2017—2019年登革病毒NS1抗原阳性预测值及影响因素分析

Positive predictive value of dengue virus-NS1 antigen and its influencing factors,2017-2016

目的评价NS1抗原阳性预测值在登革热病例监测中的应用价值,为登革热病例早诊断、早隔离提供科学依据,为疫情防控争取黄金时间。方法对2017—2019年中山市登革热病例监测数据开展描述性流行病学分析,采用二分类logistic回归分析NS1抗原阳性预测值的影响因素。登革病毒NS1抗原检测方法为胶体金法和ELISA法,复核方法为荧光定量RT-PCR(登革病毒核酸检测)和ELISA法(登革病毒IgM和IgG抗体检测)。结果1115例登革热监测病例中,NS1抗原阳性预测值为58.27%(634/1088),多因素logistic回归分析显示,NS1抗原阳性预测值的影响因素为年龄(OR=1.021,95%CI:1.011~1.031)、发病前2周外出史(境外OR=54.993,95%CI:19.954~151.560;境内OR=2.628,95%CI:1.630~4.238)、社区出现本地疫情(本地流行OR=277.918,95%CI:75.691~1020.444;本地散发OR=13.831,95%CI:3.937~48.583)、白细胞(降低OR=79.981,95%CI:31.963~200.140;正常OR=25.019,95%CI:10.471~59.783)。确诊病例发病6 d内,白细胞和血小板降低比例逐渐升高,白细胞降低在第6 d高达92.00%(46/50),血小板降低在发病5 d内仅占13.52%(71/525)。结论不能明确诊断为其他疾病的发热病例,发病6 d内白细胞正常或降低的患者是登革病毒NS1抗原筛查的重点对象,根据流行强度,应采取不同的监测策略,在登革热大范围流行的社区,医疗机构检测的NS1阳性可直接作为疫情处置的依据。

Objective To evaluate the application value of positive predictive value of NS1 antigen in surveillance of dengue,to provide a scientific basis for early diagnosis and isolation of dengue cases,and to gain prime time for epidemic prevention and control.Methods Descriptive epidemiological analysis was used to analyze the surveillance data of dengue in Zhongshan City from 2017 to 2019.Binary logistic regression analysis was performed to examine the factors associated with positive predictive value of NS1 antigen.Colloidal gold and enzyme linked immunosorbent assay(ELISA)were used to detect dengue virus-NS1 antigen.Fluorescent quantitative RT-PCR(test of dengue virus nucleic acid)and ELISA(test of IgM and IgG antibodies)were used to recheck.Results The positive predictive value of NS1 antigen was 58.27%(634/1088)in 1,115 suspected dengue fever cases.Multifactor logistic regression analysis showed that the factors influencing the positive predictive value of NS1 antigen included age(OR=1.021,95%CI:1.011-1.031),having a history of travelling within 14 days before the onset of the disease(overseas OR=54.993,95%CI:19.954-151.560,domestic OR=2.628,95%CI:1.630-4.238),local outbreaks occurring in communities(local epidemic OR=277.918,95%CI:75.691-1,020.444,local sporadic OR=13.831,95%CI:3.937-48.583),and the count of white blood cell(decline OR=79.981,95%CI:31.963-200.140,normal OR=25.019,95%CI:10.471-59.783).Within 6 days of the onset,the proportions of leukocytopenia and thrombocytopenia in the confirmed cases gradually increased,as high as 92.00%(46/50)for leukocytopenia on day 6,but only 13.52%(71/525)cases showed thrombocytopenia within 5 days of the onset.Conclusions Febrile illness cases that cannot be definitively diagnosed with other diseases,and with normal or reduced white blood cells within 6 days of the onset are the focus groups for NS1 antigen test.Different monitoring strategies should be adopted according to intensity of the epidemic.In communities that dengue is widespread,NS1 antigen positive results from medical institutions can be directly used as the basis for handing the epidemics.