The Underrecognized Burden of Influenza
http://www.100md.com
《新英格兰医药杂志》
To the Editor: Poehling et al. (July 6 issue)1 state that the underdiagnosis of influenza may lead to missed opportunities for infection control and treatment. The overwhelming majority of patients with influenza have cough, fever, or both. Precautions with regard to respiratory hygiene and cough etiquette should be implemented for patients presenting with cough, especially when fever is present.2 This strategy includes the use of a mask within 3 ft of a patient with a respiratory illness, a practice that limits the transmission of influenza, even in the absence of a laboratory diagnosis.
The rapid antigen tests that Poehling et al. recommend have limited use. False negative results, in particular, are well described.3 Public health agencies should consider supporting the dissemination of polymerase-chain-reaction (PCR)–based testing techniques for influenza to hospitals. In addition to enhancing the diagnosis and treatment of seasonal influenza,4 the development of robust diagnostic capabilities will enhance laboratory preparedness for a response to a pandemic. Even in the absence of the ability to identify specific influenza subtypes (e.g., H5N1) outside public health laboratories, PCR for influenza A is likely to be sufficient for clinical diagnosis and treatment decisions during an established pandemic, provided additional strains of influenza A are not cocirculating.
Craig S. Conover, M.D., M.P.H.
Eric E. Whitaker, M.D., M.P.H.
Illinois Department of Public Health
Springfield, IL 62761
References
Poehling KA, Edwards KM, Weinberg GA, et al. The underrecognized burden of influenza in young children. N Engl J Med 2006;355:31-40.
Centers for Disease Control and Prevention. Respiratory hygiene/cough etiquette in healthcare settings. (Accessed September 21, 2006, at http://www.cdc.gov/flu/professionals/infectioncontrol/resphygiene.htm.)
Smith NM, Bresee JS, Shay DK, Uyeki TM, Cox NJ, Strikas RA. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2006;55:1-42.
Espy MJ, Uhl JR, Sloan LM, et al. Real-time PCR in clinical microbiology: applications for routine laboratory testing. Clin Microbiol Rev 2006;19:165-256.
To the Editor: Poehling et al. do not discuss the use of unnecessary antimicrobial agents in many of the children who actually had uncomplicated influenza infections. I have often been surprised by the reluctance of many first-line providers to make a clinical diagnosis of influenza. Along with all the other important ramifications of early recognition of influenza, surely a reduction in the superfluous use of antimicrobial therapy would be a further benefit.
Deena Ages, M.D.
Humber River Regional Hospital
Toronto, ON M6B 2R9, Canada
To the Editor: The study by Poehling et al., in which my colleagues and I participated, sought to establish the incidence of influenza in children. Current recommendations are to use antiviral agents only in high-risk patients, so there is little point in using cultures or rapid tests to diagnose influenza, since such a diagnosis does not change treatment. Most of the children thus received the diagnosis of "viral illness NOS " and were counted as having an undiagnosed condition in the study, when in reality the physician was probably aware that the condition was possibly influenza. The declaration that "most influenza infections in children were not diagnosed clinically" seems to be inaccurate, since this statement implies that after taking a history and performing a physical examination, the physician was unaware that the child may have had influenza. It is equally effective, and more accurate, to state that the use of chart notes or codes from the International Classification of Diseases, 9th Revision (ICD-9) to determine the incidence rates of influenza substantially underestimates the true burden in the community. This fact has important implications for future studies and avoids suggesting that pediatricians do not recognize the signs and symptoms of influenza.
David Sullo, M.D.
Genesis Pediatrics
Rochester, NY 14624
sullo@genesispediatrics.com
The authors reply: We agree with Conover and Whitaker that respiratory precautions are needed for patients with acute respiratory illness. We also agree with Sullo that clinicians in our study may have considered the possibility of influenza in children and that diagnostic tests should be performed primarily to influence treatment decisions. However, some children who tested positive for influenza in our study presented with clinical syndromes that physicians may not associate with influenza, such as febrile seizure, suspected sepsis (febrile illness without a focus), and bronchiolitis. In addition, the results of influenza testing affect other important medical decisions, such as the need for additional diagnostic testing, prophylaxis of contacts, and "cohorting." The knowledge of a positive influenza test in children who present to emergency departments has been shown to result in an increased number of prescriptions for antiviral agents and a decreased number for antibacterial agents, as Ages suggests, as well as fewer blood and urine cultures, fewer chest radiographs, and quicker discharge from the emergency department.1,2 Children who are at least 1 year of age and present within 2 days after the onset of illness are eligible for antiviral treatment. Even when antiviral treatment is not appropriate for the child who is sick, high-risk family members may benefit from knowing the diagnosis so that they can start antiviral prophylaxis, if indicated.3
Conover and Whitaker comment on problems associated with rapid, point-of-care diagnostic tests for influenza. To maximize the positive predictive values of such tests, they should be used only when influenza is known to be circulating in the community.4 This policy requires communication between public health practitioners and clinicians. We agree with Conover and Whitaker that the characteristics of PCR are superior to those of the rapid, point-of-care tests and that wider availability of more accurate, timely, and economic diagnostic tests would make testing more attractive and could enhance preparedness for a pandemic.
The primary message of our study was that an estimated 6 to 12% of children have a health care visit for influenza annually. Although influenza-associated hospitalizations are less common among children than in other populations and deaths are rare, both of these serious outcomes are preventable, as are the frequent, less severe outcomes. New national recommendations calling for the vaccination against influenza of children 6 months to less than 5 years of age, if fully implemented, should have an important effect on children, their caregivers, and the health care system. These data on the burden of influenza in children and its varying presentations should encourage parents and providers to immunize young children with influenza vaccine each year.
Marie R. Griffin, M.D., M.P.H.
Kathryn M. Edwards, M.D.
Katherine A. Poehling, M.D., M.P.H.
Vanderbilt University Medical Center
Nashville, TN 37232
References
Bonner AB, Monroe KW, Talley LI, Klasner AE, Kimberlin DW. Impact of the rapid diagnosis of influenza on physician decision-making and patient management in the pediatric emergency department: results of a randomized, prospective, controlled trial. Pediatrics 2003;112:363-367.
Abanses JC, Dowd MD, Simon SD, Sharma V. Impact of rapid influenza testing at triage on management of febrile infants and young children. Pediatr Emerg Care 2006;22:145-149.
Smith NM, Bresee JS, Shay DK, Uyeki TM, Cox NJ, Strikas RA. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2006;55:1-42.
Grijalva C, Poehling K, Edwards K, et al. Accuracy and interpretation of rapid influenza tests in children. Pediatrics (in press).
The rapid antigen tests that Poehling et al. recommend have limited use. False negative results, in particular, are well described.3 Public health agencies should consider supporting the dissemination of polymerase-chain-reaction (PCR)–based testing techniques for influenza to hospitals. In addition to enhancing the diagnosis and treatment of seasonal influenza,4 the development of robust diagnostic capabilities will enhance laboratory preparedness for a response to a pandemic. Even in the absence of the ability to identify specific influenza subtypes (e.g., H5N1) outside public health laboratories, PCR for influenza A is likely to be sufficient for clinical diagnosis and treatment decisions during an established pandemic, provided additional strains of influenza A are not cocirculating.
Craig S. Conover, M.D., M.P.H.
Eric E. Whitaker, M.D., M.P.H.
Illinois Department of Public Health
Springfield, IL 62761
References
Poehling KA, Edwards KM, Weinberg GA, et al. The underrecognized burden of influenza in young children. N Engl J Med 2006;355:31-40.
Centers for Disease Control and Prevention. Respiratory hygiene/cough etiquette in healthcare settings. (Accessed September 21, 2006, at http://www.cdc.gov/flu/professionals/infectioncontrol/resphygiene.htm.)
Smith NM, Bresee JS, Shay DK, Uyeki TM, Cox NJ, Strikas RA. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2006;55:1-42.
Espy MJ, Uhl JR, Sloan LM, et al. Real-time PCR in clinical microbiology: applications for routine laboratory testing. Clin Microbiol Rev 2006;19:165-256.
To the Editor: Poehling et al. do not discuss the use of unnecessary antimicrobial agents in many of the children who actually had uncomplicated influenza infections. I have often been surprised by the reluctance of many first-line providers to make a clinical diagnosis of influenza. Along with all the other important ramifications of early recognition of influenza, surely a reduction in the superfluous use of antimicrobial therapy would be a further benefit.
Deena Ages, M.D.
Humber River Regional Hospital
Toronto, ON M6B 2R9, Canada
To the Editor: The study by Poehling et al., in which my colleagues and I participated, sought to establish the incidence of influenza in children. Current recommendations are to use antiviral agents only in high-risk patients, so there is little point in using cultures or rapid tests to diagnose influenza, since such a diagnosis does not change treatment. Most of the children thus received the diagnosis of "viral illness NOS " and were counted as having an undiagnosed condition in the study, when in reality the physician was probably aware that the condition was possibly influenza. The declaration that "most influenza infections in children were not diagnosed clinically" seems to be inaccurate, since this statement implies that after taking a history and performing a physical examination, the physician was unaware that the child may have had influenza. It is equally effective, and more accurate, to state that the use of chart notes or codes from the International Classification of Diseases, 9th Revision (ICD-9) to determine the incidence rates of influenza substantially underestimates the true burden in the community. This fact has important implications for future studies and avoids suggesting that pediatricians do not recognize the signs and symptoms of influenza.
David Sullo, M.D.
Genesis Pediatrics
Rochester, NY 14624
sullo@genesispediatrics.com
The authors reply: We agree with Conover and Whitaker that respiratory precautions are needed for patients with acute respiratory illness. We also agree with Sullo that clinicians in our study may have considered the possibility of influenza in children and that diagnostic tests should be performed primarily to influence treatment decisions. However, some children who tested positive for influenza in our study presented with clinical syndromes that physicians may not associate with influenza, such as febrile seizure, suspected sepsis (febrile illness without a focus), and bronchiolitis. In addition, the results of influenza testing affect other important medical decisions, such as the need for additional diagnostic testing, prophylaxis of contacts, and "cohorting." The knowledge of a positive influenza test in children who present to emergency departments has been shown to result in an increased number of prescriptions for antiviral agents and a decreased number for antibacterial agents, as Ages suggests, as well as fewer blood and urine cultures, fewer chest radiographs, and quicker discharge from the emergency department.1,2 Children who are at least 1 year of age and present within 2 days after the onset of illness are eligible for antiviral treatment. Even when antiviral treatment is not appropriate for the child who is sick, high-risk family members may benefit from knowing the diagnosis so that they can start antiviral prophylaxis, if indicated.3
Conover and Whitaker comment on problems associated with rapid, point-of-care diagnostic tests for influenza. To maximize the positive predictive values of such tests, they should be used only when influenza is known to be circulating in the community.4 This policy requires communication between public health practitioners and clinicians. We agree with Conover and Whitaker that the characteristics of PCR are superior to those of the rapid, point-of-care tests and that wider availability of more accurate, timely, and economic diagnostic tests would make testing more attractive and could enhance preparedness for a pandemic.
The primary message of our study was that an estimated 6 to 12% of children have a health care visit for influenza annually. Although influenza-associated hospitalizations are less common among children than in other populations and deaths are rare, both of these serious outcomes are preventable, as are the frequent, less severe outcomes. New national recommendations calling for the vaccination against influenza of children 6 months to less than 5 years of age, if fully implemented, should have an important effect on children, their caregivers, and the health care system. These data on the burden of influenza in children and its varying presentations should encourage parents and providers to immunize young children with influenza vaccine each year.
Marie R. Griffin, M.D., M.P.H.
Kathryn M. Edwards, M.D.
Katherine A. Poehling, M.D., M.P.H.
Vanderbilt University Medical Center
Nashville, TN 37232
References
Bonner AB, Monroe KW, Talley LI, Klasner AE, Kimberlin DW. Impact of the rapid diagnosis of influenza on physician decision-making and patient management in the pediatric emergency department: results of a randomized, prospective, controlled trial. Pediatrics 2003;112:363-367.
Abanses JC, Dowd MD, Simon SD, Sharma V. Impact of rapid influenza testing at triage on management of febrile infants and young children. Pediatr Emerg Care 2006;22:145-149.
Smith NM, Bresee JS, Shay DK, Uyeki TM, Cox NJ, Strikas RA. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2006;55:1-42.
Grijalva C, Poehling K, Edwards K, et al. Accuracy and interpretation of rapid influenza tests in children. Pediatrics (in press).