Nitya Bakshi, Diana Ross, Lakshmanan Krishnamurti

While acute episodic pain is the hallmark of sickle cell disease (SCD), transition to chronic pain is a major cause of morbidity and impaired quality of life. One of the core diagnostic criteria used by Analgesic, Anesthetic, and Addiction Clinical Trial Translations Innovations Opportunities and Networks-American Pain Society Pain Taxonomy (AAPT) to define chronic SCD pain is the presence of pain on a "majority of days" in the past 6 months in one or more locations. The frequency characteristic of "majority of days" is adapted from the criteria of 15 days or more per month, used to define chronic migraine, but there are inadequate data to support this cutoff in SCD. Using an existing dataset of adults with SCD who completed patient-reported outcomes of pain interference, physical functioning, anxiety, depression, and fatigue using the National Institutes of Health (NIH) patient-reported outcomes measures information system (PROMIS) short-form instruments, we examined the association of the presence of pain on 3 or more days per week with patient-reported outcomes of functioning. In unadjusted analyses, presence of pain on 3 or more days a week was associated with higher median PROMIS scores of pain interference, anxiety, and depression. Median PROMIS scores of fatigue and physical function were worse in women compared with men in unadjusted analyses. We did not find any difference in median PROMIS pain scores between adults aged ≤35 years compared with those aged ≥35 years. In linear regression models, after adjustment for age and sex, the presence of pain on 3 or more days a week was found to be associated with worse pain interference and anxiety. These data support the clinical relevance of the frequency characteristic of pain on a "majority of days" in the definition of chronic SCD pain, and provide the rationale for prospective studies to validate the clinical definition of chronic pain in SCD.