Sensitivity and Specificity of neurological signs using the Cambridge Neurological Invertory in Chinese patients with schizophrenia

Abstract

OBJECTIVE: This study attempted to examine the sensitivity and specificity of neurological signs in Chinese patients with schizophrenia. METHODS: A total of 250 schizophrenic patients and 90 normal controls were recruited. The Cambridge Neurological Inventory (CNI) was used to assess the prevalence of neurological signs. The CNI consists of seven subscales. Three soft signs subscales (motor coordination, sensory integration, disinhibition) and four hard signs subscales (extrapyramidal signs, dyskinesia, catatonia, pyramidal signs). RESULTS: The findings showed that patients exhibited significantly more signs than normal controls in all subscales but pyramidal signs ( p < 0.00005). Significant differences were also found in total soft signs, total hard signs as well as total neurological signs ( p < 0.0005). In view of sensitivity and specificity, the three subscales of soft signs showed a relatively better sensitivity and specificity as compared with the remaining hard signs. Improvement in sensitivity and specificity was demonstrated when the subscales were collapsed into total soft signs, total hard signs and total neurological signs. A cut-off of 4 in total soft signs yields a sensitivity of 0.63 and specificity of 0.71; whereas a cut-off of 1 in total hard signs yields a sensitivity of 0.78 and specificity of 0.89. A cut-off of 5 in total neurological signs also gets a sensitivity of 0.81 and specificity of 0.73. High levels of neurological abnormality characterize schizophrenic patients. CONCLUSION: An extended assessment battery of CNI provides even better discrimination of patients from normal controls, and soft signs are more differentially associated with schizophrenia than are hard signs in the Chinese sample.