Comparison of Acute Health Care Utilization Between Patients Receiving In-Center Hemodialysis and the General Population: A Population-Based Matched Cohort Study From Ontario, Canada

Background

Patients receiving maintenance hemodialysis have multiple comorbidities and are at high risk of presenting to the hospital. However, the incidence and cost of acute health care utilization in the in-center hemodialysis population and how this compares with other populations is poorly understood.

Objective

To determine the rate, pattern, and cost of emergency department visits and hospitalizations in patients receiving in-center hemodialysis compared with a matched general population.

Design

Population-based matched cohort study.

Setting

We used linked administrative health care databases from Ontario, Canada.

Patients

We included 25 379 patients (incident and prevalent) receiving in-center hemodialysis between January 1, 2010, and December 31, 2018. Patients were matched on birth date (±2 years), sex, and cohort entry date using a 1:4 ratio to 101 516 individuals from the general population.

Measurements

Our primary outcomes were emergency department visits (allowing for multiple visits per individual) and hospital admissions from the emergency department. We also assessed all-cause hospitalizations, all-cause readmissions within 30 days of discharge from the original hospitalization, length of stay for hospital admissions (including multiple visits per individual), and the financial cost of these admissions.

Methods

We presented the rate, percentage, median (25th, 75th percentiles), and incidence rate per 1000 person-years for emergency department visits and hospitalizations. Individual-level health care costs for emergency department visits and all-cause hospitalization were estimated using resource intensity weights multiplied by the cost per weighted case.

Results

Patients receiving in-center hemodialysis had substantially more comorbidities (eg, diabetes) than the matched general population. Eighty percent (n = 20 309) of patients receiving in-center hemodialysis had at least 1 emergency department visit compared with 56% (n = 56 452) of individuals in the matched general population, over a median follow-up of 1.8 years (25th, 75th percentiles: 0.7, 3.6) and 5.2 (2.5, 8.4) years, respectively. The incidence rate of emergency department visits, allowing for multiple visits per individual, was 2274 per 1000 person-years (95% confidence interval [CI]: 2263, 2286) for patients receiving in-center hemodialysis, which was almost 5 times as high as the matched general population (471 per 1000 person-years; 95% CI: 469, 473). The rate of hospital admissions from the emergency department and the rate of all-cause hospital admissions in the in-center hemodialysis population was more than 7 times as high as the matched general population (hospital admissions from the emergency department: 786 vs 101 per 1000 person-years; all-cause hospital admissions: 1056 vs 139 per 1000 person-years). The median number of all-cause hospitalization days per patient year was 4.0 (0, 16.5) in the in-center hemodialysis population compared with 0 (0, 0.5) in the matched general population. The cost per patient-year for emergency department visits in the in-center hemodialysis population was approximately 5.5 times as high as the matched general population while the cost of hospitalizations in the in-center hemodialysis population was approximately 11 times as high as the matched general population (emergency department visits: CAN$ 1153 vs CAN$ 209; hospitalizations: CAN$ 21 151 vs CAN$ 1873 [all costs in 2023 CAN$]).

Limitations

External generalizability and we could not determine whether emergency department visits and hospitalizations were preventable.

Conclusions

Patients receiving in-center hemodialysis have high acute health care utilization. These results improve our understanding of the burden of disease and the associated costs in the in-center hemodialysis population, highlight the need to improve acute outcomes, and can aid health care capacity planning. Additional research is needed to address the risk of hospitalization after controlling for patient comorbidities.

Trial registration

This is not applicable as this is a population-based matched cohort study and not a clinical trial.

Defining pre-emptive living kidney donor transplantation as a quality indicator

Quality indicators in kidney transplants are needed to identify care gaps and improve access to transplants. We used linked administrative health care databases to examine multiple ways of defining pre-emptive living donor kidney transplants, including different patient cohorts and censoring definitions. We included adults from Ontario, Canada with advanced chronic kidney disease between January 1, 2013, to December 31, 2018. We created 4 unique incident patient cohorts, varying the eligibility by the risk of progression to kidney failure and whether individuals had a recorded contraindication to kidney transplant (eg, home oxygen use). We explored the effect of 4 censoring event definitions. Across the 4 cohorts, size varied substantially from 20 663 to 9598 patients, with the largest reduction (a 43% reduction) occurring when we excluded patients with ≥1 recorded contraindication to kidney transplantation. The incidence rate (per 100 person-years) of pre-emptive living donor kidney transplant varied across cohorts from 1.02 (95% CI: 0.91-1.14) for our most inclusive cohort to 2.21 (95% CI: 1.96-2.49) for the most restrictive cohort. Our methods can serve as a framework for developing other quality indicators in kidney transplantation and monitoring and improving access to pre-emptive living donor kidney transplants in health care systems.

Mental health and addiction service utilization among people living with chronic kidney disease

BACKGROUND

Mental health problems, particularly anxiety and depression, are common in patients with chronic kidney disease (CKD), and negatively impact quality of life, treatment adherence, and mortality. However, the degree to which mental health and addictions services are utilized by those with CKD is unknown. We examined the history of mental health and addictions service use of individuals across levels of kidney function.

METHODS

We performed a population-based cross-sectional study using linked healthcare databases from Ontario, Canada from 2009 to 2017. We abstracted the prevalence of individuals with mental health and addictions service use within the previous 3 years across levels of kidney function (eGFR$\ \ge $60, 45 to < 60, 30 to < 45, 15 to < 30, <15 mL/min per 1.73m2 and maintenance dialysis). We calculated prevalence ratios (PR) to compare prevalence across kidney function strata, while adjusting for age, sex, year of cohort entry, urban versus rural location, area-level marginalization, and Charlson comorbidity scores.

RESULTS

Of 5 956 589 adults, 9% (n = 534 605) had an eGFR<60 mL/min per 1.73m2 or were receiving maintenance dialysis. Fewer individuals with eGFR < 60 had a history of any mental health and addictions service utilization (crude prevalence range 28% to 31%), compared to individuals with eGFR ≥ 60 (35%). Compared to eGFR ≥ 60, the lowest prevalence of individuals with any mental health and addictions service utilization was among those with eGFR 15 to < 30 (adjusted PR 0.86, 95% CI 0.85 to 0.88), eGFR < 15 (adjusted PR 0.81, 95% CI 0.76 to 0.86) and those receiving maintenance dialysis (adjusted PR 0.83, 95% CI 0.81 to 0.84). Less use of outpatient services accounted for differences in service utilization.

CONCLUSIONS

Mental health and addictions service utilization is common but less so in individuals with advanced CKD in Ontario, Canada.

Clinical Outcomes and Vaccine Effectiveness for SARS-CoV-2 Infection in People Attending Advanced CKD Clinics: A Retrospective Provincial Cohort Study

BACKGROUND

People with advanced CKD are at high risk of mortality and morbidity from coronavirus disease 2019 (COVID-19). We measured rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe outcomes in a large population attending advanced CKD clinics during the first 21 months of the pandemic. We examined risk factors for infection and case fatality, and we assessed vaccine effectiveness in this population.

METHODS

In this retrospective cohort study, we analyzed data on demographics, diagnosed SARS-CoV-2 infection rates, outcomes, and associated risk factors, including vaccine effectiveness, for people attending a province-wide network of advanced CKD clinics during the first four waves of the pandemic in Ontario, Canada.

RESULTS

In a population of 20,235 patients with advanced CKD, 607 were diagnosed with SARS-CoV-2 infection over 21 months. The case fatality rate at 30 days was 19% overall but declined from 29% in the first wave to 14% in the fourth. Hospitalization and intensive care unit (ICU) admission rates were 41% and 12%, respectively, and 4% started long-term dialysis within 90 days. Significant risk factors for diagnosed infection on multivariable analysis included lower eGFR, higher Charlson Comorbidity Index, attending advanced CKD clinics for more than 2 years, non-White ethnicity, lower income, living in the Greater Toronto Area, and long-term care home residency. Being doubly vaccinated was associated with lower 30-day case fatality rate (odds ratio [OR], 0.11; 95% confidence interval [CI], 0.03 to 0.52). Older age (OR, 1.06 per year; 95% CI, 1.04 to 1.08) and higher Charlson Comorbidity Index (OR, 1.11 per unit; 95% CI, 1.01 to 1.23) were associated with higher 30-day case fatality rate.

CONCLUSIONS

People attending advanced CKD clinics and diagnosed with SARS-CoV-2 infection in the first 21 months of the pandemic had high case fatality and hospitalization rates. Fatality rates were significantly lower in those who were doubly vaccinated.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_04_10_CJN10560922.mp3.

Effectiveness of Three Doses of mRNA COVID-19 Vaccines in the Hemodialysis Population during the Omicron Period

BACKGROUND

Coronavirus disease 2019 (COVID-19) vaccine effectiveness studies in the hemodialysis population have demonstrated that two doses of mRNA COVID-19 vaccines are effective against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe complications when Alpha and Delta were predominant variants of concern. Vaccine effectiveness after a third dose versus two doses for preventing SARS-CoV-2 infection and severe COVID-19 in the hemodialysis population against Omicron is not known.

METHODS

We conducted a retrospective cohort study in Ontario, Canada, between December 1, 2021, and February 28, 2022, in the maintenance hemodialysis population who had received two versus three doses of mRNA COVID-19 vaccines. COVID-19 vaccination, SARS-CoV-2 infection, and related hospitalization and death were determined from provincial databases. The primary outcome was the first RT-PCR confirmed SARS-CoV-2 infection, and the secondary outcome was a SARS-CoV-2-related severe outcome, defined as either hospitalization or death.

RESULTS

A total of 8457 individuals receiving in-center hemodialysis were included. At study initiation, 2334 (28%) individuals received three doses, which increased to 7468 (88%) individuals by the end of the study period. The adjusted hazard ratios (aHR) for SARS-CoV-2 infection (aHR, 0.58; 95% confidence interval [CI], 0.50 to 0.67) and severe outcomes (hospitalization or death) (aHR, 0.40; 95% CI, 0.28 to 0.56) were lower after three versus two doses of mRNA vaccine. Prior infection, independent of vaccine status, was associated with a lower risk of reinfection, with an aHR of 0.44 (95% CI, 0.27 to 0.73).

CONCLUSIONS

Three-dose mRNA COVID-19 vaccination was associated with lower incidence of SARS-CoV-2 infection and severe SARS-CoV-2-related outcomes during the Omicron period compared with two doses.

Early Experience with Modified Dose Nirmatrelvir/Ritonavir in Dialysis Patients with Coronavirus Disease 2019

BACKGROUND

Nirmatrelvir/ritonavir was approved for use in high-risk outpatients with coronavirus disease 2019 (COVID-19). However, patients with severe CKD were excluded from the phase 3 trial, and the drug is not recommended for those with GFR <30 ml/min per 1.73 m 2 . On the basis of available pharmacological data, we developed a modified low-dose regimen of nirmatrelvir/ritonavir 300/100 mg on day 1, followed by 150/100 mg daily from day 2 to 5. In this study, we report our experience with this modified dose regimen in dialysis patients in the Canadian province of Ontario.

METHODS

We included dialysis patients who developed COVID-19 and were treated with the modified dose nirmatrelvir/ritonavir regimen during a 60-day period between April 1 and May 31, 2022. Details of nirmatrelvir/ritonavir use and outcomes were captured manually, and demographic data were obtained from a provincial database. Data are presented with descriptive statistics. The principal outcomes we describe are 30-day hospitalization, 30-day mortality, and required medication changes with the modified dose regimen.

RESULTS

A total of 134 dialysis patients with COVID-19 received nirmatrelvir/ritonavir during the period of study. Fifty-six percent were men, and the mean age was 64 years. Most common symptoms were cough and/or sore throat (60%). Medication interactions were common with calcium channel blockers, statins being the most frequent. Most patients (128, 96%) were able to complete the course of nirmatrelvir/ritonavir, and none of the patients who received nirmatrelvir/ritonavir died of COVID-19 in the 30 days of follow-up.

CONCLUSIONS

A modified dose of nirmatrelvir/ritonavir use was found to be safe and well tolerated, with no serious adverse events being observed in a small sample of maintenance dialysis patients.

Vaccine Effectiveness Against SARS-CoV-2 Infection and Severe Outcomes in the Maintenance Dialysis Population in Ontario, Canada

BACKGROUND

Vaccination studies in the hemodialysis population have demonstrated decreased antibody response compared with healthy controls, but vaccine effectiveness for preventing SARS-CoV-2 infection and severe disease is undetermined.

METHODS

We conducted a retrospective cohort study in the province of Ontario, Canada, between December 21, 2020, and June 30, 2021. Receipt of vaccine, SARS-CoV-2 infection, and related severe outcomes (hospitalization or death) were determined from provincial health administrative data. Receipt of one and two doses of vaccine were modeled in a time-varying cause-specific Cox proportional hazards model, adjusting for baseline characteristics, background community infection rates, and censoring for non-COVID death, recovered kidney function, transfer out of province, solid organ transplant, and withdrawal from dialysis.

RESULTS

Among 13,759 individuals receiving maintenance dialysis, 2403 (17%) were unvaccinated and 11,356 (83%) had received at least one dose by June 30, 2021. Vaccine types were BNT162b2 (n=8455, 74%) and mRNA-1273 (n=2901, 26%); median time between the first and second dose was 36 days (IQR 28-51). The adjusted hazard ratio (HR) for SARS-CoV-2 infection and severe outcomes for one dose compared with unvaccinated was 0.59 (95% CI, 0.46 to 0.76) and 0.54 (95% CI, 0.37 to 0.77), respectively, and for two doses compared with unvaccinated was 0.31 (95% CI, 0.22 to 0.42) and 0.17 (95% CI, 0.1 to 0.3), respectively. There were no significant differences in vaccine effectiveness among age groups, dialysis modality, or vaccine type.

CONCLUSIONS

COVID-19 vaccination is effective in the dialysis population to prevent SARS-CoV-2 infection and severe outcomes, despite concerns about suboptimal antibody responses.

Acute kidney injury requiring renal replacement therapy in people with COVID-19 disease in Ontario, Canada: a prospective analysis of risk factors and outcomes

Background

Severely ill people with coronavirus disease 2019 (COVID-19) are at risk of acute kidney injury treated with renal replacement therapy (AKI-RRT). The understanding of the risk factors and outcomes for AKI-RRT is incomplete.

Methods

We prospectively collected data on the incidence, demographics, area of residence, time course, outcomes and associated risk factors for all COVID-19 AKI-RRT cases during the first two waves of the pandemic in Ontario, Canada.

Results

There were 271 people with AKI-RRT, representing 0.1% of all diagnosed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases. These included 10% of SARS-CoV-2 admissions to intensive care units (ICU). Median age was 65 years, with 11% &lt;50 years, 76% were male, 47% non-White and 48% had diabetes. Overall, 59% resided in the quintile of Ontario neighborhoods with the greatest ethnocultural composition and 51% in the two lowest income quintile neighborhoods. Mortality was 58% at 30 days after RRT initiation, and 64% at 90 days. By 90 days, 20% of survivors remained RRT-dependent and 31% were still hospitalized. On multivariable analysis, people aged &gt;70 years had higher mortality (odds ratio 2.4, 95% confidence interval 1.3, 4.6). Cases from the second versus the first COVID-19 wave were older, had more baseline comorbidity and were more likely to initiate RRT  &gt;2 weeks after SARS-CoV-2 diagnosis (34% versus 14%; P &lt; 0.001).

Conclusions

AKI-RRT is common in COVID-19 ICU admissions. Residency in areas with high ethnocultural composition and lower socioeconomic status are strong risk factors. Late-onset AKI-RRT was more common in the second wave. Mortality is high and 90-day survivors have persisting high morbidity.

Reducing clinical review burden for insertable cardiac monitors

Funding Acknowledgements

Type of funding sources: None.

Background

The insertable cardiac monitor (ICM) is an essential tool for the ambulatory diagnosis of arrhythmias. However, definitive diagnoses still rely on time-consuming, manual adjudication of electrograms (EGMs) transmitted to the patient care network. This EGM review burden may be minimized by automatically selecting a subset of EGMs for fast review without delaying the diagnosis.

Purpose

Develop EGM selection strategies to reduce the EGM review burden without delaying diagnoses.

Methods

A retrospective analysis of 1,000 randomly selected Abbott Confirm Rx devices with 90+ days of remote transmission history was performed, regardless of transmission frequency, and all EGMs were adjudicated as either true or false positive (TP, FP). Up to 3 EGMs per day per arrhythmia type were prioritized for review based on ventricular rate and episode duration, with rules specific to each arrhythmia type: atrial fibrillation (AF), tachycardia, bradycardia, and pause. The resulting reduction in EGM review burden and TP days (patient-days with at least 1 TP EGM), as well as any diagnostic delay from the first transmitted TP, were calculated relative to reviewing all transmitted EGMs.

Results

In this population and transmission period, at least one AF, tachycardia, bradycardia, and pause EGM was transmitted by 424, 343, 190, and 325 unique devices, respectively, with a total of 35,723, 12,239, 19,752, and 28,002 EGMs, and a total of 6,163, 1,572, 1,438, and 646 TP days. For these patients with ≥1 EGM, the median [IQR] EGM transmission rate was 2.6 [0.7, 11.6], 1.1 [0.4, 4.7], 2.1 [0.6, 10.7], and 3.4 [0.6, 29.9] EGMs/patient/month, respectively. The optimal EGM selection strategy reduced this EGM review burden by 43%, 67%, 76%, and 50%, while only missing 3.4%, 2.2%, 0.3%, and 0.2% of TP days, respectively. Ultimately, 97%, 99%, 99%, and 99% of devices with a TP AF, tachycardia, bradycardia, or pause EGM exhibited no diagnostic delay vs. reviewing all transmitted EGMs.

Conclusion

EGM prioritization rules for selecting up to 3 episodes/day significantly reduced EGM burden across all patients, not just "frequent fliers," with no delay-to-diagnosis in &gt;97% of patients who exhibited a true arrhythmia. Implementing these rules on the patient care network may improve clinical workflow and ICM patient management. Abstract Figure.

Growing home dialysis: The Ontario Renal Network Home Dialysis Initiative 2012-2019

The Ontario Renal Network (ORN), a provincial government agency in Ontario, Canada, launched an initiative in 2012 to increase home dialysis use province-wide. The initiative included a new modality-based funding formula, a standard mandatory informatics system, targets for prevalent home dialysis rates, the development of a 'network' of renal programmes with commitment to home dialysis and a culture of accountability with frequent meetings between ORN and each renal programme leadership to review their results. It also included funding of home dialysis coordinators, encouragement and funding of assisted peritoneal dialysis (PD), and support for catheter insertion and urgent start PD. Between 2012 and 2017, home dialysis use rose from 21.9% to 26.5% and then between 2017 and 2019 stabilised at 26% to 26.5%. Over 7 years, the absolute number of people on home dialysis increased 40% from 2222 to 3105, while the number on facility haemodialysis grew 11% from 7935 to 8767. PD prevalence rose from 16.6% to 20.9%, a relative increase of 25%. The initiative showed that a sustained multifaceted approach can increase home dialysis utilisation.

COVID-19 chez les patients ontariens sous dialyse à long terme

CONTEXTE:

Les patients sous dialyse à long terme pourraient avoir un risque accru d’infection par le coronavirus du syndrome respiratoire aigu sévère 2 (SRAS-CoV-2), et de maladie et de mortalité associées. Nous avons voulu décrire l’incidence, les facteurs de risque et les issues de l’infection chez ces patients en Ontario (Canada).

MÉTHODES:

Nous avons utilisé des ensembles de données reliées pour comparer les caractéristiques de la maladie et la mortalité chez les patients sous dialyse à long terme en Ontario qui ont testé positif pour le SRAS-CoV-2 et ceux qui n’ont pas développé d’infection, entre le 12 mars et le 20 août 2020. Nous avons recueilli des données sur l’infection par le SRAS-CoV-2 de manière prospective. Nous avons évalué les facteurs de risque d’infection et de mortalité par des analyses de régression logistique multivariées.

RÉSULTATS:

Pendant la période à l’étude, 187 patients dialysés sur 12 501 (1,5 %) ont reçu un diagnostic d’infection par le SRAS-CoV-2. Parmi eux, 117 (62,6 %) ont été hospitalisés, et le taux de mortalité était de 28,3 %. Les facteurs prédictifs significatifs associés à l’infection incluaient l’hémodialyse dans un centre plutôt que la dialyse à domicile (rapport de cotes [RC] 2,54; intervalle de confiance [IC] à 95 % 1,59–4,05), le fait de vivre dans un établissement de soins de longue durée (RC 7,67; IC à 95 % 5,30–11,11), le fait d’habiter la région du Grand Toronto (RC 3,27; IC à 95 % 2,21–4,80), les ethnicités Noire (RC 3,05; IC à 95 % 1,95–4,77), du sous-continent indien (RC 1,70; IC à 95 % 1,02–2,81) et autres non blanches (RC 2,03; IC à 95 % 1,38–2,97) et les quintiles de revenu inférieurs (RC 1,82; IC à 95 % 1,15–2,89).

INTERPRÉTATION:

Les patients sous dialyse à long terme sont exposés à un risque accru d’infection par le SRAS-CoV-2 et de mortalité due à la maladie à coronavirus 2019. Il faudra travailler à éliminer les facteurs de risque d’infection et vacciner ces patients en priorité.

COVID-19 in patients undergoing long-term dialysis in Ontario

BACKGROUND

Patients undergoing long-term dialysis may be at higher risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and of associated disease and mortality. We aimed to describe the incidence, risk factors and outcomes for infection in these patients in Ontario, Canada.

METHODS

We used linked data sets to compare disease characteristics and mortality between patients receiving long-term dialysis in Ontario who were diagnosed SARS-CoV-2 positive and those who did not acquire SARS-CoV-2 infection, between Mar. 12 and Aug. 20, 2020. We collected data on SARS-CoV-2 infection prospectively. We evaluated risk factors for infection and death using multivariable logistic regression analyses.

RESULTS

During the study period, 187 (1.5%) of 12 501 patients undergoing dialysis were diagnosed with SARS-CoV-2 infection. Of those with SARS-CoV-2 infection, 117 (62.6%) were admitted to hospital and the case fatality rate was 28.3%. Significant predictors of infection included in-centre hemodialysis versus home dialysis (odds ratio [OR] 2.54, 95% confidence interval [CI] 1.59-4.05), living in a long-term care residence (OR 7.67, 95% CI 5.30-11.11), living in the Greater Toronto Area (OR 3.27, 95% CI 2.21-4.80), Black ethnicity (OR 3.05, 95% CI 1.95-4.77), Indian subcontinent ethnicity (OR 1.70, 95% CI 1.02-2.81), other non-White ethnicities (OR 2.03, 95% CI 1.38-2.97) and lower income quintiles (OR 1.82, 95% CI 1.15-2.89).

INTERPRETATION

Patients undergoing long-term dialysis are at increased risk of SARS-CoV-2 infection and death from coronavirus disease 2019. Special attention should be paid to addressing risk factors for infection, and these patients should be prioritized for vaccination.

P5648Efficiency and accuracy of arrhythmia detection using implantable cardiac monitor: A prospective multicenter randomized clinical trial comparing Reveal LINQ and Confirm Rx

Background

Implantable cardiac monitor (ICM) has been used to detect occult cardiac arrhythmias in a variety of clinical situations. The reliability and accuracy of diagnosing cardiac arrhythmia could impact patient care. However, it is not clear the efficiency and reliability of detecting cardiac arrhythmias between currently available two ICMs.

Purpose

To compare the efficiency and accuracy of diagnosing cardiac arrhythmias between Reveal LINQ™ and Confirm Rx™.

Methods

In the prospective multicenter randomized study, a total of 80 patients (age: 61±17 years, men: 41 [51%]) with cryptogenic stroke (n=52) or recurrent unexplained episodes of palpitations (n=3) or syncope (n=25) received an ICM for detection of arrhythmias. Patients were randomized one to one into receiving either Reveal LINQ™ or Confirm Rx™. Arrhythmic events are defined as pauses of ≥3.0 seconds, bradycardia with heart rate of ≤40 bpm, tachycardia with heart rate of ≥150 bpm, and atrial fibrillation (AF). The time of detected arrhythmic events and patient activated events to the time of data availability on respective website site for analysis were compared between the two ICM. All of the arrhythmia events were adjudicated by two cardiologists to assess the accuracy.

Results

A total of 680 arrhythmic events including 352 AFs, 109 bradycardias, 167 tachycardias and 52 pauses were transmitted over a mean follow-up of 4.2±2.5 months. The mean time to data transmission was significantly faster in Confirm Rx™ than in Reveal LINQ™ (24±103 vs 475±426 min, P<0.0001). One-hundred fifty-nine of 352 AF events (45%) and 237 of 328 non-AF events (72%) were accurately detected by ICMs (P<0.0001). Twenty-eight of 51 AF events (55%) were detected accurately by Reveal LINQ™ and 131 of 301 AF events (44%) were accurately detected by Confirm Rx™ (P=0.13). The reason for inaccurate AF detection was frequent ectopic beats (n=134), P-wave oversensing (n=15), T-wave oversensing (n=8), both P- and T-waves oversensing (n=18) and sinus tachycardia with R-wave undersensing (n=18).

Conclusions

Data transmission of arrhythmic events using Confirm Rx™ is significantly faster than Reveal LINQ™. The accuracy of AF detection with current algorithms in both ICM remains suboptimal. More patients and longer follow-up is required to confirm these findings.

Educational effectiveness of gynaecological teaching associates: a multi-centre randomised controlled trial

OBJECTIVE

To evaluate, among medical students learning the female pelvic examination, the added benefits of training by gynaecological teaching associates compared with training involving a manikin only.

DESIGN

Randomised controlled trial.

SETTING

Nine university teaching hospitals.

POPULATION

Ninety-four medical students recruited prior to commencing a 4-week obstetrics and gynaecology rotation.

METHODS

The control training consisted of lectures, demonstration of the pelvic examination on a manikin, and opportunities to practise on this low-fidelity simulation (n = 40). The experimental group received additional gynaecological teaching associate training, delivered by pairs of experienced associates to groups of four medical students (n = 54).

MAIN OUTCOME MEASURES

Outcomes measured at the end of the rotation included knowledge of the correct order of examination components (Yes/No), and student comfort [Likert scales anchored between 1 (very uncomfortable) and 4 (very comfortable) on four items] and confidence [Likert scales anchored between 1 (No) and 3 (Yes) on six items]. The primary outcome, measured at the end of the academic year, was the objective structured clinical examination of a female pelvis (score range 0-54).

RESULTS

At baseline, the groups were similar in age, gender, and ethnicity. At the end of the clinical rotation, when compared with the control intervention, the experimental intervention had a moderate effect on student knowledge [difference 29.9% (95% CI 11.2-48.6%); P = 0.002] and confidence [difference 1 (95% CI 0-2); P < 0.001], and a large effect on student comfort [difference 1.8 (95% CI 0.6-3.0); P = 0.004]. At the end of the academic year, the experimental intervention had no impact on skills compared with the control [difference 2 (95% CI-1 to 4); P = 0.26].

CONCLUSIONS

Among medical students taught the female pelvic examination by low-fidelity simulation, additional training by gynaecology teaching associates improved knowledge, comfort, and confidence at the end of the clinical rotation but did not improve examination skills at end of the academic year.

Enteric outbreak surveillance in British Columbia, 2009-2013

BACKGROUND

Understanding enteric disease outbreak sources, burden of illness, mode of transmission and use of interventions informs planning, policy development and prevention programs.

OBJECTIVE

To describe trends in enteric disease outbreaks investigated in British Columbia (BC) between 2009 and 2013.

METHODS

An analysis was conducted of enteric disease outbreaks that had been entered into a national, secure web-enabled outbreak reporting system using the Canadian Network for Public Health Intelligence (CNPHI) and investigated in BC between January 1, 2009 and December 31, 2013. The data included information on pathogen, number of cases, hospitalizations, deaths, setting, mode of transmission, source, factors that contributed to the outbreak and interventions. Residential facility-based viral outbreaks and outbreaks associated with international travel were excluded.

RESULTS

There were 104 outbreaks investigated in BC between 2009 and 2013. Ninety-three were reported by BC organizations and 11 were national outbreak investigations reported by the Public Health Agency of Canada (PHAC). There was an average of 21 outbreaks per year. Overall, the annual rate of foodborne outbreaks in BC was 2.8 per one million population. Seventy-nine (76%) outbreaks had a pathogen identified, most commonly norovirus, Salmonella and E. coli. There was a total of 108 hospitalizations (3.8% of all cases) and two deaths (0.1% of all cases); one caused by botulism, the other by E. coli O157. Food service establishments were the most common setting (33.7%), followed by the community (24.0%) and private functions (12.5%). The food types most often reported were fruits and vegetables, meat and seafood. The data showed a pathogen-food source combination between Salmonella and eggs.

CONCLUSION

This is the first publication summarizing trends in enteric disease outbreaks in BC including assessing sources, burden and interventions. Ongoing reporting and analysis of outbreak data in BC will allow for improved assessment of trends in sources and pathogens over time and further understanding of the effectiveness of interventions associated with outbreaks.

Efficacy of cardiopulmonary resuscitation in the supine position with manual displacement of the uterus vs lateral tilt using a firm wedge: a manikin study

Prevention of aortocaval compression is essential for effective cardiopulmonary resuscitation in late pregnancy. This can be achieved by either lateral maternal tilt or lateral uterine displacement. Results from a previous manikin study show that a firm foam-rubber wedge allowed successful chest compressions whilst providing stable and reliable lateral tilt. However, it did not investigate resuscitation in the supine position with manual uterine displacement. The aim of this study was to compare the effectiveness of chest compressions in a manikin in the supine position vs lateral tilt using a foam-rubber wedge, both on the floor and on a typical patient bed. Overall, we found that compressions were easier to perform in the supine position (p = 0.007 (bed) and 0.048 (floor)), and with greater stability in the supine position on the floor (p = 0.011). The effectiveness of chest compressions was similar in both the supine/uterine displacement and the lateral tilt positions, suggesting that either method may be suitable for CPR.

Prevalence and associations of anisometropia and aniso-astigmatism in a population based sample of 6 year old children

AIM

To study the distribution of anisometropia and aniso-astigmatism in young Australian children, together with clinical and ocular biometry relations.

METHOD

The Sydney Myopia Study examined 1765 predominantly 6 year old children from 34 randomly selected Sydney schools during 2003-4. Keratometry, cycloplegic autorefraction, and questionnaire data were collected.

RESULTS

Spherical equivalent (SE) anisometropia (> or =1 dioptre) prevalence was 1.6% (95% confidence interval (CI) 1.1% to 2.4%). Aniso-astigmatism (>or =1D) prevalence was 1.0% (CI: 0.6% to 1.6%). Both conditions were significantly more prevalent among moderately hyperopic (SE > or =2.0D) than mildly hyperopic (SE 0.5-1.9D) children. Myopic children (SE < or =-0.5D) had higher anisometropia prevalence. Neither condition varied by age, sex, or ethnicity. In multivariate analyses, anisometropia was significantly associated with amblyopia, odds ratio (OR) 29, (CI: 8.7 to 99), exotropia (OR 7.7, CI: 1.2 to 50), and neonatal intensive care unit (NICU) admission (OR 3.6, CI: 1.1 to 12.6). Aniso-astigmatism was significantly associated with amblyopia (OR 8.2, CI: 1.4 to 47), maternal age >35 years (OR 4.0, CI: 1.3 to 11.9), and NICU admission (OR 4.6, CI: 1.2 to 17.2). Anisometropia resulted from relatively large interocular differences in axial length (p<0.0001) and anterior chamber depth (p = 0.0009). Aniso-astigmatism resulted from differences in corneal astigmatism (p<0.0001).

CONCLUSION

In this predominantly 6 year old population, anisometropia and aniso-astigmatism were uncommon, had important birth and biometry associations, and were strongly related to amblyopia and strabismus.

Enhanced infectivity of an R5-tropic simian/human immunodeficiency virus carrying human immunodeficiency virus type 1 subtype C envelope after serial passages in pig-tailed macaques (Macaca nemestrina)

The increasing prevalence of human immunodeficiency virus type 1 (HIV-1) subtype C infection worldwide calls for efforts to develop a relevant animal model for evaluating strategies against the transmission of the virus. A chimeric simian/human immunodeficiency virus (SHIV), SHIV(CHN19), was generated with a primary, non-syncytium-inducing HIV-1 subtype C envelope from a Chinese strain in the background of SHIV(33). Unlike R5-tropic SHIV(162), SHIV(CHN19) was not found to replicate in rhesus CD4(+) T lymphocytes. SHIV(CHN19) does, however, replicate in CD4(+) T lymphocytes of pig-tailed macaques (Macaca nemestrina). The observed replication competence of SHIV(CHN19) requires the full tat/rev genes and partial gp41 region derived from SHIV(33). To evaluate in vivo infectivity, SHIV(CHN19) was intravenously inoculated, at first, into two pig-tailed and two rhesus macaques. Although all four animals became infected, the virus replicated preferentially in pig-tailed macaques with an earlier plasma viral peak and a faster seroconversion. To determine whether in vivo adaptation would enhance the infectivity of SHIV(CHN19), passages were carried out serially in three groups of two pig-tailed macaques each, via intravenous blood-bone marrow transfusion. The passages greatly enhanced the infectivity of the virus as shown by the increasingly elevated viral loads during acute infection in animals with each passage. Moreover, the doubling time of plasma virus during acute infection became much shorter in passage 4 (P4) animals (0.2 day) in comparison to P1 animals (1 to 2 days). P2 to P4 animals all became seropositive around 2 to 3 weeks postinoculation and had a decline in CD4/CD8 T-cell ratio during the early phase of infection. In P4 animals, a profound depletion of CD4 T cells in the lamina propria of the jejunum was observed. Persistent plasma viremia has been found in most of the infected animals with sustained viral loads ranging from 10(3) to 10(5) per ml up to 6 months postinfection. Serial passages did not change the viral phenotype as confirmed by the persistence of the R5 tropism of SHIV(CHN19) isolated from P4 animals. In addition, the infectivity of SHIV(CHN19) in rhesus peripheral blood mononuclear cells was also increased after in vivo passages. Our data indicate that SHIV(CHN19) has adapted well to grow in macaque cells. This established R5-tropic SHIV(CHN19)/macaque model would be very useful for HIV-1 subtype C vaccine and pathogenesis studies.

HIV-1 drug resistance in newly infected individuals

CONTEXT

There is concern that the widespread use of antiretroviral drugs to treat human immunodeficiency virus 1 (HIV-1) infection may result in the increased transmission of drug-resistant virus.

OBJECTIVE

To determine the prevalence of drug resistance-conferring mutations and phenotypic resistance to antiretroviral agents in a cohort of individuals newly infected with HIV-1.

DESIGN

Case series with genetic analyses of the HIV-1 plasma-derived pol gene using reverse transcriptase polymerase chain reaction followed by direct sequencing of polymerase chain reaction products. Phenotypic analysis was performed with a recombinant virus assay.

SETTING AND PATIENTS

Eighty individuals referred, on average, 1.7 months after infection with HIV-1 to the Aaron Diamond AIDS Research Center between July 1995 and April 1999. Subjects were from large urban areas (65 from New York, NY; 11 from Los Angeles, Calif); 60 (75%) were white, and 75 (93.8%) were homosexual men.

MAIN OUTCOME MEASURES

Prevalence of known resistance-conferring genotypes and reduced susceptibility to individual antiviral agents by phenotype.

RESULTS

Thirteen individuals (16.3%) had genotypes associated with drug resistance to any antiretroviral agent. Virus with known resistance-conferring mutations to any nucleoside reverse transcriptase inhibitors was found in 10 individuals, to any nonnucleoside reverse transcriptase inhibitors in 6 subjects, and to any protease inhibitors in 2 cases. Multidrug-resistant virus was identified in 3 individuals (3.8%). Extensive polymorphism in the protease gene was identified. Interpretation of genotypes and phenotypes was concordant in 57 (85%) of the 67 cases in which both studies were performed.

CONCLUSION

The prevalence of HIV-1 variants with known resistance-conferring genotypes to any antiretroviral agent in this cohort of 80 newly infected individuals is 16.3%. These data support expanded use of resistance testing in the setting of primary HIV-1 infection. Clinical trials should be initiated to establish whether therapy guided by resistance testing, compared with the use of empirical triple combination antiretroviral therapy, provides additional virological and immunological benefit when treating primary HIV-1 infection. Further efforts to expand the study of transmission of drug-resistant HIV-1 variants, particularly in cohorts with different epidemiological profiles, are indicated.

Oral d,l sotalol reduces the incidence of postoperative atrial fibrillation in coronary artery bypass surgery patients: a randomized, double-blind, placebo-controlled study

OBJECTIVES

The purpose of this prospective, randomized, double-blind, placebo-controlled study was to assess the efficacy of preoperatively and postoperatively administered oral d,l sotalol in preventing the occurrence of postoperative atrial fibrillation (AF).

BACKGROUND

Atrial fibrillation is the most common arrhythmia following coronary artery bypass surgery (CABG). Its etiology, prevention and treatment remain highly controversial. Furthermore, its associated morbidity results in a prolongation of the length of hospital stay post-CABG.

METHODS

A total of 85 patients, of which 73 were to undergo CABG and 12 CABG plus valvular surgery (ejection fraction > or = 28% and absence of clinical heart failure), were randomized to receive either sotalol (40 patients; mean dose = 190 +/- 43 mg/day) started 24 to 48 h before open heart surgery and continued for four days postoperatively, or placebo (45 patients, mean dose = 176 +/- 32 mg/day).

RESULTS

Atrial fibrillation occurred in a total of 22/85 (26%) patients. The incidence of postoperative AF was significantly (p = 0.008) lower in patients on sotalol (12.5%) as compared with placebo (38%). Significant bradycardia/hypotension, necessitating drug withdrawal, occurred in 2 of 40 (5%) patients on sotalol and none in the placebo group (p = 0.2). None of the patients on sotalol developed Torsade de pointes or sustained ventricular arrhythmias. Postoperative mortality was not significantly different in sotalol versus placebo (0% vs. 2%, p = 1.0). Patients in the sotalol group had a nonsignificantly shorter length of hospital stay as compared with placebo (7 +/- 2 days vs. 8 +/- 4 days; p = 0.24).

CONCLUSIONS

The administration of sotalol, in dosages ranging from 80 to 120 mg, was associated with a significant decrease (67%) in postoperative AF in patients undergoing CABG without appreciable side effects. Sotalol should be considered for the prevention of postoperative AF in patients undergoing CABG in the absence of heart failure and significant left ventricular dysfunction.

Expression patterns of the HIV type 1 coreceptors CCR5 and CXCR4 on CD4+ T cells and monocytes from cord and adult blood

We have measured the surface expression of the HIV-1 coreceptors CCR5 and CXCR4 on CD4+ T cells and monocytes from cord and adult blood. The expression of CCR5 was largely restricted to the memory (CD45RAlow) subset, whereas CXCR4 was expressed on both memory and naive (CD45RAhigh) T cells. The paucity of memory CD4+ T cells in cord blood means that CCR5-positive cells are relatively uncommon, so the overall extent of CCR5 expression was reduced in cord blood, compared with adult blood. IL-2 activation of CD4+ T cells from both cord and adult bloods caused a substantial increase in CCR5 expression, but moderately decreased CXCR4 expression. PHA stimulation increased CCR5 expression slightly, but only on naive cells. Monocytes expressed both CCR5 and CXCR4 at levels that differed little between cord and adult blood.

Genotypic and phenotypic characterization of long terminal repeat sequences from long-term survivors of human immunodeficiency virus type 1 infection

Human immunodeficiency virus type 1 (HIV-1)-infected individuals who remain asymptomatic despite prolonged infection present a unique opportunity to understand virologic and immunologic factors involved in the pathogenesis of AIDS. We have previously identified a group of long-term survivors (LTS) who are clinically healthy and immunologically normal despite 13 to 15 years of HIV-1 infection. In this study, we examined the 5' long terminal repeat (5' LTR) sequences in eight of these LTS. A total of 29 nucleotide sequences were obtained from their peripheral blood mononuclear cells (PBMC). Analysis of these sequences revealed no gross deletions within the 5' LTR. Seven of the eight subjects shared nearly identical consensus sequences in the binding sites for NF-kappaB, Sp1, and the viral trans-activator Tat. In multiple samples from one individual (Pt 5), however, G-to-A hypermutations were found throughout the entire region, suggesting a genetically defective 5' LTR. The effects of the observed genetic variations on LTR transcription were studied by transient transfection of an LTR-driven luciferase reporter gene and by infection with a full-length recombinant HIV-1 containing a luciferase reporter (HIVHXBLTRluc). A wide range of basal and Tat-induced transcriptional activities was found among the 5' LTR from seven of the eight LTS in both transfected 293 cells and donor PBMC, suggesting a functionally intact 5' LTR in these individuals. It is therefore unlikely that defects in the 5' LTR are the underlying explanation for the benign clinical course associated with these seven individuals. However, functional abnormalities were found in the LTR from Pt 5 in directing both heterologous and viral gene expression, providing a possible genetic explanation for the low viral load and prolonged asymptomatic state of this individual. Last, a similar overall degree of genetic diversity was found among viruses from the LTS compared to those from patients with AIDS, reinforcing the notion that a strong correlation between the degree of genetic diversity and the rate of disease progression is unlikely.

Predictors of long-term survival in patients with malignant ventricular arrhythmias

The study consisted of 369 patients (age 62 +/- 13 years) who presented to our institution from April 1984 to April 1994 for malignant ventricular arrhythmias presenting as sustained ventricular tachycardia (VT) in 57% of patients, ventricular fibrillation in 25% of patients, and syncope due to VT in 17% of patients. Coronary artery disease was present in 74% of patients, cardiomyopathy in 19% of patients, and no evident heart disease in 7% of patients. Two hundred twenty-one patients were given drug, therapy, 47 patients underwent arrhythmia surgery, and 75 patients had an implantable cardioverter-defibrillator (ICD). During a mean follow-up of 30 months (range 1 to 101), 66 patients (18%) died from a cardiac death of which 26 (39%) were sudden. Cox regression analysis was conducted utilizing a total of 19 variables (clinical and therapeutic) in the entire population and separately in patients with coronary artery disease and cardiomyopathy. The most significant variables (multivariate analysis) of survival from cardiac mortality in the entire population were: congestive heart failure (CHF) class (p = 0.0003), ejection fraction (p = 0.02), and the use of drug therapy (p = 0.03); in patients with coronary artery disease, CHF class (p = 0.0001) and ejection fraction (p = 0.0006); and in patients with cardiomyopathy, CHF class (p = 0.009) and sustained VT on Holter monitoring (p = 0.007). Kaplan-Meier survival rates from cardiac death were: significantly lower (p = 0.005) in patients with CHF class III and IV compared with CHF class I and II (25% vs 58%, p = 0.005) with drug therapy; marginally significant (47% vs 88%, p = 0.06) from 20 to 40 months in patients with an ICD; and nonsignificant in patients who underwent arrhythmia surgery (63% vs 71%). Patients with an ICD had a better expected survival (82%) than patients who had arrhythmia surgery (69%) and drug therapy (65%). Thus, in patients with malignant ventricular arrhythmias, CHF class was the most significant independent predictor of survival from cardiac mortality over all disease substrates, and therapy influenced survival depending on the CHF class. Patients in CHF class III and IV who underwent arrhythmia surgery or had an ICD had a better expected survival than those taking drug therapy, and the negative impact of antiarrhythmic therapy was most prominent in patients with CHF class III and IV.

Identification of a replication-competent pathogenic human immunodeficiency virus type 1 with a duplication in the TCF-1alpha region but lacking NF-kappaB binding sites

Multiple human immunodeficiency virus type 1 (HIV-1) sequences with deletions of NF-kappaB binding sites at both the 5' and 3' long terminal repeats (LTRs) were identified in serial samples collected from an infected individual. The effect of this deletion on the level of transcription was studied by transient transfection of an LTR-driven luciferase reporter gene and by infection with a full-length recombinant HIV-1 containing a luciferase reporter (HIVHXBluc). Detectable levels of gene expression were found in both systems, in the presence or absence of the viral transactivator Tat. Interestingly, a duplication of a putative TCF-1alpha motif was found in place of the NF-kappaB elements in these viruses. Higher transcriptional activity was observed with HXBLTR (NF-kappaB intact) than with the patient's LTR (NF-kappaB deleted), suggesting that the NF-kappaB binding sites may promote optimal levels of viral gene transcription. The ability of these viruses with NF-kappaB deleted to replicate and cause substantial decline in CD4 cell counts demonstrates that the NF-kappaB binding sites are not absolutely required for viral replication or pathogenicity in vivo. These results are consistent with the notion that the HIV-1 LTR possesses functional redundancy which allows it to interact with multiple transcription factors, thereby ensuring viral replication in a variety of cell types.

The role of parasympathetic modulation of the reentrant arrhythmic substrate in the genesis of sustained ventricular tachycardia

The influence of parasympathetic activity on the reentrant arrhythmic substrate in the genesis of sustained ventricular tachycardia remains unclear. To assess this influence, we studied the heart rate variability in 59 patients referred for invasive electrophysiological testing. In addition, the presence of late potentials and high grade ventricular ectopy, and the left ventricular ejection fraction was determined. The 28 patients with inducible sustained ventricular tachycardia were found to have lower heart rate variability by time- and frequency-domain measurements over 24 hours when compared to the 31 subjects who were noninducible. PNN50 was 4% in the inducible patients, whereas it was 9% in the subjects who were noninducible (P = 0.03). Similarly, HFP24H was 9 and 14 msec, respectively (P = 0.02). MAXHFP1H also differed (20 vs 27 msec [P = 0.04]) but not MINHFP1H (5 vs 6 msec). There was no association between heart rate variability and late potentials, degree of ventricular ectopy, or left ventricular ejection fraction. Thus, vagal tone does not appear to correlate with the presence of late potentials, ventricular ectopy, or left ventricular dysfunction. Low mean as well as maximal vagal tone, in contrast to minimal vagal tone, predicts inducibility of sustained ventricular tachycardia. Our data suggest that the inability to modulate parasympathetic tone appears to be an important determinant in the genesis of reentrant sustained ventricular tachycardia.

Determinants of induction of ventricular tachycardia in nonsustained ventricular tachycardia after myocardial infarction and the usefulness of the signal-averaged electrocardiogram

Assessment of the implications of clinical and noninvasive variables, including the results of signal-averaged electrocardiography, was performed > or = 3 weeks after myocardial infarction in 57 patients with nonsustained ventricular tachycardia (VT) who underwent programmed ventricular stimulation to guide antiarrhythmic therapy. The clinical and noninvasive parameters assessed included ages, left ventricular ejection fractions, sites of infarction, presence of akinetic or dyskinetic left ventricular segments, history of syncope, history of coronary artery bypass surgery, and presence or absence of late potentials from signal-averaged electrocardiography. Other than the presence of late potentials, no clinical or noninvasive parameters identified such persons with a significantly higher likelihood of inducible VT. When assessed as positive if 1 or more variables were abnormal, 16 of 16 (100%) patients with versus 17 of 41 without inducible VT had late potentials (p < 0.002). With more stringent criteria required (defined as prolongation of the QRS vector complex duration and low root-mean-square voltage of the terminal 40 ms of the vector complex) 8 of 16 patients (50%) with and 4 of 41 (10%) without inducible VT had late potentials recorded (p < 0.002). Thus, the signal-averaged electrocardiogram may enable identification of persons with nonsustained VT after myocardial infarction who are most likely to have VT induced at programmed ventricular stimulation.

Total pectoral implantation: a new technique for implantation of transvenous defibrillator lead systems and implantable cardioverter defibrillator

We describe a new approach to total pectoral implantation of cardioverter defibrillators with an endocardial defibrillation lead system. Endocardial lead configuration used was an FDA approved right atrial-superior vena cava defibrillation spring electrode, right ventricular bipolar sensing electrode, and a pectoral patch. Endocardial leads were implanted via a cephalic or an axillary venesection. Pectoral patch was placed in a submuscular position. In case of failure to obtain satisfactory thresholds, a small intercostal thoracotomy was performed via the same skin incision and patch placed over the epicardium instead of submuscular position and used with the right atrial spring electrode. The device was implanted in the pectoral region, submuscularly, over the patch. Sixteen consecutive patients underwent this approach. With a submuscular patch, adequate defibrillation thresholds (< or = 15 joules [J]) were obtained in 14 (87.5%) patients. In the other two, defibrillation thresholds of < or = 15 J were obtained with a epicardial patch. Pectoral implantation of the device was feasible in all 16 patients and none needed repositioning. Average postimplant hospital stay was 5 days. During follow-up period (average 5 months), none of the patients reported any major local symptoms and no problems have been encountered in device interrogation. Thus, total pectoral implantation of the cardioverter defibrillator including the patch, leads, and the device is feasible. Furthermore, in case of failure to obtain adequate defibrillation thresholds with submuscular patch, an epicardial patch can easily be implanted and allows 100% successful defibrillation at energy levels of < or = 15 J with right atrial patch configuration.

Identification of patients with high risk of arrhythmic mortality. Role of ambulatory monitoring, signal-averaged ECG, and heart rate variability

This article discusses the roles of 24-hour ambulatory Holter monitoring, left ventricular function, the signal-averaged electrocardiogram (ECG), and heart rate variability for identification of high risk patients following myocardial infarction. Because these noninvasive tests have low positive predictive value, a combination of noninvasive tests is recommended for risk stratification.

Isolation of a unique retrovirus, MNV-1, from Macaca nemestrina

Cell cultures established from the spleen of a Macaca nemestrina with enzootic retroperitoneal fibromatosis (ERF) spontaneously released a unique retrovirus. Throughout 14 serial passages, the spleen cell cultures remained fibroblastic and no cytopathic effect was evident. The virus incorporates [3H]uridine, contains an RNA-dependent DNA polymerase (RDDP), has a buoyant density of 1.15 g/cm3 in sucrose, and was designated MNV-1. Virion-associated reverse transcriptase showed no preference for either Mg2+ or Mn2+ in standard RDDP assays. Complementary DNA (cDNA) transcribed from polyadenylated MNV-1 RNA hybridized to genomic DNA and RNA extracted from diseased tissues but not to nucleic acids from normal tissues of a healthy Macaca nemestrina or a Macaca mulatta. MNV-1 is therefore exogenous to these species. MNV-1 had no detectable homology to the endogenous macaque virus isolates MAC-1 and MMC-1. Liquid hybridization of MNV-1 cDNA to viral RNA derived from exogenous and endogenous subhuman primate retroviruses (SiSV(SSAV), GALV-SF, BaEV-M7, and BILN) did not reveal any significant sequence homologies. In addition, MNV-1 does not share homology with bovine leukemia virus or Mason-Pfizer monkey virus as determined by Southern blot hybridization. We conclude that MNV-1 is a unique retrovirus which has not previously been described. As the ultrastructure of virions in in vitro cell cultures, as well as disease involved tissue, show some particles with type C morphology and others with type D morphology, MNV-1 may be comprised of more than one component.