Night Pain Module for Rotator Cuff-Related Shoulder Pain

Night pain is an important symptom in rotator cuff-related shoulder pain. It may affect falling asleep, cause waking during the night, increase the need to change position, and make it difficult to return to sleep. Pain may also increase when the person lies on the affected shoulder. These features may not be fully described by a single pain score. This study aims to develop a short and practical Night Pain Module that can assess the different features of night pain in clinical practice and research.

The current draft of the Night Pain Module contains eight items. These items assess difficulty falling asleep because of shoulder pain, the number of nights with pain-related waking, pain intensity at the time of waking, average shoulder pain during the night, increased pain when lying on the affected shoulder, pain relief after changing position, the need to change position because of pain, and difficulty returning to sleep after waking because of shoulder pain. Participants will answer the items based on their experience during the previous seven days. The number and wording of the items may be revised after expert panel review and pilot testing.

The development process will have three stages. First, the draft items will be reviewed by a multidisciplinary panel of 20 experts, including specialists in physical medicine and rehabilitation, orthopedics and traumatology, algology, and psychiatry. The experts will rate each item for clinical relevance, clarity, and ability to represent night pain. Their ratings will be used to assess content validity and to revise or remove items when necessary.

Second, the revised module will be tested in a pilot group of approximately 20-30 participants. The pilot assessment will examine whether the items are easy to understand, how long the module takes to complete, whether any items are frequently left unanswered, and whether responses are concentrated at the lowest or highest possible scores. The pilot data will not be included in the main psychometric analyses. Necessary changes will be made before the final version is used in the main study.

Third, the final version of the Night Pain Module will be evaluated in the main study sample. Its structure will be examined using exploratory and confirmatory factor analyses. These analyses will assess whether the items measure one general night pain concept or separate features, such as sleep-disturbing pain and position-related pain. Internal consistency and item-total relationships will also be evaluated.

Approximately 60 clinically stable participants who do not receive treatment for their shoulder during the interval will complete the module again after 7-10 days. These data will be used to assess test-retest reliability.

The clinical validity of the module will be evaluated by examining its relationships with the Pittsburgh Sleep Quality Index, the Shoulder Pain and Disability Index, daytime shoulder pain intensity, and the Pain Catastrophizing Scale. Module scores will also be compared between participants with better and poorer sleep quality. These analyses will show whether the module reflects the expected relationships between night pain, sleep, shoulder function, daytime pain, and pain-related thoughts. The study is observational and does not include treatment assignment or an invasive procedure.