Phenotypic features of patients with complex regional pain syndrome compared with those with neuropathic pain.

INTRODUCTION: We hypothesized that patients with complex regional pain syndrome (CRPS) would describe a more negative pain phenotype including higher pain severity, more neuropathic pain descriptors, more centralized pain symptoms, poorer physical function, and more affective distress when compared with patients with neuropathic pain of the extremities not meeting CRPS criteria. MATERIALS AND METHODS: This was a retrospective cross-sectional study conducted at a tertiary pain center. The sample included 212 patients who met Budapest Criteria for CRPS and 175 patients with neuropathic pain of the extremities who did not meet criteria. All patients completed a packet of questionnaires before their initial visit containing validated outcome measures assessing pain severity, pain interference, physical functioning, depression, anxiety, and catastrophizing. RESULTS: Patients with CRPS reported higher physical disability (p=0.022) and more neuropathic pain symptoms (p=0.002) than patients not meeting CRPS criteria, but the groups did not otherwise differ significantly. There were no significant differences in pain severity or affective distress, despite power analyses suggesting the ability to detect small to medium effect sizes (d=0.29; w=0.14). Subanalyses of differences in neuropathic pain symptoms revealed that patients with CRPS, compared with patients not meeting CRPS criteria, were more likely to report pain with light touch (p=0.003), sudden pain attacks (p=0.003), pain with cold or heat (p=0.002), sensation of numbness (p=0.042), and pain with slight pressure (p=0.018). DISCUSSION: Counter to our hypothesis, the present study suggests that patients with CRPS do not have a worse clinical phenotype compared with patients not meeting CRPS criteria, with the exception of higher physical disability and more neuropathic pain symptoms. This corresponds to recent evidence that patients with CRPS are similar to other patient populations with chronic pain.

Trends and predictors of opioid use after total knee and total hip arthroplasty.

Few studies have assessed postoperative trends in opioid cessation and predictors of persistent opioid use after total knee arthroplasty (TKA) and total hip arthroplasty (THA). Preoperatively, 574 TKA and THA patients completed validated, self-report measures of pain, functioning, and mood and were longitudinally assessed for 6 months after surgery. Among patients who were opioid naive the day of surgery, 8.2% of TKA and 4.3% of THA patients were using opioids at 6 months. In comparison, 53.3% of TKA and 34.7% of THA patients who reported opioid use the day of surgery continued to use opioids at 6 months. Patients taking >60 mg oral morphine equivalents preoperatively had an 80% likelihood of persistent use postoperatively. Day of surgery predictors for 6-month opioid use by opioid-naive patients included greater overall body pain (P = 0.002), greater affected joint pain (knee/hip) (P = 0.034), and greater catastrophizing (P = 0.010). For both opioid-naive and opioid users on the day of surgery, decreases in overall body pain from baseline to 6 months were associated with decreased odds of being on opioids at 6 months (adjusted odds ratio [aOR] = 0.72, P = 0.050; aOR = 0.62, P = 0.001); however, change in affected joint pain (knee/hip) was not predictive of opioid use (aOR = 0.99, P = 0.939; aOR = 1.00, P = 0.963). In conclusion, many patients taking opioids before surgery continue to use opioids after arthroplasty and some opioid-naive patients remained on opioids; however, persistent opioid use was not associated with change in joint pain. Given the growing concerns about chronic opioid use, the reasons for persistent opioid use and perioperative prescribing of opioids deserve further study.