A narrative review of norovirus epidemiology, biology, and challenges to vaccine development.

Norovirus is a leading cause of acute gastroenteritis (AGE) globally. AGE resulting from norovirus causes significant morbidity and mortality in countries of all income levels, particularly among young children and older adults. Prevention of norovirus AGE represents a unique challenge as the virus is genetically diverse with multiple genogroups and genotypes cocirculating globally and causing disease in humans. Variants of the GII.4 genotype are typically the most common genotype, and other genotypes cause varying amounts of disease year-to-year, with GII.2, GII.3, and GII.6 most prevalent in recent years. Noroviruses are primarily transmitted via the fecal-oral route and only a very small number of virions are required for infection, which makes outbreaks of norovirus extremely difficult to control when they occur. Settings like long-term care facilities, daycares, and hospitals are at high risk of outbreaks and can have very high attack rates resulting in substantial costs and disease burden. Severe cases of norovirus AGE are most common in vulnerable patient populations, such as infants, the elderly, and immunocompromised individuals, with available treatments limited to rehydration therapies and supportive care. To date, there are no FDA-approved norovirus vaccines; however, several candidates are currently in development. Given the substantial human and economic burden associated with norovirus AGE, a vaccine to prevent morbidity and mortality and protect vulnerable populations could have a significant impact on global public health.

Estimated cytomegalovirus seroprevalence in the general population of the United States and Canada.

Seroprevalence data for cytomegalovirus (CMV), a widespread virus causing lifelong infection, vary widely, and contemporary data from the United States (US) and Canada are limited. Utilizing a modeling approach based on a literature review (conducted August, 2022) of data published since 2005, we determine age-, sex-, and country-specific CMV seroprevalence in the general US and Canadian populations. Sex-specific data were extracted by age categories, and a random-effects meta-regression model was used to fit the reported data (incorporating splines for the US). Seven studies reported US CMV seroprevalence (both sexes, aged 1‒89 years); all used National Health and Nutrition Examination Survey data. Due to limited population-based studies, Canadian estimates were modeled using other limited country data. In both countries, modeled seroprevalence estimates increased with age and were higher in females versus males (US: 49.0% vs. 41.6% at 18‒19 years; 61.5% vs. 50.0% at 38‒39 years; Canada: 23.7% vs. 13.7% at 18‒19 years; 32.6% vs. 22.6% at 38‒39 years). Notably, by young adulthood, one-half of US and one-quarter of Canadian females have acquired CMV. The observed differences in CMV seroprevalence in the US and Canada may partially reflect variations in general population characteristics.

Increased Risk of Venous Thromboembolism in Patients With Amyotrophic Lateral Sclerosis: Results From a US Insurance Claims Database Study.

Background and Objectives: Reduced mobility in patients with amyotrophic lateral sclerosis (ALS) is hypothesized to increase the risk of venous thromboembolism (VTE). A few small, single-center studies have investigated the risk of VTE in patients with ALS. Given the high morbidity and mortality associated with VTE, further understanding of the risk in patients with ALS may inform clinical care. The objective of this study was to investigate the incidence of VTE in patients with ALS compared with controls without ALS. Methods: Patients were identified from a US health insurance claims database, Optum's deidentified Clinformatics Data Mart Database, between 2004 and 2019. ALS cases were defined as patients aged 18 years or older with (1) 2 or more ALS claims at least 27 days apart including at least 1 claim from a neurologist visit or (2) 1 or more ALS claims and a prescription for riluzole or edaravone. Each ALS case was matched on age and sex to 5 controls without ALS. VTE was defined as at least 1 claim for VTE and at least 1 anticoagulant prescription or VTE-related procedure within 7 days before and 30 days after a VTE claim date. Incidence rates were reported per 1,000 person-years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using the Cox proportional hazards model. Results: Among 4,205 ALS cases and 21,025 controls, incident VTE occurred in 132 ALS cases (3.1%) and 244 controls (1.2%). Incidence rates of VTE were 19.9 per 1,000 person-years (95% CI 16.7-23.6) in ALS cases compared with 6.0 per 1,000 person-years (95% CI 5.0-7.1) in controls. ALS cases were about 3 times more likely to develop VTE (HR 3.3, 95% CI 2.6-4.0), with similar results among men and women. The median time to first VTE was 10 months from the initial ALS claim in ALS cases. Discussion: Consistent with previous smaller studies, a higher incidence rate of VTE was observed in a large sample of patients with ALS from across the United States, as compared to matched controls. The markedly increased risk underscores the importance of preventive efforts and careful monitoring for VTE in patients with ALS and may have implications for the management of ALS.

Comparative All-Cause Mortality Among a Large Population of Patients with Spinal Muscular Atrophy Versus Matched Controls.

INTRODUCTION: There is little information about survival of spinal muscular atrophy (SMA) patients into adulthood, in particular from population-based samples. We estimated and compared age-specific, all-cause mortality rates in patients with SMA and matched controls in a large, retrospective cohort study using electronic health records (EHRs) from the pre-treatment era. METHODS: The US Optum® de-identified EHR database contains EHRs for ~ 104 million persons (study period: January 1, 2007-December 22, 2016). SMA cases were identified by one or more International Classification of Diseases, Ninth/Tenth Edition codes for SMA. Controls with no SMA diagnosis code were matched 10:1 to SMA cases based on birth year, gender, and first diagnostic code date. For both groups, ≥ 1 month of observation and (if deceased) a valid date of death were required for inclusion. Age-specific mortality rates per person-year (PY) and hazard ratios were calculated. RESULTS: Five thousand one hundred seventy-nine SMA cases and 51,152 controls were analyzed. The overall hazard ratio comparing cases with controls was 1.76 (95% CI 1.63-1.90). In patients with SMA type III diagnostic codes only, the all-age mortality rate was 1059/100,000 PYs in cases and 603/100,000 PYs in controls. In older age groups (13-20, 21-30, 31-40, 41-50, 51-60, and > 60 years), age-specific mortality rates for cases consistently exceeded those of controls. Limitations of this study included the inability to confirm the SMA diagnosis or SMA type by genetic or clinical confirmation. CONCLUSION: Patients with SMA of all ages, including adults and type III patients, had a higher all-cause mortality rate as compared to age-matched controls during the pre-treatment era.

The incidence of hydrocephalus among patients with and without spinal muscular atrophy (SMA): Results from a US electronic health records study.

BACKGROUND: The incidence of hydrocephalus in the spinal muscular atrophy (SMA) population relative to the general population is currently unknown. Since the approval of nusinersen, an intrathecally administered drug for SMA, a small number of hydrocephalus cases among nusinersen users have been reported. Currently, the incidence of hydrocephalus in untreated SMA patients is not available, thereby making it difficult to determine if hydrocephalus is a side effect of nusinersen or part of SMA's natural history. This retrospective, matched cohort study used electronic health records (EHRs) to estimate and compare the incidence of hydrocephalus in both SMA patients and matched non-SMA controls in the time period prior to the approval of nusinersen. METHODS: The U.S. Optum® de-identified EHR database contains records for approximately 100 million persons. The current study period spanned January 1, 2007-December 22, 2016. Patients with SMA were identified by one or more International Classification of Diseases (ICD)-9 and/or ICD-10 codes for SMA appearing as primary, admission, or discharge diagnoses, without a pregnancy diagnostic code in the 1-year time before and after the first occurrence of SMA. The first occurrence of SMA defined the index date and non-SMA controls were matched to cases. Incident cases of hydrocephalus were identified with one or more ICD-9 and/or ICD-10 code for any type of hydrocephalus following the index date. Hydrocephalus incidence rates per person-months and the incidence rate ratio comparing SMA cases with non-SMA controls were calculated. RESULTS: There were 5354 SMA cases and an equal number of matched non-SMA controls. Incident hydrocephalus events were identified in 42 SMA cases and 9 non-SMA controls. Hydrocephalus incidence rates per 100,000 person-months were 15.5 (95% CI: 11.2-20.9) among SMA cases and 3.3 (95% CI: 1.5-6.3) among non-SMA controls. The incidence rate ratio was 4.7 (95% CI: 2.4-10.2). CONCLUSIONS: Based on this retrospective analysis utilizing US EHR data, SMA patients had an approximately fourfold increased risk of hydrocephalus compared with non-SMA controls in the era preceding nusinersen treatment. This study may assist in properly evaluating adverse events in nusinersen-treated SMA patients.

The role of urgency, frequency, and nocturia in defining overactive bladder adaptive behavior.

AIM: To determine the relation between urgency alone, or in combination with frequency and nocturia, and adaptive behavior in overactive bladder (OAB) syndrome. METHODS: We used survey data from the General Longitudinal Overactive Bladder Evaluation (GLOBE) of primary care patients over 40. Participants (n=2,752: 1,557 females; 1,195 males) completed the same survey at two time points, 6 months apart. Questions assessed OAB symptoms and adaptive behavior. We estimated correlation coefficients (R(2)) between urgency, frequency, and nocturia symptom scores (alone and in combination) and adaptive behavior measures at baseline and change in symptom scores and behavioral measures from baseline to 6 months. RESULTS: At baseline, urgency was the dominant predictor of all behavioral measures for females (R(2)=0.19-0.48) and males (R(2)=0.15-0.39). Lower R(2) values were observed for the change in measures from baseline to 6 months, but again change in urgency was the strongest predictor of change in adaptive behavior (R(2)=0.04-0.13 in females, and 0.02-0.08 in males). The correlation between symptoms and measures of adaptive behavior was almost completely explained by the urgency score. Frequency and nocturia did not substantially improve the overall correlation. CONCLUSION: The relation between measures of OAB symptoms and adaptive behavior at baseline and over time are largely explained by urgency, not by frequency and nocturia.

Parity is not associated with urgency with or without urinary incontinence.

INTRODUCTION AND HYPOTHESIS: Evidence varies on the relation between parity and urgency or urge incontinence (UUI). We used data from the General Longitudinal Overactive Bladder Evaluation to determine whether differences in case definitions could account for variation in findings. METHODS: We simulated case criteria to correspond to studies of urgency, UUI, and parity using data from 1,880 patients. Logistic models were run for each case-control scenario corresponding to previously used case definitions. RESULTS: Parity was significantly associated with urgency (odds ratios (OR) 1.70; CI: 1.30-2.22) and UUI (odds ratios (OR) 1.87; CI: 1.34-2.60) only when the case criteria included individuals with stress incontinence (SUI). Parity was not associated with UUI when individuals with SUI were excluded or with urgency when individuals with incontinence were excluded. CONCLUSIONS: Neither urgency nor UUI symptoms appear to be associated with parity among women 40 years of age and older. Previous associations appear to be explained by inclusion of individuals with SUI.

Elevated factor VII as a risk factor for recurrent fetal loss. Relationship to factor VII gene polymorphisms.

Haemostatic abnormalities can be detected in a portion of the women who have recurrent fetal loss. We measured factor VII coagulant activity (FVII:C) in 65 women with 3 or more fetal losses (recurrent cases), 31 women with one 2nd or 3rd trimester loss (late loss cases), and 81 women with only live births (controls). FVII:C was greater than 2 standard deviations above the mean for controls in 9 recurrent cases (13.8%) and 2 controls (2.5%) for an odds ratio of 6.35 (95% CI 1.32-30.52, p=0.012). In recurrent cases, mean levels were significantly higher than controls for FVII:C (p=0.003), FVII antigen (p=0.024), and FVIIa (p=0.001). Late loss cases had an odds ratio of 4.23 (95% CI 0.67-26.67, p=0.098) with FVII:C, FVII antigen, and FVIIa not significantly different from the controls. DNA was examined for the presence of mutations or polymorphisms in the promoter region of the FVII gene, using denaturing HPLC. Abnormal patterns were confirmed with direct sequencing. A previously reported polymorphism, -402 G>A, was found to be present in 11/14 subjects with elevated FVII:C (79%) and 43% of those with normal levels (p=0.029). FVII:C, FVII antigen and FVIIa varied significantly with genotype; however, genotype frequencies did not differ between controls and either case group. No other promoter polymorphisms were identified. This is the first report of a significant elevation of FVII in a population with recurrent fetal loss. These data suggest the need for further investigation of this potential risk factor.

Age and the prevalence of bleeding disorders in women with menorrhagia.

OBJECTIVE: A study was conducted to evaluate the frequency and types of hemostatic defects occurring in adolescent and perimenopausal-age women diagnosed with menorrhagia. METHODS: A total of 115 women with a physician diagnosis of menorrhagia, including 25 adolescent women, 25 perimenopausal-age women, and 65 women between the ages of 20 and 44, underwent comprehensive hemostatic testing for possible bleeding disorders. Frequencies of bleeding disorders were calculated and compared. RESULTS: Forty-seven percent of women were found to have hemostatic abnormalities, including platelet dysfunction, von Willebrand's disease, and coagulation factor deficiencies. Adolescents and perimenopausal-age women with menorrhagia were just as likely to have hemostatic abnormalities as were women aged 20 to 44. CONCLUSION: These results demonstrate that underlying bleeding disorders are frequently found in adolescent, postadolescent reproductive age, and perimenopausal-age women presenting with menorrhagia and suggest that women with menorrhagia should be considered for further hemostatic evaluation.

Relationship of venous thromboembolism and myocardial infarction with the renin-angiotensin system in African-Americans.

Genetic polymorphisms/mutations associated with venous thrombosis have largely been confined to the genes that encode for proteins in either the coagulant or the anticoagulant pathway. Although genetic alterations in the renin-angiotensin system have been reported to have a role in myocardial infarction and hypertension, there is recent evidence to suggest that there may also be an association with venous thrombosis. To extend our earlier observation of an association between the ACE DD genotype in African-American males and venous thrombosis, other genes in the renin-angiotensin pathway were investigated for possible disease association and were compared with African-Americans with myocardial infarction. African-American patients with a documented history of venous thrombosis or a history of myocardial infarction were eligible for participation as cases in the study. Control subjects were African-American outpatients attending a clinical laboratory for routine blood tests who had comparable age and gender distributions to the cases. Persons with a history of myocardial infarction, stroke, or thrombosis were excluded. Genes that were analyzed for known polymorphisms included angiotensinogen, angiotensin-converting enzyme (ACE), and the angiotensin II type I receptor. Our results showed that the ACE DD genotype was also associated with MI in African-American males but not in females. Racial/ethnic and sex differences were also found with respect to the genotype distribution of the ACE 4656(CT)(2/3) polymorphism. It was observed that the 2/2 genotype had a protective effective in males for myocardial infarction and venous thrombosis. The data also demonstrated that the allele frequencies of the A1166C variant of the angiotensin II type I receptor were different in African-Americans as compared to Caucasians.

A survey of gynecologists concerning menorrhagia: perceptions of bleeding disorders as a possible cause.

We sought to determine perceptions and practices of American gynecologists when treating with a woman complaining of menorrhagia, specifically with regard to an underlying bleeding disorder as a potential cause. A mail survey of Georgia members of the American College of Obstetricians and Gynecologists was conducted. The survey response was 52%, and the analysis includes 376 physicians who reported seeing at least one gynecological patient per week. On average, respondents were in practice 20 years and reported that 8% of their patient population complain of menorrhagia. Virtually all physicians reported employing a menstrual history as a starting point for the workup for menorrhagia, and 95% order a hemoglobin/hematocrit determination. About 50% of physicians considered saturating three tampons/pads per 4 hours as excessive, although the criterion varied widely (range 0-24 per 4 hours, SD = 3). The diagnoses considered most likely among reproductive age women were anovulatory bleeding or benign lesions or that the heavy bleeding was within normal limits. Only 4% of physicians would consider von Willebrand disease (VWD) for this age group (women of reproductive age). Among girls near menarche, physicians overwhelmingly consider anovulatory bleeding or bleeding within normal limits the likely diagnoses, and 16% would consider VWD in this age group. Only rarely (3%) do surveyed physicians refer menorrhagia patients to other specialists. Most respondents believe that most menorrhagia is caused by anovulation or is within normal limits. Bleeding disorders are believed to be a rare cause of menorrhagia.