Table 1.

Design Characteristics of Included Studies (All Were Cohort and Independent, with Blinding Not Explicitly Stated)

StudySettingInfluenzanPopulationReference StandardInclusion Criteria
Nicholson et al 199710CommunityA or B291Mean age, 73 years; 51.8% female4× rise in titer for Influenza ARespiratory infection (over age 60)
Carrat et al, 199712Primary care office and home visitA or B130Mean age, 33.2 years; 59% femaleFluorescent monoclonal antibodiesSuspected influenza (influenza-like illness, upper or lower respiratory tract infection, and/or fever >38 without other evidence of infection within 36 hours of onset)
Carrat et al, 19999Primary care office and home visitsA600Mean age, 38 years; 58% femaleDIF and ELISA; 25% culture + PCRSuspected influenza (all patients over age 1 with ≥1 of the following: influenza-like illness, upper or lower respiratory tract infectious syndrome, and/or temp >38°C without any infectious signs or symptoms.)
Monto et al, 199611Primary care officeA or B897NAViral culture or positive serologySuspected influenza (influenza-like illness with fever and cough or sore throat presenting between November and April)
Lina et al, 199613Primary care officeA or B340NA (broad age range)Culture or ELISASuspected influenza; data not available for patients without positive viral nasal swab.
Long et al, 199714Primary care officeA or B788Mean age, 76 in adults, 5 in childrenTissue culture, with ELISA to type the virusAdults over age 65 and children with respiratory or febrile illness in community medical and pediatric practices.
Monto et al, 20008OutpatientA or B3744Mean age, 34.7 years; 52% female.Positive culture or ≥4× increase in influenza antibody titer in convalescent vs acute samplesSuspected influenza [fever (≥37.8°C; ≥37.2°C for patients ≥65 years in one study) or feverishness (subjective fever or chills) and 2 of the following: headache, myalgia, cough, or sore throat].
  • DIF, direct immunofluorescence; ELISA, enzyme-linked immunosorbent assay; NA, not available