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Influenza

Essential Evidence

Author: Mark H. Ebell, MD, MS

Last updated: 2008-09-03 © 2008 John Wiley & Sons, Inc.

Overall Bottom Line

  • Yearly influenza vaccination is recommended for persons aged 6-59 months or 50 years and older, for healthcare workers, and for members of high-risk groups. SORT A
  • Patients classically present with rapid onset of fever, cough, chills or rigors, sore throat, and myalgias.SORT C
  • Rapid antigen tests are most useful during the beginning and end of the flu season. SORT C56
  • Treatment is largely supportive; antiviral medications are recommended only if the likelihood of influenza is high and the patient presents within 36-48 hours of symptom onset. SORT A
  • Predictors of adverse outcome in the elderly include increased age, previous hospitalization, comorbidities, gender, and number of outpatient visits in the previous year (Table 1). SORT A

Table of Contents

Background | Screening and Prevention | Diagnosis | Treatment | Prognosis | Special Populations | References and Links | Guidelines | Tools, Tables, and Images

Influenza

Background

Influenza is an acute lower respiratory tract infection with systemic manifestations caused by influenza virus and occurring most frequently in epidemics during the winter months.

Incidence

  • Onset of the flu season varies but typically begins at about week 40 of the year (early October) and peaks in January. 57

Other Impact

  • Pneumonia and influenza typically cause between 6% and 8% of deaths in the United States but may exceed that during epidemic conditions. 57

Causes of the Condition

  • Influenza A (typically 70-98%)
  • Influenza B (typically 2-30%)
  • Balance between influenza A and B varies from year to year. During 2006/2007 season, 79% were influenza A and 21% were influenza B. 57

Pathophysiology

  • Influenza is caused by single-stranded RNA viruses of the family Orthomyxoviridae.
  • Hemagglutinin and neuraminidase are surface proteins important in diagnosis and treatment. The subtype is used to describe the virus, i.e., H5N1 (avian flu) is hemagglutinin 5 and neuraminidase 1. The so-called "swine flu" is H1N1. Avian flu is discussed in more detail in a separate chapter.
  • Influenza A typically causes a more severe clinical illness than influenza B.
  • Persons are infectious from just before the onset of symptoms until 5-10 days after the onset of symptoms. Shedding is prolonged in children.

Influenza

Screening and Prevention

Bottom Line

  • Influenza vaccination is recommended for all children aged 6-59 months, for adults aged 50 years and older, for healthcare workers, and for selected high-risk groups. SORT A4647484950515253 ()34 ()13
  • While zanamivir and oseltamivir prevent flu in close contacts and family members (NNT = 25-36), the cost and concerns about developing resistance argue against use for this indication, particularly in vaccinated individuals. SORT A4142434445

Primary prevention

  • Influenza vaccination is recommended for all children aged 6-59 months, children and adolescents on long-term aspirin therapy, pregnant women, adults aged 50 years and older, and persons of any age with chronic cardiopulmonary disease (i.e. COPD, cystic fibrosis, asthma),52 ()34 immunodeficiency conditions, or neurologic conditions that could interfere with control of secretions. 49505153 ()13
  • Vaccination is also recommended for anyone living in a nursing home or chronic care facility and anyone who lives with or cares for patients at high risk of complications. 464748
  • Inactivated influenza vaccine may also be given to any other person who wishes to reduce their risk of influenza if adequate supplies of vaccine exist. Influenza vaccination of healthy working adults under age 65 years can reduce the rates of febrile illness, lost workdays, and physician visits if there is a good match between the vaccine and the circulating virus. However, it does not reduce overall cost to society. 40
  • Live attenuated intransal vaccine (LAIV) is approved for persons aged 5-50 years. Some studies have shown that it may be safe and effective for younger children. 373839
  • Flu vaccine does not prevent asthma flares or acute otitis media in children; 3536 it is safe in patients with multiple sclerosis, but data for patients with cystic fibrosis are lacking. 3334
  • Although zanamivir and oseltamivir prevent flu in close contacts and family members (NNT = 25-36), the cost and concerns about developing resistance argue against use for this indication, particularly in vaccinated individuals. 4142434445
  • Although guidelines recommend against influenza vaccination in patients with egg allergy, most can safely receive influenza vaccination containing less than 1.2 mcg/ml egg protein, but appropriate precautions should still be taken. 32
  • Patient reminder and recall systems improve immunization rates (OR 2.2 for childhood influenza vaccination, 1.7 for adult influenza vaccination). 31
  • Antibacterial household products do not reduce the risk of infectious symptoms. 30

Influenza

Diagnosis

Bottom Line

Differential Diagnosis

DiagnosisFeatures
Pneumoniaevidence of consolidation on physical examination and CXR
Pulmonary embolismhypoxia, tachycardia, and pleuritic chest pain common; fever uncommon
Other viral lower respiratory tract infectionsdifficult to distinguish without laboratory investigation

Using the History and Physical

Selecting Diagnostic Tests

  • Rapid antigen tests are more accurate in children than in adults; in both groups, specificity is very high, so a positive test helps rule in influenza, but a negative test does not rule it out, particularly in epidemic conditions.
  • Rapid antigen tests are most useful during the shoulder season (beginning and end of the flu season) when the pretest probability of influenza is 5-10%. During flu season, patients with a negative rapid antigen test still have a significant likelihood of flu, so the test is less useful (see Figure 1). 56
  • Confirmatory testing with PCR or culture is generally done only for disease surveillance.
  • A procalcitonin value <0.25 ng/ml (especially if <0.1) makes bacterial infection unlikely and during an influenza epidemic makes influenza correspondingly more likely. 28
  • Order CXR to rule out pneumonia in patients with lower respiratory tract findings or significant tachypnea or hypoxia. Two studies with approximately 2000 patients found no evidence that chest radiography improves clinical outcomes in patients with respiratory infection, though. ()15
  • Consider pulmonary embolism in any patient with dyspnea, although fever makes it less likely.

Clinical Decision Rules

  • A decision rule has been developed and validated to predict the need for hospitalization and mortality in patients presenting with acute respiratory infection. While not validated in an epidemic, it could be useful in such a setting. ()2

Approach to the Patient

History and Physical Tests

Probability of disease when finding is:
Clinical findingLR+LR-presentabsent
Influenza suspected->influenza (pretest probability 30%)
Chills61.10.6832%22.6%
Cough1.30.3835.8%14%
Fever + cough + weakness2.10.5647.4%19.4%
Sore throat1.10.8932%27.6%
Rigors80.8677.4%26.9%
Fever and cough >36 h2.60.6252.7%21%
Confined to bed2.40.550.7%17.6%
Smoker2.50.7851.7%25.1%
Influenza suspected (pediatric)->influenza (pretest probability 50%)
Cough, headache, and pharyngitis13.60.2678.3%20.6%
Influenza suspected->influenza (pretest probability 30%)
Any systemic symptom1.50.3739.1%13.7%
Fever and >=3 days ill (age >65 years)40.6763.2%22.3%
Fever + cough + nasal congestion2.30.5549.6%19.1%
Sputum1.10.9432%28.7%
Not vaccinated11.0330%30.6%
Nasal congestion1.20.7134%23.3%
Myalgia1.30.6835.8%22.6%
Sweating2.80.6454.5%21.5%
Headache1.30.5935.8%20.2%
Nasal secretions (purulent)0.81.0525.5%31%
No sneezing1.20.8334%26.2%
Unable to cope with daily activities2.30.3849.6%14%
Fatigue31.20.534%17.6%
Sinus pain1.20.7934%25.3%
Fever1.60.2940.7%11.1%
Toxic appearance30.9656.3%29.1%
Clinical judgment (>48 h sx)2.10.947.4%27.8%
Cough10.630%20.5%
Tonsillar exudates0.71.0323.1%30.6%
Clinical judgment (<48 h sx)16.80.3487.8%12.7%
Cervical adenopathy1130%30%
TM abnormality1.50.9339.1%28.5%
Tonsillar swelling0.71.0623.1%31.2%
Sinus tenderness1.50.9439.1%28.7%
Abdominal tenderness1130%30%
Wheezes0.61.1320.5%32.6%
Rhonchi0.61.0820.5%31.6%
Rales1130%30%
Decreased breath sounds0.31.1411.4%32.8%
Prolonged expiration0.51.117.6%32%

Diagnostic Tests

Probability of disease when finding is:
TestLR+LR-presentabsent
Influenza suspected (all ages)->influenza (pretest probability 30%)
Outpatient rapid test (various)44.70.0666.8%2.5%
Influenza suspected (child)->influenza (pretest probability 30%)
Rapid antigen test (QuickVue)5820.1897.2%7.2%
Influenza suspected (adult)->influenza (pretest probability 30%)
Rapid antigen test (Quidel QuickVue), >48 h3250.7591.5%24.3%
Rapid antigen test (Quidel QuickVue), <48 h140.4485.7%15.9%

Influenza

Treatment

Bottom Line

  • Treatment is largely supportive with analgesics, antipyretics, rest, adequate (but not excessive) hydration, and reevaluation if symptoms worsen. SORT C
  • Antiviral medications (rimantidine, amantadine, osteltamivir, or zanamivir) are recommended only if the probability of influenza is high (see Figure 1) and patients present within 36-48 hours of symptoms onset. SORT A21222324252627

Drug Therapy

  • When given within 36-48 hours of the onset of symptoms, antiviral agents such as oseltamivir, amantadine, rimantidine, and zanamivir reduce the duration of symptoms by 12-24 hours and may reduce the intensity somewhat. 2021222324252627
  • Amantadine and rimantidine are effective only for influenza A, whereas osteltamivir and zanamivir are effective for both influenzae A and B. They may also reduce the likelihood of complications such as otitis media. 19 ()16
  • Usual dosing in adults is oseltamivir 75 mg po twice daily, rimantidine 100 mg po twice daily, zanamivir 10 mg by MDI bid, or amantadine 100 mg po twice daily. Usual duration of therapy for all four drugs is 5 days.

Complementary/Alternative Therapy

  • Two poor-quality RCTs provide insufficient evidence to recommend "Ganmao" or "E Shu You" Chinese herbal medicines for influenza. 18
  • Two poor-quality RCTs found a small benefit to the homeopathic drug oscillococcinum; current evidence is insufficient to recommend this intervention routinely. 17

Other Treatment

  • Treatment generally includes rest, fluids, and antipyretics.
  • "Forcing fluids" is not supported by any clinical studies and may lead to hyponatremia, especially in infants and the elderly. 14
  • Supplemental oxygen may be needed for hospitalized patients.

Management of Complications

  • In a cohort study of 343 Welsh patients with influenza, complications included bronchitis (19%, 95% CI 15-23%), pneumonia (2.9%, 95% CI 1.4-5.4%), otitis media (2.3%, 95% CI 1.0-4.6%).12 See those chapters for management of those conditions.
  • Influenza may also worsen cardiac disease and diabetes mellitus control in affected individuals. 11

Influenza

Prognosis

Bottom Line

  • In a case-control study of 119 hospitalized patients and 196 matched controls, risk factors for hospitalization included COPD, more than one significant comorbidty, polypharmacy, more than 5 GP consultations in the previous year, and previous hospitalizations in patients aged 18-64 years. SORT B11
  • In the same study, risk factors for patients over age 65 years were all of the above plus CHF and minus previous hospitalizations. SORT B11
  • A clinical decision rule was developed in 16,280 patients and validated in over 11,000 patients to predict the likelihood of hospitalization or pneumonia or death from any cause during flu season in community-dwelling elderly (aged 65 years and older). Key factors include age, previous hospitalization, comorbidities, gender, and number of outpatient visits in the previous year (Table 1). SORT A10

Influenza

Management of Special Populations

The Elderly

  • Oseltamivir provided very little benefit as prophylaxis for older patients who had received influenza vaccine. 43

Infants and Children

  • Likelihood of hospitalization for flu was 7 per 10,000 child-years in an urban cohort. A history of cardiac and neuromuscular conditions was an independent predictor for hospitalization. Median age of hospitalization was 1.8 years. 9
  • Oseltamivir is approved for children over age 1 year. Dosing is 75 mg bid if >40 kg or 13 years old, 60 mg bid if 23-40 kg, 45 mg bid if 15-23 kg, and 30 mg bid if <=15 kg.
  • Zanamivir is approved for children aged 7 years and older is 10 mg by metered-dose inhaler twice daily.
  • Rimantidine is not FDA approved for treatment of influenza in children.

Influenza

References and Additional Resources

References

  1. Friedman MJ, Attia MW. Clinical predictors of influenza in children. Arch Pediatr Adolesc Med. 2004;158:391-4. PubMed
  2. Talmor D, Jones AE, Rubinson L, et al. Simple triage scoring system predicting death and the need for critical care resources for use during epidemics. Crit Care. 2007;35:1251-6. PubMed
  3. Stein J, Louie J, Flanders S, Maselli J, Hacker JK, Drew WL, Gonzales R. Performance characteristics of clinical diagnosis, a clinical decision rule, and a rapid influenza test in the detection of influenza infection in a community sample of adults. Ann Emerg Med. 2005;46:412-9. PubMed
  4. Rodriguez WJ, Schwartz RH, Thorne MM. Evaluation of diagnostic tests for influenza in a pediatric practice. Pediatr Infect Dis J. 2002;21:193-6. PubMed
  5. Poehling KA, Zhu Y, Tang YW, Edwards K. Accuracy and impact of a point-of-care rapid influenza test in young children with respiratory illnesses. Arch Pediatr Adolesc Med. 2006;160:713-8. PubMed
  6. Ebell MH, White LL, Casault T. A systematic review of the history and physical examination to diagnose influenza. J Am Board Fam Pract. 2004;17:1-5. PubMed
  7. Ebell MH. Diagnosing and treating patients with suspected influenza. Am Fam Physician. 2005;72:1789-92. PubMed
  8. Nicolson A, Toogood AA, Rahim A, Shalet SM. The prevalence of severe growth hormone deficiency in adults who received growth hormone replacement in childhood. Clin Endocrinol (Oxf). 1996;44:311-6. PubMed
  9. Coffin SE, Zaoutis TE, Rosenquist AB, et al. Incidence, complications, and risk factors for prolonged stay in children hospitalized with community-acquired influenza. Pediatrics. 2007;119:740-8. PubMed
  10. Hak E, Wei F, Nordin J, Mullooly J, Poblete S, Nichol KL. Development and validation of a clinical prediction rule for hospitalization due to pneumonia or influenza or death during influenza epidemics among community-dwelling elderly persons. J Infect Dis. 2004;189:450-8. PubMed
  11. Hak E, Verheij TJ, van Essen GA, Lafeber AB, Grobbee DE, Hoes AW. Prognostic factors for influenza-associated hospitalization and death during an epidemic. Epidemiol Infect. 2001;126:261-8. PubMed
  12. Connolly AM, Salmon RL, Lervy B, Williams DH. What are the complications of influenza and can they be prevented? Experience from the 1989 epidemic of H3N2 influenza A in general practice. BMJ. 1993;306:1452-4. PubMed
  13. Zaman K, Roy E, Arifeen SE, et al. Effectiveness of maternal influenza immunization in mothers and infants. N Engl J Med. 2008;357:1555-64. PubMed
  14. Guppy MP, Mickan SM, Del Mar CB. "Drink plenty of fluids": a systematic review of evidence for this recommendation in acute respiratory infections. BMJ. 2004;328:499-500. PubMed
  15. Swingler GH, Zwarenstein M, Swingler GH. Chest radiograph in acute respiratory infections (Cochrane Review). In: The Cochrane Library 2009 Issue 2. Chichester, UK: John Wiley and Sons, Ltd.
  16. Alves Galvao MG, Rocha Crispino Santos MA, Alves da Cunha AJL, Alves da Cunha AJL. Amantadine and rimantadine for influenza A in children and the elderly (Cochrane Review). In: The Cochrane Library 2009 Issue 2. Chichester, UK: John Wiley and Sons, Ltd.
  17. Vickers AJ, Smith C, Vickers A. Homoeopathic Oscillococcinum for preventing and treating influenza and influenza-like syndromes (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  18. Chen XY, Wu TX, Liu GJ, et al. Chinese medicinal herbs for influenza (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  19. Matheson NJ, Harnden AR, Perera R, Sheikh A, Symmonds-Abrahams M, Matheson N. Neuraminidase inhibitors for preventing and treating influenza in children (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  20. Hayden FG, Osterhaus AD, Treanor JJ, et al. Efficacy and safety of the neuraminidase inhibitor zanamivir in the treatment of influenzavirus infections. GG167 Influenza Study Group. N Engl J Med. 1997;337:874-80. PubMed
  21. Jefferson TO, Demicheli V, Pietrantonj C, Jones M, Rivetti D, Jefferson T. Neuraminidase inhibitors for preventing and treating influenza in healthy adults (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  22. Monto AS, Fleming DM, Henry D, et al. Efficacy and safety of the neuraminidase inhibitor zanamivirin the treatment of influenza A and B virus infections. J Infect Dis. 1999;180:254-61. PubMed
  23. Treanor JJ, Hayden FG, Vrooman PS, et al. Efficacy and safety of the oral neuraminidase inhibitor oseltamivir in treating acute influenza: a randomized controlled trial. US Oral Neuraminidase Study Group. JAMA. 2000;283:1016-24. PubMed
  24. Nicholson KG, Aoki FY, Osterhaus AD, et al. Efficacy and safety of oseltamivir in treatment of acute influenza: a randomised controlled trial. Neuraminidase Inhibitor Flu Treatment Investigator Group. Lancet. 2000;355:1845-50. PubMed
  25. Cooper NJ, Sutton AJ, Abrams KR, Wailoo A, Turner D, Nicholson KG. Effectiveness of neuraminidase inhibitors in treatment and prevention of influenza A and B: systematic review and meta-analyses of randomised controlled trials. BMJ. 2003;326:1235. PubMed
  26. Jefferson T, Demicheli V, Pietrantonj C, Rivetti D, Jefferson T. Amantadine and rimantadine for influenza A in adults (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  27. Jefferson T, Demicheli V, Rivetti D, et al. Antivirals for influenza in healthy adults: systematic review. Lancet. 2006;367:303-13. PubMed
  28. Christ-Crain M, Jaccard-Stolz D, Bingisser R, et al. Effect of procalcitonin-guided treatment on antibiotic use and outcome in lower respiratory tract infections: cluster-randomised, single-blinded intervention trial. Lancet. 2004;363:600-7. PubMed
  29. Monto AS, Gravenstein S, Elliott M, Colopy M, Schweinle J. Clinical signs and symptoms predicting influenza infection. Arch Intern Med. 2000;160:3243-7. PubMed
  30. Larson EL, Lin SX, Gomez-Pichardo C, Della-Latta P. Effect of antibacterial home cleaning and handwashing products on infectious disease symptoms: a randomized, double-blind trial. Ann Intern Med. 2004;140:321-9. PubMed
  31. Jacobson Vann JC, Szilagyi P, Jacobson Vann J. Patient reminder and patient recall systems for improving immunization rates (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  32. James JM, Zeiger RS, Lester MR, et al. Safe administration of influenza vaccine to patients with egg allergy. J Pediatr. 1998;133:624-8. PubMed
  33. Miller AE, Morgante LA, Buchwald LY, et al. A multicenter, randomized, double-blind, placebo-controlled trial of influenza immunization in multiple sclerosis. Neurology. 1997;48:312-4. PubMed
  34. Bhalla P, Tan A, Smyth R, Bhalla P. Vaccines for preventing influenza in people with cystic fibrosis (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  35. Hoberman A, Greenberg DP, Paradise JL, et al. Effectiveness of inactivated influenza vaccine in preventing acute otitis media in young children: a randomized controlled trial. JAMA. 2003;290:1608-16. PubMed
  36. Bueving HJ, Bernsen RM, de Jongste JC, et al. Influenza vaccination in children with asthma: randomized double-blind placebo-controlled trial. Am J Respir Crit Care Med. 2004;169:488-93. PubMed
  37. Nichol KL, Mendelman PM, Mallon KP, et al. Effectiveness of live, attenuated intranasal influenza virus vaccine in healthy, working adults: a randomized controlled trial. JAMA. 1999;282:137-44. PubMed
  38. Belshe RB, Edwards KM, Vesikari T, et al. CAIV-T Comparative Efficacy Study Group. Live attenuated versus inactivated influenza vaccine in infants and young children. N Engl J Med. 2007;356:685-96. PubMed
  39. Belshe RB, Mendelman PM, Treanor J, et al. The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenzavirus vaccine in children. N Engl J Med. 1998;338:1405-12. PubMed
  40. Bridges CB, Thompson WW, Meltzer MI, et al. Effectiveness and cost-benefit of influenza vaccination of healthy working adults: A randomized controlled trial. JAMA. 2000;284:1655-63. PubMed
  41. Hayden FG, Atmar RL, Schilling M, et al. Use of the selective oral neuraminidase inhibitor oseltamivir to prevent influenza. N Engl J Med. 1999;341:1336-43. PubMed
  42. Hayden FG, Gubareva LV, Monto AS, et al. Zanamivir Family Study Group. Inhaled zanamivir for the prevention of influenza in families. Zanamivir Family Study Group. N Engl J Med. 2000;343:1282-9. PubMed
  43. Peters PH, Jr, Gravenstein S, Norwood P, et al. Long-term use of oseltamivir for the prophylaxis of influenza in a vaccinated frail older population. J Am Geriatr Soc. 2001;49:1025-31. PubMed
  44. Welliver R, Monto AS, Carewicz O, et al, Oseltamivir Post Exposure Prophylaxis Investigator Group. Effectiveness of oseltamivir in preventing influenza in household contacts: a randomized controlled trial. JAMA. 2001;285:748-54. PubMed
  45. Monto AS, Pichichero ME, Blanckenberg SJ, et al. Zanamivir prophylaxis: an effective strategy for the prevention of influenza types A and B within households. J Infect Dis. 2002;186:1582-8. PubMed
  46. Thomas RE, Jefferson T, Demicheli V, Rivetti D, Thomas R. Influenza vaccination for healthcare workers who work with the elderly (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  47. Carman WF, Elder AG, Wallace LA, et al. Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomised controlled trial. Lancet. 2000;355:93-7. PubMed
  48. Hurwitz ES, Haber M, Chang A, et al. Effectiveness of influenza vaccination of day care children in reducing influenza-related morbidity among household contacts. JAMA. 2000;284:1677-82. PubMed
  49. Rivetti D, Jefferson T, Thomas R, et al. Vaccines for preventing influenza in the elderly (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  50. Smith S, Demicheli V, Pietrantonj C, et al. Vaccines for preventing influenza in healthy children (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  51. Demicheli V, Rivetti D, Deeks JJ, Jefferson TO, Demicheli V. Vaccines for preventing influenza in healthy adults (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  52. Poole PJ, Chacko E, Wood-Baker RWB, Cates CJ, Poole P. Influenza vaccine for patients with chronic obstructive pulmonary disease (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  53. Cates CJ, Jefferson TO, Bara AI, Rowe BH, Cates C. Vaccines for preventing influenza in people with asthma (Cochrane Review). In: The Cochrane Library 2007 Issue 1. Chichester, UK: John Wiley and Sons, Ltd.
  54. Schneider HJ, Kreitschmann-Andermahr I, Ghigo E, Stalla GK, Agha A. Hypothalamopituitary dysfunction following traumatic brain injury and aneurysmal subarachnoid hemorrhage: a systematic review. JAMA. 2007;298:1429-38. PubMed
  55. Gleeson HK, Gattamaneni HR, Smethurst L, Brennan BM, Shalet SM. Reassessment of growth hormone status is required at final height in children treated with growth hormone replacement after radiation therapy. J Clin Endocrinol Metab. 2004;89:662-6. PubMed
  56. Rothberg MB, Bellantonio S, Rose DN. Management of influenza in adults older than 65 years of age: cost-effectiveness of rapid testing and antiviral therapy. Ann Intern Med. 2003;139:321-9. PubMed
  57. U.S. Influenza Season Summary (Centers for Disease Control and Prevention Influenza Surveillance) www.cdc.gov

Influenza

Practice Guidelines

  1. Advisory Committee on Immunization Practices (ACIP), American Academy of Family Physicians (AAFP), and the American Academy of Pediatrics (AAP)
    Childhood immunization schedule 2008 (ACIP) (ACIP, 2008-03-05) www.cdc.gov
  2. Advisory Committee on Immunization Practices (ACIP), the American College of Obstetricians and Gynecologists (ACOG), and the American Academy of Family Physicians (AAFP)
    Recommended Adult Immunization Schedule, by Vaccine and Age Group. United States. 2007-2008 (ACIP) (ACIP, 2007-11-01) www.cdc.gov
  3. Advisory Committee on Immunization Practices (ACIP), the American College of Obstetricians and Gynecologists (ACOG), and the American Academy of Family Physicians (AAFP)
    Recommended Adult Immunization Schedule, by Medical Condition. United States. 2007-2008 (ACIP) (ACIP, 2007-11-01) www.cdc.gov
  4. Rutschmann OT, McCrory DC, Matchar DB, Immunization Panel of the Multiple Sclerosis Council for Clinical Practice Guidelines. Immunization and MS: a summary of published evidence and recommendations. Neurology 2002 Dec 24;59(12):1837-43.
    Immunization and multiple sclerosis: a summary of published evidence and recommendations. (AAN, 2002-12-24) www.guidelines.gov
  5. Langley JM, Faughnan ME. Prevention of influenza in the general population: recommendation statement from the Canadian Task Force on Preventive Health Care. CMAJ 2004 Nov 9;171(10):1169-70.
    Prevention of influenza in the general population. (CTFPHC, 2004-11-09) www.guidelines.gov
  6. Davis MM, Taubert K, Benin AL, et al. for the American Heart Association, American College of Cardiology. Influenza vaccination as secondary prevention for cardiovascular disease: a science advisory from the American Heart Association/American College of Cardiology. Circulation 2006 Oct 3;114(14):1549-53.
    Influenza vaccination as secondary prevention for cardiovascular disease. (AHA, 2006-10-03) www.guidelines.gov

Influenza

Tools, Tables, and Images

Tools

Figure 1: Influenza: Management

Tables

Table 1: Model to Predict Probability of Hospitalization With Pneumonia or Influenza or Death From Any Cause During Flu Season

SymptomScore
Age
70-74 years14
75-79 years28
80-89 years42
>89 years56
Male9
Outpatient visits during the previous year
1-611
7-1222
>1233
Previous hospitalization for pneumonia or influenza63
Pulmonary disease18
Heart disease6
Renal disease or transplant12
Dementia or stroke22
Cancer48
Total
ScoreProbability*
<400.3%
40 to <601.2%
60 to <1003.0%
>=10015.4%
*Hospitalization for pneumonia or influenza, or all-cause mortality during flu season. From Hak E, Wei F, Nordin J, Mullooly J, Poblete S, Nichol KL. Development and validation of a clinical prediction rule for hospitalization due to pneumonia or influenza or death during influenza epidemics among community-dwelling elderly persons. J Infect Dis. 2004; 189: 450-8.10

ICD9 Codes

DiagnosisICD9 code
Influenza487
Influenza with penumonia487.0
Influenza vaccinationV04.8

Article ID: eee676