CSOC Questionnaire Development
The developmental stage of a questionnaire consists of domain identification, item generation, and instrument construction[13]. Domain identification was accomplished by reviewing the published literature. Four papers made reference to specific questionnaires (COSS questionnaire[2, 7], modified OHIP-14[11], and patient satisfaction questionnaire[12]) and 3 analysed findings generated by applying generic QOL questionnaires (Glasgow Benefit Inventory[6, 14] and 5D-HRQoL[15]).
We chose health-related QOL as our domain of interest. The conceptual definition of QOL selected was the level of well-being resulting from a self-assessment of several dimensions of life and considering the impact of these dimensions on health status[16]. The selected dimensions were physical function and symptoms, performance of social roles, occupational activities, emotional status, and how the patient feels about their health.
The next step was to generate a list of potential items for each dimension. After interviewing patients with COS, the research team selected 20 items. Items were organized from specific conditions related with sialadenitis to complaints related to overall health status. Details of the CSOC questionnaire are shown in table 1.
Each item uses a Likert-type response scale (score 0-4). Lower scores indicate better QOL in COS, whereas higher scores are suggestive of greater degrees of impairment (Supplementary Table 1).
At the start of the questionnaire, patients were asked to score each item based on their experience over the 3 preceding months. The research group used this timeframe because of the intermittent and fluctuating nature of COS symptoms according to their own experience.