has the potential to increase immunization rates because simultaneous administration of vaccines has been shown to increase the likelihood that children will be immunized in an age-appropriate manner.⁵ Another study found that when parents are faced with their child's having to receive multiple injections, their decision to defer some vaccines to future visits results in an increased risk for the child's remaining undervaccinated. Simultaneous administration of all recommended vaccines has been shown to have great potential to improve immunization rates.⁶ The development and licensing of Pediarix was consistent with the actions called for in the National Vaccine Plan to limit the number of injections that are required to complete the recommended immunization series.⁷ In addition, the use of combination vaccines when available and indicated is recommended and preferred by the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices, the American Academy of Pediatrics, and the American Academy of Family Physicians.^8–10

By the end of 2003, Pediarix accounted for >30% of all of the diphtheria, tetanus, acellular pertussis vaccine administered in the United States.¹¹ Factors that affect the uptake of Pediarix are not well understood, but some likely involve the cost of the vaccine. The government purchase price of Pediarix exceeds the amount of each constituent vaccine by >$6.00 if purchased separately. As such, some state governments that purchase vaccine for populations beyond those that are served by the federal Vaccines for Children (VFC) program have decided not to purchase Pediarix and continue to supply providers with the constituent vaccine components. The VFC program provides for the federal purchase of vaccines for children who are enrolled in Medicaid, uninsured, Native American or Alaska Native, or underinsured (if they receive vaccine in a federally qualified health center). Funds to purchase vaccines through VFC for use in eligible children are distributed to state and large urban area immunization programs. These programs employ a continuum of state financing policy options from payment for all non-VFC vaccines for all children in some states (universal purchase states) to payment for vaccines for underinsured patients who receive them in the offices of private providers (enhanced VFC).

State vaccine financing policies can present challenges to private providers whose patient panels include both children who are eligible for public vaccine and those who are not. For example, providers who practice in states that have decided not to purchase Pediarix for non–VFC-eligible children and who wish to administer Pediarix to their insured patients would need to maintain 2 separate stocks of vaccine (ie, 1 for their private pay patients and 1 for those whose vaccine is purchased through the VFC program). Alternatively, providers also may be resident in a state that has decided to use a combination vaccine for its public purchase vaccine program but their practice has decided not to use the vaccine for their private patients.

In addition, the use of the Pediarix vaccine presents an additional economic issue for providers themselves. Providers typically charge an administration fee for each vaccine injected. Although in some states there may be a limit imposed on the number of administration fees allowable at a specific visit, combination vaccines have the potential to decrease practice income by decreasing the number of injections and therefore the amount of administration fees collected at a visit. We conducted a survey study to determine the factors that influence the use of this combined vaccine in private pediatric practices, with particular attention paid to the perceived economic impact of Pediarix and actions that have been taken to address this impact within the private pediatric setting.

	METHODS

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
Sample Selection
A random sample of 592 practicing pediatricians was obtained from the American Medical Association Masterfile via a contracted vendor, Medical Marketing Service Inc. The Masterfile is the most complete roster of physicians in the Unites States and contains physicians who are and who are not members of the American Medical Association.

Questionnaire Development and Variables of Interest
A survey instrument was developed to address the primary outcome variables of (1) whether pediatricians were using or planning to use the Pediarix vaccine in their practices, and, if so, (2) whether they were adjusting other components of their patient charges to adjust for potential decreases in administration fees. Additional questions that focused on predictor variables for the outcomes of interest were developed. These predictor variables included patient and physician preferences for decreased numbers of injections, physician perceptions of compatibility with other vaccines in the primary immunization series, and the potential for reduced staff and patient time for immunization delivery. Economic factors that were explored included the cost of the vaccine and the potential economic impact of the use of the vaccine on their practices. Demographic variables included those that described the respondents and the practice environment in which they worked. The survey was pilot-tested for clarity and ease of completion with a convenience sample of practicing pediatricians.

Survey Administration
The survey initially was sent in early November 2004. The questionnaires were accompanied by a personalized cover letter from the principal investigator (G.L.F.). Nonrespondents were contacted twice with additional letters and surveys in late November 2004 and January 2005. A $5 incentive was provided.

Data Analysis
Initially, frequency distributions were developed for all responses. Also, the vaccine financing policies of the state of practice for each respondent were determined. Each respondent was classified, on the basis of his or her state of practice, according to 1 of the following types of state vaccine programs (1): VFC only (no state funds used to pay for vaccines), (2) enhanced VFC (state funds used to supplement federal VFC funds so that some non–VFC-eligible children can receive some publicly purchased vaccines in their physician's office), (3) Universal purchase (state funds used to purchase vaccines for all non–VFC-eligible children in the state for all recommended vaccines), or (4) Universal select (state funds used to purchase vaccines for all non–VFC-eligible children in the state for most [but not all] recommended vaccines). Next, ² analysis was performed to assess any associations of the predictor variables with the outcome variables of interest, use or consideration of use of the Pediarix vaccine. Finally, logistic regression was used to determine the independent association of the predictor variables with use or consideration of use of Pediarix. Regression models which did and did not include practice ownership as a predictor variable were developed. All analyses were conducted using SAS (version 6.12; SAS Institute, Cary, NC). This study was approved by the Institutional Review Board of the University of Michigan Medical School and the Centers for Disease Control and Prevention.

	RESULTS

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
Sample Characteristics
Among 592 pediatricians in the initial sample, 27 had addresses that were no longer valid. Of the remaining 565, there were 355 respondents for an overall response rate of 63%. The only demographic variable in which nonrespondents differed from respondents was female gender (63% vs 54%; P = .045). Some respondents were ineligible for analysis because they did not see children who are younger than 2 years (n = 31), had retired or were deceased (n = 8), or were the wrong specialty (n = 4); therefore, the sample available for analysis was 312.

Demographic characteristics of the eligible respondents and descriptions of their clinical setting are shown in Table 1. For most practices, the physician partners made the decisions regarding vaccine purchase (63%; n = 198) and purchased the vaccine directly from the manufacturer or a distributor (65%; n = 204).

Of the respondents, 23% (n = 71) reported that they are not involved in the discussions or decisions about the vaccine policy and purchase activities of their practice. These pediatricians were not requested to answer the remaining questions regarding purchase policies and their determinants; therefore, the sample for the remainder of the analyses is n = 241.

Approximately half (48%; n = 116) of the remaining 241 respondents order Pediarix through their state immunization program. Among the 52% (n = 125) of respondents who did not, 23% (n = 29) reported that the vaccine was not yet available through their state program, and 47% (n = 59) stated that they did not want to use different vaccines for their public and private patients. Only 11% (n = 14) believed that Pediarix was not compatible with their other vaccine products.

Regarding uninsured children for whom the participating practices (n = 116) provide state- or federal-supplied Pediarix, 15% (n = 17) reported billing the patient their usual administration fee, whereas 31% (n = 36) offered a reduced fee, and 19% (n = 22) waived the fee entirely. The remainder either did not provide care for uninsured patients or handled the issue on a patient-by-patient basis.

Factors That Influence the Decision to Purchase Pediarix
Physicians who currently were purchasing or considering purchasing were more likely to be influenced by both parental and provider desire to decrease the number of injections at a single visit and the reduced time for immunization delivery than those who were not considering Pediarix purchase. For those who were not considering purchase of Pediarix, compatibility with other vaccines and the redundant dose hepatitis B vaccine were significant issues (Table 2). Table 3 presents the results of the regression analysis, which identified the independent factors that were associated with the decision or intention of physicians to purchase Pediarix for private patients. Of note, factors that were not found to be independently associated included practice ownership, vaccine cost, lost revenue, reduced time for vaccine provision, and vaccine compatibility.

	DISCUSSION

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

It also is likely that the financial impact of the use of combined vaccines varies by region of the country and by payer contracts of individual provider or provider groups. Although reports have noted concern related to provider reimbursement for the vaccine itself in northern California and other areas of the United States,¹² no national data regarding a greater differential in price to reimbursement for combination vaccines exist.

One additional possibility for the minimal reported financial impact of Pediarix on practice revenue is that many state programs as well as private insurers have begun to limit the number of administrative fees that are allowed to be charged at a single visit. For example, the state of North Carolina limits at 2 the number of administration fees to be paid at a single visit regardless of the number of injections actually delivered.

Some physicians and analysts have postulated that savings to practices will ensue from the use of combination vaccines, resulting from staff time saved in the administration of 1 vaccine rather than 3.^13,14 Specifically, time-motions studies have found that time savings that are associated with vaccine preparation, injection, and documentation can be up to 2 minutes per injection.¹⁵ However, these savings are viewed as speculative by some in practice¹² and may be offset by the need to stock a larger inventory of new combination vaccines, thereby increasing administrative costs that are associated with purchase and storage.¹³ In addition, although combination vaccines may reduce tasks that are associated directly with the injection itself, they do not decrease the time needed to address non–injection-related activities that support vaccination, including counseling patients about the risks and benefits of the vaccine that they are receiving and maintaining office systems to track and remind or recall patients who are due or overdue for recommended vaccines. Furthermore, patients who transfer into a physician's practice may have received vaccines that were not believed to be compatible with the combination products that were in use by that physician. This would necessitate the purchase of additional vaccines for such patients on an individual basis, potentially negating a portion of any efficiencies achieved.

To assess the economic value to parents for combined vaccines, Myerhoff et al¹⁶ developed a willingness-to-pay model to estimate the cost that parents were willing to bear to avoid the pain to their child that was associated with an injection of a recommended vaccine. Their analysis found that parents would absorb a mean increased cost of $30.28 per injection avoided. Whether such findings would actually translate into parental willingness to pay for the added cost of a combination vaccine remains to be seen. Others have suggested that combination vaccines will minimize discomfort for the child, reduce parental stress, and improve vaccination coverage.¹⁷

Previous studies have demonstrated that some parents may be concerned regarding the use of combined vaccines with multiple antigens for their children. Gellin et al¹⁸ found that 23% of parents studied believed that their child received more vaccines than was good for them and that 25% believed that too many immunizations can compromise a child's immune system.

Other studies have shown that the willingness of parents to allow multiple injections for their children can have an impact on their acceptance of a newly recommended vaccine.¹⁹ The use of combination vaccines then, at least theoretically, would make introduction of additional vaccines more palatable to parents, especially when the number of injections that otherwise would be required at a single visit would be >4.²⁰

It is interesting that studies have shown that physicians seem to be more concerned about the number of injections that are given at a single visit than are parents.^20–24 Physicians may project their concerns onto patients, parents, and nurses.

In addition to the potential benefits for patients, a decrease in the number of injections decreases the risk for needle sticks to staff within practices.¹⁷ Furthermore, some have suggested that the simplification of the delivery of these antigens in a single injection will simplify the immunization schedule for both providers and patients.¹¹ However, as other competing combination vaccines enter the marketplace, additional confusion may ensue because the specific antigens that they contain may differ or result in greater redundancy of antigens administered. This redundancy, or potential for extra or unnecessary doses of 1 or more vaccine antigens, has been a significant clinical concern regarding combined vaccines. With specific regard to Pediarix, newborns who receive their first hepatitis B vaccine before leaving the hospital will receive an extra dose of this antigen when completing the primary immunization series if this combination product is used.¹⁴ Although studies have demonstrated the lack of negative impact on immunogenicity and the safety of such practices,²⁵ some physicians remain skeptical.¹⁷

The effect of state vaccine financing strategy has been shown to have an impact on adoption of new immunizations.²⁶ Physicians in states that do not use state funds to supplement federal VFC funding (or do so only partially) must maintain separate stocks of vaccine for their VFC- and non–VFC-eligible patients. Provider willingness or reluctance to maintain this extra administrative burden has been shown to affect adoption rates.²⁷ It is interesting that use of Pediarix for private patients by physicians in our study was found to be more likely in VFC-only states, where state funds are not used to supplement the VFC program. However, the practices were much less likely to purchase Pediarix privately when they did not order Pediarix through the VFC program. These findings are consistent with the previous studies by demonstrating the reluctance of physicians to use 1 vaccine for a certain group of patients and another vaccine for a different group.^26,27

	CONCLUSION

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
Adoption of new vaccines is a complex process that takes place over time. However, important lessons for the introduction of future combined vaccines can be gleaned from this study. First, the role of the availability of a given vaccine through the VFC program is important in its adoption into practice. Second, parental desire to decrease the number of injections that their child receives is an important issue for providers. Third, additional research is needed to delineate better the economic impact of combination vaccines on provider practices.

	FOOTNOTES

 
Accepted Feb 17, 2006.

Address correspondence to Gary L. Freed, MD, MPH, University of Michigan, 300 North Ingalls Building 6E08, Ann Arbor, MI 48109-0456. E-mail: gfreed{at}med.umich.edu

The authors have indicated they have no financial relationships relevant to this article to disclose.

	REFERENCES

TOP ABSTRACT METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 

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This Article Abstract Full Text (PDF) P3Rs: Submit a response Alert me when this article is cited Alert me when P3Rs are posted Alert me if a correction is posted Citation Map Services E-mail this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My File Cabinet Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Freed, G. L. Articles by Bradley, J. Search for Related Content PubMed PubMed Citation Articles by Freed, G. L. Articles by Bradley, J. Related Collections Infectious Disease & Immunity

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