Temporal dynamics of pain: an application of regime-switching models to ecological momentary assessments in patients with rheumatic diseases

Abstract

Advances in pain measurement using ecological momentary assessments offer novel opportunities for understanding the temporal dynamics of pain. This study examined whether regime-switching models, which capture processes characterized by recurrent shifts between different states, provide clinically relevant information for characterizing individuals based on their temporal pain patterns. Patients with rheumatic diseases (N = 116) provided 7 to 8 momentary pain ratings per day for 2 weekly periods, separated by 3 months. Regime-switching models extracted measures of Average pain (mean level over time), Amplitude (magnitude of shifts in pain levels), Persistence (average duration of pain states), and Dominance (relative duration of higher vs lower pain states) for each patient and assessment period. After controlling for Average pain, the Persistence of pain states uniquely predicted emotional functioning measures, whereas the Dominance of higher pain uniquely predicted physical functioning and pain interference. Longitudinal analyses of changes over the 3 months largely replicated cross-sectional results. Furthermore, patients' retrospective judgments of their pain were uniquely predicted by Amplitude and Dominance of higher pain states, and global impressions of change over the 3 months were predicted by changes on Dominance, controlling for Average pain levels. The results suggest that regime-switching models can usefully capture temporal dynamics of pain and can contribute to an improved measurement of patients' pain intensity.

An Ecological Momentary Assessment Study of Pain Intensity Variability: Ascertaining Extent, Predictors, and Associations With Quality of Life, Interference and Health Care Utilization Among Individuals Living With Chronic Low Back Pain

“…Our results are in contrast with some other studies that showed depressive ratings, selfefficacy, and emotional and physical functioning to be associated with intra-individual variability in pain intensity scores 67,69,90 . Some of these studies, however, either looked at variability across daily pain averages 67,90 , or used different metrics of pain intensity variability such as average duration of pain states 69 .…”

High-resolution, field approaches for assessing pain: Ecological Momentary Assessment

“…One study took a more methodological approach investigating the feasibility of promising statistical models. 42 The flexibility of EMA designs for studies of pain is evident in these studies.…”

“… 45 Borrowing from statistical models in research on emotion regulation, novel summary statistics have been developed to capture a patient's pain variability from EMA, including the probability a patient experiences acute changes in pain 35 , 41 and the relative durability of pain at elevated vs lower levels. 42 Such summary statistics of symptom variability could enhance accurate classification of chronic pain conditions 18 and facilitate detection of effective treatments. Women with fibromyalgia have, for example, shown more variability in fatigue levels compared to women with rheumatoid arthritis and osteoarthritis, highlighting important differences between conditions.…”

“…Eleven original articles were found that reported results from 9 different projects (see Supplemental Table 1, available at http://links.lww.com/PAIN/B159 ). 6 , 7 , 9 , 15 , 19 , 28 , 38 , 42 , 49 , 55 All the studies were observational designs and most investigated pain intensity, 9 , 15 , 19 , 28 , 34 , 38 , 42 , 49 , 55 pain interference, 7 , 19 , 27 and pain behavior, 19 or examined relationships between pain and other domains (such as sleep 55 or social support 9 ). One study took a more methodological approach investigating the feasibility of promising statistical models.…”

Beyond Average: Providers' Assessments of Indices for Measuring Pain Intensity in Patients With Chronic Pain

“…Over the past decades, real-time data collection methods involving Experience Sampling or Ecological Momentary Assessment (EMA) have received increasing attention in pain research. Using EMA, patients rate their momentary pain intensity multiple times per day in their natural environment, which makes it possible to capture temporal features of patients' pain intensity in great detail (7)(8)(9)(10). While assessments of specific aspects of pain intensity other than average pain are beginning to be acknowledged in research on chronic pain, to date, it is unclear which temporal indices of patients' pain intensity should be assessed to achieve the greatest utility.…”