Chiachen Hsu, R. Norman Harden, Tim Houle

{\it } Nicotine and caffeine are vasoconstrictors. Complex regional pain syndrome (CRPS) is defined to involve disproportionate pain and autonomic dysfunction [1]. The objectives of this study were to identify the prevalence of smoking and caffeine intake in CRPS, to explore the relationship of pain intensity with smoking and caffeine consumption, and to explore the relationship of pain intensity, anxiety and disability among CRPS patients who smoke, use caffeine, or both. {\it } One hundred eleven patients, with CRPS type I or II, from two academic rehabilitation pain clinics were reviewed. Data were collected retrospectively by reviewing CRPS patients' self-reported pain level using visual analogue scales (VAS), Beck Depression Inventory (BDI), Pain Disability Index (PDI), and Pain Anxiety Symptoms Scale (PASS). Status of daily smoking and caffeine consumption were also recorded. {\it } Smoking prevalence among CRPS was significant higher than the national average (p < 0.001). There were no significant relationships between the perceived pain level and either daily smoking, daily caffeine intake, or both (p > 0.430). In patients with CRPS I higher PASS scores were positively associated with dichotomous use of smoking and caffeine (p < 0.05). The PASS scores among patients with CRPS~II were not available for analysis. {\it } The smoking prevalence was higher than the national average among patients with CRPS I and II. Among patients with CRPS~I smoking and caffeine consumption were greater in those who reported more pain-related anxiety, but did not influence pain intensity. The clinical implications of these findings will be discussed.