基于非处方药销量的流感样病例残差预警研究

Residual early warning of influenza-like illness based on the OTC sales volume

目的探讨流感样病例就诊比例(ILI%)与药店非处方药(over-the-counter pharmaceuticals,OTC)销量的早期预警阈值。方法从杭州市32家药店选择销量大且稳定的OTC进行监测,并对OTC销量进行标化;采用控制图法计算ILI%预测基线、警戒线、行动线水平及OTC销量百分位数,以ILI%与OTC销量串联、并联预警;计算各候选预警阈值的灵敏度、特异度、阳性预测值,绘制ROC曲线,比较各候选预警阈值的功效,从中选出合适的预警阈值。结果预期基线水平预警阈值ILI%为P75或P80。感冒药标化的用药天数(daily drug dose,DDD)为P50或P60或P65,止咳药DDD是P95,二者合计DDD为P65。串联时感冒药DDD预期基线水平为P65或P70或P75或P80,并联时为P95;串联时止咳药DDD预期基线水平为P70或P75或P80,并联时为P90;二者合计DDD串联时预期基线水平为P65或P70或P75或P80,并联时为P95。结论控制图法可以作为OTC销量预警流感样病例的预警方法。

Objective To explore the early-warning threshold of ILI%(percentage of doctor visits of influenzalike illness)versus over-the-counter pharmaceuticals(OTC)sales volume. Methods OTCs which were consistently sold in large volumes were selected from 32 pharmacies to be monitored and sales volumes were standardized.Control chart method was applied to calculate the expected baseline,cordon,active line level of ILI%as well as the percentile of OTC sales volume.The early warning was made through cascading and paralleling the ILI% and OTC sales volume.The sensitivity,specificity and positive predictive value of candidate warning threshold were calculated and the efficacies of the candidate warning thresholds were compared in order to get optical ones. Results The early-warning threshold of expected baseline was P75 or P80for ILI%,and P50 or P60or P65 for daily drug dose(DDD)of standardized cold medication,and P95 for DDD of anti-coughing drugs.The expected baseline warning threshold was P65 or P70or P75 when being cascaded and was P95 when being paralleled for anti cold drug DDD,and was P70 or P75or P80 and P90for anti coughing drug DDD.Conclusions The control chart method based on the OTC sales volume may be used for the early warning of ILI.