Urine Metabolites as Indicators of Chronic Pain and Related Symptoms in Active-Duty Service Members: A Secondary Data Analysis of a Pragmatic Clinical Trial With SMART Design

Background Chronic pain is a major cause of distress and disability, and biomarkers may aid in the assessment and treatment of it. Urine metabolites may be valuable bioindicators that can provide biological insight regarding chronic pain. Objectives To investigate the relationship between a multimarker composite measure of metabolites and patient-reported outcomes scores in adults with chronic pain, using data from a pragmatic clinical trial with a sequential, multiple-assignment randomized trial design. Methods Self-reported measures and urine samples from 169 active-duty service members with chronic pain were collected. Urine was analyzed using a preestablished panel of metabolites, including four previously identified biomarkers of pain: kynurenic acid, pyroglutamic acid, ethylmalonic acid, and methylmalonate. Multivariable linear regression models—adjusted for participant characteristics such as age and sex—were used to cross-sectionally examine the relationship between 11 patient-reported outcomes (fatigue, sleep-related impairment, anxiety, depression, anger, pain catastrophizing, physical function, pain interference, satisfaction with participation with social roles, pain intensity, and pain impact score) and the four urine metabolites both individually and as a composite (urine metabolite pain indicator, or UMPI). Given the study’s small sample size and exploratory nature, a significance threshold of p ≤ .10 was used for all analyses. Results The UMPI showed statistically significant associations with five self-reported measures (fatigue, anxiety, depression, physical functioning, and pain impact score); adjusted Pearson correlations ranged from .18 to .25. Individual metabolite analyses supported these findings, with all relationships between individual metabolites and self-reported measures showing positive associations. Kynurenic acid and ethylmalonic acid showed the strongest associations, each having statistically significant relationships with four individual self-reported measures, while pyroglutamic acid had statistically significant relationships with three self-reported measures and methylmalonate with none. The UMPI demonstrated feasible reliability. Discussion Our finding of associations between the UMPI and components of the self-reported measures supports the development of the UMPI and these four urine metabolites as biomarkers for chronic pain outcomes. Further research is planned and will be essential for establishing mechanistic insight and guiding biomarker development within the context of pain management.

Interindividual Variability in Self-Monitoring of Blood Pressure Using Consumer-Purchased Wireless Devices

Background Engagement with self-monitoring of blood pressure (BP) declines, on average, over time but may vary substantially by individual. Objectives We aimed to describe different 1-year patterns (groups) of self-monitoring of BP behaviors, identify predictors of those groups, and examine the association of self-monitoring of BP groups with BP levels over time. Methods We analyzed device-recorded BP measurements collected by the Health eHeart Study—an ongoing prospective eCohort study—from participants with a wireless consumer-purchased device that transmitted date- and time-stamped BP data to the study through a full 12 months of observation starting from the first day they used the device. Participants received no instruction on device use. We applied clustering analysis to identify 1-year self-monitoring, of BP patterns. Results Participants had a mean age of 52 years and were male and White. Using clustering algorithms, we found that a model with three groups fit the data well: persistent daily use (9.1% of participants), persistent weekly use (21.2%), and sporadic use only (69.7%). Persistent daily use was more common among older participants who had higher Week 1 self-monitoring of BP frequency and was associated with lower BP levels than the persistent weekly use or sporadic use groups throughout the year. Conclusion We identified three distinct self-monitoring of BP groups, with nearly 10% sustaining a daily use pattern associated with lower BP levels.