Search

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with an increasing case number and extensive geographical expansion, raising concerns locally and globally; however, the description of its clinical features needs to be addressed by large studies. We aimed to determine all the clinical features of SFTS in a large population of patients in an endemic area., Methods: In this prospective observational study, data were collected on patients admitted to the People's Liberation Army Hospital in Xinyang, Henan Province, China, with laboratory-diagnosed SFTS. Demographic, clinical, laboratory, and treatment data were collected for each patient, and patients were followed up within 2 weeks after discharge or discontinuation of treatment. The association between each demographic, clinical, and laboratory variable with a fatal outcome was assessed. A clinical scoring model was designed for the early prediction of a fatal outcome, and the effect of treatment on outcome was analysed., Findings: Between April 1, 2011, and Oct 31, 2017, 2096 patients with laboratory-confirmed SFTS were admitted. Mean age at admission was 61·4 years (SD 12·2) and 1239 (59%) patients were female. The case fatality rate (CFR) was 16·2% (95% CI 14·6-17·8). A higher risk was associated with being male (unadjusted odds ratio [OR] 1·45, 95% CI 1·15-1·83; p=0·002), older age (for a 10-year increase, unadjusted OR 1·82, 95% CI 1·62-2·04; p<0·0001), longer delay in admission (for every extra day taken before admission to hospital, unadjusted OR 1·18, 1·12-1·24; p<0·0001), presence of diarrhoea (adjusted OR 1·44, 1·12-1·87; p=0·005) or dyspnoea (adjusted OR 8·35, 5·97-11·69; p<0·0001), and development of haemorrhagic signs (adjusted OR 2·79, 95% CI 2·18-3·57; p<0·0001) or neurological symptoms (adjusted OR 30·26, 21·39-42·81; p<0·0001). Laboratory variables that were associated with death included abnormal concentrations of lactate dehydrogenase, aspartate aminotransferase, and blood urea nitrogen, and abnormal neutrophil percentage, which together with age and neurological symptoms were combined in the clinical scoring system. A total score of more than 8 was the optimal threshold to predict risk of death for patients who were evaluated within 6 days after symptom onset (area under the curve 0·879, 95% CI 0·855-0·902). For all participants, viraemia was a strong predictor of fatal outcome (all p<0·0001). Ribavirin therapy was effective in reducing CFR from 6·25% (15 of 240 participants) to 1·16% (two of 173 participants), but only in patients with a viral load below 1×10 6 copies per mL (hazard ratio 9·72, 95% CI 1·30-72·87; p=0·027)., Interpretation: The changing epidemiological features and high CFR of SFTS underscore the necessity of continued surveillance. Early prediction of fatal outcome can be attained by monitoring of clinical and laboratory data. Ribavirin should be applied early, with best results achieved before the viral load reaches 1 × 10 6 copies per mL., Funding: National Natural Science Foundation of China., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by a novel bunyavirus named SFTS virus (SFTSV). We hypothesize that host genetic variations may contribute to susceptibility to SFTS., Results: Compared with the rs1800818 AA genotype, AG + GG genotypes were significantly associated with increased susceptibility to SFTS (odds ratio, 1.66, 95% confidence interval = 1.28-2.16; P < 0.001). By using the ELISA assay, we observed that PDGF-BB concentration was significantly reduced in acute phase of patients than in the controls (P < 0.001) and recovered patients at 6 month (P = 0.007) and 12 month (P = 0.003). A persistently reduced PDGF-BB was also revealed from the SFTSV-infected C57BL/6J mice (P < 0.001). The rs1800818 G allele was associated with decreased serum PDGF-BB levels in SFTS patients at their early infection (P = 0.015). In accordance, the relative mRNA levels of the at-risk G allele of 1800818 were lower than those of the A allele in heterozygous cell from acute phase of SFTS patients. PDGF-B rs1800818 conferred no susceptibility to severe or fatal outcome in SFTS patients., Materials and Methods: An initially small-scale case-control association study guided the selection of platelet derived growth factor-B (PDGF-B) rs1800818 in 1020 SFTS patients and 1353 controls. Functional analyses were conducted to verify the biological significance of rs1800818 polymorphism., Conclusions: Our findings suggest that the PDGF-B rs1800818 polymorphism might play a role in mediating the susceptibility to SFTS., Competing Interests: The authors declare that they have no conflict of interest.

In 2009, a novel Bunyavirus, called severe fever with thrombocytopenia syndrome virus (SFTSV) was identified in the vicinity of Huaiyangshan, China. Clinical symptoms of this zoonotic virus included severe fever, thrombocytopenia, and leukocytopenia, with a mortality rate of ~10%. By the end of 2011 the disease associated with this pathogen had been reported from eleven Chinese provinces and human-to-human transmission suspected. However, current understanding of the evolution and molecular epidemiology of SFTSV before and after its identification is limited. To address this we undertake phylogenetic, evolutionary and structural analyses of all available SFTSV genetic sequences, including a new SFTSV complete genome isolated from a patient from Henan in 2011. Our discovery of a mosaic L segment sequence, which is descended from two major circulating lineages of SFTSV in China, represents the first evidence that homologous recombination plays a role in SFTSV evolution. Selection analyses indicate that negative selection is predominant in SFTSV genes, yet differences in selective forces among genes are consistent between Phlebovirus species. Further analysis reveals structural conservation between SFTSV and Rift Valley fever virus in the residues of their nucleocapsids that are responsible for oligomerisation and RNA-binding, suggesting the viruses share similar modes of higher-order assembly. We reconstruct the epidemic history of SFTSV using molecular clock and coalescent-based methods, revealing that the extant SFTSV lineages originated 50-150 years ago, and that the viral population experienced a recent growth phase that concurs with and extends the earliest serological reports of SFTSV infection. Taken together, our combined structural and phylogenetic analyses shed light into the evolutionary behaviour of SFTSV in the context of other, better-known, pathogenic Phleboviruses., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Objective: To analyze the clinical characteristics of severe fever with thrombocytopenia syndrome (SFTS) so as to improve the recognition of the emerging infectious disease., Methods: A retrospective analysis was performed upon clinical manifestations, laboratory test results and prognostic features of 169 patients with SFTS admitted to the 154 Hospital, Chinese People's Liberation Army from October 2010 to May 2011. The patients were divided into moderate disease group and severe disease group according to the prognosis. The differences between two groups were compared to explore the prognostic indicator of severe type., Results: All patients with SFTS inhabited in hilly ground with history of field work. The main clinical symptoms were severe fever (98.8%, 167/169), headache (52.1%, 88/169), muscle soreness (95.9%, 162/169), nausea (73.4%, 124/169), vomiting (67.5%, 114/169), coughing (61.5%, 104/169), etc. Superficial lymph node enlargement with haphalgesia was observed in 45.0% (76/169) patients. Petechia or ecchymosis was observed in 36.7% (62/169) patients. Critical patients were mainly aged > 60 years, associated with nerve and circulatory system syndrome, prominent hemoptysis, dyspnea, and nearly 73.3% (22/30) of severe thrombocytopenia. Serum levels of aspartate aminotransferase, creatinine and urea nitrogen were significantly higher in severe disease group than those in moderate disease group [235 (47 - 1750) U/L vs 88 (14 - 2000) U/L, 997(281 - 2601) U/L vs 399 (26 - 2633) U/L, 101 (62 - 291) µmol/L vs 70 (26 - 205) µmol/L, 7.0 (2.2 - 20.0) mmol/L vs 4.8 (1.4 - 18.5) mmol/L, all P values < 0.001]., Conclusion: Nerves system syndrome, transaminase and urea nitrogen are risk factors of prognosis of severe SFTS to whom deserves paying attention.

Background: The pathogenesis of severe fever with thrombocytopenia syndrome (SFTS) remained unclear. We aimed to profile the metabolic alterations in urine of SFTS patients and provide new evidence for its pathogenesis. Methods: A case–control study was conducted in the 154th hospital in China. Totally 88 cases and 22 controls aged ≥ 18 years were enrolled. The cases were selected from laboratory-confirmed SFTS patients. The controls were selected among SFTSV-negative population. Those with diabetes, cancer, hepatitis and other sexually transmitted diseases were excluded in both groups. Fatal cases and survival cases were 1:1 matched. Inter-group differential metabolites and pathways were obtained, and the inter-group discrimination ability was evaluated. Results: Tryptophan metabolism and phenylalanine metabolism were the top one important metabolism pathway in differentiating the control and case groups, and the survival and fatal groups, respectively. The significant increase of differential metabolites in tryptophan metabolism, including 5-hydroxyindoleacetate (5-HIAA), L-kynurenine (KYN), 5-hydroxy-L-tryptophan (5-HTP), 3-hydroxyanthranilic acid (3-HAA), and the increase of phenylpyruvic acid and decrease of hippuric acid in phenylalanine metabolism indicated the potential metabolic alterations in SFTSV infection. The increase of 5-HIAA, KYN, 5-HTP, phenylpyruvic acid and hippuric acid were involved in the fatal progress of SFTS patients. Conclusions: Tryptophan metabolism and phenylalanine metabolism might be involved in the pathogenesis of SFTSV infection. These findings provided new evidence for the pathogenesis and treatment of SFTS. [ABSTRACT FROM AUTHOR]

Background: Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne disease with high mortality. However, detailed analysis is lacking to explore the complex effect of sex with age or comorbidities. Methods: A retrospective cohort study was performed among 2,938 SFTS patients entered during 2011–2020 in Xinyang, China. The case fatality rate (CFR) was estimated for their association with sex, age, and comorbidities by an interactive way. The difference of immune response between sex was explored in an age dependent way. Results: An overall CFR of 15.3% (450/2,938) was obtained, which appeared to be higher in males than in females [17.7% vs. 13.6%, adjusted odds ratio (aOR) = 1.24; 95% CI, 1.00–1.53; P = 0.048] and increased dramatically with age (P < 0.001). The associations between sex and SFTS fatal outcome were age-dependent and varied according to the status of comorbidities. The mortality-related risk conferred by older age was more pronounced in males, with aOR (95% CI) to be 5.76 (3.75–8.84) vs. 5.30 (3.54–7.95) in female. Sex-stratified analysis disclosed significant associations between death and comorbidities among female patients (aOR = 1.87, 95% CI: 1.40–2.49; P < 0.001), while none among males. Among females, the significant associations between presence of comorbidity and fatal outcome differed among age groups, with aOR (95% CI) decreased from 2.28 (1.16–4.46) in ≤60 years, to 2.06 (1.34–3.18) in 60–70 years and further to 1.55 (0.97–2.47) in >70 years. Altogether 194 SFTS patients were randomly selected for the test of B cells, natural killer (NK) cells, CD4 cells percentages, and anti-SFTSV IgM antibody level, the results revealed that males >60 years had significantly decreased percentages of B cells, CD4 cells, lower anti-SFTSV IgM antibody titer, and increased level of NK cells than male aged ≤60 years, while none of these age specific differences was observed in the females. This finding underlies the more pronounced age specific difference in CFR among male than female. Conclusions: Males had a significantly higher mortality of SFTS than did females, and more likely to be affected by aging for SFTS mortality. This difference can be explained by the effect from comorbidities and the host immunity. It is essential to take a sex- and age-based approach to SFTS treatment and management. [ABSTRACT FROM AUTHOR]

Severe Fever with Thrombocytopenia Syndrome (SFTS) is an emerging infectious disease caused by a novel bunyavirus, SFTS virus (SFTSV), with fatal outcome developed in approximately 17% of the cases. Thrombocytopenia is a hallmark feature of SFTS, and associated with a higher risk of fatal outcome, however, the pathophysiological involvement of platelet in the clinical outcome of SFTS remained under-investigated. In the current study, by retrospectively analyzing 1538 confirmed SFTS patients, we observed that thrombocytopenia was associated with enhanced activation of the cytokine network and the vascular endothelium, also with a disturbed coagulation response. The platelet phenotypes were also extensively altered in the process of thrombocytopenia development of SFTS patients. More importantly, all these disturbed host responses were related to the severity of thrombocytopenia, thus were considered to play in a synergistic way to influence the disease outcome. Moreover, the clinical effect of platelet transfusion was assessed by comparing two groups of patients with or without receiving this therapy. As a result, we observed no therapy effect in altering frequencies of fatal outcome, clinical bleeding development, or dynamic change of platelet count during the hospitalization. It's suggested that platelet supplementation alone acted a minor role in improving disease outcome, therefore new therapeutic intervention to regulate host response should be proposed. The current results revealed some evidence of interrelationship between platelet count and clinical outcome of SFTS disease from the perspective of activation of the cytokine network, the vascular endothelium, and the coagulation/fibrinolysis system. These evaluations might help to attain a better understanding of the pathogenesis and therapy choice in SFTS. Author summary: Thrombocytopenia in SFTSV is a multifactor-process involving a combination of platelet size or morphology alterations, fibrinolysis activation and coagulation abnormalities, increased inflammatory response and endothelial injury. Platelet supplementation alone shows minor role in improving disease, therefore new therapeutic intervention to regulate host response should be proposed. [ABSTRACT FROM AUTHOR]

During 2014-2017, we screened for Rickettsia japonica infection in Xinyang, China, and identified 20 cases. The major clinical manifestations of monoinfection were fever, asthenia, myalgia, rash, and anorexia; laboratory findings included thrombocytopenia and elevated hepatic aminotransferase concentrations. Physicians in China should consider R. japonica infection in at-risk patients. [ABSTRACT FROM AUTHOR]

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that is caused by a novel bunyavirus, SFTSV. We assessed whether the single nucleotide polymorphisms (SNPs) in the tumor necrosis factor-alpha (TNF-α) were associated with risk to severity of SFTS. Five TNF-α SNPs (SNP1: T-1031C; SNP2: C-863A; SNP3: C-857T; SNP4: G-308A; SNP5: G-238A) were genotyped in 987 hospitalized SFTS patients and 633 asymptomatic/mild SFTSV-infected subjects of Chinese Han origin. Multivariate logistic regression analysis was used to calculate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). The hospitalized SFTS patients had significantly lower frequency of G-238A A allele than those with mild/asymptomatic infection (P = 0.006). Furthermore, T-1031C C allele (P < 0.001) and G-238A A allele (P < 0.001) were significantly associated with decreased risk of death. Multiple haplotypes were significantly associated with decreased risk of SFTS hospital admission (SNP1-2, CC; SNP1-3, CCC; SNP1-4, CCCG; SNP1-5, CCCGA; SNP2-4, CCGA; SNP3-5, CGA; SNP4-5, GA) and death (SNP1-2, CA; SNP1-3, CAG; SNP1-4, CACG; SNP1-5, CACGG; SNP2-3, AC; SNP2-4, ACG; SNP2-5, ACGG) after correction for multiple comparisons. By using the ELISA assay, we observed that TNF-α concentration of hospitalized patients was significantly increased in acute phase than in convalescent phase (P < 0.001). Elevated TNF-α concentration was also revealed from fatal patients (P < 0.001). The -238A allele was associated with decreased serum TNF-α levels in SFTS patients in acute phase (P = 0.01). Our findings suggest that polymorphisms in TNF-α gene may play a role in mediating the risk to disease severity of SFTS in Chinese Han population. [ABSTRACT FROM AUTHOR]

Background. Rickettsia raoultii is frequently detected in multiple tick species, whereas human infection remains scarcely studied. Methods. A surveillance study was performed at 3 sentinel hospitals in China, to recruit participants with suspected tick exposure. Rickettsia raoultii infection was identified through polymerase chain reaction, followed by sequencing, and confirmed serologically. Isolation by cell culture was performed and the isolates were genome sequenced. Results. Twenty-six subjects were determined to have R. raoultii infection, including 7 with asymptomatic infection, 15 with mild to moderate illness, and 4 with severe illness. Common nonspecific manifestations in the 19 patients with mild to moderate or severe illness included fever (100%), malaise (95%), myalgia (58%), lymphadenopathy (53%), and nausea (42%). Only 5% of them had rash, and 16% had eschar. Scalp eschar and neck lymphadenopathy after a tick bite syndrome was only seen in 2 patients. Of the 4 patients with severe complications, 3 developed pulmonary edema, and 1 developed clouding of consciousness and lethargy. Frequent abnormalities of laboratory testing included leukopenia, thrombocytopenia, lymphopenia, neutropenia, hypoproteinemia, and elevated levels of total bilirubin, hepatic aminotransferases, lactate dehydrogenase, and creatine kinase. All the 19 patients recovered without sequelae after receiving doxycycline treatment. Two R. raoultii strains were isolated, and a significantly less degraded genome was observed than other more virulent Rickettsia strains, indicating a low pathogenicity of the current strain. Conclusions. Human infection with R. raoultii has a wide clinical spectrum that ranged from subclinical infection to severe complications. Physicians need to be aware of the high potential and clinical complexity of R.raoultii infection, to ensure appropriate testing and treatment in endemic regions. [ABSTRACT FROM AUTHOR]

Background: Pathogenesis of severe fever with thrombocytopenia syndrome (SFTS) has not been well described yet. Recent studies indicate that SFTSV could replicate in endothelial cells. Here we performed a case-control study to determine whether endothelial activation/dysfunction occurred in SFTSV infection and to identify the biomarkers reflecting endothelial dysfunction. Methodology/Principal findings: In a case-control study of 134 SFTS patients and 68 healthy controls, serum levels of plasminogen activator inhibitor 1, tissue plasminogen activator, P-selectin, platelet endothelial cell adhesion molecular, CD40 ligand, E-selectin, vascular endothelial growth factor A, serum amyloid antigen 1 (SAA-1) and vascular cell adhesion molecular 1 were significantly enhanced in the patients than the controls (all P<0.05), indicating the occurrence of endothelial activation/dysfunction in SFTS. The intercellular adhesion molecular 1 (ICAM-1) and SAA-1 at the convalescent phase were also significantly associated with severe patients, after adjusting for the potential confounders. The odds ratio was estimated to be 3.364 (95% CI 1.074–10.534) for ICAM-1, and 1.881 (95% CI 1.166–3.034) for SAA-1, respectively. Cutoff value of 1.1×107 pg/mL SAA-1 or 1.2×106 pg/mL ICAM-1 were found to have moderate power of predicting fatal cases. Conclusions: The endothelial dysfunction may be one of the pathogenic mechanism of SFTS. The serum levels of ICAM-1 and SAA-1 might be used to predict adverse outcome. [ABSTRACT FROM AUTHOR]

During 2013-2015 in central China, co-infection with spotted fever group rickettsiae was identified in 77 of 823 patients infected with severe fever with thrombocytopenia syndrome virus. Co-infection resulted in delayed recovery and increased risk for death, prompting clinical practices in the region to consider co-infection in patients with severe fever with thrombocytopenia syndrome. [ABSTRACT FROM AUTHOR]

Background The immunological responses of patients with severe fever with thrombocytopenia syndrome (SFTS) remain largely unknown. We aim to study the magnitude and sustainability of host immune responses and their correlation with clinical, virological and hematological parameters. Methods A longitudinal cohort study was performed in a SFTS reference hospital. The sequential immunological evaluation was determined for SFTSV infected patients, including anti-SFTSV IgM, IgG antibodies and the lymphocyte subsets. Results Altogether 298 laboratory-confirmed SFTS cases were analyzed, from whom 55 patients were followed after convalescence. SFTSV specific IgM antibody could be detected at medium of 9 days, surged to peak levels by 4 weeks, and remained persistent until 6 months after disease onset. SFTSV specific IgG antibody could be detected at medium of 6 weeks; surged to peak levels by 6 months, and remained positive in most of the patients even at 3 years after infection. SFTS patients experienced obvious T cell, B cell and NK cells loss during the first week of infection, which was rapidly restored to normal levels. A significantly lower level of humoral immunity was identified concurrently from severe disease, especially in acute phase of the infection. These abnormalities can be used as a potential indicator in the prediction of an adverse clinical outcome. Conclusions Information gained from this study have clinical significance in enhancing our understanding of SFTS immunological characteristics and the disease pathogenesis. [ABSTRACT FROM AUTHOR]

Background: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease discovered in rural areas of Central China in 2009, caused by a novel bunyavirus, SFTS virus (SFTSV). The disease usually presents as fever, thrombocytopenia, and leukocytopenia, with case-fatality rates ranging from 2.5% to 30%. Haemaphysalis longicornis was suspected to be the most likely vector of SFTSV. By the end of 2012, the disease had expanded to 13 provinces of China. SFTS patients have been reported in Japan and South Korea, and a disease similar to SFTS has been reported in the United States. Methodology/Principal Findings: We characterized the epidemiologic features of 504 confirmed SFTS cases in Xinyang Region, the most severely SFTS-afflicted region in China from 2011 to 2012, and assessed the environmental risk factors. All cases occurred during March to November, with the epidemic peaking from May to July. The patients' ages ranged from 7 to 87 years (median 61 years), and the annual incidence increased with age (χ2 test for trend, P<0.001). The female-to-male ratio of cases was 1.58, and 97.0% of the cases were farmers who resided in the southern and western parts of the region. The Poisson regression analysis revealed that the spatial variations of SFTS incidence were significantly associated with the shrub, forest, and rain-fed cropland areas. Conclusions: The distribution of SFTS showed highly significant temporal and spatial heterogeneity in Xinyang Region, with the majority of SFTS cases being elderly farmers who resided in the southern and western parts of the region, mostly acquiring infection between May and July when H. longicornis is highly active. The shrub, rain-fed, and rain-fed cropland areas were associated with high risk for this disease. Author Summary: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease discovered in rural areas of Central China in 2009, caused by a novel bunyavirus, SFTS virus (SFTSV). The disease usually presents as fever, thrombocytopenia, and leukocytopenia, with case-fatality rates ranging from 2.5% to 30%. By the end of 2012, the disease had expanded to 13 provinces of China. SFTS patients have been reported in Japan and South Korea, and a disease similar to SFTS has been reported in the United States. Here we characterized the epidemiologic features of 504 confirmed SFTS cases in Xinyang, the most severely SFTS-affected region in China from 2011 to 2012, and identified the environmental risk factors. We found the distribution of SFTS cases showed highly significant temporal and spatial heterogeneity, with the majority of SFTS cases being elderly farmers who resided in the southern and western parts of the region, mostly acquiring infection between May and July when H. longicornis is highly active. The shrub, forest, and rain-fed cropland areas were strongly associated with high risk for SFTS. [ABSTRACT FROM AUTHOR]

An effective differentiation between severe fever with thrombocytopenia syndrome and hemorrhagic fever with renal syndrome was attained by a model considering patients' age, mouse/tick contact, presence of blush, low back pain, diarrhea, enlarged lymph nodes, and white blood cell count. [ABSTRACT FROM AUTHOR]

• Neutralizing antibody (NAb) levels gradually declined from 2 months to 10 years after symptom onset. • NAb was undetectable in patients with fatal severe fever with thrombocytopenia syndrome (SFTS) during the hospitalization. • Patients with SFTS with mild illness or low viremia may experience early NAb seroconversion. • Distinct dynamic patterns of NAb were noted in patients with SFTS. Severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) is an emerging tick-borne bunyavirus with a high pathogenicity. Little is known about the longitudinal dynamics of the SFTSV-specific neutralizing antibody (NAb) and the related factors in patients with SFTS. A prospective cohort study of patients with laboratory-confirmed SFTS were conducted. Antiglomerulonephritis-immunoglobulin G (anti-Gn-IgG) and NAb titers were examined in serially collected serum samples, and their dynamic features were analyzed. NAb was initially detected at 15 days after symptom onset in surviving patients with SFTS, with positive rates of 37.21% (16/43), whereas neither anti-Gn-IgG antibody nor NAb was detected in patients with fatal SFTS during their hospitalization. The NAb levels reached the peak at 2 months after symptom onset, and then gradually declined, with a rapid downward trend from 6 months to 4 years and a relatively slow downward trend from 5 to 10 years. There was a positive correlation between NAb and anti-Gn-IgG titers in surviving patients with SFTS (r = 0.699, P <0.001). Patients with a mild illness or low viral load experienced early NAb seroconversion. Six different dynamic patterns of NAb were noted in surviving patients. These data provide useful information regarding the dynamic changes in NAb in patients with SFTS during the acute and convalescent phases and the follow-up period. [ABSTRACT FROM AUTHOR]