Value of cerebral spinal fluid measurement of hypocretin-1 in the diagnosis of Chinese patients with narcolepsy

Abstract

To evaluate the diagnostic value of cerebral spinal fluid (CSF) measurement of hypocretin-1 (hcrt-1) in Chinese patients with narcolepsy. A total of 139 narcoleptic patients, including 111 narcolepsy with typical cataplexy (NC) and 28 narcolepsy without cataplexy (NWC), were diagnosed at the sleep centre of Peking University People's Hospital from April 2003 to March 2012. And 64 non-narcoleptic controls were recruited. CSF hcrt-1 levels were measured in all subjects.Receiver operating characteristic curve (ROC) was applied to determine the cutoff value of hcrt-1 for Chinese narcoleptic patients. The diagnostic utility of hcrt-1 ≤ 110.0 ng/L and hcrt-1 ≤ 30% of mean normal level defined by International Classification of Sleep Disorders-II and the new Chinese cutoff value were evaluated respectively. The level of hcrt-1 in narcolepsy patients was significantly lower than that of normal controls and the NC group was even lower than NWC group (20 (13, 36) vs 319 (244, 379) and 36 (15, 114) ng/L) (all P < 0.01).Using the international criteria of CSF hcrt-1 ≤ 110.0 ng/L or a level of 1/3 of mean normal control values, a specificity of 100% and sensitivity of 90.6% were generated.ROC curve indicated that CSF hcrt-1 level of 138.0 ng/L was the best cutoff value for the diagnosis of narcolepsy in Chinese narcoleptic patients. There were a specificity of 100%, a sensitivity of 92.8% and the area under the ROC curve of 0.98. CSF hcrt-1 measurement with high specificity and sensitivity is a useful diagnostic tool for Chinese narcoleptics. And the level of 138.0 ng/L may be the optimal cutoff for the diagnosis of narcolepsy in this group of patients.