Position statement on how can we can implement the Greendeal in our gastrointestinal and gastrointestinal endoscopy department in Belgium

The importance to reach the target to be carbon net zero by 2050, as presented by the European Commission in the European Green Deal, cannot be overestimated. In a current endoscopy world, where single use has found its place and techniques are constantly evolving, it will be a challenge to reach these goals. How can we reconcile this evolution to a carbon neutral status by 2050 without compromising patients care, clinical standards and training needs? The European Society of Gastrointestinal Endoscopy (ESGE) together with the European Society of Gastroenterology and Endoscopy Nurses and Associates (ESGENA) recently published a position statement (1) whereas in the UK there is the work from the green endoscopy group (2) in line with the strategy of the British Society of Gastroenterology (BSG) on sustainability (3). In Flanders, a project called "greendeal in duurzame zorg" had its kick off in March 2023 (4) so it is about time that we in Belgium, as gastroenterologists, start with tangible actions to a more sustainable daily practice. We wrote this position statement in cooperation with the Vlaamse Vereniging voor Gastro-Enterologie (VVGE), the Société royale belge de Gastro-entérologie (SRBGE) and the Belgian Society of Gastrointestinal Endoscopy (BSGIE). We will also work together in the coming years to continue to motivate our members to work on these initiatives and to co-opt new projects within the framework of the greendeal.

BSGIE survey on COVID-19 and gastrointestinal endoscopy in Belgium : results and recommendations

BACKGROUND AND AIMS

With the first wave of the COVID-19 pandemic declining, activities in the gastrointestinal clinic are being recommenced after a period of stringent measures. Since a second COVID-19 wave is not entirely ruled out health care professionals might remain faced with the need to perform endoscopic procedures in patients with a confirmed positive or unknown COVID-19 status. With this report we aim to provide a practical relevant overview of preparation and protective measures for gastroenterologists based on the currently available guidelines and our local experience and results of a national Belgian survey, to guarantee a fast recall of an adequate infection prevention if COVID-19 reoccurs.

METHODS

From the 23rd of March 2020 and the 13th of May 2020 we performed a Pubmed, Embase and Medline search, resulting in 37 papers on COVID-19 and endoscopy. Additionally, we combined these data with data acquired from the national BSGIE survey amongst Belgian gastroenterologists.

RESULTS

Based on 72 completed surveys in both university and non-university hospitals, the results show (1) a dramatic (<20%) or substantial (<50%) decrease of normal daily endoscopy in 74% and 22% of the units respectively, (2) a difference in screening and protective measures between university and non-university hospitals. These findings were subsequently compared with the current guidelines.

CONCLUSION

Based on new data from the BSGIE survey and current guidelines we tried to realistically represent the current COVID-19 trends in protective measures, screening and indications for endoscopy and to provide a practical overview as preparation for a possible second wave.

The social contact hypothesis under the assumption of endemic equilibrium: Elucidating the transmission potential of VZV in Europe

The basic reproduction number R0 and the effective reproduction number R are pivotal parameters in infectious disease epidemiology, quantifying the transmission potential of an infection in a population. We estimate both parameters from 13 pre-vaccination serological data sets on varicella zoster virus (VZV) in 12 European countries and from population-based social contact surveys under the commonly made assumptions of endemic and demographic equilibrium. The fit to the serology is evaluated using the inferred effective reproduction number R as a model eligibility criterion combined with AIC as a model selection criterion. For only 2 out of 12 countries, the common choice of a constant proportionality factor is sufficient to provide a good fit to the seroprevalence data. For the other countries, an age-specific proportionality factor provides a better fit, assuming physical contacts lasting longer than 15 min are a good proxy for potential varicella transmission events. In all countries, primary infection with VZV most often occurs in early childhood, but there is substantial variation in transmission potential with R0 ranging from 2.8 in England and Wales to 7.6 in The Netherlands. Two non-parametric methods, the maximal information coefficient (MIC) and a random forest approach, are used to explain these differences in R0 in terms of relevant country-specific characteristics. Our results suggest an association with three general factors: inequality in wealth, infant vaccination coverage and child care attendance. This illustrates the need to consider fundamental differences between European countries when formulating and parameterizing infectious disease models.

Susceptibility-weighted imaging improves the diagnostic accuracy of 3T brain MRI in the work-up of parkinsonism

BACKGROUND AND PURPOSE

The differentiation between Parkinson disease and atypical parkinsonian syndromes can be challenging in clinical practice, especially in early disease stages. Brain MR imaging can help to increase certainty about the diagnosis. Our goal was to evaluate the added value of SWI in relation to conventional 3T brain MR imaging for the diagnostic work-up of early-stage parkinsonism.

MATERIALS AND METHODS

This was a prospective observational cohort study of 65 patients presenting with parkinsonism but with an uncertain initial clinical diagnosis. At baseline, 3T brain MR imaging with conventional and SWI sequences was performed. After clinical follow-up, probable diagnoses could be made in 56 patients, 38 patients diagnosed with Parkinson disease and 18 patients diagnosed with atypical parkinsonian syndromes, including 12 patients diagnosed with multiple system atrophy-parkinsonian form. In addition, 13 healthy controls were evaluated with SWI. Abnormal findings on conventional brain MR imaging were grouped into disease-specific scores. SWI was analyzed by a region-of-interest method of different brain structures. One-way ANOVA was performed to analyze group differences. Receiver operating characteristic analyses were performed to evaluate the diagnostic accuracy of conventional brain MR imaging separately and combined with SWI.

RESULTS

Disease-specific scores of conventional brain MR imaging had a high specificity for atypical parkinsonian syndromes (80%-90%), but sensitivity was limited (50%-80%). The mean SWI signal intensity of the putamen was significantly lower for multiple system atrophy-parkinsonian form than for Parkinson disease and controls (P < .001). The presence of severe dorsal putaminal hypointensity improved the accuracy of brain MR imaging: The area under the curve was increased from 0.75 to 0.83 for identifying multiple system atrophy-parkinsonian form, and it was increased from 0.76 to 0.82 for identifying atypical parkinsonian syndromes as a group.

CONCLUSIONS

SWI improves the diagnostic accuracy of 3T brain MR imaging in the work-up of parkinsonism by identifying severe putaminal hypointensity as a sign indicative of multiple system atrophy-parkinsonian form.

Surgical management of gastrointestinal stromal tumours: a single centre experience during the past 17 years

BACKGROUND

Gastrointestinal stromal tumour (GIST) is a rare tumour that can arise anywhere within the gastrointestinal tract.

OBJECTIVES

Our objective was to present our experience managing this rare tumour of the gastrointestinal tract. We reviewed the clinico-pathological and morphological features, our experience with surgical treatment, and the outcome GIST in our centre.

PATIENTS AND METHODS

The current retrospective analysis included 64 patients with GIST observed between February 1995 and September 2012.

RESULTS

There were 39 males and 25 females. The mean age was 63.2 (range 36-83). The GISTs were located in the stomach in the majority of patients (60 patients, 94.0%). The tumour was asymptomatic in 14 (21.9%) patients. The tumour size varied from 0.4 to 25 cm with a mean size of 7.9 cm. Five patients showed peritoneal or liver metastasis at diagnosis. All patients had surgery. Five patients had a R2 resection and in one patient the resection-free margin was uncertain. In our cohort we had 5 patients with metastasis at diagnosis who received adjuvant imatinib. Four patients developed metastasis in the follow-up period. Three patients died due to GIST, three other patients died due to other disease.

CONCLUSIONS

Gastric GIST were more common than GIST at other locations. Surgical treatment was the main therapeutic option. Tyosine kinase receptor inhibitors was used as a first line treatment in patients with metastatic GISTs or in patients with recurrence of the disease.

Gastrointestinal stromal tumor of the stomach: progresses in diagnosis and treatment

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal smooth muscle neoplasms that can arise anywhere within the gastrointestinal tract. Approximately 60-70% are located in the stomach. Once considered variants of smooth muscle tumors, they are now understood as originating from the interstitial cells of Cajal or their stem cell precursors. The majority of GISTs (approximately 95%) express the CD117 antigen (KIT), a proto-oncogene product ; 85-95% of these neoplasms have mutations in the c-KIT gene; only 5-7% has mutations in platelet-derived-growth factor a (PDGFRa). GISTs can be asymptomatic and incidentally found during examination for other pathologies or at autopsy. The most common symptoms of gastric GIST are abdominal pain and bleeding. Diagnostic work up consists of endoscopy with ultrasonography and cross-sectional imaging studies (computed tomography and/or magnetic resonance imaging). Surgery remains the first-line treatment for localized gastric GISTs. Both open and laparoscopic operations have been shown to reduce recurrence rates and improve long-term survival. The use of small-molecule selective tyrosine kinase receptor inhibitors has revolutionized the treatment of advanced GISTs.

Estimating the population prevalence and force of infection directly from antibody titres

The use of threshold values in order to diagnose individual subjects as being ‘susceptible’ or ‘infected or recovered/immune’ for a specific infection is virtually always prone to false positive, false negative or inconclusive classifications. Such misclassifications might lead to biased estimates for epidemiological parameters, such as the prevalence and the force of infection. In this article, we propose to estimate these epidemiological parameters directly from antibody titres, using an underlying mixture model. The method is applied to estimate the Salmonella serological prevalence in pigs and the age-dependent force of infection using serological data on the Varicella-Zoster virus (VZV) in humans. The threshold and direct method are compared through a simulation study.

Validation of MALDI-TOF MS for rapid classification and identification of lactic acid bacteria, with a focus on isolates from traditional fermented foods in Northern Vietnam

AIMS

To evaluate the potential use of MALDI-TOF MS for fast and reliable classification and identification of lactic acid bacteria (LAB) from traditional fermented foods.

METHODS AND RESULTS

A total of 119 strains of LAB from fermented meat (nem chua) were analysed with both (GTG)(5)-PCR fingerprinting and MALDI-TOF MS. Cluster analysis of the profiles revealed five species represented by a single isolate both in (GTG)(5)-PCR and in MALDI-TOF MS; five species grouped alike for (GTG)(5)-PCR and for MALDI-TOF MS; however, differences in minimal similarity between the delineated (GTG)(5)-PCR and MALDI-TOF MS clusters could be observed; three species showed more heterogeneity in their MALDI-TOF MS profiles compared to their (GTG)(5)-PCR profiles; two species, each represented by a single MALDI-TOF cluster, were subdivided in the corresponding (GTG)(5)-PCR dendrogram. As proof of the identification potential of MALDI-TOF MS, LAB diversity from one fermented mustard sample was analysed using MALDI-TOF MS. PheS gene sequencing was used for validation.

CONCLUSIONS

MALDI-TOF MS is a powerful, fast, reliable and cost-effective technique for the identification of LAB associated with the production of fermented foods.

SIGNIFICANCE AND IMPACT OF THE STUDY

Food LAB can be identified using MALDI-TOF MS, and its application could possibly be extended to other food matrices and/or other food-derived micro-organisms.

Durable remission of inoperable liver metastasis from rectal cancer after hepatic arterial infusion of oxaliplatin and 5-fluorouracil in combination with intravenous cetuximab

At diagnosis of a cT3N0M1 adenocarcinoma of the rectum with synchronous inoperable liver metastases, a 59-year-old man was treated with preoperative radiotherapy (5×5 Gy), followed by laparoscopy-assisted anterior resection of the rectum with total mesorectal excision. At the first postoperative evaluation, a new lung metastasis was detected. First-line chemotherapy with folfiri (5-fluorouracil, irinotecan, leucovorin) resulted in transient stabilization of the metastatic liver disease. At progression, oxaliplatin and 5-fluorouracil-folinic acid were administered by intrahepatic arterial infusion, in combination with intravenous cetuximab. A partial radiologic response was obtained, with complete metabolic response on fluorodeoxyglucose positron-emission tomography, and normalization of carcinoembryonic antigen values. The solitary lung metastasis was sequentially treated with radiotherapy and resection. Five years after the initial diagnosis, this patient remains free from progression, with residual cystic remnants of the liver metastases visible on conventional computed tomography imaging, but not enhancing with fluorodeoxyglucose positron-emission tomography.

Daily cannabis use and the digestive tract: an underrecognized relationship

A 33-year-old man presented with recurrent episodes of hyperemesis with symptom-free intervals since eight years. The diagnosis of cyclic vomiting syndrome due to longstanding and daily cannabis use was retained, after exclusion of any organic cause of vomiting. Although the patient was informed that the clinical response after cessation of smoking is proven to be spectacular, he continued the use of cannabis and kept on presenting with cyclic symptoms of hyperemesis.

Kinetics of maternal antibodies against rubella and varicella in infants

Kinetics of maternal rubella and varicella antibodies in 213 mother-infant pairs are described in a longitudinal study in Belgium. Blood samples are taken at 7 time points (week 36 of pregnancy, birth (cord), 1, 3, 6, 9, and 12 months), and analyzed for anti-rubella IgG and anti-varicella IgG by enzyme linked immunosorbent assay (ELISA). A generalized exponential model is used to analyse maternal antibody decay in infants. Model based, the mean duration of passive immunity is 2.1 months for rubella and 2.4 months for varicella. Infants are susceptible at young age for rubella, a disease with high vaccination coverage, as well as for varicella, an endemic disease in Western Europe.

Modelling distortions in seroprevalence data using change-point fractional polynomials

This paper shows how to model seroprevalence data using change-point fractional polynomials (FPs). The inclusion of a change point in the FP framework allows to detect distortions arising from common (often untestable) assumptions made in the estimation of the age-specific prevalence and force of infection from cross-sectional data. The method is motivated using seroprevalence data on the parvovirus B19 and the varicella zoster virus in Belgium.

Early waning of maternal measles antibodies in era of measles elimination: longitudinal study

OBJECTIVE

To investigate the duration of the presence of maternal antibodies to measles in infants.

DESIGN

Prospective study (May 2006 to November 2008).

SETTING

Five hospitals in the Province of Antwerp, Belgium.

PARTICIPANTS

Of 221 pregnant women recruited, 207 healthy woman-infant pairs were included-divided into a vaccinated group (n=87) and naturally immune group (n=120), according to vaccination documents and history.

MAIN OUTCOME MEASURE

Measles IgG antibodies measured by enzyme linked immunosorbent assay (ELISA) at seven time points (week 36 of pregnancy, birth (cord), and 1, 6, 9, and 12 months); decay of maternal antibody in infants modelled with linear mixed models.

RESULTS

Vaccinated women had significantly fewer IgG antibodies (geometric mean titre 779 (95% confidence interval 581 to 1045) mIU/ml) than did naturally immune women (2687 (2126 to 3373) mIU/ml) (P<0.001). Maternal values were highly correlated with neonatal values (r=0.93 at birth). Infants of vaccinated women had significantly lower antibody concentrations than did infants of naturally immune women (P<0.001 at all ages over the follow-up period). Presence of maternal antibodies endured for a median of 2.61 months-3.78 months for infants of naturally infected women and 0.97 months for infants of vaccinated women. At 6 months of age, more than 99% of infants of vaccinated women and 95% of infants of naturally immune women had lost maternal antibodies according to the model.

CONCLUSIONS

This study describes a very early susceptibility to measles in infants of both vaccinated women and women with naturally acquired immunity. This finding is important in view of recent outbreaks and is an argument for timeliness of the first dose of a measles vaccine and vaccination of travelling or migrating children under the age of 1 year.

Insights into the venom composition of the ectoparasitoid wasp Nasonia vitripennis from bioinformatic and proteomic studies

With the Nasonia vitripennis genome sequences available, we attempted to determine the proteins present in venom by two different approaches. First, we searched for the transcripts of venom proteins by a bioinformatic approach using amino acid sequences of known hymenopteran venom proteins. Second, we performed proteomic analyses of crude N. vitripennis venom removed from the venom reservoir, implementing both an off-line two-dimensional liquid chromatography matrix-assisted laser desorption/ ionization time-of-flight (2D-LC-MALDI-TOF) mass spectrometry (MS) and a two-dimensional liquid chromatography electrospray ionization Founer transform ion cyclotron resonance (2D-LC-ESI-FT-ICR) MS setup. This combination of bioinformatic and proteomic studies resulted in an extraordinary richness of identified venom constituents. Moreover, half of the 79 identified proteins were not yet associated with insect venoms: 16 proteins showed similarity only to known proteins from other tissues or secretions, and an additional 23 did not show similarity to any known protein. Serine proteases and their inhibitors were the most represented. Fifteen nonsecretory proteins were also identified by proteomic means and probably represent so-called 'venom trace elements'. The present study contributes greatly to the understanding of the biological diversity of the venom of parasitoid wasps at the molecular level.

Salmonella serosurveillance: different statistical methods to categorise pig herds based on serological data

This study proposes three different statistical methods that can be applied in order to categorise pig herds into two groups (high seroreactors vs. low seroreactors) based on serological test results for Salmonella-specific antibodies in pigs. All proposed statistical methods were restricted to allocate about 10% of the herds into the group defined by each of the statistical approaches as high seroreactors. Previously, semi-parametric quantile regression has been used for this purpose, and here we compare it with two other alternatives: a naive method (based on the mean values) and another based on activity region finder methodology in combination with random forest regression models. The serological response values (the sample-to-positive ratio (S/P ratio)) of 13 649 pigs from 314 Belgian pig herds were used for this comparison. Nearly 14% of these herds were assigned to the high-seroreactor-herd group by at least one of these three methods. The corrected level of agreement was calculated together with the pair-wise agreement among all three methods in order to classify herds as high- or low-level seroreactors, resulting in an agreement level greater than 92%. The results obtained from a fourth method, which is adopted by the Belgian Federal Agency for the Safety of the Food Chain (FASFC), were also compared to the previous three methods. The methods were compared in terms of their agreement as well as their advantages and disadvantages. Recommendations for each applied method are presented in relation to the objectives and the requisite policy for classifying pig herds based on serological data.

Estimating the impact of vaccination using age-time-dependent incidence rates of hepatitis B

The objective of this study was to model the age-time-dependent incidence of hepatitis B while estimating the impact of vaccination. While stochastic models/time-series have been used before to model hepatitis B cases in the absence of knowledge on the number of susceptibles, this paper proposed using a method that fits into the generalized additive model framework. Generalized additive models with penalized regression splines are used to exploit the underlying continuity of both age and time in a flexible non-parametric way. Based on a unique case notification dataset, we have shown that the implemented immunization programme in Bulgaria resulted in a significant decrease in incidence for infants in their first year of life with 82% (79-84%). Moreover, we have shown that conditional on an assumed baseline susceptibility percentage, a smooth force-of-infection profile can be obtained from which two local maxima were observed at ages 9 and 24 years.

On the Use of Historical Control Data in Pre-Clinical Safety Studies

A number of methods to formally incorporate historical control information in pre-clinical safety evaluation studies have been proposed in literature. However, it remains unclear when one should use historical data. Focusing on the logistic-normal model, we investigate situations where historical studies may prove to be useful. Aspects of estimation (precision and bias) and testing (power) for treatment effect are investigated under different conditions such as the number of historical control studies, the degree of homogeneity amongst them, the level of treatment effect and different control rates. The possibility to use a selected subset of historical control studies is also explored.

Model selection for incomplete and design-based samples

The Akaike information criterion, AIC, is one of the most frequently used methods to select one or a few good, optimal regression models from a set of candidate models. In case the sample is incomplete, the naive use of this criterion on the so-called complete cases can lead to the selection of poor or inappropriate models. A similar problem occurs when a sample based on a design with unequal selection probabilities, is treated as a simple random sample. In this paper, we consider a modification of AIC, based on reweighing the sample in analogy with the weighted Horvitz-Thompson estimates. It is shown that this weighted AIC-criterion provides better model choices for both incomplete and design-based samples. The use of the weighted AIC-criterion is illustrated on data from the Belgian Health Interview Survey, which motivated this research. Simulations show its performance in a variety of settings.

Techniques for the placement of hepatic artery catheters for regional chemotherapy in unresectable liver metastases

AIMS

For patients with unresectable liver metastases from colorectal cancer (CRC), hepatic artery infusion chemotherapy (HAIC) can produce higher response rates as compared to systemic chemotherapy. However, the added morbidity and early dysfunction after catheter placement have negatively influenced the outcomes of randomized studies.

METHODS

Between July 1998 and March 2006, 29 patients with unresectable liver metastases from CRC were included in three different HAIC protocols. A catheter was laparoscopically placed in the gastroduodenal artery, retrograde to the common hepatic artery and was attached to a subcutaneous access port. Perioperative parameters and catheter-associated adverse events during chemotherapy were studied.

RESULTS

Mean operating time was 106+/-29 min and median duration of hospitalization was 2 days (range: 1-13). No major perioperative complications occurred but there was 1 death (3.6%) 1 week after surgery due to hemorrhagic shock after necrosis and rupture of the hepatic artery. During a median follow-up of 10 months (range: 0-35) we observed 5 (17%) catheter-associated adverse events, but in only 2 patients (7%) this resulted in a loss of catheter function before the end of chemotherapy. Overall median duration of HAIC was 8 months (range: 1-28).

CONCLUSION

Laparoscopic placement of a hepatic artery catheter is associated with a low operative morbidity. The observed functionality of the hepatic artery ports in our series is encouraging for the use in future studies of HAIC.

Modelling age-dependent force of infection from prevalence data using fractional polynomials

The force of infection is one of the primary epidemiological parameters of infectious diseases. For many infectious diseases it is assumed that the force of infection is age-dependent. Although the force of infection can be estimated directly from a follow up study, it is much more common to have cross-sectional seroprevalence data from which the prevalence and the force of infection can be estimated. In this paper, we propose to model the force of infection within the framework of fractional polynomials. We discuss several parametric examples from the literature and show that all of these examples can be expressed as special cases of fractional polynomial models. We illustrate the method on five seroprevalence samples, two of Hepatitis A, and one of Rubella, Mumps and Varicella.

Evidence for a substantial role of sharing of injecting paraphernalia other than syringes/needles to the spread of hepatitis C among injecting drug users

In industrialized countries, transmission of hepatitis C occurs primarily through injecting drug use. Transmission of hepatitis C in injecting drug users is mainly associated with the sharing of contaminated syringes/needles, although evidence for risk of hepatitis C infection through sharing of other injecting paraphernalia is increasing. In this paper, the independent effects of sharing paraphernalia other than syringes/needles have been estimated. The prevalence and force of infection were modelled using three serological data sets from drug users in three centres in Belgium as a function of the sharing behaviour. It was found that sharing of materials other than syringes/needles indeed seemed to contribute substantially to the spread of hepatitis C among injecting drug users.

Social mixing patterns for transmission models of close contact infections: exploring self-evaluation and diary-based data collection through a web-based interface

Although mixing patterns are crucial in dynamic transmission models of close contact infections, they are largely estimated by intuition. Using a convenience sample (n=73), we tested self-evaluation and prospective diary surveys with a web-based interface, in order to obtain social contact data. The number of recorded contacts was significantly (P<0.01) greater on workdays (18.1) vs. weekend days (12.3) for conversations, and vice versa for touching (5.4 and 7.2 respectively). Mixing was highly assortative with age for both (adults contacting other adults vs. 0- to 5-year-olds, odds ratio 8.9-10.8). Respondents shared a closed environment significantly more often with >20 other adults than with >20 children. The difference in number of contacts per day was non-significant between self-evaluation and diary (P=0.619 for conversations, P=0.125 for touching). We conclude that self-evaluation could yield similar results to diary surveys for general or very recent mixing information. More detailed data could be collected by diary, at little effort to respondents.

Risk factors for bovine herpesvirus-1 seropositivity

This paper reports the investigation of risk factors for bovine herpesvirus-1-seropositivity, based on a cluster-sample survey of the Belgian cattle population. This serosurvey was carried out in 1998 in 309 randomly selected unvaccinated herds of all types (dairy, mixed and beef) were all bovids (N = 11,284) were sampled. Older and male cattle had higher seroprevalence. Origin (homebred or purchased) and herd size interacted; for smaller herds (< or = 50 cattle on the premises), purchase status and larger herd size were risk factors, whereas these effects were not observed for larger herds.

A tree based lack-of-fit test for multiple logistic regression

Several omnibus tests have been developed to assess the fit of a regression model. But many of these lack-of-fit tests focus on the simple regression setting. Here, we focus on multiple logistic regression. Pearson's well-known chi-square test statistic and the deviance statistic are no longer valid in the case that the model contains one or more continuous covariates. To overcome this difficulty, Hosmer and Lemeshow proposed a Pearson type statistic based on groups defined by the so-called deciles of risk. We propose a test statistic that is similar in approach to the Hosmer and Lemeshow statistic in that the observations are classified into distinct groups. In the procedure proposed here however, the grouping is not according to probabilities fitted under the null model. We use a recursive partitioning algorithm to divide the sample space into different groups. This generally allows for a more powerful assessment of the model fit. Simulations are carried out to compare the results of the proposed test to that of Hosmer and Lemeshow. Three data examples illustrate the performance of the tree based lack-of-fit test, in comparison to several other tests.

Hepatitis B in St Petersburg, Russia (1994-1999): incidence, prevalence and force of infection

Hepatitis B (HB) is thought to be an expanding health problem in Russia. The incidence of infection was estimated from mandatorily reported HB cases in St Petersburg. The two-sided t-test for independent samples and the LOESS (locally-weighted regression) smoother were used to compare the age at infection for symptomatic, asymptomatic and chronic infections, by gender. The force of infection was estimated from seroprevalence data (907 sera taken in 1999) using a newly developed nonparametric method based on local polynomials, as well as an earlier method based on isotonic regression and kernel smoothers. With the local polynomial method, pointwise confidence intervals (95%) were constructed by bootstrapping. On average, men contracted HB infection at a significantly younger age than women (in 1999, 21.8 vs 22.7 years, respectively). The overall male to female ratio was 1.92. In 1999 the overall incidence almost doubled compared with the preceding years and tripled among the age groups with highest incidence (15-29-year olds: 85% of cases in 1999). The incidence increase was associated with a lower average age at infection (24.1 years in 1994 vs 22.1 years in 1999). The age and gender-specific force of infection estimates generally confirmed the incidence estimates and emphasized the usefulness of local polynomials to do this. Hence HB transmission in St Petersburg occurs mainly in young adults. The dramatic increase of infections in 1999 was probably due to injecting drug use. Without intervention, HB virus is expected to continue to spread rapidly with a greater proportion of female infections caused by sexual transmission. These trends may also provide an indication for HIV transmission.

Chest pain in general practice or in the hospital emergency department: is it the same?

OBJECTIVE

The aim of the present study was to provide a description of the impact of setting on the diagnostic case mix that is identified in consecutive patients presenting with chest pain.

METHODS

A cross-sectional study was carried out of patients presenting with chest pain according to setting: general practice, self-referred, referred or arriving by ambulance at the hospital emergency department (ED). GPs from 25 general practices situated in the Flemish part of Belgium were recruited, and the hospital involved was a major teaching hospital in the same area. A total of 320 patients in general practice and 580 patients in the hospital ED were studied. The difference in prevalence rates for the major diagnostic categories was the main outcome measure.

RESULTS

Gastrointestinal disorders, musculoskeletal problems and psychopathology are identified more frequently in general practice; and serious lung diseases and cardiovascular diseases in the hospital ED. Within the hospital, there is a strong trend towards increasing frequency of serious cardiovascular diseases including unstable angina (P = 0.01) from self-referred to referred patients and those rushed in by ambulance. The opposite trend was identified for respiratory (P = 0.02) and musculoskeletal (P = 0.07) diseases. The diagnostic case mix in self-referred patients tends to be more similar to the other groups of hospital patients than to patients in general practice.

CONCLUSIONS

There is a large difference between the diagnostic case mix presented in general practice compared with the ED and among referral-related subgroups within the hospital emergency department.

Naegleria australiensis: experimental meningoencephalitis in mice

Naegleria australiensis was recently described as a new species of free-living amoeba pathogenic for mice. Infections of human brain by the free-living amoebae N. fowleri and Acanthamoeba spp. are well known. We here describe the clinicopathological features of experimental infection of the central nervous system of mice by N. australiensis. Weanling mice were inoculated intranasally and intracerebrally. The involvement of the nasal mucosa, olfactory neuroepithelium and lobes, cerebrum and cerebellum was detected in haematoxylin-eosin stained paraffin-embedded sections. Amoebic trophozoites sparsely located throughout the central nervous system were shown better by the immunoperoxidase method. Cysts were not detected. The histopathological changes differ from those produced by N. fowleri, especially in the degree of severity. They may be confused with those caused by Acanthamoeba spp. which usually produced subacute and chronic encephalitis with a prolonged clinical course.