Direction of results by number of studies reporting each factor for factors investigated by 3 or more studies

FactoraNo. of studies with:Total no. of studies
Positive associationNegative associationNo significant association
Patient level
    Male sex1910
    Medical insurance type*178
    Black vs white race156
    Purulent sputum55
    Respiratory physical exam findings55
    Desire for antibiotics314
    Duration of illness123
    Household income123
    Sinus pain on exam33
    Tonsillar exudate33
    Tympanic membrane abnormality33
Physician level
    Perception of desire for antibiotics66
    Severity of patient illness44
    High-vol practice123
    International medical graduate213
    Geographic location*167
    Rural vs urban347
    Yr of visit44
    Visit location (office, emergency department, hospital clinic)*123
  • a An asterisk denotes a categorical variable with different possible reference groups; therefore, the direction of effect is not always comparable. We have categorized any study that found a statistically significant association in one direction as a positive association for illustrative purposes.