Discussion
In a recent literature research, we identified 2 specific English-language questionnaires used to assess QOL in patients with COS: modified OHIP-14[11] and (COSS)[2, 7–10], one questionnaire to assess patient satisfaction post sialendoscopy[12] and another questionnaire (Multidisciplinary Salivary Gland Society (MSGS) questionnaire) to quantify the burden of symptoms caused by xerostomia and sialadenitis[20].
The primary purpose of the present article was to design a specific questionnaire in Spanish to assess QOL in patients with COS (Supplementary Table 3) across six selected dimensions (physical function and symptoms, social roles, occupational activities, emotional status, and health perception). There are some similarities between items of the CSOC and the Modified OHIP-14, COSS and MSGS. The patient satisfaction questionnaire, on the other hand, is quite different[12];it contains 14 questions that cover pre-sialendoscopy symptoms, progress post-sialendoscopy, change in QOL, and overall patient satisfaction and does not evaluate social roles, sleep disorders, or emotional status[12]. The modified OHIP-14 was designed to measure self-reported functional limitation, discomfort, and disability in patients with salivary gland pathology[11]; the COSS examines sialadenitis symptoms, daily functions, emotional symptoms, sleeping and daily activities[7]; and the MSGSevaluatesxerostomia and sialadenitis symptoms as well as their frequency, intensity, and associated discomfort[20].
As we can see, all 5 specific questionnaires measure the presence of symptoms and functional limitations. The CSOC, modified OHIP-14[11], and COSS[7] include items that target social roles. The CSOC and modified OHIP- 14 assess emotional status. The CSOC includes recreational activities to cover the whole occupational dimension. The modified OHIP-14 has an item on work[11] that does not take unemployed or retired people into account, and the COSS prompts participants to provide information on daily activities in general[7]. The COSS and CSOC have an item evaluating sleep.
A complete validation process was conducted with a pilot study as well asassessment of content and construct validity. None of the existing studies describes a process of content validity such as ours,which includes an expert panel.
After the pilot study and assessment of content validity,the CSOC was modified to include 18 items. The analysis of the new 18-items psychometric properties suggested that CSOC has high feasibility (absence of missing responses and around 5 minutes required to fill out the questionnaire), high stability (test retest of 0.86), high internal consistency (Cronbach α coefficient of 0.90), and high responsiveness to change. The absence of missing responses and the short time required indicate that the responders found the CSOC to be easy to use. The significant difference between the scores of pre- and postsialendoscopy CSOC means that CSOC is a good tool to assess the improvement of COS after sialendoscopy. Additionally, CSOC proved its capacity to distinguish between patients with frequent and occasional episodes of sialadenitis.
On the other hand, CSOC had a low to moderate negative correlation with the different dimensions and component summaries of SF-36. The correlation has the expected direction, and the low correlation could be explained by the fact that SF-36 is not sensitive enough to capture the difference in COS symptoms[2, 7].
This study has three main limitations. First, we were unable to assess criterion validity due to the lack of a validated gold standard test. Second, we did not use a healthy control group. Third, the subjects used for the validation process only represent those patients who have an indication for sialendoscopy; to validate CSOC for all COS patients, a study which includes patients with and without indication for sialendoscopy should be conducted.