OBJECTIVETo select the premium alert threshold for major communicable disease by using the control graph alert technique based on the local disease information.

METHOD8 major communicable diseases in Songjiang district were ascertained by analysis of the national early warning detection information system which include the other diarrhea, mumps, chickenpox, scarlet fever, rubella, hand foot mouth disease, influenza and dysentery; weekly reported cases from 2008 to 2011 were used to establish the early detection model (PERCENTILE (array, x), array (4×5), x = 0.05, 0.10…0.95) by moving percentile method, next applying the established early detection model and the golden standard (AKX(-)D ± 2s) to predict the expected weekly cases in 2012 respectively, and then ascertain the predict results by comparison with the actual weekly cases in 2012 respectively, finally the premium threshold was selected by comparison of the model predicted results with the golden standard predicted results after comprehensive consideration of the sensitivity, specificity, positive predictive value and negative predictive value and receiver operating characteristic (ROC) curve.

RESULTSThe premium alert threshold for mumps, other diarrhea and rubella was P90, dysentery was P75, scarlet fever and chickenpox was P80, and the premium threshold for hand-foot-mouth disease (HFMD) and influenza was P95, the sensitivity of 8 major communicable diseases were 100%, 100%, 86%, 100%, 100%, 100%, 94%, 100%, respectively; the specificities were 92%, 73%, 72%, 77%, 73%, 92%, 66%, 80%, respectively; the positive predictive values were 43%, 40%, 32%, 8%, 24%, 20%, 59%, 47%, respectively; and the negative predictive values were 100%, 100%, 97%, 100%, 100%, 100%, 96%, 100%, respectively. The national recommended alert thresholds for the 8 major communicable diseases were P80, except for chickenpox (P50) and HFMD (CUSUM).

CONCLUSION6 out of 8 major communicable diseases' early detection thresholds in Songjiang district should be adjusted according to the analysis results. Premium alert threshold selection need to consider the local disease report and the characteristics of infectious diseases to upgrade the early detection capability.