Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Breast cancer patients presenting with cardiotoxicity - risk factors and role of cardioprotective drugs

Funding Acknowledgements

Type of funding sources: None.

Introduction

Recent advances in cancer treatment have led to improved survival, albeit with cardiovascular adverse effects being some of the most frequent and feared consequences. Patient’s risk stratification, prevention and treatment are still to be fully elucidated. Our aim was to evaluate the risk and therapy of cardiotoxicity (CT) secondary to cancer treatment in a subset of patients with breast cancer (BC).

Methods

We collected a retrospective cohort of female with BC treated with conventional chemotherapy (CHT) and/or anti-HER2-targeted therapies (AHT) referred to Cardio-oncology consultation from January 2017 to March 2020. All patients were evaluated before CHT and at least at 3, 6 and 12-months with echocardiogram and cardiac biomarkers, namely high sensitivity troponin I (hs-cTnI) and brain natriuretic peptide (BNP). CT was defined as left ventricle ejection fraction (LVEF) under 50% or decline of at least 10% in LVEF during follow-up. As cardioprotective drugs (CPD) we considered renin-angiotensin-aldosterone system inhibitors and beta-blockers.

Results

A total of 203 women were enrolled, with mean age 50.9 ± 10.9 year-old. As for the cardiovascular risk factors, 23.5% had hypertension, 32.4% dyslipidaemia, 9.8% diabetes and 33.0% were smokers or previous smokers. The majority of patients had a high or very-high CT risk score (98.5% with score ≥ 5) and 35.5% were already on CPD before CHT. All patients were submitted to CHT: anthracyclines (AC) and AHT were applied to 83.8% and 41.7% of patients, respectively, with 27.9% of patients on both therapies; 81.4% were submitted to radiotherapy (RT). At presentation, all patients had normal cardiac function with mean LVEF of 62.9% and mean global longitudinal strain (GLS) of -19.4; mean hs-cTnI and BNP were 3.3 ng/L and 33.4 pg/mL, respectively. During a median follow-up of 16 months, 8.5% of patients developed CT, leading to initiation or titration of CPD in 76.9% and treatment interruption in 23.5%; most of them recovered (88.2%). During treatment there was a significantly increase of hs-cTnI (mean 19.7 ng/L at 3 months, p < 0.001) and a decrease of GLS and LVEF at 12 months (decrease of 1.1 and 2.2%, respectively, both p < 0.001). Both AHT and AHT plus AC were significantly associated with CT (p = 0.002 and p < 0.001, respectively), with an extremely high prevalence in the latter group (19.6%). Nor CVRF neither RT raised the risk of CT. Although patients on CPD did not had lower prevalence of CT (5.6% vs 10.2%, p = 0.268), its initiation was associated with a higher rate of cardiac function recovery (100.0% vs 66.7%, p = 0.057).

Conclusion

Patients submitted to AHT or AHT plus AC were at higher risk of developing CT. This and the significant LVEF decline during follow-up highlight the importance of long-term-monitoring of these patients. CPD seemed to be associated with cardiac recovery, although this finding needs further validation.

HER2 positive breast cancer: is there a preventive role of cardioprotective drugs?

Introduction

In patients with breast cancer, anti-HER2-targeted therapies (AHT) are highly associated with cardiotoxicity (CT), being the main reason for treatment interruption in patients receiving adjuvant trastuzumab. Guidelines recommend regular left ventricular ejection fraction (LVEF) assessments and CT's management with cardioprotective drugs (CPD). However, while secondary prevention has already entered clinical practice, primary prevention is still in the research domain. Our aim was to evaluate risk of CT and the role of CPD in a subset of breast cancer patients treated with AHT.

Methods

We retrospectively analyzed a population of breast cancer female patients treated with AHT referred to Cardio-oncology consultation at a tertiary center from January 2017 to March 2020. All patients were evaluated with echocardiogram before treatment initiation and at least at 3, 6, 9 and 12-months. CT was defined as LVEF under 50% or decline of at least 10% in LVEF during follow-up. As CPD we considered renin-angiotensin-aldosterone system inhibitors and beta-blockers.

Results

A total of 85 patients were included with mean age of 52.4±10.2 year-old. Concerning cardiovascular risk factors 11.8% had diabetes, 32.9% dyslipidaemia, 29.4% hypertension and 22.4% were smokers or previous smokers; most patients had a high or very-high CT risk score (98.8% with score ≥5). Besides AHT, 68.2% and 80% were also on anthracyclines and radiotherapy, respectively. Patients were followed for a median follow-up of 16 months. At baseline, mean high sensitivity troponin I was 3.9 ng/L, mean LVEF was 63.1% and mean global longitudinal strain was −19.7, with all patients having normal cardiac function. During follow-up, 15.7% developed CT with a higher prevalence in patients concomitantly on anthracyclines (19.6% vs 7.4%, p=0.151). CPD was initiated or titrated in 84.6% of patients and 30.8% needed to suspend AHT; overall 92.3% of CT patients recovered. Unlike AHT suspension, CPD initiation after CT was associated with a higher rate of cardiac function recovery (100.0% vs 50.0%, p=0.020). When comparing patients already medicated with CPD before cancer treatment (41.7%) to those naïve of CPD, the first group presented a significative lower incidence of CT [2.9% vs 25.0%, p=0.006, OR=0.09 (95% CI 0.01 – 0.72)]. When analysed all sample (with or without CT), patients already on CPD also presented a higher LVEF at 6 months follow-up (62.5% vs 59.2%, t(69)=−2.4, p=0.017 at 6 months), despite a non-significative lower LVEF at baseline (62.3% vs 63.6%, p=0.139). Medication with statins before chemotherapy didn't reduce the risk of CT.

Conclusion

Pre-treatment with CPD was significantly associated with a lower prevalence of CT and a higher LVEF at 6-months follow-up. CPD initiation after CT was associated with cardiac function recovery. These results highlights the importance of cardiac evaluation in HER2+ patients and strengthen the primary prevention field in these patients.

Funding Acknowledgement

Type of funding sources: None.

Suicidal behaviors: Relationship with body mass index and serological indicators

Introduction

Current research has demonstrated associations between variables of a biomedical nature with the presence of psychological indicators.

Objectives

To analyze the relationship between levels of total cholesterol, triglycerides, and Body Mass Index (BMI) with suicidal behaviors, on a non-smoking sample, without women who take birth control pills and participants without depressive pathologyTo analyze the relationship between levels of total cholesterol, triglycerides, and Body Mass Index (BMI) with suicidal behaviors, on a non-smoking sample, without women who take birth control pills and participants without depressive pathology.

Methods

We used a sociodemographic questionnaire and the Suicidal Behaviors Questionnaire - revised (SBQ-R) to evaluate the suicide ideation, suicide attempt and the probability of committing suicide. The sample is composed of 166 participants with ages between 18 and 89-years-old, 54.2% are men and 45.8% are women.

Results

We observed a weak association between serological indicators with some components of suicidal behaviors. It is also observed that higher cholesterol levels are associated with a higher probability of suicide; normal BMI is related to an increase of suicidal ideation; and the age group of 41 to 89 years-old presents a higher probability of committing suicide.

Conclusions

It is further concluded that age, gender, marital status, place of residence, education and professional status are significantly associated with suicidality. Yet, the influence of cholesterol, triglycerides, and BMI levels on suicide behaviors was not supported.

Tissue characterization and myocardium strain by cardiac magnetic resonance imaging in the early detection of anthracycline cardiotoxicity

Background

Cardiotoxicity (CT) remains an important cause of morbidity and mortality in patients with lymphomas treated with anthracyclines. Current strategies for early detection of CT during chemotherapy are not yet fully established.

Purpose

To evaluate the performance of cardiac magnetic resonance with T1 mapping and myocardium strain by feature tracking during chemotherapy in detecting anthracycline CT in patients with lymphoma.

Methods

From June 2017 to March 2019, patients with lymphoma planned to start chemotherapy with anthracyclines were evaluated by a cardiologist to check the eligibility criteria. At baseline (Time 1), at the end of 3° cycle (Time 2) and 30 days after the final cycle (Time 3), patients were evaluated through cardiac biomarkers, electrocardiogram and cardiac magnetic resonance (CMR). Strain, MapT1 and extracellular volume (ECV) were evaluated in all patients. CT was defined as drop of the left ventricular fraction (LVEF) >10% or LVEF decrease below 50%. A p value <0.05 was considered statistically significant.

Result

We included 48 patients, mean age was 45.32 (± 17.84) years-old and 25 (52.1%) were female. The prevalence of hypertension, diabetes and dyslipidemia was 18.8%, 10.4% and 10.4%, respectively. CT was diagnosed in 13 patients (27%). At baseline, there was no difference between cardiotoxicity group (CTG) and no cardiotoxicity group (nCTG) in CMR diastolic volume, systolic volume, nativeT1 map and global longitudinal strain (GLS), respectively (116 [103.6–138.1]ml vs 136.3 [115.7–173.8], p=0.069), (46 [38.0–58.5] ml vs 63.0 [44.5–74.2, p=0.069), (1540.6 [1478.3–1591.1]ms vs 1514.8 [1487.5–1786.3]ms, p=0.568) and (−15.94±2.91% vs −14.84±2.65%, p=0.243). Regarding the others CMR parameters, we showed that comparing CTG patients with nCTG patients at Time 3, systolic volumes were higher (54.8 [45.0–67.0] ml vs 78.51 [53.9–96.3] ml, p=0.007), right ejection fraction was lower (53.41±9.73% vs 46.29±3.93%, p=0.002), LVEF was lower (58.7±5.69% vs 46.67±8.12%, p<0.001) and GLS and radial strain were also reduced (−13.92±1.76% vs −12.44±2.7%, p=0.043) and (22.9 [21.18–27.43]% vs 19.84 [17.12–21.73], p=0.017), respectively. We did not observe any difference between groups in the native T1 map between groups at Time 2 and 3 1537.75 (1493.76–1589.72)ms vs 1601.99 (1501.12–1673.44)ms (p 0.383) and 1538.43 (1479.03–1633.6)ms and 1612.85 (1522.74–1638.34) ms (p=0.289). Similarly, the ECV value was no difference between groups at Time 2 and 3 (25.17 [23.62–32.83]% vs 24.42 [22.75–27.47], p=0.281 and 27.5 [23.59 - 31,9]% vs 27.2 [23.84–28.47]%, p=0.529, respectively).

Conclusions

Cardiotoxicity is a frequent complication in anthracycline treated patients. CMR evaluation, through analysis of volumes, ejection fraction and strain might early identify these patients, allowing prevention strategies to be initiated to improve cardiovascular outcomes.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Fundação de Apoio a pesquisa do estado de São Paulo - FAPESP

P14.89 What happens after 15 years? A clinical picture of a cohort of survivors of CNS tumors treated with whole-brain irradiation in a National Cancer Center

BACKGROUND

Radiotherapy (RT) is standard curative treatment for many tumours, specially brain tumours. However, RT causes damage to normal brain tissue due to genetic instability, impairment of synaptic plasticity and increased oxidative stress and inflammation. With improved treatment, patient survival also increased in years, making long-term effect of RT more evident. Late toxicities of RT are well described for pediatric survivors but there is scant literature on late toxicities in adult survivors and, in general, the adult brain is considered less susceptible to radiation damage.

MATERIAL AND METHODS

Retrospective analysis of adult patients treated with whole-brain RT with more than 15 years of follow-up. Clinical charts were reviewed to collect clinical, demographic and outcome data.

RESULTS

From 18 patients found (mean age at diagnosis of 27 years, 13 male/ 5 female), 5 were diagnosed with medulloblastoma, 5 CNS lymphoma, 5 with germinoma, 3 with ependymoma and 1 with teratocarcinoma. Most common presentations were headache (61,1%), seizure (16,7%) and dizziness (16,7%). 5 patients (27,8%) had hydrocephalus at diagnosis. All patients received whole-brain RT (mean 40Gys, varying between 21 to 60Gys), alongside with complete surgical resection in 11 patients (61,1%) and chemotherapy in 10 patients (55,6%). Mean follow-up time was 23,6 years and only 1 patient died due to lymphoma recurrence 16,7 years after the initial diagnosis. During follow-up, all patients had late RT induced changes, leukoencephalopathy in 16 patients (88,9%; mean 8,6 years after RT), ischemic stroke in 9 patients (50,0%; mean 16,0 years after RT), cerebral microbleeds in 14 patients (77,8%; mean 15,4 years after RT), cognitive decline in 12 patients (66,7%; mean 15,8 years after RT), radio-induced meningioma in 3 patients (16,7%; mean 18,1 years after RT) and epilepsy in 2 patients (11,1%; mean 10,5 years after RT). Also 1 patient had neurosensorial loss 14,2 years after RT and another one had subarachnoid haemorrhage due to ruptured aneurysm 19 years after RT.

CONCLUSION

Our results show that late RT induced effects are progressive and irreversible in the adult survivors, in a very similar manner as has been reported in the pediatric survivors. The impact on quality of live is increasing as patients survive longer. RT is still an important tool in neuro-oncology, but its role in curing brain tumors needs further study.

Molecular characterization of two sub-family specific monoclonal antibodies to meningococcal Factor H binding protein

Factor H binding protein (FHbp) is a component of two licensed vaccines for prevention of sepsis and meningitis caused by serogroup B meningococci. FHbp binds human Factor H (FH), which contributes to evasion of host immunity and FHbp sequence variants can be classified into two sub-families. Antibodies against FHbp elicit complement-mediated killing and can inhibit recruitment of FH to the bacterial surface. We report epitope mapping studies of two murine IgG mAbs, designated JAR 31 and JAR 36, isolated from a mouse immunized with FHbp in sub-family A, which is present in ∼30-40% of invasive isolates. In the present study, we tested the reactivity of mAbs JAR 31 and JAR 36 with seven natural FHbp sequence variants from different phylogenic groups. We screened bacteriophage-displayed peptide libraries to identify amino acid residues contributing to the JAR 36 epitope. Based on the reactivities of mAbs JAR 31 and JAR 36 with the seven FHbp variants, and the frequent occurrences of aspartate (D) and lysine (K) residues in the JAR 36-bound phage peptides, we selected six residues in the carboxyl-terminal region of FHbp for replacement with alanine (A). The D201A and K203A substitutions respectively eliminated and decreased binding of mAbs JAR 31 and JAR 36 to FHbp. These substitutions did not affect binding of the control mAb JAR 33 or of human FH. JAR 31 or JAR 36 mediated cooperative complement-mediated bactericidal activity with other anti-FHbp mAbs. The identification of two amino acid residues involved in the epitopes recognized by these anti-FHbp mAbs may contribute to a more complete understanding of the spatial requirements for cooperative anti-FHbp mAb bactericidal activity.

Effects of mesenchymal stromal cells play a role the oxidant/antioxidant balance in a murine model of asthma

Asthma is a heterogeneous disease characterised by chronic airway inflammation. One of the most devastating consequences of this inflammatory process is the generation of reactive oxygen and nitrogen species responsible for oxidative stress. The aim of this study is to analyse the efficiency of treatment with human bone marrow-derived mesenchymal stromal cells (hMSC) in maintaining the oxidative balance in a murine model of allergic asthma by quantifying nitrotyrosine in lung tissues. After confirmation of asthma in the experimental model, samples of lung parenchyma were submitted to immunohistochemical assessment. Intravenous administration of hMSC reduced the levels of nitrotyrosine in the ASTHMA-hMSC group compared to those in the ASTHMA-SAL group. In conclusion, therapeutic administration of hMSC had a beneficial effect on oxidative stress, reducing the levels of nitrotyrosine in lung tissues in a model of allergic asthma.

Polyphenols journey through blood-brain barrier towards neuronal protection

Age-related complications such as neurodegenerative disorders are increasing and remain cureless. The possibility of altering the progression or the development of these multifactorial diseases through diet is an emerging and attractive approach with increasing experimental support. We examined the potential of known bioavailable phenolic sulfates, arising from colonic metabolism of berries, to influence hallmarks of neurodegenerative processes. In silico predictions and in vitro transport studies across blood-brain barrier (BBB) endothelial cells, at circulating concentrations, provided evidence for differential transport, likely related to chemical structure. Moreover, endothelial metabolism of these phenolic sulfates produced a plethora of novel chemical entities with further potential bioactivies. Pre-conditioning with phenolic sulfates improved cellular responses to oxidative, excitotoxicity and inflammatory injuries and this attenuation of neuroinflammation was achieved via modulation of NF-κB pathway. Our results support the hypothesis that these small molecules, derived from dietary (poly)phenols may cross the BBB, reach brain cells, modulate microglia-mediated inflammation and exert neuroprotective effects, with potential for alleviation of neurodegenerative diseases.

Residential Unit for the Elderly: Cases Study and Reflections on the First 18 Months of Functioning

Introduction

The Residential Unit for the Elderly (RUE) was established in August 2015 and has capacity for 8 inpatients. It is intended to behavioral reorganization and caregiver rest of elderly patients with behavioral changes, particularly in cases of cognitive impairment.

Aim

We intend to describe the hospitalized population in the first 18 months and discuss the unit functioning and its impact on clinical stability of patients.

Methods

Socio-demographic and clinical data were analyzed using the STATA v13.1 software, using multivariate regression model with a 0.05 significance level.

Results

We present preliminary results from the first twelve months. Twenty-six patients admitted, 18 (69.2%) were female, with an average age of 76.7 years-old (IQR 71–86-years-old). The main reasons for referral were: caregiver rest (38.4%), psychopathological stabilization (30.7%) and autonomy training/cognitive stimulation (15.4%). Most patients had dementia (65.4%). Patients were hospitalized on average 78 days (IQR 30–98 days). Complications occurred in 18 patients (69.2%). There was an 85.7% reduction in the number of hospitalizations for any cause within 6 months after hospitalization in the RUE (P < 0.001) and a 75% reduction in hospitalizations from psychiatric cause (P = 0.001). Regarding visits to the emergency room (ER), we found a decrease of 87.1% in visits for psychiatric motive (P < 0.001) and 85.4% in visits for any cause (P < 0.001).

Conclusion

Inpatient care in RUE has contributed to the clinical stability of patients with consequent reduced use of health services. Although the results still concern a short operating period, they appear to be promising.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

In vitro Evaluation of Corrosion and Cytotoxicity of Orthodontic Brackets

The corrosion resistance of AISI 304 stainless steel (AISI 304 SS) and manganese stainless steel (low-nickel SS) brackets in artificial saliva was investigated. The cytotoxic effects of their corrosion products on L929 cell culture were compared by two assays, crystal violet, to evaluate cell viability, and MTT (3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide), for cell metabolism and proliferation. The atomic absorption spectroscopic analysis of the corrosion products demonstrated that nickel and manganese ion concentrations were higher for the AISI 304 SS-bracket immersion solution as compared with the low-nickel SS brackets. Scanning electron microscopy and energy-dispersive spectroscopy demonstrated less corrosion resistance for the AISI 304 SS brackets. Although none of the bracket extracts altered L929 cell viability or morphology, the AISI 304 SS-bracket extracts decreased cellular metabolism slightly. The results indicated that the low-nickel SS presents better in vitro biocompatibility than AISI 304 SS brackets. Abbreviations used: AISI, American Iron and Steel Institute; EDS, energy-dispersive spectroscopy; OD, optical density; ISO, International Organization for Standardization; MTT, (3-{4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NiSO4, nickel sulfate; SEM, standard error of the mean; WHO, World Health Organization; and TNF, tumor necrosis factor.

Surveillance of norovirus in Portugal and the emergence of the Sydney variant, 2011-2013

This report presents the results of the national surveillance system of diarrhea etiology of the National Institute of Health of Portugal concerning norovirus (NoV) during a two-year period, May 2011-2013. Of the total 580 stool samples collected from patients hospitalized for acute diarrhea in 13 Hospitals of Portugal, 67 (11.6%) tested positive for NoV. From May 2011 to March 2012 the GII.4 variant New Orleans 2009 was the most predominant strain having been replaced by the new GII.4 variant Sydney 2012 since then till the end of the survey. To our knowledge this is the first study showing the circulation of GII.4 as the norovirus strain most commonly associated to gastroenteritis and the first to report the replacement of GII.4 New Orleans by GII.4 Sydney 2012 variant in Portugal.

Routine screening of harmful microorganisms in beach sands: implications to public health

Beaches worldwide provide recreational opportunities to hundreds of millions of people and serve as important components of coastal economies. Beach water is often monitored for microbiological quality to detect the presence of indicators of human sewage contamination so as to prevent public health outbreaks associated with water contact. However, growing evidence suggests that beach sand can harbor microbes harmful to human health, often in concentrations greater than the beach water. Currently, there are no standards for monitoring, sampling, analyzing, or managing beach sand quality. In addition to indicator microbes, growing evidence has identified pathogenic bacteria, viruses, and fungi in a variety of beach sands worldwide. The public health threat associated with these populations through direct and indirect contact is unknown because so little research has been conducted relating to health outcomes associated with sand quality. In this manuscript, we present the consensus findings of a workshop of experts convened in Lisbon, Portugal to discuss the current state of knowledge on beach sand microbiological quality and to develop suggestions for standardizing the evaluation of sand at coastal beaches. The expert group at the "Microareias 2012" workshop recommends that 1) beach sand should be screened for a variety of pathogens harmful to human health, and sand monitoring should then be initiated alongside regular water monitoring; 2) sampling and analysis protocols should be standardized to allow proper comparisons among beach locations; and 3) further studies are needed to estimate human health risk with exposure to contaminated beach sand. Much of the manuscript is focused on research specific to Portugal, but similar results have been found elsewhere, and the findings have worldwide implications.

Inhibition of norovirus replication by the nucleoside analogue 2'-C-methylcytidine

We here report on the activity of 2'-C-methylcytidine (2CMC) [a nucleoside polymerase inhibitor of the hepatitis C virus (HCV)] on the in vitro replication of (murine) norovirus (MNV). 2CMC inhibits (i) virus-induced CPE formation, (ii) viral RNA synthesis and (iii) infectious progeny formation with EC(50) values of ∼2μM. 2CMC acts at a time-point that coincides with the onset of viral RNA synthesis. Even following 30 passages of selective pressure no MNV-resistant virus was selected, which is in line with the high barrier to resistance of the nucleoside analogue for HCV. When combined with the broad-spectrum RNA virus inhibitor ribavirin, a marked antagonistic activity was observed indicating that these molecules should not be combined for the treatment of norovirus infections. Our results suggest that 2'-C-methyl nucleoside analogues should be further explored for the treatment and prophylaxis of norovirus infections.