A convexity result for single-server exponential loss systems with non-stationary arrivals

We consider single-server loss systems with exponential service times and non-stationary Poisson input. We prove that if the arrival rate is given by a periodic function, the proportion of lost customers is convex increasing in the amplitude.

An M/G/c queue in which the number of servers required is random

Many queueing situations such as computer, communications and emergency systems have the feature that customers may require service from several servers at the same time. They may thus be delayed until the required number of servers is available and servers may be idle when customers are waiting. We consider general server-completion-time distributions and derive approximation methods for the computation of the steady-state distribution of the number of customers in queue as well as the moments of the waiting-time distribution. Extensive computational results are reported.

Delivering results to clients: a question of satisfying needs or desires?

Demand for genitourinary (GU) medicine services is outstripping supply. Improving efficiency can modulate the supply side of the equation, e.g. decreasing the number of clients having to return for their results. This survey explored how clients at two central London GU medicine clinics would like to receive their results and their views were reflected against what was offered by London GU medicine clinics. There was a significant difference between the result delivery services that the clients wanted and what the clinics provided ( P <0.0001, χ2). Of the clients, 92% wanted to know their results regardless of outcome whereas 22% of London clinics would only inform clients of positive results. This study questions the importance and feasibility of patient choice, an important aspect of the National Strategy for Sexual Health and HIV. Clinics may not individually be able to provide choice but between them, they do provide a wide range of alternatives for the client.

The epidemiology and outcomes of women with postpartum haemorrhage requiring massive transfusion with eight or more units of red cells: a national cross-sectional study

OBJECTIVE

To ascertain the incidence of massive transfusion (MT) in obstetrics in the UK, and describe its management and clinical outcomes.

DESIGN

A population-based cross-sectional study conducted through the UK Obstetric Surveillance System (UKOSS).

SETTINGS

All UK hospitals with consultant-led maternity units.

POPULATION

Any pregnant woman at ≥20 weeks of gestation receiving ≥8 units of red blood cells within 24 hours of giving birth, from July 2012 to June 2013.

METHODS

Prospective case identification through the monthly mailing of UKOSS.

RESULTS

We identified 181 women who had undergone MT, making the estimated incidence of MT associated with postpartum haemorrhage (PPH) 23 per 100 000 maternities (95% confidence interval 19-26) per year. The median estimated blood loss was 6 l (interquartile range 4.5-8.0 l). The majority of women presented outside working hours (63%), 40% had had previous caesarean sections and 3% had normal vaginal births without risk factors. The main cause for MT was uterine atony (40%) and the main mode of birth was caesarean section (69%). Of the 181 women, 15 received >20 units of red blood cells. In total, 45% of women underwent hysterectomy, and among all causes of PPH, placenta accreta had the highest hysterectomy rate. Two women died, 82% were admitted to intensive care/high-dependency units, and 28% developed major morbidities.

CONCLUSION

Massive transfusion due to PPH is associated with high rates of morbidity and hysterectomy. Clinical and research efforts should focus on approaches to recognise and optimise timely resuscitation and management of these severe cases.

TWEETABLE ABSTRACT

Massive transfusion due to postpartum haemorrhage is associated with high rates of morbidity and hysterectomy.

Minor salivary gland basal cell adenocarcinoma: a systematic review and report of a new case

IMPORTANCE

Basal cell adenocarcinoma (BCAC) of the minor salivary gland is an extremely rare disease: the most recent substantive literature review reports only 25 cases. Owing to the rarity of this disease, it has not yet been well characterized in the literature.

OBJECTIVE

We sought to expand the knowledge of minor salivary gland BCAC by performing an exhaustive literature review and adding to it a new case that is rare owing to the tumor's size, aggressive nature, and mixed histologic pattern. The review emphasizes epidemiologic patterns, diagnostic characteristics, treatment patterns, and expected prognosis for minor salivary gland BCAC.

EVIDENCE ACQUISITION

In June 2012, PubMed was queried using the term "salivary gland basal cell adenocarcinoma," and the resultant articles were reviewed. Those specifically mentioning a minor salivary gland BCAC were included in this study. Those that did not differentiate minor salivary gland BCAC from major salivary gland BCAC were excluded. The search was not limited by language and included articles from North America, Europe, Africa, and Asia from 1978 to June 2012.

RESULTS

The PubMed search resulted in 195 articles, of which 33 articles reported at least 1 case of minor salivary gland BCAC. We report herein 72 cases of minor salivary gland BCAC (71 cases from the literature review and 1 new case reported herein). The mean patient age at the time of presentation was 56 years (range, 24-90 years), and the disease showed no sex predilection. The most common location was the palate, and the average lesions size was 2.4 cm (range, 0.7-4.2 cm). The treatment modality of choice was wide local excision (n = 57; 79%). There was a high local recurrence rate (n = 30; 41%) but a low rate of distant metastasis (n = 8; 11%).

CONCLUSIONS AND RELEVANCE

We present a comprehensive review of minor salivary gland BCAC, describing nearly 3 times as many cases as has been previously reported. This review characterizes a rare disease and increases awareness of the disease among otolaryngologists. Minor salivary gland BCAC is similar to major salivary gland BCAC and minor salivary gland tumors in general with regard to patient age, sex, tumor site, treatment modality, recurrence, metastasis, and mortality.

Early cryoprecipitate for major haemorrhage in trauma: a randomised controlled feasibility trial

BACKGROUND

Low fibrinogen (Fg) concentrations in trauma haemorrhage are associated with poorer outcomes. Cryoprecipitate is the standard source for Fg administration in the UK and USA and is often given in the later stages of transfusion therapy. It is not known whether early cryoprecipitate therapy improves clinical outcomes. The primary aim of this feasibility study was to determine whether it was possible to administer cryoprecipitate, within 90 min of admission to hospital. Secondary aims were to evaluate laboratory measures of Fg and clinical outcomes including thrombotic events, organ failure, length of hospital stay and mortality.

METHODS

This was an unblinded RCT, conducted at two civilian UK major trauma centres of adult trauma patients (age ≥16 yrs), with active bleeding and requiring activation of the major haemorrhage protocol. Participants were randomised to standard major haemorrhage therapy (STANDARD) (n=22), or to standard haemorrhage therapy plus two early pools of cryoprecipitate (CRYO) (n=21).

RESULTS

85% (95% CI: 69-100%) CRYO participants received cryoprecipitate within 90 min, median time 60 min (IQR: 57-76) compared with 108 min (67-147), CRYO and STANDARD arms respectively (P=0.002). Fg concentrations were higher in the CRYO arm and were maintained above 1.8 g litre(-1) at all time-points during active haemorrhage. All-cause mortality at 28 days was not significantly different (P=0.14).

CONCLUSIONS

Early Fg supplementation using cryoprecipitate is feasible in trauma patients. This study supports the need for a definitive RCT to determine the effect of early Fg supplementation on mortality and other clinical outcomes.

TRIAL REGISTRY NUMBER

ISRCTN55509212.

Thawed and liquid plasma--what do we know?

There is increasing interest in the use of liquid or frozen plasma thawed and stored for extended periods (>24 h) to reduce wastage and to improve rapid availability of plasma in massive transfusion protocols advocating the early use of plasma in trauma by some centres. There is now a body of studies that have assessed individual coagulation factors during storage of thawed plasma. These show that factor VIII (FVIII) is the worst affected factor and that its activity is mainly lost during the first 24 h following thawing. However, for most factors studied, there is a continual decline during further storage. The few studies that have assessed thrombin generation in thawed plasma have shown variable results. Extended storage of plasma is associated with an increase in levels of DEHP in the component and could theoretically increase the risk of bacterial contamination, although the latter does not appear to have been an issue in countries that have adopted the use of thawed plasma. There are no clinical studies relating to the efficacy of extended-thawed plasma, and therefore, the potential reduction in its efficacy must be balanced with the clinical need for the component.

Modern banking, collection, compatibility testing and storage of blood and blood components

The clinical practice of blood transfusion has changed considerably over the last few decades. The potential risk of transfusion transmissible diseases has directed efforts towards the production of safe and high quality blood. All transfusion services now operate in an environment of ever-increasing regulatory controls encompassing all aspects of blood collection, processing and storage. Stringent donor selection, identification of pathogens that can be transmitted through blood, and development of technologies that can enhance the quality of blood, have all led to a substantial reduction in potential risks and complications associated with blood transfusion. In this article, we will discuss the current standards required for the manufacture of blood, starting from blood collection, through processing and on to storage.

Risk factors for Barrett's esophagus compared between African Americans and non-Hispanic Whites

OBJECTIVES

Esophageal adenocarcinoma is more common among non-Hispanic Whites (NHWs) than African Americans (AAs). It is unclear whether its precursor, Barrett's esophagus (BE), is also less common among AAs, and whether differences in risk factor profiles explain the racial disparity.

METHODS

Data were from a case-control study among eligible Veterans Affairs patients scheduled for an upper endoscopy, and a sample identified from primary care clinics. Participants completed a questionnaire on sociodemographic and clinical factors and underwent a study esophagogastroduodenoscopy. We calculated race-specific BE prevalence rates and used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) for BE.

RESULTS

There were 301 BE cases and 1,651 controls. BE prevalence was significantly higher among NHWs than AAs (21.3 vs. 5.0%; P<0.001). NHWs were more likely than AAs to be male, have a high waist-to-hip ratio (WHR), hiatal hernia, and use proton-pump inhibitors (PPIs), but less likely to have Helicobacter pylori (P<0.001). Among cases, NHWs were more likely to have long-segment BE and dysplasia than AAs. Independent BE risk factors for AAs included a hiatus hernia ≥3 cm (OR 4.12; 95% CI, 1.57-10.81) and a history of gastroesophageal reflux disease or PPI use (OR, 3.70; 95% CI, 1.40-9.78), whereas high WHR (OR, 2.82; 95% CI, 1.41-5.63), hiatus hernia ≥3 cm (OR, 4.95; 95% CI, 3.05-8.03), PPI use (OR, 1.88; 95% CI, 1.33-2.66), and H. pylori (OR, 0.64; 95% CI, 0.41-0.99) were statistically significantly associated with BE risk for NHWs. Among all cases and controls, race was a risk factor for BE, independent of other BE risk factors (OR for AAs, 0.26; 95% CI, 0.17-0.38).

CONCLUSIONS

Among veterans, the prevalence of BE was lower in AAs compared with NHWs. This disparity was not accounted for by differences in risk estimates or prevalence of risk factors between NHWs and AAs.

Discounting of delayed rewards across the life span: age differences in individual discounting functions

The present effort addressed both the issue of the generality of choice models and the issue of possible qualitative developmental change in temporal discounting by examining behavior at the individual level across the life span. Data from individual children, young adults, and older adults who participated in two previous studies were analyzed [Green, L., Fry, A.F., Myerson, J., 1994. Discounting of delayed rewards: a life-span comparison. Psychol. Sci. 5, 33-36; Green, L., Myerson, J., Lichtman, D., Rosen, S., Fry, A., 1996. Temporal discounting in choice between delayed rewards: the role of age and income. Psychol. Aging 11, 79-84]. At all ages, a hyperbola-like function originally proposed by Green et al. (1994) based on group data, provided the best description of individual discounting functions. Two developmental trends were observed. The rate at which individuals discounted the value of delayed rewards decreased with age, and there was a systematic change in the shape of the discounting function. Each of these trends was reflected in a separate parameter of the model. The fact that the same mathematical model described the behavior of individuals of different ages suggests that age and individual differences in the discounting of delayed rewards are primarily quantitative in nature and reflect variations on fundamentally similar choice processes.

Hepatitis C prevalence in HIV-infected individuals: a comparison of inpatient and outpatient care

Summary Due to the shared risk factors for viral transmission, coinfection of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) is common. This study examined the seroprevalence of HCV among HIV-infected patients in inpatient and outpatient settings. A retrospective chart review of 256 HIV-infected patients was conducted in Prince George's Hospital Center (inpatients from 1 September 2011 to 1 March 2012) and Glenridge Medical Center (outpatients from 1 January 2011 to 31 December 2012). The mean age of the population was 46 ± 12 and 44 ± 11 for inpatients and outpatients, respectively. HIV-infected men comprised 61.9% inpatients and 64.8% outpatients. The overall prevalence of HCV infection in HIV/AIDS patients was 12.5% (32/256), with a higher prevalence in the inpatient group than that in the outpatient group (24.6% vs 11.2%, p < 0.01). The percentages of drug abuse (43.8% vs 16.5%, p < 0.01) and alcoholism (25.0% and 14.3%, p < 0.05) in HCV/HIV-coinfected patients were higher than those in HIV-monoinfected patients. In addition, only 64.9% of HIV-infected and 50.0% of HCV/HIV-coinfected inpatients were followed up with outside care after discharge. To our knowledge, this study, for the first time, revealed that HCV/HIV coinfection was significantly higher in inpatients compared to outpatients. Considering the high prevalence and comorbidities associated with HCV/HIV coinfection, it is recommended that evaluation of hepatic damage, especially fibrosis, should be initiated during hospitalization as well as outpatient care.

Policy compliance of smokers on a tobacco-free university campus

OBJECTIVES

To explore factors influencing compliance with campus tobacco policies and strategies to increase compliance.

PARTICIPANTS

Sixty tobacco smokers (April 2012).

METHODS

A 22-item intercept-interview with closed- and open-ended questions was conducted with smokers in adjacent compliant and noncompliant areas at 1 university with a 100% tobacco ban. Data were analyzed using descriptive statistics and content analysis.

RESULTS

Most reported that the smoking policy was not enforced. Noncompliant smokers had less knowledge of locations where tobacco use was permitted and were more likely to identify their smoking location as compliant and had knowingly violated the policy. Choice of location to smoke was related to convenience and a desire to follow the policy. Smokers recommended consequences for noncompliance and structures that accommodated smoking to increase adherence to the tobacco ban.

CONCLUSIONS

Additional education, environmental, and contingency strategies are needed to increase compliance with the policy banning tobacco use on this campus.