- Email: [email protected]
How many pediatricians? pitfalls in analysis and possible approaches
and would opt to do it again even if it were optional. They found significant value in the application of knowledge gained from the experience to their subsequent careers. Many of those finishing training at Children’s Memorial have continued to participate in some form of research, including research performed in the setting of a general pediatric practice. The Pediatric Practice Research Group and the American Academy of Pediatrics’ Pediatric Research in Office Settings (PROS) network are examples of how general practitioners can actively contribute to our understanding of disease processes.5,6 Participation in scholarly activity during residency training appears to foster the development of intellectual curiosity and helps one to read the literature with a critical eye and with a solid understanding of study design, research methodology, and statistical analysis. The rub with participation in research activity is that it must be balanced within an increasingly full residency training curriculum. The recent introduction of stricter work hour regulations further adds to the constraints. For example, after being on-call the night before, a trainee may not go to the laboratory or engage in a clinical research project any differently than were he or she to be caring for patients. The trainee will find, however, that the time spent in research and other scholarly activities will assist in the preparation for Board certification. The American Board of Pediatrics, while neither encouraging nor discouraging involvement in research during general pediatric residency training as part of its eligibility requirements to take the certifying examination in general pediatrics, does require a working knowledge of research study design and methodology, as well as an understanding of statistics related to the biomedical arena
and the principles of evidence-based medicine. A candidate taking the certifying examination will likely see questions related to these subjects. Active involvement in a research project during residency training will, if appropriately structured, foster the acquisition of such knowledge. No one can deny that properly mentored participation in research, over and above clinical training, has merit during general pediatric residency training. Research experiences may or may not foster the development of a greater cadre of physician-scientists, but, like music lessons, they are of value for virtually everyone. James A. Stockman, III, MD President, American Board of Pediatrics Clinical Professor of Pediatrics Duke University Medical Center University of North Carolina School of Medicine Chapel Hill, NC 27514
REFERENCES 1. Cull WL, Yudkowsky BK, Schonfeld DJ, Berkowitz CD, Pan RJ. Research exposure during pediatric residency: influence on career expectation. J Pediatr 2003;143:564-9. 2. Stiehm ER. Some of my best clinical pediatricians are researchers. Am J Dis Child 1988;142:1283. 3. Winter RJ. Research during residency. Am J Dis Child 1989;143:521. 4. Sharon Unti, Residency Program Director, Department of Pediatrics, Northwestern University, The Feinberg School of Medicine and Children’s Memorial Hospital, Chicago, Illinois (personal communication). 5. Christoffel KK, Binns HJ, Stockman JA III, McGuire J, Poncher J, Unti S, et al, and the Pediatric Practice Research Group. Practice-based research: opportunities and obstacles. Pediatrics 1988;82:399-406. 6. Haggerty RJ, Green M. History of academic, general, and ambulatory pediatrics. Pediatr Res 2003;53:188-97.
HOW MANY PEDIATRICIANS? PITFALLS IN ANALYSIS AND POSSIBLE APPROACHES
An assessment of the workforce needs for the number of pediatricians in the United States at any point in time, and on an ongoing basis, is both vexing and a highly complex task. Work force numbers are especially problematic in the United States for several reasons: (1) it is the world’s third largest country in population and size; (2) it has no national healthcare system; (3) there exists a maldistribution of pediatric generalists and subspecialists on a geographic and socioeconomic basis, and (4) more than 12 million children lack even basic health insurance. The census of children is not always accurate because of undeclared aliens, and Census Bureau predictions about numbers of children show declines followed by increases moving from decade to decade. The proportion of child health visits or children that are cared for by pediatricians and by other providers (eg, family physicians, advanced-practice nurses) is changing, and market-driven forces appear to be relevant to workforce needs. 550
Editorials
A science of workforce number predictions has emerged that uses a number of methods to define these needs.1-6 Any discussion of these methods generally reaches the conclusion that no single method is sufficient to achieve unequivocal answers and accurately predict workforce needs. As indicated by Freed et al,1 See related article, p 570. attempts at predicting workforce needs necessarily make assumptions about the ex- Reprint requests: Russell W. Chesney, MD, Le Bonheur Children’s Medical pected demand for health Center, 50 N Dunlap St, Rm 306, care, on the work product Memphis, TN 38103. E-mail: rchesney@ per physician, and about the utmem.edu. J Pediatr 2003;143:550-2. substitution of physician laCopyright ª 2003 Mosby, Inc. All rights bor by others in the health reserved. care system. The most fa- 0022-3476/2003/$30.00 + 0 mous study, The Graduate 10.1067/S0022-3476(03)00541-9 The Journal of Pediatrics November 2003
Medical Education National Advisory Committee report,2 an early model for predicting the number of physicians needed in the United States, ultimately proved to be unreliable. Other methods were more detailed and focused on precise issues of physician effort to enhance survey accuracy.3 Indeed, a number of studies have tried to predict physician supply and demand using an interlinking set of factors including activities, time spent in patient care, and length of a physician’s career.4 A number of studies from the mid-1990s predicted an oversupply of physicians by the year 2000, often by as much as 30%,5 but this does not appear to be so. In fact, there is a shortage of physicians in certain specialties and subspecialties, and medically under-served areas continue to exist. The final report of the Future of Pediatric Education II Task Force confirmed the recommendations of a pediatric work force workgroup.6 This group examined several models for workforce needs including: (1) needs-based models, such as those developed for a Kaiser Permanente Portland, Oregon HMO model, which placed pediatrician needs at 11.9 per 100,000 population; and (2) demand-based estimates, which take into account the large demand for primary care services in their delivery systems. This report also examined the method of reviewing the degree of difficulty that graduates of training programs had in obtaining a position. The article also pointed out a number of factors that influence workforce needs: international medical graduates, increasing numbers of women graduates, geographic distribution of both children and physicians, the impact of managed care, and telemedicine. The report also strongly recommended that ‘‘in devising appropriate estimates of pediatrician needs in the future, one should place greater reliance on models that have utilized recent changes in the demographics of pediatrician supply.’’6 Of interest, a new and somewhat controversial method of workforce prediction has emerged that has been termed trend analysis.7 This method is underpinned by assessments of macrotrends such as economic expansion, population growth, the work effort of physicians, and the role of nonphysician clinicians. This method has been strongly criticized by experts in work force calculations, especially because the reliance on free-market principles as the guide to a determination of physician supply runs counter to many government policies.8 Cooper’s trend analysis demonstrates that trend lines based on the gross domestic product over time indicate physician shortages as the economy expands.7 Indeed, a fully government-planned supply of physicians would probably be unpalatable to the free market philosophy of the majority of Americans. As Kevin Grumbach intimates, Adam Smith’s principle of ‘‘the invisible hand of the market’’ is our mantra.8 In this issue of The Journal, Freed’s group has used macroeconomic trend analysis to predict the pediatric workforce.1 They point out that champions of trend analysis have shown that ongoing economic expansion is the main factor that drives the utilization of health care and the growth of the physician workforce. Their study found a high degree of correlation between gross domestic product per capita and the number of active pediatricians, both generalists and specialists, in Editorials
the United States from 1963 to 2000. Their conclusion was that this methodology was highly accurate over a 37-year period. What of the future? Although, thanks to Yogi Berra, we all know that the future is tough to predict, Freed et al1 carry out these trend lines until 2020 and project a possible shortage of pediatricians in relation to expectations. In addition, the panoply of services that fall under the baileywick of the pediatrician—counseling, behavioral interventions, obesity prevention and treatment, safety matters, substance abuse, care of the chronically ill child—are recognized as being difficult to fully implement by busy pediatric offices. Nevertheless, Freed et al1 readily concede that they cannot predict all the factors that would cause the number of pediatricians to follow these trend lines. As Grumbach indicates, Congress may change the equation that allows the market to continue to expand the physician workforce. As he states, the federal government, which supplies the bulk of graduate medical education dollars, may ‘‘use a renewed debate about the adequacy of the nation’s physician supply as an opportunity to create a more rational and accountable system of federal physician workforce regulation and funding.’’8 A final thought on workforce analysis was a central focus 227 years ago when Adam Smith examined the importance of self-betterment in the economic well-being of society. In his analysis, the role of government was irrelevant and he suggested that the market should operate in an unfettered fashion to enhance the economic prosperity of its citizens.9 Although the importance of state and federal government intervention to the health care system cannot be overstated, we live in the nation that has embraced Smith’s dictums most firmly. This may in part explain the remarkable correlation found between the gross domestic product and the number of pediatricians over the past 37 years in the study in this issue of The Journal.1 Trend analysis of the pediatric workforce is clearly a method we should try to understand if we are to estimate the size of the pediatric workforce pipeline. Russell W. Chesney, MD LeBonheur Professor and Chair of Pediatrics The University of Tennessee Health Science Center Memphis, TN 38103
REFERENCES 1. Freed GL, Nahra TA, Wheeler JR. Predicting the pediatric workforce: the use of trend analysis. J Pediatr 2003;143:570-5. 2. Ginzberg E. Physician supply in the year 2000. Health Affairs 1989;8:84-90. 3. Weiner JP. Forecasting the effects of health reform on US physician workforce requirement: evidence from HMO staff patterns. JAMA 1994; 272:222-30. 4. Greenberg L, Cultice JM. Forecasting the need for physicians in the United States: the Health Resources and Services Administration’s physician requirements model. Health Services Res 1997;31:723-37. 5. Politzer RM, Gamliel SR, Cultice JM, Bazell CM, Rivo ML, Mullan F. Matching physician supply and requirements: testing policy recommendations. Inquiry 1996;33:181-94.
551
6. DeAngelis C, Feigin R, DeWitt T, First LR, Jewett EA, Kelch R, et al. Final Report of the FOPE II Pediatric Workforce Workgroup. Pediatrics 2000;106:1245-55. 7. Cooper RA, Getzen TE, McKee HJ, Laud P. Economic and demographic trends signal an impending physician shortage. Health Affairs 2002;21:140-54.
8. Grumbach K. Fighting hand to hand over physician workforce policy. Health Affairs 2002;21:13-27. 9. Smith A. 1776, An inquiry into the nature and causes of wealth of nations. In: Edwin Cannan’s 1904 compilation of Adam Smith’s. 5th ed. Methuen and Co, Ltd; 1789. Available online at: http://www.econlib.org/library/smith/ smWN.html.
ARE PERTUSSIS FATALITIES IN INFANTS ON THE RISE? WHAT CAN BE DONE TO PREVENT THEM?
Before widespread use of whole-cell pertussis vaccines, there were as many as 270,000 cases of pertussis reported each year in the United States with 10,000 deaths.1 Reported frequency of pertussis declined markedly after the introduction of vaccine in the late 1940s, to a nadir of 1010 cases reported in 1976.1 Since then, the frequency of pertussis has increased progressively to 7867 cases reported in 2000, the highest number since 1964.2 In the United States, the ‘‘resurgence’’ of disease has been greatest among older children and adults, reflecting waning vaccine-induced immunity and greater awareness of disease. Pertussis morbidity and mortality also has increased in infants younger than 6 months of age, too young to have completed their primary pertussis immunization series. Seventeen fatal infant pertussis cases were reported in 2000.3 However, this is likely a gross underestimate, because at our own institution during the same period, four pertussis deaths occurred, all in infants younger than 3 months of age.4 In Canada, the past decade has been marked by pertussis outbreaks in infants and children. This is likely the result of the extensive use of whole cell pertussis vaccines that generated significantly lower antibody titers to pertussis toxin, when compared with vaccines used in other countries.5 To monitor the increased pertussis disease burden, comprehensive culture and serologic-based surveillance systems were established throughout Canada.6 These surveillance systems have contributed greatly to the understanding of pertussis epidemiology, particularly to defining the role of adolescents and adults in transmission and disease.7 Pediatric infectious disease experts in Canada also have established a unique hospitalbased active surveillance system to detect selected vaccine preventable diseases that result in hospitalization. This surveillance system called IMPACT (Immunization Monitoring Pro-gram, Active) was established in 1991 at five centers and has been expanded to include 12 pediatric hospitals that provide more than 90% of the tertiary care hospital beds in Canada.8 In this issue of The Journal, Mikelova et al used the IMPACT network to conduct a case-control study to provide a description of the clinical characteristics, epidemiology, management, and course of fatal cases of pertussis and to identify predictors of fatal outcome in infants hospitalized for pertussis.9 Sixteen fatal infant pertussis cases were matched by age, date, and geography with 32 nonfatal cases. In the 16 fatal cases, all infants were 6 months of age or younger, and 15 were 2 months of age or younger, too young to have received the 552
Editorials
complete primary vaccination series. Thirteen of the fatal cases occurred in females. Cases had higher peripheral white blood cell counts and were more likely to have pneumonia when compared with the nonfatal controls. Cases were also more likely to receive nontraditional methods of ventilation such as extracorporeal membrane oxygenation (ECMO). Unfortunately, as stated by the authors, identifying risk factors associated with mortality generally does not change the course of disease. New innovative preventive strategies are needed to prevent infant pertussis deaths. Both household contact studies and outbreak investigations have identified adolescents and adults as the source of pertussis transmission to infants.10-12 Using modern molecular tools, investigators from Belgium recently have shown ‘‘that identical pertussis strains can cause full pertussis disease in children and asymptomatic infection in adults and adolescents.’’13 During the pertussis outbreak in Chicago in the late 1990s, the major risk factor for infant pertussis was having an adolescent mother with cough.14 To interrupt pertussis transmission, we and others have proposed the administration of a booster dose of acellular pertussis vaccine to adolescents and adults.15,16 The safety and immunogenicity of this approach has been clearly documented.17,18 In fact, acellular pertussis vaccines are currently licensed for adolescent and adult use in France, Germany, and Canada. It is time for the licensure of acellular pertussis vaccines for adults and adolescents in the United States. Could maternal immunization provide another solution? Although previous studies have documented that maternal pertussis antibodies are low, maternal levels are effectively passed to the newborn by what appears to be both an active and a passive process.19,20 Decades earlier, immunization of pregnant women with whole cell pertussis vaccines demonstrated that mothers immunized in the third trimester could mount an effecSee related article, p 576. tive immune response with adequate placental transfer of maternal antibodies.21 How- Reprint requests: Kathryn M. Edwards, MD, CCC-5323 Medical Center North, ever, pre-existing maternal Vanderbilt University School of Mediantibodies interfered with cine, Nashville, TN 37232-2581. E-mail: infants’ subsequent immune [email protected]. J Pediatr 2003;143:552-3. responses to whole-cell perCopyright ª 2003 Mosby, Inc. All rights tussis vaccines given in the reserved. primary vaccination series. In 0022-3476/2003/$30.00 + 0 marked contrast, pre-existing 10.1067/S0022-3476(03)00529-8 The Journal of Pediatrics November 2003
and the principles of evidence-based medicine. A candidate taking the certifying examination will likely see questions related to these subjects. Active involvement in a research project during residency training will, if appropriately structured, foster the acquisition of such knowledge. No one can deny that properly mentored participation in research, over and above clinical training, has merit during general pediatric residency training. Research experiences may or may not foster the development of a greater cadre of physician-scientists, but, like music lessons, they are of value for virtually everyone. James A. Stockman, III, MD President, American Board of Pediatrics Clinical Professor of Pediatrics Duke University Medical Center University of North Carolina School of Medicine Chapel Hill, NC 27514
REFERENCES 1. Cull WL, Yudkowsky BK, Schonfeld DJ, Berkowitz CD, Pan RJ. Research exposure during pediatric residency: influence on career expectation. J Pediatr 2003;143:564-9. 2. Stiehm ER. Some of my best clinical pediatricians are researchers. Am J Dis Child 1988;142:1283. 3. Winter RJ. Research during residency. Am J Dis Child 1989;143:521. 4. Sharon Unti, Residency Program Director, Department of Pediatrics, Northwestern University, The Feinberg School of Medicine and Children’s Memorial Hospital, Chicago, Illinois (personal communication). 5. Christoffel KK, Binns HJ, Stockman JA III, McGuire J, Poncher J, Unti S, et al, and the Pediatric Practice Research Group. Practice-based research: opportunities and obstacles. Pediatrics 1988;82:399-406. 6. Haggerty RJ, Green M. History of academic, general, and ambulatory pediatrics. Pediatr Res 2003;53:188-97.
HOW MANY PEDIATRICIANS? PITFALLS IN ANALYSIS AND POSSIBLE APPROACHES
An assessment of the workforce needs for the number of pediatricians in the United States at any point in time, and on an ongoing basis, is both vexing and a highly complex task. Work force numbers are especially problematic in the United States for several reasons: (1) it is the world’s third largest country in population and size; (2) it has no national healthcare system; (3) there exists a maldistribution of pediatric generalists and subspecialists on a geographic and socioeconomic basis, and (4) more than 12 million children lack even basic health insurance. The census of children is not always accurate because of undeclared aliens, and Census Bureau predictions about numbers of children show declines followed by increases moving from decade to decade. The proportion of child health visits or children that are cared for by pediatricians and by other providers (eg, family physicians, advanced-practice nurses) is changing, and market-driven forces appear to be relevant to workforce needs. 550
Editorials
A science of workforce number predictions has emerged that uses a number of methods to define these needs.1-6 Any discussion of these methods generally reaches the conclusion that no single method is sufficient to achieve unequivocal answers and accurately predict workforce needs. As indicated by Freed et al,1 See related article, p 570. attempts at predicting workforce needs necessarily make assumptions about the ex- Reprint requests: Russell W. Chesney, MD, Le Bonheur Children’s Medical pected demand for health Center, 50 N Dunlap St, Rm 306, care, on the work product Memphis, TN 38103. E-mail: rchesney@ per physician, and about the utmem.edu. J Pediatr 2003;143:550-2. substitution of physician laCopyright ª 2003 Mosby, Inc. All rights bor by others in the health reserved. care system. The most fa- 0022-3476/2003/$30.00 + 0 mous study, The Graduate 10.1067/S0022-3476(03)00541-9 The Journal of Pediatrics November 2003
Medical Education National Advisory Committee report,2 an early model for predicting the number of physicians needed in the United States, ultimately proved to be unreliable. Other methods were more detailed and focused on precise issues of physician effort to enhance survey accuracy.3 Indeed, a number of studies have tried to predict physician supply and demand using an interlinking set of factors including activities, time spent in patient care, and length of a physician’s career.4 A number of studies from the mid-1990s predicted an oversupply of physicians by the year 2000, often by as much as 30%,5 but this does not appear to be so. In fact, there is a shortage of physicians in certain specialties and subspecialties, and medically under-served areas continue to exist. The final report of the Future of Pediatric Education II Task Force confirmed the recommendations of a pediatric work force workgroup.6 This group examined several models for workforce needs including: (1) needs-based models, such as those developed for a Kaiser Permanente Portland, Oregon HMO model, which placed pediatrician needs at 11.9 per 100,000 population; and (2) demand-based estimates, which take into account the large demand for primary care services in their delivery systems. This report also examined the method of reviewing the degree of difficulty that graduates of training programs had in obtaining a position. The article also pointed out a number of factors that influence workforce needs: international medical graduates, increasing numbers of women graduates, geographic distribution of both children and physicians, the impact of managed care, and telemedicine. The report also strongly recommended that ‘‘in devising appropriate estimates of pediatrician needs in the future, one should place greater reliance on models that have utilized recent changes in the demographics of pediatrician supply.’’6 Of interest, a new and somewhat controversial method of workforce prediction has emerged that has been termed trend analysis.7 This method is underpinned by assessments of macrotrends such as economic expansion, population growth, the work effort of physicians, and the role of nonphysician clinicians. This method has been strongly criticized by experts in work force calculations, especially because the reliance on free-market principles as the guide to a determination of physician supply runs counter to many government policies.8 Cooper’s trend analysis demonstrates that trend lines based on the gross domestic product over time indicate physician shortages as the economy expands.7 Indeed, a fully government-planned supply of physicians would probably be unpalatable to the free market philosophy of the majority of Americans. As Kevin Grumbach intimates, Adam Smith’s principle of ‘‘the invisible hand of the market’’ is our mantra.8 In this issue of The Journal, Freed’s group has used macroeconomic trend analysis to predict the pediatric workforce.1 They point out that champions of trend analysis have shown that ongoing economic expansion is the main factor that drives the utilization of health care and the growth of the physician workforce. Their study found a high degree of correlation between gross domestic product per capita and the number of active pediatricians, both generalists and specialists, in Editorials
the United States from 1963 to 2000. Their conclusion was that this methodology was highly accurate over a 37-year period. What of the future? Although, thanks to Yogi Berra, we all know that the future is tough to predict, Freed et al1 carry out these trend lines until 2020 and project a possible shortage of pediatricians in relation to expectations. In addition, the panoply of services that fall under the baileywick of the pediatrician—counseling, behavioral interventions, obesity prevention and treatment, safety matters, substance abuse, care of the chronically ill child—are recognized as being difficult to fully implement by busy pediatric offices. Nevertheless, Freed et al1 readily concede that they cannot predict all the factors that would cause the number of pediatricians to follow these trend lines. As Grumbach indicates, Congress may change the equation that allows the market to continue to expand the physician workforce. As he states, the federal government, which supplies the bulk of graduate medical education dollars, may ‘‘use a renewed debate about the adequacy of the nation’s physician supply as an opportunity to create a more rational and accountable system of federal physician workforce regulation and funding.’’8 A final thought on workforce analysis was a central focus 227 years ago when Adam Smith examined the importance of self-betterment in the economic well-being of society. In his analysis, the role of government was irrelevant and he suggested that the market should operate in an unfettered fashion to enhance the economic prosperity of its citizens.9 Although the importance of state and federal government intervention to the health care system cannot be overstated, we live in the nation that has embraced Smith’s dictums most firmly. This may in part explain the remarkable correlation found between the gross domestic product and the number of pediatricians over the past 37 years in the study in this issue of The Journal.1 Trend analysis of the pediatric workforce is clearly a method we should try to understand if we are to estimate the size of the pediatric workforce pipeline. Russell W. Chesney, MD LeBonheur Professor and Chair of Pediatrics The University of Tennessee Health Science Center Memphis, TN 38103
REFERENCES 1. Freed GL, Nahra TA, Wheeler JR. Predicting the pediatric workforce: the use of trend analysis. J Pediatr 2003;143:570-5. 2. Ginzberg E. Physician supply in the year 2000. Health Affairs 1989;8:84-90. 3. Weiner JP. Forecasting the effects of health reform on US physician workforce requirement: evidence from HMO staff patterns. JAMA 1994; 272:222-30. 4. Greenberg L, Cultice JM. Forecasting the need for physicians in the United States: the Health Resources and Services Administration’s physician requirements model. Health Services Res 1997;31:723-37. 5. Politzer RM, Gamliel SR, Cultice JM, Bazell CM, Rivo ML, Mullan F. Matching physician supply and requirements: testing policy recommendations. Inquiry 1996;33:181-94.
551
6. DeAngelis C, Feigin R, DeWitt T, First LR, Jewett EA, Kelch R, et al. Final Report of the FOPE II Pediatric Workforce Workgroup. Pediatrics 2000;106:1245-55. 7. Cooper RA, Getzen TE, McKee HJ, Laud P. Economic and demographic trends signal an impending physician shortage. Health Affairs 2002;21:140-54.
8. Grumbach K. Fighting hand to hand over physician workforce policy. Health Affairs 2002;21:13-27. 9. Smith A. 1776, An inquiry into the nature and causes of wealth of nations. In: Edwin Cannan’s 1904 compilation of Adam Smith’s. 5th ed. Methuen and Co, Ltd; 1789. Available online at: http://www.econlib.org/library/smith/ smWN.html.
ARE PERTUSSIS FATALITIES IN INFANTS ON THE RISE? WHAT CAN BE DONE TO PREVENT THEM?
Before widespread use of whole-cell pertussis vaccines, there were as many as 270,000 cases of pertussis reported each year in the United States with 10,000 deaths.1 Reported frequency of pertussis declined markedly after the introduction of vaccine in the late 1940s, to a nadir of 1010 cases reported in 1976.1 Since then, the frequency of pertussis has increased progressively to 7867 cases reported in 2000, the highest number since 1964.2 In the United States, the ‘‘resurgence’’ of disease has been greatest among older children and adults, reflecting waning vaccine-induced immunity and greater awareness of disease. Pertussis morbidity and mortality also has increased in infants younger than 6 months of age, too young to have completed their primary pertussis immunization series. Seventeen fatal infant pertussis cases were reported in 2000.3 However, this is likely a gross underestimate, because at our own institution during the same period, four pertussis deaths occurred, all in infants younger than 3 months of age.4 In Canada, the past decade has been marked by pertussis outbreaks in infants and children. This is likely the result of the extensive use of whole cell pertussis vaccines that generated significantly lower antibody titers to pertussis toxin, when compared with vaccines used in other countries.5 To monitor the increased pertussis disease burden, comprehensive culture and serologic-based surveillance systems were established throughout Canada.6 These surveillance systems have contributed greatly to the understanding of pertussis epidemiology, particularly to defining the role of adolescents and adults in transmission and disease.7 Pediatric infectious disease experts in Canada also have established a unique hospitalbased active surveillance system to detect selected vaccine preventable diseases that result in hospitalization. This surveillance system called IMPACT (Immunization Monitoring Pro-gram, Active) was established in 1991 at five centers and has been expanded to include 12 pediatric hospitals that provide more than 90% of the tertiary care hospital beds in Canada.8 In this issue of The Journal, Mikelova et al used the IMPACT network to conduct a case-control study to provide a description of the clinical characteristics, epidemiology, management, and course of fatal cases of pertussis and to identify predictors of fatal outcome in infants hospitalized for pertussis.9 Sixteen fatal infant pertussis cases were matched by age, date, and geography with 32 nonfatal cases. In the 16 fatal cases, all infants were 6 months of age or younger, and 15 were 2 months of age or younger, too young to have received the 552
Editorials
complete primary vaccination series. Thirteen of the fatal cases occurred in females. Cases had higher peripheral white blood cell counts and were more likely to have pneumonia when compared with the nonfatal controls. Cases were also more likely to receive nontraditional methods of ventilation such as extracorporeal membrane oxygenation (ECMO). Unfortunately, as stated by the authors, identifying risk factors associated with mortality generally does not change the course of disease. New innovative preventive strategies are needed to prevent infant pertussis deaths. Both household contact studies and outbreak investigations have identified adolescents and adults as the source of pertussis transmission to infants.10-12 Using modern molecular tools, investigators from Belgium recently have shown ‘‘that identical pertussis strains can cause full pertussis disease in children and asymptomatic infection in adults and adolescents.’’13 During the pertussis outbreak in Chicago in the late 1990s, the major risk factor for infant pertussis was having an adolescent mother with cough.14 To interrupt pertussis transmission, we and others have proposed the administration of a booster dose of acellular pertussis vaccine to adolescents and adults.15,16 The safety and immunogenicity of this approach has been clearly documented.17,18 In fact, acellular pertussis vaccines are currently licensed for adolescent and adult use in France, Germany, and Canada. It is time for the licensure of acellular pertussis vaccines for adults and adolescents in the United States. Could maternal immunization provide another solution? Although previous studies have documented that maternal pertussis antibodies are low, maternal levels are effectively passed to the newborn by what appears to be both an active and a passive process.19,20 Decades earlier, immunization of pregnant women with whole cell pertussis vaccines demonstrated that mothers immunized in the third trimester could mount an effecSee related article, p 576. tive immune response with adequate placental transfer of maternal antibodies.21 How- Reprint requests: Kathryn M. Edwards, MD, CCC-5323 Medical Center North, ever, pre-existing maternal Vanderbilt University School of Mediantibodies interfered with cine, Nashville, TN 37232-2581. E-mail: infants’ subsequent immune [email protected]. J Pediatr 2003;143:552-3. responses to whole-cell perCopyright ª 2003 Mosby, Inc. All rights tussis vaccines given in the reserved. primary vaccination series. In 0022-3476/2003/$30.00 + 0 marked contrast, pre-existing 10.1067/S0022-3476(03)00529-8 The Journal of Pediatrics November 2003