Evaluation on performance of communicable disease automatic early warning system in Zhongshan, Guangdong, 2008-2011

Objective To evaluate the performance of communicable disease automatic early warning system in Zhongshan, Guangdong province and provide scientific evidence for the improvement of the system. Methods The analysis was conducted on the early warning data generated by moving percentile method and sum and control method and the incidence data of public health emergency from 21 April 2008 to 31 December 2011 in Zhongshan to evaluate the timeliness, sensitivity and specificity of the early warning. Results Totally 3543 signals were generated by the system. The response rate of the signals was 100%. After preliminary verification, 13 signals were considered to be suspected (0.37%). The average interval between early warning and outbreak, sensitivity and specificity for the communicable diseases with high incidences were 1 day, 83.33% and 74.20%, the relevant indicators for the communicable disease with low incidences were 0 day, 100% and 96.32%. The early warning-outbreak interval, sensitivity and specificity of the early warning for newly included hand foot and month disease was 0 day, 100% and 76.18%. Conclusion The timeliness, sensitivity and specificity of the early warning by the system for communicable diseases with low incidences were better than those with high incidences, the specificity of the early warning for the communicable diseases with low incidences was better than that for newly included notifiable communicable disease. The early warning of communicable disease epidemic by this system has been achieved basically, but further improvement is still needed by setting reasonable threshold to reduce false early warning.