The Wisconsin Upper Respiratory Symptom Survey is responsive, reliable, and valid

Abstract 

Objective

To assess reliability, responsiveness, importance to patients, and convergent validity for the Wisconsin Upper Respiratory Symptom Survey (WURSS-44) and to develop a short-form WURSS.

Study Design and Setting

Community-based recruitment of participants with colds. Prospective monitoring from within 48 hours of first symptom until 2 days after end of cold. The WURSS-44 includes 1 global illness severity item, 32 symptom-based items, 10 functional quality-of-life items, and 1 item assessing global change. The SF-36, SF-8, and the Jackson cold scale were used as external comparators.

Results

Participants included 104 women and 45 men, aged 18 to 80 years, self-reporting on 1,681 person-days of illness. Factor analysis suggested 10 dimensions, with reliability coefficients from 0.62 to 0.93. Comparing daily WURSS-44 to Jackson and SF-8 yielded Pearson correlation coefficients from 0.73 to 0.93, and from −0.60 to −0.84, respectively. Importance to patients and responsiveness assessment yielded a short version, the WURSS-21. Guyatt's responsiveness index was 0.54 for the SF-8, 0.61 for the Jackson, 0.71 for the WURSS-44, and 0.80 for the WURSS-21, suggesting that a two-armed trial would require 74 participants for the WURSS-21, 92 for the WURSS-44, 124 for the Jackson scale, and 156 for the SF-8.

Conclusions

The construct validity of WURSS-44 is supported by measures of reliability, responsiveness, importance to patients, and convergence. A shorter version, the WURSS-21, may be even more responsive.

Keywords: Clinical significance, Common cold, Controlled trials, Evidence-based medicine, Minimal important difference, Psychometrics, Quality of life, Questionnaires, Symptom measurement, Upper respiratory infection, Validation