Is CRPS-1 a Chronic Disabling Disease? A Long-term, Real-Life Study on Patients Treated With Neridronate.

Background: Complex Regional Pain Syndrome type 1 (CRPS-1) is severely debilitating and painful disease that is difficult to treat.

Objective: The objective was to evaluate the long-term residual disability of patients with CRPS-1 following parenteral neridronate treatment.

Design: This is real-life retrospective observational study.

Methods: Patients affected by CRPS-1 of the upper limb were treated with neridronate infusions (400 mg over 10 days) between February 2017 and December 2021 for whom clinical and demographic information was collected. From November 2022, patients treated ⩾1 year previously were recalled for clinical evaluation. A dedicated instrument (DASH questionnaire, Disabilities of the Arm, Shoulder and Hand) was employed to assess residual disability. Multivariate logistic regression analysis was used to investigate predictors of disability.

Results: Forty-nine patients aged 61.1 ± 11.5 years and 73.5% female with CRPS-1 of the upper limb were included. Disease duration before treatment was 9.9 ± 8.0 weeks, and the mean length of follow-up was 4 years (47.7 ± 22.0 months). The disease had fully resolved in 46 patients (93.9%) for whom the diagnostic criteria were no longer recognized. According to the DASH score, 38 patients (77.6%) resulted free of functional limitations, whereas 11 patients (22.4%) were still suffering from disability. The DASH score was positively correlated with residual visual analogue scale (VAS; Spearman's Rho = 0.61; P < .001). Predictors of residual disability were younger age (odds ratio [OR]: 0.77, 95% CI: 0.63-0.93; P = .012) and delay between disease onset and treatment (OR: 1.45, 95% CI: 1.13-1.96; P = .004).

Conclusions: In this real-life study, neridronate parenteral treatment provided a full recovery of CRPS-1 in over 3 quarters of patients, provided they are treated early.