Abstract: Creatine kinase is a muscle enzyme that has been reported at various levels in different studies involving patients with amyotrophic lateral sclerosis. In the present retrospective case-control study, we included 582 patients with amyotrophic lateral sclerosis and 582 age- and sex-matched healthy controls. All amyotrophic lateral sclerosis participants received treatment in the Department of Neurology, West China Hospital, China, between May 2008 and December 2018. Serum creatine kinase levels in patients with amyotrophic lateral sclerosis were significantly higher than those in healthy controls. Subgroup analysis revealed that serum creatine kinase levels in men were higher than those in women in both amyotrophic lateral sclerosis patients and healthy controls. Compared with patients with bulbar-onset amyotrophic lateral sclerosis, patients with limb-onset amyotrophic lateral sclerosis had higher creatine kinase levels. Spearman’s correlation analysis revealed that serum creatine kinase levels were not correlated with body mass index, amyotrophic lateral sclerosis Functional Rating Scale-Revised score, or progression rate. After adjusting for prognostic covariates, higher log creatine kinase values were correlated with higher overall survival in the amyotrophic lateral sclerosis patients. We also investigated the longitudinal changes in serum creatine kinase levels in 81 amyotrophic lateral sclerosis patients; serum creatine kinase levels were decreased at the second blood test, which was sampled at least 6 months after the first blood test. Together, our results suggest that serum creatine kinase levels can be used as an independent factor for predicting the prognosis of amyotrophic lateral sclerosis patients. This study received ethical approval from the Ethics Committee of West China Hospital, China (approval no. 2015(236)) on December 23, 2015.

Key words: amyotrophic lateral sclerosis, biomarker, creatine kinase, diagnosis, epidemiological study, prognosis, serology, survival