The PAncreatic Surgery Composite Endpoint PACE - Development and Validation of a Clinically Relevant Endpoint Requiring Lower Sample Sizes

OBJECTIVE

To provide a composite endpoint in pancreatic surgery.

SUMMARY BACKGROUND DATA

Single endpoints in prospective and randomized studies have become impractical due to their low frequency and the marginal benefit of new interventions.

METHODS

Data from prospective studies were used to develop (n=1273) and validate (n=544) a composite endpoint based on postoperative pancreatic fistula, post-pancreatectomy hemorrhage as well as reoperation and reinterventions. All patients had pancreatectomies of different extents. The association of the developed PAncreatic surgery Composite Endpoint (PACE) with prolonged length of hospital stay (LOS) >75th percentile and mortality was assessed. A single-institution database was used for external validation (n = 2666). Sample size calculations were made for single outcomes and the composite endpoint.

RESULTS

In the internal validation cohort, the PACE demonstrated an AUC of 78.0%, a sensitivity of 90.4% and a specificity of 67.6% in predicting a prolonged LOS. In the external cohort, the AUC was 76.9%, the sensitivity 73.8% and the specificity 80.1%. The 90-day mortality rate was significantly different for patients with a positive versus a negative PACE both in the development and internal validation cohort (5.1% vs 0.9%; P< 0.001), as well as in the external validation cohort (8.5% vs 1.2%, P< 0.001). The PACE enabled sample size reductions of up to 80.5% compared to single outcomes.

CONCLUSION

The PACE performed well in predicting prolonged hospital stays and can be used as a standardized and clinically relevant endpoint for future prospective trials enabling lower sample sizes and therefore improved feasibility compared to single outcome parameters.

Robust hand tracking for surgical telestration

PURPOSE

As human failure has been shown to be one primary cause for post-operative death, surgical training is of the utmost socioeconomic importance. In this context, the concept of surgical telestration has been introduced to enable experienced surgeons to efficiently and effectively mentor trainees in an intuitive way. While previous approaches to telestration have concentrated on overlaying drawings on surgical videos, we explore the augmented reality (AR) visualization of surgical hands to imitate the direct interaction with the situs.

METHODS

We present a real-time hand tracking pipeline specifically designed for the application of surgical telestration. It comprises three modules, dedicated to (1) the coarse localization of the expert's hand and the subsequent (2) segmentation of the hand for AR visualization in the field of view of the trainee and (3) regression of keypoints making up the hand's skeleton. The semantic representation is obtained to offer the ability for structured reporting of the motions performed as part of the teaching.

RESULTS

According to a comprehensive validation based on a large data set comprising more than 14,000 annotated images with varying application-relevant conditions, our algorithm enables real-time hand tracking and is sufficiently accurate for the task of surgical telestration. In a retrospective validation study, a mean detection accuracy of 98%, a mean keypoint regression accuracy of 10.0 px and a mean Dice Similarity Coefficient of 0.95 were achieved. In a prospective validation study, it showed uncompromised performance when the sensor, operator or gesture varied.

CONCLUSION

Due to its high accuracy and fast inference time, our neural network-based approach to hand tracking is well suited for an AR approach to surgical telestration. Future work should be directed to evaluating the clinical value of the approach.

The effects of weightlessness on the human organism and mammalian cells

It has always been a desire of mankind to conquest Space. A major step in realizing this dream was the completion of the International Space Station (ISS). Living there for several months confirmed early observations of short-term spaceflights that a loss of gravity affects the health of astronauts. Space medicine tries to understand the mechanism of microgravity-induced health problems and to conceive potent countermeasures. There are four different aspects which make space medicine appealing: i) finding better strategies for adapting astronauts to weightlessness; ii) identification of microgravity-induced diseases (e.g. osteoporosis, muscle atrophy, cardiac problems and others); iii) defining new therapies to conquer these diseases which will benefit astronauts as well as people on Earth in the end; and iv) on top of that, unveiling the mechanisms of weightlessness-dependent molecular and cellular changes is a requirement for improving space medicine. In mammalian cells, microgravity induces apoptosis and alters the cytoskeleton and affects signal transduction pathways, cell differentiation, growth, proliferation, migration and adhesion. This review focused on gravi-sensitive signal transduction elements and pathways as well as molecular mechanisms in human cells, aiming to understand the cellular changes in altered gravity. Moreover, the latest information on how these changes lead to clinically relevant health problems and current strategies of countermeasures are reviewed.

The front end test stand high performance H- ion source at Rutherford Appleton Laboratory

The aim of the front end test stand (FETS) project is to demonstrate that chopped low energy beams of high quality can be produced. FETS consists of a 60 mA Penning Surface Plasma Ion Source, a three solenoid low energy beam transport, a 3 MeV radio frequency quadrupole, a chopper, and a comprehensive suite of diagnostics. This paper details the design and initial performance of the ion source and the laser profile measurement system. Beam current, profile, and emittance measurements are shown for different operating conditions.

Extracellular superoxide production by Enterococcus faecalis requires demethylmenaquinone and is attenuated by functional terminal quinol oxidases

The intestinal commensal bacterium, Enterococcus faecalis, is unusual among prokaryotic organisms in its ability to produce substantial extracellular superoxide. Transposon mutagenesis, allelic replacement, and electron spin resonance (ESR)-spin trapping showed that superoxide production and generation of derivative hydroxyl radical were dependent on membrane-associated demethylmenaquinone. Extracellular superoxide was generated through univalent reduction of oxygen by reduced demethylmenaquinone. Moreover, extracellular superoxide production was inhibited by exogenous haematin, an essential cofactor for cytochrome bd, and by fumarate, a substrate for fumarate reductase. As integral membrane quinol oxidases, cytochrome bd and fumarate reductase redox cycle demethylmenaquinone, and are necessary for aerobic and anaerobic respiration respectively. A rat model of intestinal colonization demonstrated that conditions exist in the mammalian intestinal tract that permit a mode of respiration for E. faecalis that results in the formation of hydroxyl radical. These results identify and characterize the mechanism by which E. faecalis generates extracellular free radicals.

Molecular epidemiology of preterm delivery: methodology and challenges

Preterm delivery (PTD) appears to be a complex trait determined by both genetic and environmental factors. Few studies have examined genetic influence on PTD. The overall goal of our study is to examine major candidate genes of PTD and to test gene-environment interactions. Our study includes 500 preterm trios, including 500 preterm babies and their parents and 500 maternal age-matched term controls. We will perform the transmission/disequilibrium test (TDT) on candidate genes thought to be important in each of the four biological pathways of PTD: (1) decidual chorioamionotic inflammation: interleukin 1 (IL-1), IL-6, and tumour necrosis factor (TNF); (2) maternal and fetal stress: corticotropin-releasing hormone (CRH); (3) uteroplacental vascular lesions: methylenetereahydrofolate reductase (MTHFR); and (4) susceptibility to environmental toxins: GSTM1, GSTT1, CYP1A1, CYP2D6, CYP2E1, NAT2, NQO1, ALDH2, and EPHX. We will also perform standard case-control analyses on the 500 preterm cases and 500 term controls to examine gene-environment interactions. The major environmental, nutritional and social factors as well as clinical variables known or suspected to be associated with PTD will be used to test for gene-environment interactions. This study integrates epidemiological and clinical data as well as genetic markers along major pathogenic pathways of PTD. The findings from this study should improve our understanding of genetic influences on PTD and gene-environment interactions.

Assessing the effects of welfare reform policies on reproductive and infant health

OBJECTIVES

The welfare reform law of 1996 marked a historical moment in US policy toward the poor by ending the entitlement to cash assistance, by requiring work, and by establishing time limits. This article examines the potential impact on the health of women and children, the primary recipients of welfare benefits.

METHODS

The authors outline the reproductive health outcomes most likely to be sensitive to welfare policies, identify indicators that might be used to assess these outcomes, review empirical evidence, and suggest specific methods and data sources.

RESULTS

State welfare requirements could improve health outcomes or deter families from Medicaid and food stamps, as well as income support, thus worsening health outcomes. National and state data may prove useful in detecting these effects; however, new data sources may be required for specific health-related questions.

CONCLUSIONS

Assessing the effects of welfare policies on reproductive and infant health is possible, although challenging. Reauthorization of the legislation is required in 2002; it is essential that the consequences for health be included in the next round of public debate.

Failure to screen newborns for inborn disorders: a potential consequence of changes in newborn care

OBJECTIVES

To determine how changes in the structure of the hospital care of infants, such as shortened post-natal stays, affect the completeness of newborn screening.

DESIGN

Cohort.

SETTING

Two large maternity hospitals.

PARTICIPANTS

8751 consecutive births at the study hospitals during 1993.

MAIN OUTCOME MEASURE

The completeness of initial specimen collection and processing as determined by matching of birth and screening records.

RESULTS

At least one specimen was received by the screening program for 8675 (99.1%) of the births. Most non-screened patients (71/76, 93%) had been admitted to the neonatal intensive care unit (NICU). Of these, 53/71 (75%) were low birth weight infants who died within 48 h of birth. Even after excluding these non-survivors, NICU patients were 37 times more likely to be unscreened than their healthy counterparts (22 vs. 0.6 per 1000 infants, 95% C.I. 12.8, 92.8 P < 0.01). A common characteristic of non-screened NICU survivors, (12/18) was interhospital transfer for sub-specialty care. Among patients in the healthy-baby nursery, early discharge (i.e. < 24 h of age) accounted for 2/5 (40%) of the cases of non-screening. The non-screening rate among patients discharged early was 25 times higher than for those discharged after 24 h (9.8 vs. 0.4 per 1000 infants, 95% C.I. 4.2, 149 P < 0.01).

CONCLUSIONS

Although the overall rate of screening was high, NICU patients, especially those requiring transfer, are disproportionately at risk for non-screening. Early discharge of healthy newborns was also significantly associated with non-screening. This latter finding is of special importance given the current trend toward shorter hospital stays for newborns. Increased attention to ensuring the collection of specimens from these two high-risk populations is warranted.

Pharmaceutical trials in general practice: the first 100 protocols. An audit by the clinical research ethics committee of the Royal College of General Practitioners

OBJECTIVE

To assess the outcome of 100 general practice based, multicentre research projects submitted to the ethics committee of the Royal College of General Practitioners by pharmaceutical companies or their agents between 1984 and 1989.

DESIGN

Analysis of consecutive submitted protocols for stated objectives, study design, and outcomes; detailed review of committee minutes and correspondence in relation to amendment and approval; assessment of final reports submitted at conclusion of studies.

SUBJECTS

82 finally approved protocols, embracing 34,523 proposed trial subjects and 1195 proposed general practice investigators.

MAIN OUTCOME MEASURES

Success at enrolling subjects and investigators; commencement and completion data; validity of final report's assessment of efficacy, safety, tolerability, and acceptability; and method of use and dissemination of findings.

RESULTS

18 studies were not approved and 45 had to be amended. Randomised controlled trials comprised 46 of the original submissions. Remuneration considerations, inadequate information or consent sheets, pregnancy safety, the need to discontinue existing therapy, and suboptimal scientific content were major reasons for rejecting studies or asking for amendments. Of the 82 approved studies 8 were not started. Shortfalls of investigators (of 39%) and trial subjects (of 37%) and an overall 23% withdrawal rate were responsible for a significant incidence of inconclusive results. Within the six year follow up interval, only 19 of the studies had been formally published.

CONCLUSIONS

This audit identified substantial ethical concerns in the process of approving multicentre general practice pharmaceutical research.

Community study of infant mortality in San Diego County

Infant mortality in San Diego County (USA) in 1988 was 6.9 per 1000 live births. This rate had remained unchanged since 1980. It rose to 8.3 in 1989 and fell to 7.0 in 1990. This study describes the results of an investigation into the causes of infant mortality during 1985. A total of 333 infant deaths were recorded. Nearly half the neonatal deaths were related to perinatal causes and more than half the post-neonatal deaths were attributed to the Sudden Infant Death Syndrome. Two-thirds of all infant deaths occurred in the neonatal period. The contribution of factors in the maternal background and those related to care during labour, as well as postnatally, is described.

Model Programs Addressing Perinatal Drug Exposure and Human Immunodeficiency Virus Infection: Integrating Women's and Children's Needs

Many of the efforts to address perinatal drug exposure and human immunodeficiency virus infection have been influenced by a perspective of conflict between the interests of mother and infant. This article highlights several programs that integrate women's and children's services while dealing with these health issues. It discusses the challenges encountered by these programs, such as funding restrictions, institutional barriers, professional attitudes, regulatory constraints, and local political issues. It presents strategies for overcoming these barriers including the creative coordination of funding streams, innovative relationships with child protective agencies, effective collaboration with other agencies, and advocacy on behalf of clients and programs, and makes recommendations for certain policy changes, which could foster the development of programs that serve women and children together.

Oral spironolactone: an effective treatment for acne vulgaris in women

The effect of oral spironolactone (200 mg daily) on acne vulgaris has been studied in 21 women in a randomized, placebo-controlled, double-blind crossover study using 3 month treatment periods. Compared with placebo, spironolactone produced significant improvement as assessed by subjective benefit (P less than 0. 001), number of inflamed lesions (P less than 0 . 001) and by an independently evaluated photographic method (P less than 0 .02). There was a fall in sex hormone binding globulin but no significant changes in plasma testosterone and derived free testosterone. Initial plasma androgen levels were no higher in responders than in non-responders, nor did oral contraceptive use appear to affect clinical response. Spironolactone is a useful alternative therapy for women with acne vulgaris.

The effect of spironolactone on hirsutism and female androgen metabolism

An objective evaluation of the anti-androgen effects of spironolactone was performed in a consecutive series of 12 hirsute patients receiving a daily dose of 150 mg; nine completed the study. Using a computer assisted image analyser, hair diameter on two weekly shavings decreased significantly over a 12 month period in three of the patients, although growth rate and mean diameter did not change in the group as a whole. Plasma testosterone fell significantly to a mean of 53% of basal levels. The mean free testosterone (derived) fell significantly to 64% of basal by the sixth month (P = less than 0.005) and remained significantly depressed the remainder of the study. There was subjective benefit in hair growth and greasiness and a significant reduction in the semi-objective Ferriman-Gallwey index in nine of 10 subjects assessed for at least 9 months. We conclude that although spironolactone was not consistently successful, it may represent effective therapy for a sub group of patients with hirsutism.

Correlation of stress with outcome of radioiodine therapy for Graves' disease

Between November 1965 and December 1983, 293 patients were treated for Graves' disease using 131I. All patients were asked to identify a stressful event antedating the onset of overt clinical symptoms. Eighty-one patients were able to do this (27.6%). Six patients were lost to follow-up, the others were followed from 1 to 155 mo. Two hundred forty-four patients received a single treatment, 49 required two or more treatments. Stress and nonstress individuals were consistent with respect to age, sex, number of treatments and the dose of radioiodine. Patients with stress initiating the symptoms of Graves' disease became hypothyroid earlier, 50% at 12 mo compared with 36 mo for the nonstress group, p = 0.01. At 10 yr 5% of the stress group remained euthyroid compared with 17% nonstress. We conclude that stress in the 12 mo or less before the onset of clinical symptoms potentiates the development of hypothyroidism induced by a standard dose of radioiodine.

Oral spironolactone improves acne vulgaris and reduces sebum excretion

In a consecutive series of thirty-six male and female patients referred with severe acne, the effect of 3 months' treatment with placebo or spironolactone (50-200 mg daily) on sebum excretion and clinical and endocrine status was evaluated double-blind. Twenty-six patients completed the study. Abnormal free androgen indices were found in 27% of the original nineteen female subjects. Spironolactone reduced sebum excretion in all female subjects, but there was no correlation between sebum response and androgen status. The clinical response was dose-dependent, with maximum subjective and objective benefit when spironolactone doses of 150-200 mg were used.

Evidence that patients with Addison's disease are undertreated with fludrocortisone

Ten patients with Addison's disease, nine with undetectable plasma aldosterone, were found to be sodium and water depleted with high levels of plasma-renin activity despite receiving 0.05-0.1 mg/day of fludrocortisone and optimum doses of glucocorticoid replacement therapy. Fludrocortisone was withdrawn while patients were in hospital on a fixed sodium intake. There was an immediate natriuresis with a further increase in plasma-renin activity. When a daily dose of 0.3 mg of fludrocortisone was given all patients retained sodium and water and gained weight. There was a fall in plasma-renin activity in all patients and an associated fall in blood urea and plasma potassium, and an increase in plasma volume; oedema developed in some patients. At outpatient follow-up, the dose of fludrocortisone was adjusted according to plasma-renin activity. Most patients required 0.2 mg of fludrocortisone to maintain adequate sodium and water balance. These results suggest that patients with Addison's disease on 0.05-0.1 mg of fludrocortisone with undetectable plasma aldosterone levels are currently being undertreated with fludrocortisone. The best way of assessing sodium balance in these patients and their response to fludrocortisone is by measurement of plasma-renin activity in conjunction with 24 h urinary sodium excretion.

Modified fluid gelatin in leukapheresis accumulation and persistence in the body

Current methods for centrifuged granulocyte procurement involve the use of an agent to produce red cell rouleaux and enhance separation of leukocytes. Hydroxyethyl starch (HES), the agent most frequently used, has the disadvantage of causing progressive volume expansion and persisting in the circulation for long periods. We therefore assessed modified fluid gelatin (MFG) as a possible replacement for HES during granulocyte collection. We found that MFG is cleared more rapidly from the circulation with no traces remaining 7 days after multiple exposure, as determined by hydroxyproline measurement. However, after four consecutive daily infusions, we measured 0.60 liters plasma expansion in four individuals tested, somewhat lower than the 0.85 liters previously reported for HES. Modified fluid gelatin causes no impairment of coagulation with normal prothrombin time (PT), partial thromboplastin time (PTT), and platelet function.

Jaw wiring in treatment of obesity

17 patients with severe (median percentage above ideal weight 100%) and resistant obesity underwent jaw wiring. There were no major complications and patients tolerated the procedure and subsequent minor inconveniences. All patients lost weight at a rate (median 25-3 kg in six months) comparable with that of intestinal bypass surgery and one achieved and maintained her ideal weight. Two-thirds of the patients, however, regained some weight after the wires were removed. Jaw wiring is a simple effective procedure which can be carried out in most hospitals, and has a place in an integrated approach to obesity.