205 Vascular Outcomes in TIA Patients

Aim

To identify vascular outcomes in patients presenting with TIA

Method

We completed a closed loop audit at the University Hospital of Wales assessing vascular outcomes in TIA patients. We audited the first 100 patients with significant carotid ultrasound findings from January 1st, 2020, and then the first 75 patients with significant findings in the repeat study from July 1st, 2021. We assessed the time between symptom onset, referral, and consultation, whether that be geriatric or vascular, and the outcome of that consultation. If patients required surgical vascular intervention, we assessed whether this was conducted within the 14-day window outlined by national and international guidelines.

Results

We found that for a multitude of reasons, including delayed patient presentation and arduous referral processes, that patients with significant findings were not receiving vascular input within the 14-day window, let alone receive an operation. We suggested that a centralised vascular referral pathway and a consultant of the week would facilitate a more efficient TIA-vascular process, allowing for carotid endarerectomies to be performed within the internationally advised timeframe. The closed loop revealed that although patient presentation and referral times were obviously unaffected, that vascular consultations were occurring far more rapidly, as aided by the newly incorporated consultant of the week.

Conclusions

That a centralised departmental coordinator, and a consultant of the week delegated towards facilitating TIA referrals for potental carotid endarterecomy, was beneficial in terms of meeting standardised timeframes, but that more could be done to improve the service.

356 An Unfortunate Case of Spinal Injury and Bladder Dysfunction During the Covid-19 Pandemic

There is no doubt that COVID-19 has had a profound impact on every medical and surgical speciality. In the height of the pandemic many non-emergency services were shut down, including dental services, with unexpected consequences. We present a case which highlights the unexpected and indirect consequences of a national lockdown on a Urology patient and discuss learning points.

A 54-year-old male, previously fit and well suffered with a small dental abscess, media outlets were reporting that dental surgeries were closed, and he therefore attempted to drain the abscess himself. The infection spread to his epidural space, causing compression via a collection at L2 and consequently spinal cord injury. This was managed with urgent lumbar decompression and antibiotics.

A specialist functional urology team were involved after his transfer to the tertiary spinal unit 3 months after his first presentation. He was catheterised but suffered with recurrent catheter blockages. Video urodynamics demonstrated a stable bladder with a low-pressure leak point, managed with urethral catheterisation. A repeat video urodynamics demonstrated a loss of compliance and stress incontinence. Unclear as to whether he would regain function rehabilitation techniques are currently being attempted prior for definitive operative management with an artificial sphincter.

This case highlights the indirect impact of COVID-19 on UK urology services, and this has not been widely reported.

324 Outcomes of Prostate Artery Embolisation In Catheterised Patients: A Case Series

Aim

Prostate artery embolisation (PAE) is an approved treatment for men with lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH-LUTS). Evidence of efficacy for PAE in patients who are unable to void urine spontaneously is scant, however. Traditional treatments for BPH-LUTS have evidence in retention patients and this series aims to report outcomes for PAE in catheterised patients.

Method

The records of consecutive men with BPH-LUTS which required either an indwelling bladder catheter or clean intermittent self-catheterisation (CISC) who subsequently underwent PAE were retrospectively reviewed. Basic demographics were collected along with information on the prostate volume and PAE procedure specifics. The primary outcome was whether patients were catheter/CISC free at 3 months. Other outcomes include complications, use of medications and the need for other surgical treatments post-PAE.

Results

63 men underwent PAE for urinary retention and BPH-LUTS between 2013 and 2020. Of these, 7 underwent a unilateral embolisation for aberrant anatomy. The mean prostate volume was 128ml. 61% of men were free from a catheter/CISC post-treatment. 4 patients suffered post-PAE UTI, whilst 3 patients subsequently underwent Transurethral Resection of the Prostate following PAE for failure to become catheter free. 13 men were entirely free from BPH-LUTS medications.

Conclusions

PAE for catheterised men results in a similar catheter-free rate post procedure to several more invasive BPH treatments. It has a low side-effect profile and gives men with poor health an option to try to become catheter free. PAE should be discussed with men with catheters as a treatment option.

Presenting or Spinning Facts? Deconstructing the U.S. Centers for Disease Control Statement on the Importance of Reopening Schools Under COVID-19

Credible, reliable and consistent information to the public, as well as health professionals and decision makers, is crucial to help navigate uncertainty and risk in times of crisis and concern. Traditionally, information and health communications issued by respected and established government agencies have been regarded as factual, unbiased and credible. The U.S. Centers for Disease Control and Prevention (CDC) is such an agency that addresses all aspects of health and public health on behalf of the U.S Government for the benefit of its citizens. In July 2020, the CDC issued guidelines on reopening schools which resulted in open criticism by the U.S. President and others, prompting a review and publication of revised guidelines together with a special "Statement on the Importance of Reopening Schools under COVID-19." We hypothesize that this statement introduced bias with the intention to shift the public perception and media narrative in favor of reopening of schools. Using a mixed methods approach, including an online text analysis tool, we demonstrate that document title and structure, word frequencies, word choice, and website presentation did not provide a balanced account of the complexity and uncertainty surrounding school reopening during the COVID-19 pandemic. Despite available scientific guidance and practical evidence-based advice on how to manage infection risks when reopening schools, the CDC Statement was intentionally overriding possible parent and public health concerns. The CDC Statement provides an example of how political influence is exercised over the presentation of science in the context of a major pandemic. It was withdrawn by the CDC in November 2020.

The association between secondary care multimorbidity in mid-life and premature mortality

Background

Multimorbidity (MM) is the co-existence of two or more health conditions. Whilst its prevalence is higher in older adults, in absolute numbers there are more multimorbid young people. Recently, the trends for increasing life expectancy observed in high income countries have stalled or reversed. The relationship between MM and premature mortality requires exploration. We assessed the prevalence of secondary care MM in mid-life and its association with premature mortality in the Scottish Aberdeen Children of the 1950s (ACONF) cohort.

Methods

Prospective cohort study. ACONF members were linked to electronic hospital records and mortality records. Secondary care MM was assessed using hospital records in 2001 when participants were aged 45-51 years. The association between MM and mortality over 15 years (to age 60-66 years) was assessed using Cox proportional hazards regression. There was adjustment for key covariates: age, gender, social class at birth, childhood intelligence, educational attainment, alcohol, smoking, body mass index and adult social class.

Results

Of 9,625 participants (51% male), 3% had MM. Higher childhood intelligence and adult social class were associated with reduced MM. In relation to the reference group (no MM), those with MM had a mortality hazard ratio of 4.5 (95% CI 3.4-6.0) over 15 years. The association remained when adjusted for the covariates (2.5 [95% CI 1.5-4.0]).

Conclusions

Secondary care MM prevalence was 3% in mid-life and associated with premature mortality. Younger adults with MM are an important group at risk of premature mortality which should be the focus of public health action. This includes reducing the impact of social inequality and reconfiguring secondary care services to offer comprehensive management of younger multimorbid adults.

Key messages

Multimorbidity in mid-life is associated with premature mortality and may be an important influence on reducing life expectancy trends. Much focus is upon multimorbidity in older adults, however younger adults with multimorbidity are at risk of premature mortality, requiring public health action.

The epidemiology of polypharmacy in a large cohort with linked health records in Scotland

Background

Our understanding of the potential harm of taking multiple medications in older, multi-morbid populations is limited. We aimed to investigate the prevalence of polypharmacy and its association with hospitalisation in a large cohort with linked health data.

Methods

Prescription data and hospital admission records of the Aberdeen Children of the 1950s (ACONF) Cohort were extracted from the National Health Services Scotland database and linked from 2011-2016. We estimated polypharmacy by measuring monthly drug exposure for 1) total number of prescribed medications and 2) total number of defined daily doses (DDDs). Cox proportional hazard models (adjusted for demographics, socioeconomic circumstances and health conditions) were used to examine the association of polypharmacy and hospitalisation.

Results

Prescription records were linked for 8,713 cohort members. Mean age at baseline was 58.5 years (SD = 1.5) and 50% were female. 1,994 individuals (23%) had at least one health condition and 8% of population had multimorbidity. The proportion of cohort with polypharmacy assessed using taking 5+ medications and taking 5+ DDDs at baseline were 12.7% (female=12.6% vs male=12.7%, P = 0.179), and 15.5% (female=13.8% vs male=17.1%, P < 0.001) respectively. Of all the cohort, 4,365 admitted to hospital (mean follow-up of 3.5 years, total 30,269 person-years). Adjusted hazard ratios for hospitalisation were 1.51 (95 % CI 1.39,1.64, P < 0.001) for polypharmacy measured by number of medications and 1.40 (95 % CI 1.29,1.51 P < 0.001) for polypharmacy estimated by number of daily doses.

Conclusions

Polypharmacy is independently associated with increased risk of hospitalisation. This association could signify polypharmacy as a risk factor and a marker of poor outcome. Data linkage can generate evidence-based information for future policy and health services to improve polypharmacy measurement and management.

Key messages

Data linkage is a cost effective and contemporary return on the investment in data collection and research in public health. Improvement in evidence to better understand the relationship between polypharmacy and health outcomes should be a priority to optimise treatment in older people with various chronic conditions.

Co-design of data collection with participants of the Aberdeen Children of the 1950s cohort study

Background

The Aberdeen Children of the 1950s (ACONF) cohort comprises 12,150 people born in Scotland in the 50s. It contains rich early life data, questionnaire data from mid-life and linked electronic health records. Involving participants in designing future data collection is key to ensure research is acceptable and reflects public priorities.

Aim

Gather ACONF members views to inform how to: research healthy ageing, optimise recruitment and maximise participation.

Methods

3 co-design workshops with 30 ACONF members. A discussion was led by a facilitator using guidance questions developed by the study team. Workshops were recorded and transcribed.

Results

Participants viewed healthy ageing as keeping socially and physically active, taking responsibility for oneself and having a positive attitude to ageing. Research priorities were dementia, improvements in the social care system and engaging hard-to-reach groups. Members were keen for future research involvement. Recruitment may be maximised by: more information online, involving participants in recruiting other study members and clarity about potential benefits to themselves or others. It was acceptable to ask their offspring to participate. There were high levels of trust in researchers, but ongoing data protection is vital. Participation may be improved by regular contact (informing members of results, engagement events, phone “apps”). Participants viewed various data collection methods (questionnaires, applications, wearable devices, in-person tests, DNA collection and electronic record linkage) as acceptable.

Conclusions

Participant involvement is a fundamental part of securing a social license for research. Participants were in favour of ongoing research, including recruitment of their children. The workshops highlighted key considerations for future research and data collection.

Key messages

Co-design is vital for highlighting research topics which are important and relevant to the general population. Co-design can highlight strategies for maximising research participation and securing a social license for research.

The association between psychological distress in mid-life and hospital-based multimorbidity

Background

Mental ill-health is common with significant impact on individuals and services. Using healthcare records to identify poor mental health missed individuals who do not seek healthcare treatment. A screening questionnaire (General Health Questionnaire (GHQ)) can detect psychological distress. However, before considering implementing such a screening tool, we need to understand if it detects those at high risk of experiencing poorer outcomes. Hospital-based multimorbidity is a rising healthcare challenge. The aim was to assess the prevalence of psychological distress in mid-life and its influence on hospital-based multimorbidity by older age in the Aberdeen Children of the 1950s (ACONF) cohort.

Methods

Prospective cohort study using ACONF. GHQ-4 was measured in mid-life from questionnaire. Multimorbidity (2 or more co-existing conditions) was measured using linked hospital records in older age (15 years after the questionnaire). The relationship between psychological distress (GHQ-4 score of 1 or more) and multimorbidity was assessed using logistic regression with adjustment for key life-course variables.

Results

Of 5,839 individuals (48% male, mean age 48), psychological distress prevalence was 20% and was associated with being female, lower childhood cognition, lower educational attainment, lower adult social class, unemployment, higher adult body mass index, smoking and alcohol misuse. In comparison to the asymptomatic reference group, the odds ratio for multimorbidity in older age in those with psychological distress was 2.2 (95% CI 1.8-2.7) in the unadjusted model. In the adjusted model this was 1.4 (95% CI 1.1-1.8).

Conclusions

1 in 5 individuals in the general population in mid-life had psychological distress. This was associated with hospital-based multimorbidity by older age. Intervening early could reduce costs to both individuals and healthcare services. The next step is research of the cost-effectiveness of population screening for psychological distress.

Key messages

Psychological distress in mid-life is associated with hospital-based multimorbidity by older age. Screening for psychological distress early in life should be explored as an intervention to reduce costs to individuals and healthcare services.

A14 GUT-RESIDING BACTERIA CAN SHAPE HOST DRUG METABOLISM IN THE SMALL INTESTINE THROUGH AN INNATE LYMPHOID CELL-IL-22 DRIVEN AXIS

Background

The ability of the intestinal microbiota to influence drug metabolism has been recognized, however the mechanisms through which this occurs remain unexplored. Recent work in germ-free mice showed that conventionalization with specific pathogen free (SPF) microbiota influences the expression of cytochrome P450 (CYP) enzymes in the liver and small intestine (SI), two important sites of drug metabolism. Given that CYP enzymes, including CYP3A11 in mice, account for roughly 70% of total drug metabolism, we hypothesized that commensal gut bacteria can shape the CYP landscape to influence drug metabolism and therapeutic outcomes.

Aims

To investigate the role of specific gut-residing microbes in shaping the expression and activity of host drug metabolism enzymes.

Methods

Segmented filamentous bacteria (SFB)-free mice were obtained from Jackson Lab (Jax) and colonized with feces from SFB-mono-associated mice via oral gavage. 14 days later, expression of drug metabolism enzymes in the SI were probed using PCR arrays, and lamina propria cells isolated for flow cytometry. A monoclonal antibody for Thy1.2 was used to deplete innate lymphoid cells (ILCs) in RAG1-/- mice (lacking T- and B-cells). CYP3A11 activity was determined through the colorimetric breakdown of the CYP3A11-specific substrate 7-benzyloxyresorufin. SI organoids were generated from mice and humans, and treated with IL-22 to further assess the dynamics of CYP3A11/CYP3A4 expression and activity.

Results

Colonization of Jax mice with immunomodulatory SFB altered the expression of various CYP enzymes in the SI (but not liver), with Cyp3a11 being the most downregulated gene. Further analysis showed that SFB-induced IL-22 production by type 3 ILCs (ILC3) correlated with reduced SI Cyp3a11 expression. Additionally, SFB colonization had no effect on the expression of Cyp3a11 in the SI of mice in which ILCs were depleted. Both SFB colonization and administration of IL-23, to induce IL-22 from ILC3, increased the ability of the CYP3A11-metabolized drug glyburide to decrease blood glucose levels when given orally. In mouse SI enteroid cultures, IL-22 dose-dependently reduced the expression of Cyp3a11 and decreased the ability of enteroids to metabolize CYP3A11-specific substrates. Finally, IL-22 induced wide changes in the transcriptome of human SI enteroids, with substantial effects on a drug metabolism pathway centred around CYP3A.

Conclusions

Our data suggest that a gut-resident microbe (SFB) can influence the expression and activity of the drug metabolising enzyme CYP3A11 in the SI through an ILC3-IL-22 dependent mechanism. These findings provide an understanding of how the intestinal microbiota may modulate host drug metabolism to influence the efficacy and toxicity of various pharmaceutical compounds.

Funding Agencies

CAG, CIHRAbbvie, Lloyd Sutherland Investigatorship

Quantitative data analysis of perceived barriers and motivators to physical activity in stroke survivors

BACKGROUND

Levels of physical activity after stroke are low, despite multiple health benefits. We explored stroke survivors' perceived barriers, motivators, self-efficacy and intention to physical activity.

METHODS

Fifty independently mobile stroke survivors were recruited prior to hospital discharge. Participants rated nine possible motivators and four possible barriers based on the Mutrie Scale, as having 'no influence', 'some influence' or 'a major influence' on physical activity. Participants also rated their self-efficacy and intention to increasing walking.

RESULTS

The most common motivator was 'physical activity is good for health' [34 (68%)]. The most common barrier was 'feeling too tired' [24 (48%)]. Intention and self-efficacy were high. Self-efficacy was graded as either 4 or 5 (highly confident) on a five-point scale by [34 (68%)] participants, while 42 (84%) 'strongly agreed' or 'agreed' that they intended to increase their walking.

CONCLUSION

Participants felt capable of increasing physical activity but fatigue was often perceived as a barrier to physical activity. This needs to be considered when encouraging stroke survivors to be more active.

Developing patient-centred MRI safety culture: a quality improvement report

Objective:

Despite having a detailed MRI-safety questionnaire check at the point of referral, we have encountered a significant number of near-misses with patients being identified with MRI-Unsafe devices at the time of appointments, making this an important safety hazard.

Methods and materials:

A two-part survey was performed to assess referrer compliance of asking MRI-questionnaires. 120 outpatients across 3 MRI sites were interviewed at the time of appointment to confirm whether their referrers completed the MRI questionnaires with them at the time of referral.

Location:

Department of Radiology, Ninewells Hospital, Perth Royal Infirmary and Stracathro Hospital in Scotland.

Results:

Only 50–55 % of patients confirmed that they were asked about presence of a pacemaker at the point of referral. Less than 50 % of patients reported being asked about other potential hazards.

Suggested strategies for change: (1) Risk Alert—Sent to all MRI referrers in the organization. ( 2) Changes to MRI Safety Questionnaire. (3) Feedback mechanism to referrers—NHS trust website publications on number of recorded near-misses and wasted appointments due to MRI-safety issues. (4) Compulsory education/training of future referrers (junior doctors/allied health professionals). (5) Education of patients/public on MRI safety—Displaying patient information leaflets/posters in waiting areas of the hospital.

Key measures for improvement: (1) Reduction in number of recorded near-misses. (2) System improvements, referrer and patient education, reduction of wasted MRI appointments and improvement of waiting-times for MRI appointments

Effects of survey and conclusions: The survey highlights the possibility of inadequate referrer attention, and poor patient communication about MRI safety questionnaire with regards to potential hazards of MRI examination in presence of undeclared implants. It initiated several interventions resulting in improved patient safety, with no events in next 12 months, whilst promoting public and referrer’s understanding of potential MRI safety issues. Such actions are recommended for all NHS centres across UK since there are significant similarities in functioning across UK.

Achieving Self-Directed Integrated Cancer Aftercare (ASICA) in melanoma: protocol for a randomised patient-focused pilot trial of delivering the ASICA intervention as a means to earlier detection of recurrent and second primary melanoma

BACKGROUND

Melanoma is common; 15,906 people in the UK were diagnosed with melanoma in 2015 and incidence has increased fivefold in 30 years. Melanoma affects old and young people, with poor prognosis once metastatic. UK guidelines recommend people treated for cutaneous melanoma receive extended outpatient, hospital follow up to detect recurrence or new primaries. Such follow up of the growing population of melanoma survivors is burdensome for both individuals and health services. Follow up is important since approximately 20% of patients with early-stage melanoma experience a recurrence and 4-8% develop a new primary; the risk of either is highest in the first 5 years. Achieving Self-directed Integrated Cancer Aftercare (ASICA) is a digital intervention to increase total-skin-self-examination (TSSE) by people treated for melanoma, with usual follow up.

METHODS

We aim to recruit 240 adults with a previous first-stage 0-2C primary cutaneous melanoma, from secondary care in North-East Scotland and the East of England. Participants will be randomised to receive the ASICA intervention (a tablet-based digital intervention to prompt and support TSSE) or control group (treatment as usual). Patient-reported and clinical data will be collected at baseline, including the modified Melanoma Worry Scale (MWS), the Hospital Anxiety and Depression Scale (HADs), the EuroQoL 5-dimension 5-level questionnaire (EQ-5D-5 L), and questions about TSSE practice, intentions, self-efficacy and planning. Participants will be followed up by postal questionnaire at 3, 6 and 12 months following randomization, along with a 12-month review of clinical data. The primary timepoint for outcome analyses will be12 months after randomisation.

DISCUSSION

If the ASICA intervention improves the practice of TSSE in those affected by melanoma, this may lead to improved psychological well-being and earlier detection of recurrent and new primary melanoma. This could impact both patients and National Health Service (NHS) resources. This study will determine if a full-scale randomised controlled trial can be undertaken in the UK NHS to provide the high-quality evidence needed to determine the effectiveness of the intervention. ASICA is a pilot study evaluating the effectiveness of the practice of digitally supported TSSE in those affected by melanoma.

TRIAL REGISTRATION

Clinical Trials.gov, NCT03328247 . Registered on 1 November 2017.

IN MEMORIAM

John (Jack) B. Hay, PhDDecember 24, 1942 - February 25, 2019Lymphoimmunologist and Mentor Extraordinaire

Evaluation of a Soluble Fibrin Assay in Patients with Suspected Deep Vein Thrombosis

Background. The objective of this study was to determine the clinical utility of an enzyme immunoassay (HIA) for soluble fibrin in patients with clinically suspected deep vein thrombosis (DVT).

Methods and Results. 101 unselected patients with clinically suspected DVT underwent blood sampling for measurement of plasma levels of soluble fibrin, and objective testing for DVT. According to results of the objective tests, patients were classified as DVT-positive (n = 34) or DVT-negative (n = 67). Using different cut-points of soluble fibrin results, the sensitivities, specificities, positive and negative predictive values of the soluble fibrin assay were calculated. A soluble fibrin result of ≤0.75 mg/ml showed a sensitivity and negative predictive value of 100%, and a specificity of 17.9% for DVT, a soluble fibrin result of ≤ 1.40 mg/ml showed a sensitivity of 91.2% and a negative predictive value of 93.6%, and a specificity of 65.7% for DVT, whereas a soluble fibrin result of ≤ 8.0 mg/ml showed a specificity and positive predicive value of 100% for DVT.

Conclusions. This study demonstrates that the soluble fibrin assay used in the study has potential clinical utility as a diagnostic test in patients with clinically suspected DVT and supports further evaluation of this assay.

Do Coagulation Screening Tests Detect Increased Generation of Thrombin and Plasmin in Sick Newborn Infants?

Background: Disseminated intravascular coagulation (DIC) is usually diagnosed in sick infants who have prolonged clotting times, depletion of platelets and coagulation factors, and elevated levels of fibrin derivatives. However, the diagnostic accuracy of abnormal coagulation profiles in neonates at risk of DIC has been uncertain. Since DIC is characterized by activation of both the coagulation and fibrinolytic systems, the objective of this study was to determine whether coagulation screening tests correctly identify infants with biochemical evidence of increased thrombin and plasmin generation.

Methods: Non-surgical patients in a tertiary care nursery who were sick enough to require an indwelling arterial catheter for monitoring purposes, were enrolled in a prospective cohort study. Blood samples for thrombin/antithrombin III (TAT) complexes and the plasmin-derived fibrinopeptide Bβ1-42 were drawn 36 to 72 h after birth from a free-flowing arterial line. Platelet counts, D-Dimer levels, plasma fibrinogen concentrations and prothrombin times, expressed as International Normalized Ratios or INR, were measured at the same time.

Results: One hundred patients were studied. Fifty-seven infants had elevated levels of TAT (≥4 μg/l) and Bβ1-42 (≥4 nmol/l). The sensitivities of platelets <150 × 109/l, D-Dimer >500 ng/ml, fibrinogen <1.5 g/l, and INR >1.5 were 39%, 30%, 12%, and 11%, respectively. Corresponding specificities were 88%, 91%, 98%, and 95%.

Conclusions: Abnormal coagulation screens in sick newborn infants strongly support a diagnosis of DIC. However, normal screens do not exclude activation of the coagulation and fibrinolytic systems.

The Relationship of Antiphospholipid Antibodies to Thromboembolic Disease in Systemic Lupus Erythematosus: A Cross-Sectional Study

In order to determine whether an association exists between antiphospholipid antibodies (APLA) and thromboembolic events in patients with systemic lupus erythematosus (SLE), we performed a cross-sectional study of consecutive unselected SLE patients. The occurrence of previous thromboembolic events was determined by investigators blinded to the APLA status of the patients by critical review of objective tests that had been performed at the time of symptomatic presentation and by performing venous Doppler ultrasound of the legs to elicit venous reflux as an indication of previous venous thrombosis. The presence of APLA was determined by coagulation assays for the lupus anticoagulant (LA) using five tests with well-defined control ranges and by ELISA assay for anticardiolipin antibodies (ACLA). These tests were measured on two separate occasions. The results of the study demonstrate a statistically significant association between persistently abnormal ACLA assays and thromboembolic events and a non-significant trend between persistently abnormal LA and thromboembolic events. Transient abnormalities of LA and ACLA were less strongly associated with thromboembolic events. We conclude that in patients with SLE, there is a significant association between thromboembolism and APLA.

Free Protein S Deficiency May Be Found in Patients with Antiphospholipid Antibodies who Do not Have Systemic Lupus Erythematosus

In order to determine if there is a relationship between antiphospholipid antibodies and reduced free protein S levels, we evaluated 21 patients who had an antiphospholipid antibody but had neither a history of venous thromboembolism nor systemic lupus erythematosus (cases) and 55 matched controls, who did not have an antiphospholipid antibody, a history of thrombosis or systemic lupus erythematosus. Cases and controls had similar protein C and antithrombin levels. Six of 21 cases had reduced free protein S antigen levels, compared to 5 of 55 controls (x 2 = 5.823 p <0.025). In addition, the mean free protein S level was significantly lower in cases than in controls (0.30 ± 0.09 units vs 0.39 ± 0.13 units, p <0.01, two-tailed Student’s t-test). We conclude that antiphospholipid antibodies are associated with a significant decrease in free protein S levels, and that this acquired free protein S deficiency may contribute to the thrombotic diathesis seen in patients with antiphospholipid antibodies.

Evaluation of a Soluble Fibrin Assay in Patients with Suspected Pulmonary Embolism

In order to determine the clinical utility of an enzyme immunoassay (EIA) for soluble fibrin in patients with suspected pulmonary embolism (PE), 195 unselected patients with suspected PE underwent blood sampling for measurement of plasma levels of soluble fibrin, and objective testing for PE. A soluble fibrin result of ≤ 0.75 Μg/ml showed a sensitivity of 100% for PE and a specificity of 12.8%, whereas a soluble fibrin result of ≤ 1.35 Μg/ml showed a sensitivity of 90.3% and a specificity of 49.4% for PE. The soluble fibrin assay has potential clinical utility in excluding PE.

Heparin Therapy during Cardiopulmonary Bypass in Children Requires Ongoing Quality Control

Heparin therapy for children undergoing cardiopulmonary bypass (CPB) is monitored in the operating room by automated whole blood activated clotting times (ACT). For many years our institution used Hemochron (HC) ACT machines but changed to HemoTec (HT) ACT machines because they required a smaller blood sample and provided results in duplicate. When HemoTec ACT machines were introduced at our institution, the surgical team was concerned that increased amounts of heparin were being administered to our patients during CPB. This study was conducted to investigate the potential mechanisms responsible for these clinical observations. First, we compared ACT values on ex vivo blood samples from 20 consecutive pediatric patients (6 samples each) during CPB. The HC ACT values were significantly and systematically increased over HT ACT values (HC: 750 ± 40 vs HT: 418 ± 26, Mean ± SEM, p <0.01). 94% of all HC ACT values were above 450 s compared to only 27% of HT ACT values. If HT ACT values had been used for patient monitoring, all patients would have received more heparin to achieve ACT values above 450 s. The two machines reported similar ACT values when heparin was added in vitro to whole blood (0.1-5.0 units/ml), (HC: Y = 98X + 104, r2 = 0.93 HT: Y = 82X + 109, r2 = 0.94). Heparin concentrations in our patients following a bolus of 300 U/kg of heparin, but prior to CPB were 3.2 ± 0.07 units/ml. Following the initiation of CPB, heparin concentrations decreased to 1.3 ± 0.05, reflecting, in part, hemodilution by the pump prime (1 U of heparin/ml). In contrast to the in vitro results, there was no relationship between ACT values measured by either machine and plasma heparin concentrations in ex vivo samples. Finally, plasma concentrations of 8 coagulation proteins measured prior to CPB and following CPB were decreased by 27-55%, predominantly reflecting the final dilution by CPB. In conclusion: 1) HT and HC machines cannot be used interchangeably in pediatric patients without risk of altering clinical practice in an uncontrolled fashion; and 2) ACT values from children on CPB correlate poorly with heparin concentrations, likely due to hemodilution. Optimal use of anticoagulant therapy during CPB in children requires further study in clinical trials and ongoing quality control.

An Antithrombin III Assay Based on Factor Xa Inhibition Provides a More Reliable Test to Identify Congenital Antithrombin III Deficiency Than an Assay Based on Thrombin Inhibition

Objectives: To determine whether functional antithrombin III (AT-III) levels measured by a factor Xa inhibition (AT-III-Xa) assay identifies AT-III deficient individuals more reliably than functional AT-III levels measured by a thrombin inhibition (AT-III-IIa) assay.

Study design: Cross-sectional study.

Patient population: Sixty-seven members of a large family with type 2 AT-III deficiency.

Intervention: DNA analysis was used as the reference diagnostic standard for AT-III status and subjects were classified as AT-III deficient or non deficient according to these results. Functional AT-III levels were measured in all subjects using: 1) a chromogenic substrate for thrombin and added human thrombin (AT-III-IIa), and 2) a chromogenic substrate for factor Xa and added bovine factor Xa (AT-III-Xa). Functional heparin cofactor II (HC-II) levels were measured using a commercially available kit. The proportions of 125I-α-thrombin complexed to AT-III and HC-II were measured by polyacrylamide gel electrophoresis and autoradiography.

Results: Thirty-one (46%) individuals were classified as AT-III deficient and 36 (54%) as AT-III non deficient. AT-III-Xa assay measured a significantly lower mean AT-III value and a narrower range for individuals classified as AT-III deficient than the AT-III-IIa assay. Using the AT-III-IIa assay, six subjects had borderline AT-III levels compared to none with the AT-III-Xa assay. Thrombin inhibition by HC-II likely accounts for the AT-III-IIa assay giving higher values than the AT-III-Xa assay since 1) there was a significant correlation between the difference in AT-III-IIa and AT-III-Xa levels and HC-II levels, 2) the mean level of HC-II was significantly higher for individuals who had a positive difference between AT-III-IIa and AT-III-Xa levels compared to those who had a negative difference and 3) there was a significant correlation between the difference in AT-III-IIa and AT-III-Xa levels and the percentage of 125I-α-thrombin complexed to HC-II.

Conclusion: The AT-III-Xa assay is a better discriminant between AT-III deficient and AT-III non deficient individuals than the AT-III-IIa assay.

Pre-operative Plasma Levels of Thrombin-Antithrombin III Complexes Correlate with the Development of Venous Thrombosis after Major Hip or Knee Surgery

Study objective. To determine whether levels of thrombin-antithrombin III (TAT) in plasma, taken two weeks pre-operatively, predict the development of deep vein thrombosis (DVT) in patients undergoing major hip or knee surgery.

Design. Prospective cohort.

Setting. Tertiary-care referral centre, university-affiliated hospital.

Patients. Ninety eight consecutive patients undergoing elective hip or knee surgery.

Intervention. All eligible consenting patients were seen in a preoperative clinic two weeks prior to surgery and had blood taken for measurement of plasma TAT level. After surgery, they received a combination of unfractionated heparin 5000 Units 12-hourly subcutaneously, and antiembolism stockings (TEDS), as prophylaxis against DVT. Contrast venography was performed prior to discharge, and according to the results, patients were classified as having proximal (popliteal and/or more proximal) DVT (n = 12), calf DVT (n = 7) or no DVT (n = 79).

Measurements and Results. The mean TAT level was significantly higher in patients who developed DVT (5.7 μg/l) than in those who did not (4.1 μg/l), p = 0.035. Using cut-points of 3.5 and 5.5 μg/l for the TAT level, patients could be categorized as high, intermediate, and low risk for the development of DVT. The proportion of patients with TAT levels of ≥3.5μg/l who developed calf or proximal DVT was significantly higher than the proportion of patients with TAT levels of <3.5 μg/l who developed calf or proximal DVT (p = 0.02). The proportion of patients with TAT levels >5.5 μg/l who developed proximal DVT was significantly higher than the proportion of patients with TAT levels of ≤5.5 μg/l who developed proximal DVT (p = 0.03).

Conclusions. This study demonstrates that pre-operative TAT levels correlate with the risk of developing DVT after major orthopedic surgery. Further studies are needed to determine the reason(s) for this observation and whether rational recommendations about prophylaxis and screening for DVT can be made based on the results of a pre-operative TAT level.

D-Dimer and Thrombin-Antithrombin III Complexes in Patients with Clinically Suspected Pulmonary Embolism

One hundred and fifty-six consecutive patients with clinically suspected pulmonary embolism (PE) had blood drawn to measure levels of D-dimer and thrombin-antithrombin (TAT) complexes and underwent ventilation/perfusion (V/Q) lung scanning and bilateral impedance plethysmography (IPG); pulmonary angiography was performed in 10 patients. Patients were classified as: PE-positive (positive pulmonary angiography or high probability lung scan or non-high probability lung scan and abnormal IPG) or, PE-negative (normal lung scan or normal pulmonary angiography) or PE-unlikely (non-high probability lung scan and normal serial IPG and absence of venous thromboembolism in follow-up). Thirty patients were classified as PE-positive, 64 as PE-negative and 62 patients as PE-unlikely. PE-positive patients were treated with anticoagulants, whereas PE-negative and PE-unlikely patients were not. PE-unlikely patients were followed for 3 months with repeat IPG and clinical evaluation for the occurrence of venous thromboembolism. The sensitivities, specificities, positive predictive values and negative predictive values of the D-dimer and TAT complex assays were calculated for patients classified as PE-positive and PE-negative. In addition, the prevalences of normal D-dimer and TAT complex assays were calculated for PE-unlikely patients.

Cutoffs of 300 ng/ml for D-dimer and 3.5 μg/ml for TAT complexes provided sensitivities of 96% for both assays, negative predictive values of 97% for D-dimer and 96% for TAT complexes and specificities of 52% for D-dimer and 51% for TAT complexes. The specificities of the assays were higher in patients without comorbid conditions and in outpatients. Among PE-unlikely patients, 14 had normal D-dimer levels and 5 had normal levels of TAT complexes. None of these patients developed venous thromboembolism in follow-up.

Our study indicates that: 1) PE is highly unlikely in patients who have D-dimer levels of less than 300 ng/ml and/or levels of TAT complexes below 3.5 μg/ml, and 2), because of their relatively low positive predictive values, further investigation is required if levels of D-dimer and/or TAT complexes are above these cutoffs. These results should be confirmed in future clinical management trials.

"ProC Global": A functional screening test that predicts recurrent venous thromboembolism

Abnormalities of the Protein C (PC) pathway are found in the majority of patients with thrombophilia. ProC Global is a coagulation assay that reflects the net effect of the PC pathway by measuring the activated partial thromboplastin time (APTT) of patient and control plasma, before and after activation of endogenous PC by Protac, a snake venom. Previous studies have suggested that abnormalities in this test are associated with an increased risk of venous thromboembolism (VTE). A retrospective analysis was performed using frozen plasma samples from 140 patients with confirmed VTE to determine whether an abnormal ProC Global result (in the presence and in the absence of known abnormalities in the PC pathway) is a predictor of initial and recurrent VTE. Patients were tested for the presence of activated protein C resistance, Factor V Leiden, PC and protein S (PS) deficiency, and non-specific inhibitor positivity. Mean ProC Global results were significantly lower in patients with recurrent VTE than in patients without recurrent VTE. The association between abnormal ProC Global result and recurrent VTE showed a strong trend, before (odds ratio, OR 3.6) and after (OR 3.1) exclusion of known thrombophilic abnormalities. Patients with a first episode of idiopathic VTE also expressed significant lower ProC Global results than those with secondary VTE. After exclusion of known PC pathway abnormalities, there was a statistically significant association between abnormal ProC Global and initial idiopathic VTE (p=0.04). These results suggest that ProC Global may serve as a predictor of recurrent VTE and potentially for first episode of idiopathic VTE. ProC Global may help identify patients at increased risk of initial and recurrent VTE.

Evaluation of Frozen Plasma Calibrants for Enhanced Standardization of the International Normalized Ratio (INR): A Multi-Center Study

Local ISI calibration has been proposed to improve INR accuracy and inter-laboratory precision. We evaluated the affect of local PT calibration on INR precision and accuracy using six levels of frozen plasma calibrants prepared and pooled from normal donors and patients stabilized on sodium warfarin (coumarin) based oral anticoagulant therapy (OAT). Reference prothrombin time (PT) and INR values were assigned to these calibrants in accordance with World Health Organization (WHO) procedure using rTF 95 international reference preparation (IRP) of thromboplastin (human recombinant). These calibrants, along with five similarly characterized individual OAT patient plasmas, were distributed to 127 laboratories in a multi-center study. Calibrant plasmas were evaluated and INR’s subsequently determined on the 5 OAT test samples using: 1) the ISI and MNPT in place before the study (the local system), 2) the locally calibrated ISI value (local system with ISI calibration) and 3) a PT-INR calibration curve. Precision of INR results improved across the study group using the local system with ISI calibration and the PT-INR calibration curve methods, while accuracy of INR results improved using the PT-INR calibration curve approach only and not the local ISI calibration. The authors conclude that frozen plasma calibrants can be used locally to enhance precision and accuracy of PT results as reported in INR. These calibrants are effective over a range of reagents and instrument combinations. Furthermore, the PT-INR calibration curve appears to be the superior method for local calibration.

Multicenter Evaluation of Lyophilized and Deep-frozen Plasmas for Assignment of the International Normalized Ratio

The interlaboratory variation of the International Normalized Ratio (INR) in various external quality assessment schemes is still relatively high. This is partly caused by inaccuracy of manufacturers’ stated International Sensitivity Index (ISI) and/or local instrumentation effects. The interlaboratory variation and accuracy of INR determinations may be improved by a local calibration procedure based on lyophilized plasmas with assigned INRs. The purpose of the present study was to determine INR values for different types of lyophilized plasmas to be used for local calibration. A total of 13 lyophilized plasmas (one normal, six from coumarin-treated patients, six artificially depleted) were analyzed by 10 laboratories, each using five calibrated prothrombin time (PT) systems. INRs were calculated for each plasma using each laboratory’s specific ISI and mean normal prothrombin time values. In the same way, five deep-frozen pooled plasmas from coumarin-treated patients were analyzed. There were significant INR differences for the lyophilized plasmas between the prothrombin time systems. The differences were relatively small for the deep-frozen coumarin plasmas (CV 2.6-3.3%) and three lyophilized coumarin plasmas from one manufacturer (CV 3.7-4.8%). Important INR differences were observed for three lyophilized coumarin plasmas from another manufacturer (CV 9.5-14.1%) and several artificially depleted plasmas (CV 5.3-12.8%). The citrate concentrations in the artificially depleted plasmas were lower than those in the normal and coumarin plasmas. These differences should be considered in the selection and certification of plasmas as calibrants for local calibration of PT systems. The lyophilized plasmas’ INR values obtained in the present study will be used for a field study of local PT calibration to assess their efficacy.

A Comparison of Point-of-Care Instruments Designed for Monitoring Oral Anticoagulation with Standard Laboratory Methods

Our study compared point-of-care (POC) device monitoring with traditional clinical laboratory methods device of patients on oral anticoagulant therapy. The POC devices used in the study were Coumatrak, CoaguChek, CoaguChek Plus, Thrombolytic Assessment System (TAS) PT-One, TAS PTNC, TAS PT, Hemachron Jr. Signature, Protime Microcoagulation System, and Medtronics ACT II. The clinical laboratory method used thromboplastins with different ISI values: Innovin and Thromboplastin C Plus (TPC). All POC INRs showed strong correlation with both laboratory methods, with correlation coefficients of >0.900. All POC methods demonstrated a significant (p <0.05) difference in INR values, except the TAS PTNC and ACT II INRs (p: 0.12 and 0.71 respectively) when compared with Innovin INRs. All POC INRs were significantly different from TPC generated INRs (p <0.05). Comparisons of the POC INRs to the group mean of the POC methods, show higher correlation (R>0.93), but there were still significant (p<0.05) differences noted between the POC group INR mean and CoaguChek Plus, ACT II, TAS PT-One, TAS PTNC, and Hemachron Jr Signature INRs. These data indicate that POC INR biases exist between laboratory methods and POC devices. Until a suitable whole blood INR standardization method is available, we conclude that clinicians using point-of-care anticoagulation monitoring should be aware of differences between POC and parent laboratory values.

Influence of Three Types of Automated Coagulometers on the International Sensitivity Index (ISI) of Rabbit, Human, and Recombinant Human Tissue Factor Preparations

Five tissue factor reagents and three types of automated instruments for prothrombin time (PT) determination were studied in an international multicenter collaborative exercise. The purpose of this work was to determine the international sensitivity index (ISI) for each combination of reagent and instrument against the international reference preparation RBT/90. Each type of instrument was used by 3 or 4 centers to assess the interlaboratory variation of the ISI. The interlaboratory variation of the ISI for each combination of reagent and instrument ranged between 0.4% and 7.8% coefficient of variation. For three reagents, the mean ISI values for ACL (nephelometric) and STA (mechanical) were practically identical, but the mean ISI values for MLA (photo-optical) were at least 10% higher. For two other reagents prepared from rabbit tissue, the mean ISI values increased in the order ACL, STA, MLA. The widest range of mean ISI values was noted with one rabbit tissue factor reagent: 1.68 for ACL and 2.00 for MLA. Exclusion of patient specimens with INR <1.5 and INR >4.5 determined by the international reference preparation resulted in a slight decrease of the mean ISI.

The interlaboratory variation of the International Normalized Ratio (INR) was assessed from the results obtained with common lyophilized and deep-frozen plasmas. The use of instrument-specific ISI values resulted in reduced interlaboratory variation of the INR. It is recommended that thromboplastin manufacturers provide instrument-specific ISI values.

Fibrinolytic Variables in Patients with Recurrent Venous Thrombosis: a Prospective Cohort Study

To determine whether fibrinolytic testing predicts recurrent venous thrombosis, we have performed a prospective cohort study in which 303 patients with a first episode of venous thromboembolism underwent comprehensive fibrinolytic testing while receiving oral anticoagulants, and after anticoagulants had been discontinued. They were then followed for up to 3 years for recurrent venous thrombosis. No systematic differences in the levels or activity of type 1 plasminogen activator inhibitor (PAI-1), tissue plasminogen activator (tPA) or euglobulin clot lysis times were detected between patients who did, or did not, suffer recurrent thrombosis. There were also no differences in these variables when patients whose initial thrombosis was idiopathic were compared to patients whose thrombosis occurred in the setting of a known thrombotic risk factor. Based on these results, neither measuring fibrinolytic parameters in patients with venous thromboembolism, nor modification of treatment based on the results of such testing, are justified. Our study also confirms that patients with idiopathic venous thromboembolism have a high risk of recurrence.

Does motor imagery training improve hand function in chronic stroke patients? A pilot study

Objective: To assess the efficacy of motor imagery training for arm function in chronic stroke patients. The relation between mental processes such as attentional and perceived personal control over recovery, and motor imagery was additionally investigated.

Design and subjects: Twenty patients with long-term motor impairments (mean two years post stroke), were assessed before and after four weeks of training. Ten patients mentally rehearsed movements with their affected arm. Their recovery was compared with patients who performed nonmotor imagery (n =5), or who were not engaged in mental rehearsal (n =5).

Setting: Patients were recruited from the stroke database of Ninewells Hospital, Dundee. Assessment and training were performed at the patients' home.

Interventions: The motor imagery group was asked to practise daily imagining moving tokens with their affected arm. The nonmotor imagery group rehearsed visual imagery of previously seen pictures. All patients practised physically moving the tokens.

Main measures: The following variables were assessed before and after training: motor function (training task, pegboard and dynamometer), perceived locus of control, attention control and ADL independence.

Results: All patient groups improved on all motor tasks except the dynamometer. Improvement was greater for the motor imagery group on the training task only (average of 14% versus 6%). No effect of motor imagery training was found on perceived or attentional control.

Conclusions: Motor imagery training without supervision at home may improve performance on the trained task only. The relation between movement imagery, attention and perceived personal control over recovery remained unclear.