50 years follow-up on plasma creatinine levels after spinal cord injury

Study design: Retrospective chart review. Objectives: To investigate the role of plasma creatinine (p-creatinine) in monitoring renal deterioration in patients up to 50 years after spinal cord injury (SCI). Setting: The Clinic for Spinal Cord Injuries, Rigshospitalet, Denmark. Methods: A total of 119 patients with a traumatic SCI during the years 1944-1975 were included in the study. P-creatinine measurements, results from renography and glomerular filtration rate (GFR) measured with Cr-51-EDTA clearance were obtained from medical records and analyzed using a linear mixed model and linear regression analyses. Results: When compared with median p-creatinine level in the first 5-year period after injury, the level of p-creatinine was stable throughout the first 30 years and decreased significantly after the 30th until 45th year post injury. Only patients with a functional distribution outside the 30-70% limits on renography or a relative GFR <= 51% of that expected had a significantly elevated level of p-creatinine. Significance was not found for patients with a distribution outside the 40-60% limits on renography or relative GFR <= 75%. By comparing Cr-EDTA clearance and p-creatinine in terms of exceeding the upper reference level, p-creatinine revealed 17% sensitivity, 100% specificity, 100% positive predictive value and 73% negative predictive value as a diagnostic test for renal deterioration defined as GFR <= 75%. Conclusion: P-creatinine decreases over time in patients with SCI with a level below the upper reference limit and is a poor detector of early renal deterioration in patients with SCI.