Influenza contributes significantly to morbidity and mortality in the winter season. The aim of the study was to identify clinical signs and symptoms most predictive of influenza infection in children and adults with influenza-like illness. A prospective systematic sampling analysis of clinical data collected through sentinel surveillance system for influenza in 32 primary care centers and one tertiary care hospital in Slovenia during two consecutive influenza seasons (2004/2005 and 2005/2006) was carried out. Children and adults who had influenza-like illness, defined as febrille illness with sudden onset, prostration and weakness, muscle and joint pain and at least (cough, sore throat, coryza) were included and tested for influenza A and B virus, adenovirus, respiratory syncytial virus and enterovirus by RT-PCR. Clinical data were evaluated in statistical models to identify the best predictors for the confirmation of influenza for children (under age of 15) and adults. Of 1,286 patients with influenza-like symptoms in both seasons 211 were confirmed to have influenza A or B alone and compared to 780 influenza-negative patients. A fever over 38°C, chills, headache, malaise and sore eyes revealed a significant association with positive RT-PCR test for influenza virus in children. In adults, only three symptoms were significantly related to PCR-confirmed influenza infection: fever, cough and abnormal breath sounds. The stepwise logistic regression analysis showed that four symptoms predicted influenza in children: fever (38°C or more) (p=0.010), headache (p=0.030), cough (p=0.044) and absence of abnormal breathing sounds (p=0.015) with sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 5.1%, 98.1%, 57.1% and 80.1%, respectively. For adults, the strongest impact on influenza positivity was found for fever (p=0.008) and cough (p=0.085). The model for adults had less favorable characteristics, with sensitivity, specificity, PPV and NPV of 0%, 100%, 0% and 76.4%, respectively. Differences in clinical predictors of influenza in children compared to adults were found. The model for adults was acceptable but not a good one. The model for children was found to be more reliable than the prediction model for adults.
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 Fleming D.M., Elliot A.J, The impact of influenza on the health and health care utilisation of elderly people, Vaccine, 2005, 23,Suppl 1, S1–S9 http://dx.doi.org/10.1016/j.vaccine.2005.04.018
 Simonsen L., Clarke M.J., Williamson G.D., Stroup D.F., Arden N.H., Schonberger L.B., The impact of influenza epidemic on mortality: introducing a severity index, Am. J. Pub. Health, 1997, 87, 1944–1950 http://dx.doi.org/10.2105/AJPH.87.12.1944
 Kyncl J., Prochazka B., Goddard N.L., Havlickova M., Castkova J., Otavova M.,et al., A study of excess mortality during influenza epidemics in the Czech Republic, 1982–2000, Eur. J. Epidemiol., 2005, 20, 365–371 http://dx.doi.org/10.1007/s10654-005-1067-y
 Neuzil K.M., Hohlbein C., Zhu Y., Illness among schoolchildren absenteeism from work, and secondary illness in families, Arch. Pediatr. Adolesc. Med., 2002, 156, 986–991
 Falsey A.R., Treanor J.J., Betts R.F., Walsh E.E., Viral respiratory infections in the institutionalized erlderly: clinical and epidemiologic findings, J. Am. Geriatr. Soc., 1992, 40, 115–119
 Peltola V., Reunanen T., Ziegler T., Silvennoinen H., Heikkinen T., Accuracy of clinical diagnosis of influenza in outpatient children, Clin. Infect. Dis., 2005, 41, 1198–1200 http://dx.doi.org/10.1086/444508
 Monmany J., Rabella N., Margall N., Domingo P., Gich I., Vázquez G., Umasking influenza virus in patients attended to in the emergency department, Infection, 2004, 32, 89–97 http://dx.doi.org/10.1007/s15010-004-3088-y
 Ebell M.H., White L.L., Casault T., A systematic review of the history and physical examination to diagnose influenza, J. Am. Board. Fam. Pract., 2004, 17, 1–5 http://dx.doi.org/10.3122/jabfm.17.1.1
 Babock H.M., Merz L.R., Fraser V., Is influenza an influenza like illness? Clinical presentation of influenza in hospitalized patients, Infect. Control. Hosp. Epidemiol., 2006, 27, 266–270 http://dx.doi.org/10.1086/501539
 Monto A.S., Gravenstein S., Elliot M., Colopy M., Schweinle J, Clinical signs and symptoms predicting influenza infection, Arch. Intern. Med., 2000, 160, 3243–3247 http://dx.doi.org/10.1001/archinte.160.21.3243
 Govaert T.M., Dinant G.J., Aretz K., Knottnerus J.A., The predicitve value of influenza symptomatology in elderly people, Fam. Pract. 1998, 15, 16–22 http://dx.doi.org/10.1093/fampra/15.1.16
 Boivin G., Hardy I., Tellier G., Mazaide J., Predicting influenza infections during epidemics with use of a clinical case definition, Clin. Infect. Dis., 2000, 31, 1166–1169 http://dx.doi.org/10.1086/317425
 Friedman M.J., Attia M.W., Clinical predictors of influenza in children, Arch. Pediatr. Adolesc. Med., 2004, 158, 391–394 http://dx.doi.org/10.1001/archpedi.158.4.391
 Ohmit S.E., Monto A.S., Symptomatic predictors of influenza virus positivity in children during the influenza season, Clin. Infect. Dis., 2006, 43, 564–568 http://dx.doi.org/10.1086/506352
 Brownstein J.S., Kleinman K.P., Mandl K.D., Identifying pediatric age groups for influenza vaccination using a real-time regional surveillance system, Am. J. Epidemiol,, 2005, 162, 686–693 http://dx.doi.org/10.1093/aje/kwi257
 Göndahl B., Puppe W., Hoppe A., Kühne I., Weigl J.A.I, Schmidt H.J,. Rapid identification of nine microorganisms causing acute respiratory tract infections by single-tube multiplex Reverse Transcription-PC: Feasibility Study, J. Clin. Microbiol., 1999, 37, 1–7
 Stocton J., Ellis J.S., Saville M., Clewley J.P., Zambon M.C,. Multiplex PCR for typing and subtyping influenza and respiratory syncytial viruses, J. Clin. Microbiol., 1998, 36, 2990–2995
 Poddar S.K., Influenza virus types and subtypes detection by single step single tube multiplex reverse transcription-polymerase chain reaction (RT-PCR) and agarose gel electrophoresis, J. Vir. Meth., 2002, 99, 63–70 http://dx.doi.org/10.1016/S0166-0934(01)00380-9
 Carrat F., Tachet A., Housset B., Valleron A.J., Rouzioux C., Influenza and influenza-like illness in general practice: drawing lessons for surveillance from a pilot study in Paris, France, Brit. J. Gen. Pract., 1997, 47, 217–220
 van Elden L.J., van Essen G.A., Boucher C.A., van Loon A.M., Nijhuis M., Schipper P., et al., Clinical diagnosis of influenza virus infection: evaluation of diagnostic tools in general practice, Br. J. Gen. Pract., 2001, 51, 630–634
 Sharma V., Dowd M.D., Slaughter A.J., Simon S.D., Effect of rapid diagnosis of influenza virus type A on the emergency department management of febrile infants and toddlers, Arch. Pediatr. Adolesc. Med., 2002, 156, 41–43
 Zitterkopf N.L., Leekha S., Espy M.J., Wood C.M., Sampathkumar P., Smith T.F., Relevance of influenza A virus detection by PCR, shell vial assay, and tube cell culture to rapid reporting procedures, J. Clin. Microbiol., 2006, 44, 3366–3367 http://dx.doi.org/10.1128/JCM.00314-06
 Wolf D.G., Greenberg D., Kalkstein D., Shemer-Avni Y., Givon-Lavi N., Saleh N., Goldberg M.D., Dagan R., Comparison of human metapneumovirus, respiratory syncytial virus and influenza A virus lower respiratory tract infections in hospitalized young children, Pediatr. Infect. Dis. J., 2006, 25, 320–324 http://dx.doi.org/10.1097/01.inf.0000207395.80657.cf
 Carrat F., Tachet A., Rouzioux C., Housset B., Valleron A.J., Evaluation of clinical case definitions of influenza: detailed investigation of patients during the 1995–1996 epidemic in France, Clin. Infect. Dis., 1999, 28, 283–290 http://dx.doi.org/10.1086/515117
 Fleming D.M., van der Velden J.K., Paget W.J., The evolution of influenza surveillance in Europe and prospects for the next ten years, Vaccine, 2003, 21, 1749–1753 http://dx.doi.org/10.1016/S0264-410X(03)00066-5
 European Influenza Surveillance Scheme. Annual report. 2003–2004 influenza season. Utrecht, The Netherlands: NIVEL, January 2005. http://www.eiss.org/html/annual_reports.html. Accessed 15 July 2007.
 Navarro-Mari J.M., Perez-Ruiz M., Cantudo-Munoz P., Petit-Gancedo C., Jimenez-Valera M., Rosa-Fraile M., Influenza Surveillance Network in Andalusia, Spain. Influenza-like illness criteria were poorly related to laboratory-confirmed influenza in a sentinel surveillance study. J. Clin. Epidemiol., 2005., 58, 275–279 http://dx.doi.org/10.1016/j.jclinepi.2004.08.014
 Call S.A., Vollenwieder M.A., Hornung C.A., Simel D.L., McKinney P.W., Does this patient have influenza?, JAMA, 2005, 293, 987–997 http://dx.doi.org/10.1001/jama.293.8.987
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