Predictors of mental health and academic outcomes in first-year university students: Identifying prevention and early-intervention targets.

BACKGROUND: Although there is growing interest in mental health problems in university students there is limited understanding of the scope of need and determinants to inform intervention efforts. AIMS: To longitudinally examine the extent and persistence of mental health symptoms and the importance of psychosocial and lifestyle factors for student mental health and academic outcomes. METHOD: Undergraduates at a Canadian university were invited to complete electronic surveys at entry and completion of their first year. The baseline survey measured important distal and proximal risk factors and the follow-up assessed mental health and well-being. Surveys were linked to academic grades. Multivariable models of risk factors and mental health and academic outcomes were fit and adjusted for confounders. RESULTS: In 1530 students surveyed at entry to university 28% and 33% screened positive for clinically significant depressive and anxiety symptoms respectively, which increased to 36% and 39% at the completion of first year. Over the academic year, 14% of students reported suicidal thoughts and 1.6% suicide attempts. Moreover, there was persistence and overlap in these mental health outcomes. Modifiable psychosocial and lifestyle factors at entry were associated with positive screens for mental health outcomes at completion of first year, while anxiety and depressive symptoms were associated with lower grades and university well-being. CONCLUSIONS: Clinically significant mental health symptoms are common and persistent among first-year university students and have a negative impact on academic performance and well-being. A comprehensive mental health strategy that includes a whole university approach to prevention and targeted early-intervention measures and associated research is justified.

Low-dose phase contrast mammography with conventional x-ray sources.

PURPOSE: To provide an x-ray phase contrast imaging (XPCI) method working with conventional sources that could be readily translated into clinical practice. XPCI shows potential in synchrotron studies but attempts at translating it for use with conventional sources are subject to limitations in terms of field of view, stability, exposure time, and possibly most importantly, delivered dose. METHODS: Following the adaptation of our "edge-illumination" XPCI technique for use with conventional x-ray sources through the use of x-ray masks, the authors have further modified the design of such masks to allow further reducing the dose delivered to the sample without affecting the phase sensitivity of the method. RESULTS: The authors have built a prototype based on the new mask design and used it to image ex vivo breast tissue samples containing malignant lesions. The authors compared images acquired with this prototype to those obtained with a conventional system. The authors demonstrate and quantify image improvements, especially in terms of microcalcification detection. On calcifications detected also by the conventional system, the authors measure contrast increases from five to nine fold; calcifications and other features were also detected which are completely invisible in the conventional image. Dose measurements confirmed that the above enhancements were achieved while delivering doses compatible with clinical practice. CONCLUSIONS: The authors obtained phase-related image enhancements in mammography by means of a system built with components available off-the-shelf that operates under exposure time and dose conditions compatible with clinical practice. This opens the way to a straightforward translation of phase enhanced imaging methods into clinical practice.

Attachment and temperament profiles among the offspring of a parent with bipolar disorder.

INTRODUCTION: Attachment is associated both with the risk of developing a mood disorder and temperamental profile. Relatively little is known about these associations in children of a parent with bipolar disorder (BD). The present study is a preliminary analysis of the association between attachment, temperament and psychopathology among high-risk offspring. METHODS: As part of an ongoing prospective cohort study, offspring from families with one parent with BD (HR) and offspring from families with unaffected parents (C) were clinically assessed using KSADS-PL format interviews annually. Validated self-report measures of perceived attachment and temperament were completed. RESULTS: Perceived attachment did not differentiate HR from C offspring and did not predict psychopathology or mood disorder in particular. However, high emotionality significantly predicted the risk of psychopathology in HR offspring, where 1 standard deviation increase in emotionality significantly increased the hazard of psychopathology by a factor of 1.36 (p=0.0009) and mood disorder by a factor of 1.24 (p=0.02). LIMITATIONS: Use of retrospective measures and low sample size for some models. CONCLUSIONS: There may be no gross abnormalities in attachment among HR compared to C offspring. It remains unclear if emotionality is a barometer of illness or a true risk factor in this population. More longitudinal research is needed to advance understanding of the influential pathways by which psychosocial risk factors impact the development of BD. This research has implications for targeted early interventions in HR youth.

Ties between event times and jump times in the Cox model.

Methods for dealing with tied event times in the Cox proportional hazards model are well developed. Also, the partial likelihood provides a natural way to handle covariates that change over time. However, ties between event times and the times that discrete time-varying covariates change have not been systematically studied in the literature. In this article, we discuss the default behavior of current software and propose some simple methods for dealing with such ties. A simulation study shows that the default behavior of current software can lead to biased estimates of the coefficient of a binary time-varying covariate and that two proposed methods (Random Jitter and Equally Weighted) reduce estimation bias. The proposed methods can be easily implemented with existing software. The methods are illustrated on the well-known Stanford heart transplant data and data from a study on intimate partner violence and smoking.

Image quality evaluation of breast tomosynthesis with synchrotron radiation.

PURPOSE: This study investigates the image quality of tomosynthesis slices obtained from several acquisition sets with synchrotron radiation using a breast phantom incorporating details that mimic various breast lesions, in a heterogeneous background. METHODS: A complex Breast phantom (MAMMAX) with a heterogeneous background and thickness that corresponds to 4.5 cm compressed breast with an average composition of 50% adipose and 50% glandular tissue was assembled using two commercial phantoms. Projection images using acquisition arcs of 24°, 32°, 40°, 48°, and 56° at incident energy of 17 keV were obtained from the phantom with the synchrotron radiation for medical physics beamline at ELETTRA Synchrotron Light Laboratory. The total mean glandular dose was set equal to 2.5 mGy. Tomograms were reconstructed with simple multiple projection algorithm (MPA) and filtered MPA. In the latter case, a median filter, a sinc filter, and a combination of those two filters were applied on the experimental data prior to MPA reconstruction. Visual inspection, contrast to noise ratio, contrast, and artifact spread function were the figures of merit used in the evaluation of the visualisation and detection of low- and high-contrast breast features, as a function of the reconstruction algorithm and acquisition arc. To study the benefits of using monochromatic beams, single projection images at incident energies ranging from 14 to 27 keV were acquired with the same phantom and weighted to synthesize polychromatic images at a typical incident x-ray spectrum with W target. RESULTS: Filters were optimised to reconstruct features with different attenuation characteristics and dimensions. In the case of 6 mm low-contrast details, improved visual appearance as well as higher contrast to noise ratio and contrast values were observed for the two filtered MPA algorithms that exploit the sinc filter. These features are better visualized at extended arc length, as the acquisition arc of 56° with 15 projection images demonstrates the highest image reconstruction quality. For microcalcifications, filtered MPA implemented with a combination of median and sinc filters indicates better feature appearance due to efficient suppression of background tissue. The image quality of these features is less sensitive to the acquisition arc. Calcifications with size ranging from 170 to 500 µm, like the ones presently studied, are well identified and visualized for all arcs used. The comparison of single projection images obtained under different beam conditions showed that the use of monochromatic beam can produce an image with higher contrast and contrast to noise ratio compared to an image corresponding to a polychromatic beam even when the latter is acquired with double incident exposure. CONCLUSIONS: Filter optimization in respect to the type of feature characteristics is important before the reconstruction. The MPA combined with median and sinc filters results in improved reconstruction of microcalcifications and low-contrast features. The latter are better visualized at extended arc length, while microcalcifications are less sensitive to this acquisition parameter. Use of monochromatic beams may result in tomographic images with higher contrast acquired at lower incident exposures.

Diagnosis and management of acute kidney injury: deficiencies in the knowledge base of non-specialist, trainee medical staff.

Enhanced education has been recommended to improve non-specialist management of acute kidney injury (AKI). However, the extent of any gaps in knowledge has yet to be defined fully. The aim of this study was to assess understanding of trainee doctors in the prevention, diagnosis and initial management of AKI. An anonymised questionnaire was completed by hospital-based trainees across Newcastle Renal Unit's catchment area. Responses were evaluated against a panel of pre-defined ideal answers. The median score was 9.5 out of 20 (n = 146; range 0-17) and was lower in more junior trainees. Fifty percent of trainees could not define AKI, 30% could not name more than two risk factors for AKI and 37% could not name even one indication for renal referral. These serious gaps in knowledge highlight the need for enhanced education aimed at all training grades. Organisational changes may also be required to optimise patient safety.

Justification in clinical radiological practice: a survey among staff of five London hospitals.

This study represents a survey performed among staff who, according to the Ionising Radiation (Medical Exposures) Regulations of 2000 (IRMER), are responsible for justifying radiological examinations in the UK. The aim of the survey is to map the current situation regarding knowledge of risks from X-ray exposures and the criteria used for their justification. An anonymous electronic questionnaire was emailed to 219 radiologists and radiographers of five National Health Service hospitals. The questions were designed to investigate the way the sample group defines/assesses risk and benefit when justifying medical exposures, and to test their knowledge on radiation doses, risk communication, and on relevant national legislation. The majority of the respondents are aware of the relevant legislation/guidelines. Patient's medical condition, age and sex, and alternative techniques using less or no ionising radiation are the main criteria used for justification. However, when estimating the effective dose of various examinations in chest radiograph equivalents, the majority of the responses were incorrect. Although there is good knowledge of legislation around justification of medical exposures, there seems to be a lack of knowledge on radiation doses and risks among IRMER practitioners.

Characterization of breast tissue using energy-dispersive X-ray diffraction computed tomography.

A method for sample characterization using energy-dispersive X-ray diffraction computed tomography (EDXRDCT) is presented. The procedures for extracting diffraction patterns from the data and the corrections applied are discussed. The procedures were applied to the characterization of breast tissue samples, 6mm in diameter. Comparison with histological sections of the samples confirmed the possibility of grouping the patterns into five families, corresponding to adipose tissue, fibrosis, poorly differentiated cancer, well differentiated cancer and benign tumour.

Evaluation of digital breast tomosynthesis reconstruction algorithms using synchrotron radiation in standard geometry.

PURPOSE: In this article, the image quality of reconstructed volumes by four algorithms for digital tomosynthesis, applied in the case of breast, is investigated using synchrotron radiation. METHODS: An angular data set of 21 images of a complex phantom with heterogeneous tissue-mimicking background was obtained using the SYRMEP beamline at ELETTRA Synchrotron Light Laboratory, Trieste, Italy. The irradiated part was reconstructed using the multiple projection algorithm (MPA) and the filtered backprojection with ramp followed by hamming windows (FBR-RH) and filtered backprojection with ramp (FBP-R). Additionally, an algorithm for reducing the noise in reconstructed planes based on noise mask subtraction from the planes of the originally reconstructed volume using MPA (MPA-NM) has been further developed. The reconstruction techniques were evaluated in terms of calculations and comparison of the contrast-to-noise ratio (CNR) and artifact spread function. RESULTS: It was found that the MPA-NM resulted in higher CNR, comparable with the CNR of FBP-RH for high contrast details. Low contrast objects are well visualized and characterized by high CNR using the simple MPA and the MPA-NM. In addition, the image quality of the reconstructed features in terms of CNR and visual appearance as a function of the initial number of projection images and the reconstruction arc was carried out. Slices reconstructed with more input projection images result in less reconstruction artifacts and higher detail CNR, while those reconstructed from projection images acquired in reduced angular range causes pronounced streak artifacts. CONCLUSIONS: Of the reconstruction algorithms implemented, the MPA-NM and MPA are a good choice for detecting low contrast objects, while the FBP-RH, FBP-R, and MPA-NM provide high CNR and well outlined edges in case of microcalcifications.

Experimental validation of a radiographic simulation code using breast phantom for X-ray imaging.

Computer models and simulations of X-ray imaging systems are becoming a very precious tool during the development and evaluation of new X-ray imaging techniques. To provide, however, a faithful simulation of a system, all components must be accurately modelled and tested, followed by verification through experimental measurements. This paper presents a validation study of the XRayImagingSimulator, an in-house developed X-ray imaging simulator, which is extensively used as a basic tool in carrying out complex breast imaging simulations. The approach followed compares results obtained via an experimental setup for breast phantom (CIRS 011A) imaging, using synchrotron radiation (SYRMEP beamline at ELETTRA), with those from its simulated setup under the same conditions. The study demonstrated a very good agreement between experimental and simulated images compared both in terms of subjective and objective criteria. The combination of the XRayImagingSimulator with our BreastSimulator provides a powerful tool for in silico testing of new X-ray breast imaging approaches.

A decade of stigma and discrimination in mental health: plus ça change, plus c'est la même chose (the more things change, the more they stay the same).

In recent years, efforts to combat stigma and discrimination experienced by mental health service users have ranged from small local initiatives to national and international campaigns. Success has been mixed, with significant, lasting benefits appearing to be elusive. This paper explores the current nature and extent of stigma and discrimination in an area of the north of England and compares findings with those from a study undertaken a decade previously in 1997. Qualitative responses to a postal questionnaire received in 2007 were thematically analysed and compared and contrasted with findings from the 1997 study. Four broad categories of discrimination--(1) employment; (2) professional; (3) communities; and (4) family and friends--arose from the 2007 data, the most common being discrimination in employment. There were close similarities in both sets of data. Stigma and discrimination remain largely as strong, damaging and enduring as they were a decade ago. A range of pre-emptive interventions that support people prior to the escalation of mental health crises could limit the impact of stigma.

Mental health crisis and respite services: service user and carer aspirations.

There is emerging evidence that crisis resolution services can provide alternatives to hospital admission, reducing demand on inpatient beds. Following a public consultation exercise in Lancashire (England), a team of nurses undertook a study, using interactive research methodology, to gain an understanding of how users and carers define a crisis and what range of crisis services, resources and interventions service users and carers thought would help avoid unnecessary hospital admission. Data collection comprised postal questionnaires and 24 group meetings with service users and carers, which were held during 2006. Data were analysed, and seven themes were identified: (1) definitions of a crisis; (2) access to services; (3) interventions; (4) range of services required (before, during and after crisis); (5) place of treatment; (6) recovery and rehabilitation; and (7) community support. We conclude that expressed preferences of service users and carers for pre-emptive services that are delivered flexibly will present a challenge for service commissioners and providers, particularly where stringent access criteria are used. Home-based pre-emptive services that reduce the need for unnecessary hospital treatment may avoid progression to social exclusion of service users.

Correlation of energy dispersive diffraction signatures and microCT of small breast tissue samples with pathological analysis.

Identification of specific tissue types in conventional mammographic examinations is extremely limited. However, the use of x-ray diffraction effects during imaging has the potential to characterize the tissue types present due to the fact that each tissue type produces its own unique diffraction signature. Nevertheless, the analysis and categorization of these diffraction signatures by tissue type can be hampered by the inhomogeneous nature of breast tissue, leading to categorization errors where several types are present. This work aims to reduce sample categorization errors by combining spectral diffraction signature collection with sample imaging, giving more detailed data on the composition of each sample. Diffraction microCT was carried out on 19 unfixed breast tissue samples using an energy resolving translate-rotate CT system. High-resolution transmission microCT images were also recorded for comparison and sample composition analysis. Following imaging, the samples were subjected to histopathological analysis. Reconstructing on various momentum transfer regions allows different tissue types to be identified in the diffraction images. Results show a correlation between measured x-ray diffraction images and stained histopathological tissue sections. X-ray diffraction signatures generated from the measured data were categorized and analysed, with a t-test indicating that they have the potential for use in tissue type identification.

A novel method for producing x-ray test objects and phantoms.

A novel method for producing customized x-ray test objects and clinically realistic phantoms has been developed. Test objects can be created with a drawing software package and the digital images can be printed on a standard inkjet printer but using potassium iodide solution in place of the cartridge's ink. The reproducibility and the consistency, the limiting spatial resolution, the uniformity as well as the potassium iodide thickness per print have been evaluated. The relationship between the number of prints, grey levels and the radiation contrast was investigated and quantified. A copy of the Leeds TO10 contrast detail test object was printed and the x-ray images of the Leeds TO10 and of the printed Leeds TO10 were compared. In addition, the potential use of this method was demonstrated by reproducing a percutaneous transluminal coronary angioplasty clinical digital image. The reproducibility and consistency of this method was found to be better than 0.1%. The limiting spatial resolution of the printer using ink was found to be 3.55 1p mm(-1) but it deteriorated when the ink was replaced with potassium iodide and as the print density increases. The uniformity across the printed area was found to be satisfactory although an artefact due to the printer was present in the x-ray images. The comparison between the Leeds TO10 and the printed Leeds TO10 gave differences less than 10%. A good agreement between the clinical image and the printed clinical image was found. In conclusion, the method is a reliable, cost-effective, flexible and alternative way for producing x-ray test objects and clinically related phantoms.

Pharmaceutical interventions for emotionalism after stroke.

BACKGROUND: Antidepressants may be useful in the treatment of abnormal crying associated with stroke. OBJECTIVES: To determine whether pharmaceutical treatment reduces the frequency of emotional displays in people who suffer from emotionalism after stroke. SEARCH STRATEGY: We searched the Cochrane Stroke Group Trials Register (last searched June 2003). In addition we searched the following electronic databases: Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3 2002), MEDLINE (1966 to September 2002), EMBASE (1980 to September 2002), CINAHL (1982 to September 2002), PsychINFO (1967 to September 2002), Applied Science and Technology Plus (1986 to September 2002), Arts and Humanities Index (1991 to September 2002), Biological Abstracts (1969 to September 2002), General Science Plus (1994 to September 2002), Science Citation Index (1992 to September 2002), Social Sciences Citation Index (1991 to September 2002), and Sociofile (1974 to September 2002). We searched reference lists from relevant articles and textbooks, and contacted authors of known studies and pharmaceutical companies who manufacture psychotropic medications. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials, comparing psychotropic medication to placebo, in people with stroke and emotionalism (also known as emotional lability or pathological crying and laughing). DATA COLLECTION AND ANALYSIS: Data were obtained on people who no longer met criteria for emotionalism, as defined in studies, and on reduction in frequency of crying at the end of treatment. Data were not pooled because of the multiplicity of definitions and outcome measures. MAIN RESULTS: Five trials involving 103 participants were included. Four trials showed large effects of treatment: 50% reduction in emotionalism, improvements (reduction) in the frequency of compulsive laughter, and lower (better) scores on the Pathological Laughter and Crying scale. The confidence intervals were wide, however, indicating that treatment may have had only a small positive effect, or even a small negative effect (in one trial). Subgroup analysis was not performed due to the multiple methods of assessment of emotionalism within and between trials. Only one study systematically recorded and reported adverse events; no discernible difference was seen between groups. Participants allocated active treatment were more likely to leave early from trials. REVIEWERS' CONCLUSIONS: Antidepressants can reduce the frequency and severity of crying or laughing episodes. The effect do not seem specific to one drug or class of drugs. However, our conclusions must be qualified by several methodological deficiencies in the studies. More reliable data are required before recommendations can be made about the treatment of post-stroke emotionalism.

A study on radiation doses and irradiated areas in cerebral embolisation.

Patient radiation doses during interventional radiology procedures may reach the thresholds for radiation-induced skin and eye lens injuries. This study investigates the irradiated areas and doses received by patients undergoing cerebral embolisation, which is regarded as a high dose interventional radiology procedure. For each procedure the fluoroscopic and digital dose-area product (DAP), the fluoroscopic time, the total number of acquired images and entrance-skin dose (ESD) calculated by the angiographic unit were recorded. The ESD was measured by means of thermoluminescent dosimeters. In this study, the skin, eye and thyroid gland doses and the irradiated area for 30 patients were recorded. The average ESD was found to be 0.77 Gy for the posteroanterior plane and 0.78 Gy for the lateral plane. The average DAP was 48 Gy cm(2) for the posteroanterior plane and 58 Gy cm(2) for the lateral plane. The patient's average right eye dose was 60 mGy and the dose to the thyroid gland was 24 mGy. Seven patients received a dose above 1 Gy, one patient exceeded the threshold for transient erythema and one exceeded the threshold for temporary epilation. A good correlation between the DAP and the ESD for both planes has been found. The doctor's eye dose has also been measured for 17 procedures and the average dose per procedure was 0.13 mGy.

Optimization of scanning parameters for CT colonography.

To determine the optimal collimation, pitch and reconstruction interval for CT colonography, 10 spherical polyps between 1 mm and 10 mm diameter and made of tissue equivalent material with a CT number of 40 Hounsfield units (HU) were placed in the colon of an anthropomorphic phantom. The phantom was scanned at slice thicknesses of 3 mm, 5 mm and 7 mm and pitches of 1.0, 1.3, 1.5, 1.7 and 2.0 on an IGE Hispeed advantage system. Images were reconstructed for each scanning parameter at the minimum intervals allowed along the z-axis. The optimum scanning protocol was assessed by measuring maximum contrast between the polyp and air, sensitivity for detection of each polyp along the z-axis, and relative radiation dose. In addition, images were reviewed separately by two radiologists who graded polyp conspicuity as: 0, not seen; 1, faintly seen; 2, well seen. It was found that varying the scanning parameters caused a marked alteration in the maximum contrast between each polyp and air. For example, for the 5 mm polyp, the range of contrasts from best to worst case was 910-490 HU. It was noted that with contrasts of less than 500 HU, polyps were only faintly seen. A slice thickness of 3 mm with a pitch of 2 offers optimal polyp conspicuity with a relatively low radiation dose, we conclude that scanning parameters can be optimized for threshold contrast, radiation dose and subjective conspicuity. We propose an optimal parameter of 3 mm slice thickness and pitch 2.

The effect of decreasing mAs on image quality and patient dose in sinus CT.

The aim of this study was to determine the effect of reducing mAs on the diagnostic quality of images and the radiation dose to the orbits in patients undergoing sinus CT. We studied 40 consecutive patients undergoing paranasal sinus CT for inflammatory disease prior to functional endoscopic sinus surgery (FESS). Four groups of 10 patients were scanned at 200 mAs, 150 mAs, 100 mAs and 50 mAs, respectively. Orbital radiation dose was measured using thermoluminescent dosemeters. Images were reviewed independently by two observers who were unaware of the mAs setting used. Image quality was evaluated using a semi-quantitative scoring system for six anatomical structures. The osteomeatal complex, uncinate process, infundibulum, frontal recess, middle turbinate and optic nerve were assessed as: clearly demonstrated (2 points); demonstrated but not clearly visualized (1 point); or not seen (0 points). No significant difference was shown between any of the four groups in terms of image quality according to the scoring system used in this study. Mean radiation dose to the orbit was reduced by 77%, from 13.5 mGy at 200 mAs to 3.1 mGy at 50 mAs (p<0.05). CT of the sinuses can be performed in patients prior to FESS at greatly reduced mAs without loss of diagnostic quality of the images. This is important in reducing the radiation dose to the lens.

Quantitative analysis of herpesvirus sequences from normal tissue and fibropapillomas of marine turtles with real-time PCR.

Quantitative real-time PCR has been used to measure fibropapilloma-associated turtle herpesvirus (FPTHV) pol DNA loads in fibropapillomas, fibromas, and uninvolved tissues of green, loggerhead, and olive ridley turtles from Hawaii, Florida, Costa Rica, Australia, Mexico, and the West Indies. The viral DNA loads from tumors obtained from terminal animals were relatively homogeneous (range 2-20 copies/cell), whereas DNA copy numbers from biopsied tumors and skin of otherwise healthy turtles displayed a wide variation (range 0.001-170 copies/cell) and may reflect the stage of tumor development. FPTHV DNA loads in tumors were 2.5-4.5 logs higher than in uninvolved skin from the same animal regardless of geographic location, further implying a role for FPTHV in the etiology of fibropapillomatosis. Although FPTHV pol sequences amplified from tumors are highly related to each other, single signature amino acid substitutions distinguish the Australia/Hawaii, Mexico/Costa Rica, and Florida/Caribbean groups.

Effects of digoxin on acute, atrial fibrillation-induced changes in atrial refractoriness.

BACKGROUND: Atrial fibrillation (AF) shortens the atrial effective refractory period (ERP) and predisposes to further episodes of AF. The acute changes in atrial refractoriness may be related to tachycardia-induced intracellular calcium overload. The purpose of this study was to determine whether digoxin, which increases intracellular calcium, potentiates the acute effects of AF on atrial refractoriness in humans. METHODS AND RESULTS: In 38 healthy adults, atrial ERP was measured at basic drive cycle lengths (BDCLs) of 350 and 500 ms after autonomic blockade. Nineteen patients had been treated with digoxin for 2 weeks. After a several-minute episode of AF, atrial ERP was measured serially at alternating BDCLs. Compared with pre-AF ERPs, the first post-AF ERPs were significantly shorter in both the digoxin and the control groups (P:<0.001). The post-AF ERP at a BDCL of 350 ms shortened to a greater degree in the digoxin group (37+/-16 ms) than in the control group (20+/-13 ms, P:<0.001); similar changes occurred at a BDCL of 500 ms. During post-AF determinations of the atrial ERP, secondary AF episodes occurred significantly more often in the digoxin group (32% versus 16%; P:<0. 04). CONCLUSIONS: After a brief episode of AF, digoxin augments the shortening that occurs in atrial refractoriness and predisposes to the reinduction of AF. These effects occur in the setting of autonomic blockade and therefore are more likely to be due to the effects of digoxin on intracellular calcium than to its vagotonic effects.