Characteristics of Included Studies
| Swiss Population* (n = 201) | US Population† (n = 258) | |
|---|---|---|
| Data collection period | December 1999 to February 2000 | January to March 2002 |
| Study design | Prospective cohort | Prospective cohort |
| Setting | University primary care clinic that serves an urban population of 150,000 in Lausanne, Switzerland | Emergency department or urgent care ambulatory patients in a large tertiary care university hospital in San Francisco, California |
| Inclusion criteria | Adult outpatients with influenza-like illness as determined by the primary care physician | Consecutive adults with symptoms of an acute respiratory tract infection (cough, sinus pain, congestion/rhinorrhea, sore throat or fever) developing in past 3 weeks |
| Outcome | Presence of influenza A or B | Presence of influenza A or B |
| Reference standard | Culture | PCR |
| Prevalence of influenza | 104 (52.8) | 53 (20.5) |
| Men | 101 (50) | 103‡ (40) |
| Mean age, years (range) | 34.3 (17–86) | 38.8 (18–90) |
| Fever | 116 (58) | 54 (21) |
| Cough | 186 (93) | 235 (91) |
| Sore throat | 151 (75) | 181 (70) |
| Myalgia | 181 (90) | 154 (60) |
| Rhinitis | 163 (81) | 185 (72) |
| Headache | 169 (84) | 190 (74) |
| Chills/sweating | 166 (83) | 158 (61) |
| Fatigue | 184 (92) | 197 (76) |
| Onset <48 hours | 106 (53) | 45 (17) |