Reliabilities of Intra-Individual Mean and Intra-Individual Variability of Self-Reported Pain Derived From Ecological Momentary Assessments: Results From the Einstein Aging Study.

An individual's pain experiences vary substantially over time. Though variability in pain may be an important metric which usually predicts health consequences, research on the measurement of pain variability estimates is lacking among older adults. We aimed to examine the reliabilities of both intra-individual mean (IIM) and intra-individual variability (IIV) of pain assessed using ecological momentary assessments (EMA) among racially diverse, systematically recruited community dwelling cohort of older adults. Participants (N = 311, age = 70-91) completed a 14-day EMA protocol which included self-reports of pain intensity, pain interference with activities, and pain interference with concentration multiple times a day. Over a 2-week period, we found excellent reliabilities for both pain IIM (.99), and pain IIV (≥.90). We also found that we need 5 to 6 days to achieve good reliability (.8) for pain IIV, suggesting that a shorter protocol may be used to reduce participants' burden among the current sample, although caution is required when using this result to determine EMA study designs among different samples. Future studies are required to examine the associations of various EMA pain metrics with different health outcomes among older adults to facilitate the detection of underlying mechanisms linking pain to health as a prelude to interventions. PERSPECTIVE: Mean levels and variability in pain intensity, pain interference with activities, and pain interference with concentration can be reliably measured to be linked with various health outcomes in older adults. Future studies including these pain metrics will assess the natural history, the consequences, and effects of intervention of pain.