Relations among questionnaire and laboratory measures of rhinovirus infection

Due to high incidence and quality-of-life impact, upper respiratory infection substantially impacts on population health. To test or compare treatment effectiveness, a well-designed and validated illness-specific quality-of-life instrument is needed. Data reported in the current study were obtained from a trial testing echinacea for induced rhinovirus infection. Laboratory-assessed biomarkers included interleukin (IL)-8, nasal neutrophil count (polymorphonuclear neutrophils (PMN)), mucus weight, viral titre and seroconversion. The questionnaires used included the general health short form (SF)-8 (24-h recall version), the eight-item Jackson cold scale, and the 44-item Wisconsin Upper Respiratory Symptom Survey (WURSS). In total, 399 participants were inoculated with rhinovirus and monitored over 2,088 person-days. Statistically significant associations were found among nearly all variables. Between-questionnaire correlations were: WURSS-Jackson = 0.81; WURSS-SF-8 = 0.62; and Jackson-SF-8 = 0.60. Correlations with laboratory values were as follows: WURSS-mucus weight = 0.53; Jackson-mucus weight = 0.55; WURSS-viral titre = 0.37; Jackson-viral titre = 0.46; WURSS-IL-8 = 0.31; Jackson-IL-8 = 0.36; WURSS-PMN = 0.31; and Jackson-PMN = 0.28. Neither WURSS nor Jackson yielded satisfactory cut-off scores for diagnosis of infection. Symptomatic and biological outcomes of upper respiratory infection are highly variable, with only modest associations. While Wisconsin Upper Respiratory Symptom Survey and Jackson questionnaires both correlate with biomarkers, neither is a good predictor of induced infection. The inclusion of functional and quality-of-life items in the Wisconsin Upper Respiratory Symptom Survey does not significantly decrease the strength of association with laboratory-assessed biomarkers.