Patient Recruitment into Acute Spinal Cord Injury Clinical Trials of Early Therapeutic Interventions: How Many Patients Can Really Be Enrolled?

Abstract

Introduction While there is a desperate need for effective treatments for acute spinal cord injury (SCI), the clinical validation of novel therapeutic interventions is severely hampered by the need to recruit relatively large numbers of patients into clinical trials for sufficient statistical power. While a centre might annually admit 100 acute SCI patients, only a fraction may satisfy the basic inclusion criteria for an acute clinical trial, which typically requires patients of a certain injury severity (eg ASIA A), within a specific time window (eg. 12 hours from injury), and without other major injuries or conditions that would cloud the baseline neurologic assessment. This study was conducted to define that “fraction” of SCI patients that would theoretically satisfy standard inclusion criteria of an acute clinical trial. Methods Using a local database, we reviewed patients admitted to our Level 1 trauma center with a complete (ASIA A) or an incomplete (ASIA B, C and D) acute SCI involving bony spinal levels between C0 and sacrum. All patients admitted over the 4 year period from 2005 to 2009 were reviewed. Demographic information and data about the patients9 SCI and other injuries were reviewed. We then determined how many of the total number of SCI patients would be eligible for enrolment into a hypothetical acute clinical trial that required a valid baseline assessment of neurologic impairment, and an enrolment window of either 12 hours, 24 hours, or 48 hours. Results 408 acute traumatic SCI patients were admitted over the 4 year period. 253 of 408 (62%) patients presented within 12 hours of injury, 60 (15%) between 12–24 hours, and 28 (7%) between 24–48 hours. 42% of patients were ASIA A, 13% B, 18% C and 27% D. The number of patients who presented with injuries or other conditions that would exclude them from enrolment was relatively high: 4% had penetrating injuries, 12% had illicit drug use, and 20% had either alcohol intoxication or head injuries which precluded a valid baseline neurologic examination. Conclusions Out of a total of 408 patients admitted over 4 years, the number who would have been optimistically eligible for an acute neuroprotective trial was disappointingly small. Given that acute clinical trials are increasingly interested in cervical ASIA A patients (in whom segmental motor recovery can be assessed), the number of such patients who would actually be eligible for an acute intervention was surprisingly low. Given that additional inclusion/exclusion criteria would also be applicable in a real clinical trial, the true number of “eligible” or “recruitable” patients is conservatively even lower. This study is the first to quantify this challenging aspects of conducting acute SCI clinical trials, and provides valuable information for those planning such initiative