Predictors of Sustained Response to Functional Restoration in a Military Population.

INTRODUCTION: The purpose of this study was to determine if improvement in pain impact and functional performance following a functional restoration (FR) program was sustained up to 6 months posttreatment and to identify predictors of sustained improvement. MATERIALS AND METHODS: Secondary analysis of data collected during randomized clinical trial. Study population included 108 US active duty service members who completed an FR program, as well as 3- and/or 6-month follow-up assessments. Primary outcome measure was the NIH Research Task Force (pain) impact score (PIS). Secondary outcome was a composite functional performance measure of treadmill, lifting, and carrying tolerances. Variables analyzed to determine their predictive value included demographics; treatment hours; measures of pain intensity, function, mood, sleep, social satisfaction, pain catastrophizing, kinesiophobia, self-efficacy, pain acceptance, patient activation, functional performance, and neuropathic pain. RESULTS: Mean PIS and functional performance improved significantly immediately following FR, but after 6 months, only improvement in functional performance sustained. Responder analysis showed that 6 months after FR, 42% of participants reported improvement that exceeded the minimal clinically important difference in PIS or functional performance. Predictors of sustained PIS improvement included younger age, absence of neuropathic pain features, less self-rated disability, better baseline functional performance, and worse baseline PIS. Predictors of sustained functional performance improvement included more treatment hours, lower baseline pain catastrophizing, and lower baseline functional performance. CONCLUSIONS: This study supports the investment of treatment time in FR to yield sustained clinically meaningful improvement, as observed in over 40% of this study's military participants. Pretreatment predictors of sustained response included lower pain catastrophizing and absence of neuropathic pain. Further research is needed to determine if treatments that improve pain catastrophizing and neuropathic pain will result in sustained improvement in pain impact and functional performance following FR program participation.

Pattern of Cumulative Treatment Hours on Pain Impact and PROMIS Outcomes.

INTRODUCTION: Participation in interdisciplinary treatments is associated with improvement in pain intensity, physical function, and additional pain-related outcome domains. However, the effect of cumulative treatment hours on outcomes remains unknown among military patients. The present analysis examined the relationship between cumulative interdisciplinary treatment hours and pain management outcomes at a single interdisciplinary pain management center (IPMC). MATERIALS AND METHODS: This is a retrospective observational study of data previously collected as standard of care at the Madigan Army Medical Center, approved by the Institutional Review Board. We included patients who received treatment at the IPMC and completed at least two self-report assessment batteries: one at baseline and at least one between 90 and 180 days after baseline (n = 882). The primary outcome was pain impact. Secondary outcomes included fatigue, depression, anxiety, and sleep-related impairment. RESULTS: Generalized additive models indicated that cumulative treatment hours were significantly associated with improvement in pain impact, fatigue, and depression. Patients who had higher baseline pain impact, who had mild or no depressive symptoms, and who were >40 years of age had greater improvements in pain impact following treatment, relative to those with lower pain impact, moderate-to-severe depressive symptoms, and were 40 years of age or younger, respectively. Additional research is needed to elucidate the effect of different therapies and additional patient factors in understanding the "therapeutic dose" of interdisciplinary pain management. CONCLUSIONS: A higher number of cumulative treatment hours was associated with improvement of pain impact, fatigue, and depression among military personnel receiving interdisciplinary pain treatment. At least 30 hours of sustained interdisciplinary treatment appears to be the threshold for improvement in pain impact and related outcomes.