Upper respiratory tract infection: predisposing factors and duration of symptoms in patients over 12 years of age.

Some patients suffer greatly from upper respiratory tract infections, while others suffer much less. Various factors, such as allergy and nasal injury, have been suggested in the literature to predispose patients to infection. Predisposing factors and patterns of disease were examined in a prospective, controlled study of 238 patients attending two general practices. A questionnaire, designed to study the development and duration of upper respiratory symptoms and the occurrence of factors which predispose patients to disease, was completed for index and control patients when they presented with symptoms. A follow-up card was completed by index patients one month later.Family history of catarrh was found to be a significant predisposing factor to upper respiratory tract infection. However, no significant differences between index and control patients were found for any of the other generally accepted factors. Heavy smoking and increased age were associated with prolonged symptoms lasting 60 days or more.It is concluded that traditional theories of the causes of upper respiratory tract infections may need to be revised.