Richard J. Crossman

Multi-centre retrospective analysis of anaphylaxis during general anaesthesia in the United Kingdom: aetiology and diagnostic performance of acute serum tryptase

This is the first multi‐centre retrospective survey from the United Kingdom to evaluate the aetiology and diagnostic performance of tryptase in anaphylaxis during general anaesthesia (GA). Data were collected retrospectively (2005–12) from 161 patients [mean ± standard deviation (s.d.), 50 ± 15 years] referred to four regional UK centres. Receiver operating characteristic curves (ROC) were constructed to assess the utility of tryptase measurements in the diagnosis of immunoglobulin (Ig)E‐mediated anaphylaxis and the performance of percentage change from baseline [percentage change (PC)] and absolute tryptase (AT) quantitation. An IgE‐mediated cause was identified in 103 patients (64%); neuromuscular blocking agents (NMBA) constituted the leading cause (38%) followed by antibiotics (8%), patent blue dye (6%), chlorhexidine (5%) and other agents (7%). In contrast to previous reports, latex‐induced anaphylaxis was rare (0·6%). A non‐IgE‐mediated cause was attributed in 10 patients (6%) and no cause could be established in 48 cases (30%). Three serial tryptase measurements were available in 34% of patients and a ROC analysis of area under the curve (AUC) showed comparable performance for PC and AT. A ≥ 80% PPV for identifying an IgE‐mediated anaphylaxis was achieved with a PC of >141% or an AT of >15·7 mg/l. NMBAs were the leading cause of anaphylaxis, followed by antibiotics, with latex allergy being uncommon. Chlorhexidine and patent blue dye are emerging important health‐care‐associated allergens that may lead to anaphylaxis. An elevated acute serum tryptase (PC >141%, AT >15·7 mg/l) is highly predictive of IgE‐mediated anaphylaxis, and both methods of interpretation are comparable.

Validation of digital pathology imaging for primary histopathological diagnosis

Digital pathology (DP) offers advantages over glass slide microscopy (GS), but data demonstrating a statistically valid equivalent (i.e. non‐inferior) performance of DP against GS are required to permit its use in diagnosis. The aim of this study is to provide evidence of non‐inferiority.

Classification with decision trees from a nonparametric predictive inference perspective

An application of nonparametric predictive inference for multinomial data (NPI) to classification tasks is presented. This model is applied to an established procedure for building classification trees using imprecise probabilities and uncertainty measures, thus far used only with the imprecise Dirichlet model (IDM), that is defined through the use of a parameter expressing previous knowledge. The accuracy of that procedure of classification has a significant dependence on the value of the parameter used when the IDM is applied. A detailed study involving 40 data sets shows that the procedure using the NPI model (which has no parameter dependence) obtains a better trade-off between accuracy and size of tree than does the procedure when the IDM is used, whatever the choice of parameter. In a bias-variance study of the errors, it is proved that the procedure with the NPI model has a lower variance than the one with the IDM, implying a lower level of over-fitting.

Full Thickness Skin Grafts in Periocular Reconstructions: Long-Term Outcomes

Purpose: To evaluate the outcomes of eyelid reconstruction in patients who underwent full thickness skin grafts. Methods: A retrospective, noncomparative intervention study of patients who underwent periocular reconstruction with full thickness skin grafts between 2005 and 2011. Results: One hundred consecutive Caucasian patients were included in the study, 54 women and 46 men. Mean follow up was 32 months. Indications for full thickness skin grafts were excision of eyelid tumors (98%) and cicatricial ectropion (2%). Site of lid defects were lower lid (60%), medial canthus (32%), upper lid (6%), and lateral canthus (2%). The skin graft donor sites were supraclavicular (44%), upper eyelid (24%), inner brachial (18%), and postauricular (14%). Early postoperative complications included lower eyelid graft contracture (1%) and partial failure (1%). Late sequelae included lower eyelid graft contracture (4%) and hypertrophic scarring (23%). Of the 23 patients with hypertrophic scar, 21 achieved good outcomes following massage with silicone gel and steroid ointment and 2 had persistent moderate lumpiness. No statistically significant association was found between graft hypertrophy and donor site or graft size. As high as 95% of all patients achieved good final eyelid position. Good color match was seen in 94% and graft hypopigmentation in 6%. An association between hypopigmentation and supraclavicular and inner brachial donor site was found to be statistically significant. Conclusions: Most patients (94%) achieved good eyelid position and color match. Majority (91%) of the early postoperative cicatricial sequelae can be reversed by massage, steroid ointment, and silicone gel application. Full thickness skin grafts have excellent graft survival rates and have minimal donor site morbidity.

Imprecise Markov chains with absorption

We consider convergence of Markov chains with uncertain parameters, known as imprecise Markov chains, which contain an absorbing state. We prove that under conditioning on non-absorption the imprecise conditional probabilities converge independently of the initial imprecise probability distribution if some regularity conditions are assumed. This is a generalisation of a known result from the classical theory of Markov chains by Darroch and Seneta [6].

Anaphylaxis and ethnicity: higher incidence in British South Asians.

The incidence of anaphylaxis in South Asians (Indian, Pakistani and Bangladeshi ethnicity) is unknown. Birmingham is a British city with a disproportionately large population of South Asians (22.5%) compared with the rest of the UK (4.9%). The main aims of this study were to determine the incidence and severity of anaphylaxis in this population and to investigate the differences between the South Asian and White populations.

Time-Homogeneous Birth-Death Processes with Probability Intervals and Absorbing State

This paper concerns discrete-time time-homogeneous birth-death processes on a finite state space, containing a single absorbing state, with interval-valued transition probabilities. As absorption is certain, the quasi-stationary behaviour of the process is studied with the distribution of the process conditional on non-absorption. It is shown that the set of all possible limiting conditional distributions is the set of all possible quasi-stationary distributions. An approximation of the possibly infinite set of conditional distributions at time n is presented, together with an example.

A cluster randomized controlled trial of the effectiveness and cost-effectiveness of Intermediate Care Clinics for Diabetes (ICCD): study protocol for a randomized controlled trial

AbstractBackgroundWorld-wide healthcare systems are faced with an epidemic of type 2 diabetes. In the United Kingdom, clinical care is primarily provided by general practitioners (GPs) rather than hospital specialists. Intermediate care clinics for diabetes (ICCD) potentially provide a model for supporting GPs in their care of people with poorly controlled type 2 diabetes and in their management of cardiovascular risk factors. This study aims to (1) compare patients with type 2 diabetes registered with practices that have access to an ICCD service with those that have access only to usual hospital care; (2) assess the cost-effectiveness of the intervention; and (3) explore the views and experiences of patients, health professionals and other stakeholders.Methods/DesignThis two-arm cluster randomized controlled trial (with integral economic evaluation and qualitative study) is set in general practices in three UK Primary Care Trusts. Practices are randomized to one of two groups with patients referred to either an ICCD (intervention) or to hospital care (control). Intervention group: GP practices in the intervention arm have the opportunity to refer patients to an ICCD - a multidisciplinary team led by a specialist nurse and a diabetologist. Patients are reviewed and managed in the ICCD for a short period with a goal of improving diabetes and cardiovascular risk factor control and are then referred back to practice.or Control group: Standard GP care, with referral to secondary care as required, but no access to ICCD.Participants are adults aged 18 years or older who have type 2 diabetes that is difficult for their GPs to control. The primary outcome is the proportion of participants reaching three risk factor targets: HbA1c (≤7.0%); blood pressure (<140/80); and cholesterol (<4 mmol/l), at the end of the 18-month intervention period. The main secondary outcomes are the proportion of participants reaching individual risk factor targets and the overall 10-year risks for coronary heart disease(CHD) and stroke assessed by the United Kingdom Prospective Diabetes Study (UKPDS) risk engine. Other secondary outcomes include body mass index and waist circumference, use of medication, reported smoking, emotional adjustment, patient satisfaction and views on continuity, costs and health related quality of life. We aimed to randomize 50 practices and recruit 2,555 patients.DiscussionForty-nine practices have been randomized, 1,997 patients have been recruited to the trial, and 20 patients have been recruited to the qualitative study. Results will be available late 2012.Trial registration[ClinicalTrials.gov: Identifier NCT00945204]

Father absence and age at first birth in a western sample

Although a large literature has shown links between “father absence” during early childhood, and earlier puberty and sexual behavior in girls in Western populations, there are only a few studies which have looked at timing of reproduction, and only one of these fully incorporated childless respondents to investigate whether father absence is associated with increased hazard of becoming a parent at one time point (early) more than another. Here we sought to clarify exactly when, if at all, father absence increased the likelihood of first birth in a Western sample.

Accuracy of clinical diagnosis of benign eyelid lesions: Is a dedicated nurse-led service safe and effective?

ABSTRACT This article compares an independent nurse-led benign lesion service with a doctor-led one, and assesses the impact of clinician seniority on diagnostic accuracy rates. Retrospective review of benign lesions referred to a teaching hospital and managed in either a doctor- or nurse-led lid service. All lesions were diagnosed clinically, excised and then sent for histological diagnosis. Lesions were categorized into subtypes. Pre-excision clinical diagnoses were compared with histological diagnoses. Sensitivity, specificity and missed malignancy rates were calculated for each subtype. Accuracy was compared between different grades of doctors and a specialist nurse. 264 and 332 lesions were managed in a doctor-led and nurse-led service, respectively. Rates of accurate sub-typing were 79.6% and 80.4% in the doctor- and nurse-led services, respectively (p > 0.05). Clinician seniority had no bearing. Missed malignancies or pre-malignancies accounted for 1.1% and 1.5% of lesions in the doctor and nurse-led services, respectively (p > 0.05). Overall, the remaining misdiagnoses were benign lesions of another subtype (13.6%) or non-specific histological findings (5.0%) and 98.6% of lesions were confirmed as benign on histology. Overall sensitivity and specificity values were: benign epithelial proliferations 95.6% and 92.2%, epidermal inclusion cysts 92.2% and 88.0%, xanthelasma 97.5% and 100.0%, cysts of Moll 66.7% and 96.6%, naevi 39.4% and 99.8% and molluscum 20.0% and 99.8%, respectively. A dedicated nurse-led service is as effective in managing a range of clinically benign lid lesions as a doctor-led one, and clinician seniority has little impact on the diagnostic accuracy of these lesions.