The search for objective disease measures with which to compare symptom scores has also progressed. To date, the following measures have been evaluated: detection of virus with culture or polymerase chain reaction,16,19 cytokine measurement,20-22 serologic markers,23 physical examination,9,24 radiologic imaging,25,26 rhinomanometry,27,28 mucus weight,29 mucus velocity, and number of tissues used.30 None have been shown to be superior to self-reported symptoms in terms of precision, reliability, or responsiveness or in their ability to predict functional impairment or subsequent illness. Perhaps more important, none have been shown to reflect the values of the people who experience colds. Although a number of quality-of-life instruments have been developed to assess allergic rhinitis,31-36 we have been unable to locate any specifically developed to assess URI.
We therefore decided to develop the Wisconsin Upper Respiratory Symptom Survey (WURSS) to provide a standardized measure for evaluating the negative consequences of the common cold. We were particularly interested in developing a health-related quality of life instrument that would represent the symptomatic and functional dimensions that are important to cold-sufferers.37-40 The instrument should be able to discriminate accurately between active intervention and placebo effects in randomized therapeutic trials and should balance brevity and ease of use with optimal precision, reliability, and responsiveness.41-43 It should be based on self-diagnosis and self-assessment because neither accepted criteria nor adequate tests are available to diagnose “upper respiratory infection” or “acute infectious rhinosinusitis”(with or without “pharyngitis”) and because the vast majority of cold treatments will be taken without professional input after self-diagnosis.
Methods
Phase 1: Initial development during a randomized trial
The development of this study began in 1998 during the design of a randomized controlled trial (RCT) of echinacea as a cold treatment. We created our first instrument by showing successive drafts to friends and colleagues (mostly family physicians), stopping once we were satisfied that the questionnaire had reasonable face validity. This initial instrument rated global severity of illness (“How sick do you feel today?”) and 15 individual symptoms on a 9-point Likert-type scale. The 15 symptom-measuring items were complemented by 4 dichotomous (yes/no) functional outcome questions, adapted with permission from the validated Medical Outcomes Study 36-item Short-Form Health Survey (SF-36).44
This initial instrument was used in the spring of 1999 in the echinacea RCT.45 This experience provided a good initial test of our instrument, as the participants were recruited within 36 hours of their first symptom and monitored each day until they had answered “No” to the question, “Do you think that you are still sick today?” for 2 days in a row. Each participant was asked to fill out the questionnaire both on paper and on a computerized data-collecting facsimile (available at http://www.fammed.wisc.edu/samplecold).
Phase 2: Further instrument development using qualitative methods
After the echinacea RCT was completed, our primary concern was that we might be overlooking or under-representing important illness domains. We also suspected that wording, question order, response range, and other formatting concerns could be improved. To achieve these goals, we used qualitative instrument-development methodologies, involving the people we wanted to measure–cold-sufferers–in the development process.40,46-50
After obtaining approval from the University of Wisconsin Medical School Human Subjects Committee, we began interviewing Madison-area adults who responded to community advertising asking for volunteers with colds. Inclusion criteria required answering “Yes” to the question, “Do you believe that you have a cold?” For an interview to be arranged, at least one cold symptom had to be present, and the research assistant had to be convinced that the caller was indeed suffering from a common cold. Prospective participants with itchy eyes, sneezing, or a history of allergy were excluded if either the participant or the interviewer felt that any current symptoms might have been caused by allergy. Interviews were held in a location of mutual convenience and with the aid of an interview guide developed by our research team. Interviewers were carefully trained in the research protocol and used interview guides for both the initial telephone screen and the in-person interviews. Interviewers included both clinicians and nonclinicians.
The semistructured interview guide used open-ended questions designed to elicit the participants’ own terminology for describing their colds (Table 1).51-53 We aimed for an understanding of how the experience of the cold influenced the lives of the participants. Participants were first asked to list all their symptoms, then to describe how each symptom bothered them. Next, we asked which symptom(s) appeared first and which one(s) followed. We then asked which symptoms were most bothersome and why. Participants were asked to describe what they did to relieve their cold symptoms, why, and whether the therapy provided any relief. Participants were then asked about how their cold affected their lifestyle with regard to work, relationships, activities, and so forth. Additionally, we asked about symptoms and effects of previous colds. This exploratory phase of the interview lasted approximately 20 to 30 minutes.