Evaluation of the impact of fibromyalgia on patients' sleep and the content validity of two sleep scales
BACKGROUND
Disturbed sleep is commonly reported in fibromyalgia (FM). Both the Sleep Quality Numeric Rating Scale (NRS) and the Medical Outcomes Study Sleep Scale (MOS-Sleep) have demonstrated positive psychometric properties in patients with FM. However, these assessments were developed prior to the current recommendation to include patient input during the concept elicitation or item generation phases. Therefore, the objective of this study was to evaluate the impact of FM on participants, including their sleep, and to test the content validity of these two sleep measures in FM patients.


METHODS
Qualitative interviews were conducted in Raleigh, North Carolina and Detroit, Michigan with 20 adults who reported a physician diagnosis of FM. Sixteen participants were female, 13 were white, and the average age was 50 years. Two researchers conducted all interviews using a structured guide.


RESULTS
Participants consistently reported that FM had a debilitating impact on their lives and their sleep, particularly getting to sleep and staying asleep. Participants responded positively to the Sleep Quality NRS as an assessment of their sleep. The majority of participants stated that they would not change the response numbering or wording of the item's anchors. Participants also responded positively to the 24-hour recall period of the Sleep Quality NRS. Participants found the 12-item MOS-Sleep to be appropriate and relevant; 19 participants indicated the measure captured all of their sleep-related symptoms. However, areas for potential modification were identified, such as the need to separate the item regarding awakening short of breath and awakening with a headache into two separate questions. Participants also questioned the relevance of the snoring and awakening short of breath items to FM. Half of participants expressed a preference for a daily rather than a weekly recall period.


CONCLUSION
This study demonstrates the significant impact that FM has on patients' lives, particularly sleep. While patients with FM were not part of the development of the generic sleep assessments that were evaluated, this study provides evidence of their content validity, supporting their use in FM studies. Modifications to the MOS-Sleep may improve the psychometric properties and relevance to patients with FM.