Illness and otological changes during upper respiratory virus infection

Objectives: Upper respiratory virus infection is associated with the expres sion of symptoms and signs of illness, and with the development of complica tions in anatomically contiguous structures. In most epidemiological studie s, the frequency of the various complications is expressed as a fraction of the total population judged to be ill by report, signs, or symptoms. Becau se not all infected subjects become ill and because infected non-ill subjec ts may develop complications, such risk estimates could be inaccurate. The objective of this study was to estimate the magnitude of the presentation b ias during controlled, experimental infections. Study Design: This was a pr ospective, experimental study of the relationship between illness and otolo gical complications during experimental upper respiratory virus infection i n 316 adult volunteers. Methods: The data for illness and for abnormal midd le ear underpressure in adult (18-54 y) volunteers experimentally infected with one of three viruses (rhinovirus type 39, rhinovirus strain hanks, inf luenza A virus) were analyzed and expressed as the relative frequencies of infected subjects reporting illness, developing abnormal middle ear pressur e, and developing abnormal middle ear pressure in the absence of illness. R esults: For all three viruses, illness was documented in approximately 50% of the infected subjects. While the frequency of persons developing abnorma l middle ear underpressure was greater in the infected-ill subjects, approx imately one third of all infected subjects developing that complication did not report illness. Conclusions: These results support a large presentatio n bias in epidemiological surveys of viral upper respiratory infections, an d infer that those surveys underestimate the true frequency of complication s resulting from such infections.