Implementation of a fast-track pathway for complex regional pain syndrome: associations with referral delay and one-year clinical outcomes.

Complex regional pain syndrome is a rare but disabling post-traumatic pain condition in which delayed recognition and fragmented care may contribute to chronicity. In 2020, a structured fast-track pathway was implemented at a Swiss tertiary hospital to support recognition, early management, and specialist referral. This retrospective cohort study with a historical control group (pre-pathway: 2015-2019; post-pathway: 2020-2023) included adults referred to an outpatient pain clinic with suspected or confirmed disease. The pathway combined standardised screening, early guideline-based treatment initiated by non-pain specialists, and predefined escalation to specialist pain care. The primary outcome was the time from inciting event to first pain clinic consultation; secondary outcomes included time to first documented clinical features, time to first documented suspicion or diagnosis, and clinician-adjudicated improvement at 12 months. Among 3,797 screened records, 179 patients met inclusion criteria (73 pre-pathway, 106 post-pathway). Median time to pain clinic consultation was shorter post-pathway than pre-pathway (165 vs 438 days; P<0.001). At 12 months, 59 of 95 post-pathway patients (62.1%) and 25 of 65 pre-pathway patients (38.5%) were classified as improved (risk difference 23.6%, 95% confidence interval 7.9-37.8; P=0.003). Longer disease duration was associated with lower odds of improvement (adjusted odds ratio per month 0.97, 95% confidence interval 0.95-0.99), with a non-linear association across disease duration. These findings support referral delay as a clinically relevant timing factor in the care of complex regional pain syndrome that health systems can act on. PERSPECTIVE: In this retrospective cohort, a structured fast-track pathway for suspected complex regional pain syndrome was associated with shorter referral latency and higher clinician-adjudicated improvement at 12 months. Longer disease duration was independently associated with lower improvement odds, consistent with a narrowing therapeutic window that health systems can act on.