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 Nov;46(5):412-9. doi: 10.1016/j.annemergmed.2005.05.020. Epub 2005 Aug 15.


Study objective: The accurate diagnosis of influenza remains a diagnostic dilemma. We examine the performance of various strategies for diagnosing influenza infection in an unselected sample of adults during influenza season.

Methods: Consecutive adults presenting to a university emergency department or urgent care clinic between January and March 2002 with acute respiratory complaints were eligible for this prospective observational study. The performance of clinician judgment, a rapid influenza test, and a clinical prediction rule in predicting influenza infection was evaluated using referent standard of reverse transcriptase polymerase chain reaction. Statistical significance was assessed using McNemar's test of proportions.

Results: Fifty-three of 258 (21%) patients had a positive influenza reverse transcriptase polymerase chain reaction test. Overall, clinician judgment showed sensitivity of 29% (95% confidence interval [CI] 18% to 43%) and specificity of 92% (95% CI 87% to 95%). The rapid influenza test showed a sensitivity of 33% (95% CI 22% to 47%) and specificity of 98% (95% CI 96% to 99%). The clinical prediction rule showed a sensitivity of 40% (95% CI 27% to 54%) and specificity of 92% (95% CI 87% to 95%). Clinician judgment when patients presented within 48 hours showed a sensitivity of 67% (95% CI 39% to 86%) and specificity of 96% (95% CI 81% to 99%). Neither the rapid influenza test (P=.10) nor the clinical prediction rule (P=.42) was superior to clinician judgment alone in the diagnosis of influenza.

Conclusion: The suggestion that a clinical decision rule or a rapid influenza test is better than clinical judgment alone for the diagnosis of influenza in an unselected patient population is not supported by this study.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Clinical Competence
  • Clinical Laboratory Techniques / methods
  • Community-Acquired Infections / diagnosis
  • Decision Support Techniques
  • Emergency Medicine / instrumentation*
  • Emergency Medicine / methods*
  • Female
  • Humans
  • Influenza, Human / diagnosis*
  • Male
  • Middle Aged
  • Process Assessment, Health Care
  • Prospective Studies
  • Sensitivity and Specificity