Cognitive flexibility and persistent post-surgical pain: the FLEXCAPP prospective observational study.

BACKGROUND: Impaired performance on tasks assessing executive function has been linked to chronic pain. We hypothesised that poor performance on tests assessing the ability to adjust thinking in response to changing environmental stimuli (cognitive flexibility) would be associated with persistent post-surgical pain. METHODS: We conducted a single-centre prospective observational study in two perioperative cohorts: patients undergoing total knee arthroplasty or noncardiac chest surgical procedures. The co-primary outcome measures compared preoperative performance on the Trail Making Test and the colour-word matching Stroop test between patients who developed persistent post-surgical pain and those who did not. Secondary outcome measures included the associations between these test scores and pain severity at 6 months. RESULTS: Of 300 participants enrolled, 198 provided 6 month follow-up data. There were no significant differences in preoperative Trail Making Test B minus A times (33 vs 34 s; P=0.59) or Stroop interference T-scores (47th vs 48th percentile; P=0.50) between patients with and without persistent post-surgical pain (primary outcome). Of those who reported persistent post-surgical pain, poorer baseline performance on the colour-word matching Stroop test was associated with higher pain scores at 6 months in both knee arthroplasty (r=-0.32; P=0.04) and chest (r=-0.44; P=0.02) surgeries (secondary outcome). CONCLUSIONS: Preoperative cognitive flexibility test performance was not predictive of overall persistent post-surgical pain incidence 6 months after surgery. However, poor performance on the colour-word matching Stroop test was independently associated with more severe persistent post-surgical pain in both cohorts. CLINICAL TRIAL REGISTRATION: NCT02579538.

Associations between clinical diagnostic criteria and pretreatment patient-reported outcomes measures in a prospective observational cohort of patients with neurogenic thoracic outlet syndrome.

OBJECTIVE: Neurogenic thoracic outlet syndrome (NTOS) is caused by dynamic compression of the brachial plexus at the level of the supraclavicular scalene triangle or the subcoracoid (pectoralis minor) space, or both. The purpose of this study was to characterize relationships between 14 clinical diagnostic criteria (CDC) and seven pretreatment patient-reported outcomes measures (PROMs) in a prospective cohort of patients with NTOS. METHODS: There were 183 new patient referrals between July 1 and December 31, 2015, with 150 (82%) meeting an established set of predefined CDC for NTOS. PROMs were evaluated across five domains: pain severity, functional disability, depression, quality of life, and pain catastrophizing. Linear regression and Pearson correlation statistics were used to analyze associations between CDC and PROMs. RESULTS: Mean ± standard error patient age was 37.1 ± 1.1 years (range, 12-66 years), and 107 (71%) were women. Five (3%) had a cervical rib, and 15 (10%) had recurrent NTOS. The most frequently positive CDC were neck or upper extremity pain (99%), upper extremity or hand paresthesia (94%), symptom exacerbation by arm elevation (97%), localized supraclavicular or subcoracoid tenderness to palpation (96%), and a positive 3-minute elevated arm stress test (94%; mean duration, 102.0 ± 5.1 seconds). The number of positive CDC (mean, 9.6 ± 0.1) correlated with the degree of tenderness to palpation and the duration of elevated arm stress test, as well as with PROMs for pain severity, functional disability, depression, physical quality of life, and pain catastrophizing (all P < .0001). PROMs across multiple domains were also strongly correlated with each other. Patients with clinically significant pain catastrophizing exhibited a greater level of functional disability than noncatastrophizing patients (P < .0001). CONCLUSIONS: This study illustrates the relative strengths of 14 CDC and seven PROMs to evaluate patients with NTOS, helping validate the selected CDC and highlighting the potential role of pain catastrophizing in functional disability. This cohort will provide valuable information on the utility of different CDC and PROMs to predict treatment outcomes.