Clinical characteristics of 3090 cases of hemorrhagic fever with renal syndrome and risk factor analysis

Abstract

Objective In this paper we analyzed the major risk factors of hemorrhagic fever with renal syndrome(HFRS) as well as its clinical manifestation,so as to provide a basis for clinical diagnosis and effective control of HFRS in Xi'an.Methods The method of retrospective study was used to collect clinical data of hospitalized patients with HFRS between 2005 and 2010 in the Hospitals for Infectious Diseases in Xi'an city,Zhouzhi and Huxian counties and then clinical manifestations of the patients with HFRS were analyzed and classified according to the national standards for clinical symptoms and test indicators of HFRS.HFRS patients matched by the ratio of 1 ∶ 2 healthy human controls were retrospectively investigated in order to obtain risk factors relevant to HFRS incidence using casecontrol study.Odds ratio(OR) method was used for single factor study.While for the multifactor study,we took the conditional Logistic regression approach.We also built models for both studies.Factor with OR ＞ 1 and P ＜ 0.05 was judged to be a risk factor.Results A total of 3090 cases information of patients with HFRS and 6018 healthy controls were collected.Of the 3090 cases of HFRS patients,sixty vaccinated patients showed atypical clinical manifestations and they were mild or moderate cases and no deaths.A total of 3030 nonvaccinated patients had obvious clinical symptoms.Severe or critical cases accounted for 39.07％(1184/3030)and 60 patients died and the fatality rate was 1.98％ (60/3030).The results of single factor Logistic regression analysis showed that of the 16 factors analyzed,the difference of 11 risk factors between the case group and the control group was statistically significant.Multivariate Logistic regression analysis showed that of the 11 factors,the difference of six factors between the case group and the control group was statistically significant.The main risk factors of suffering HFRS in the order were:exposure to rat pollutants,living in the affected areas,sitting or lying on grass fields in the affected areas,working in the affected areas,house rat infestation,and domesticated cats or dogs(OR =6.826,5.764,4.882,4.857,3.126 and 2.875; P ＜ 0.01 or P ＜ 0.05).Conclusions Vaccines are very useful in the sense that vaccinated HFRS patients tend to have mild symptoms and good prognosis.Health education in this area should be focused on the six risk factors in order to prevent the spreading of HFRS. Key words: Hemorrhagic fever with renal syndrome; Vaccination; Risk factors; Analysis