Sampling designs for rare time-dependent exposures: a comparison of the nested exposure case-control design and exposure density sampling.

In extensive cohort studies, the ascertainment of covariate information on all individuals can be challenging. In hospital epidemiology, an additional issue is often the time-dependency of the exposure of interest. We revisit and compare two sampling designs constructed for rare time-dependent exposures and possibly common outcomes - the nested exposure case-control design and exposure density sampling. Both designs enable efficient hazard ratio estimation by sampling all exposed individuals but only a small fraction of the unexposed ones. Moreover, they account for time-dependent exposure to avoid immortal time bias. We evaluate and compare their performance using data of patients hospitalised in the neuro-intensive care unit at the Burdenko Neurosurgery Institute in Moscow, Russia. Three different types of hospital-acquired infections with different prevalence are considered. Additionally, inflation factors, a primary performance measure, are discussed. We enhance both designs to allow for a competitive analysis of combined and competing endpoints compared to the full cohort approach while substantially reducing the amount of necessary information. Nonetheless, exposure density sampling outperforms the nested exposure case-control design concerning efficiency and accuracy in most considered settings.

Impact of investigator initiated trials and industry sponsored trials on medical practice (IMPACT): rationale and study design.

BACKGROUND: The German Research Foundation (DFG) and the Federal Ministry of Education and Research (BMBF) initiated large research programs to foster high quality clinical research in the academic area. These investigator initiated trials (IITs) cover important areas of medical research and often go beyond the scope of industry sponsored trials (ISTs). The purpose of this project was to understand to what extent results of randomized controlled IITs and ISTs have an impact on medical practice, measured by their availability for decisions in healthcare and their implementation in clinical practice. We aimed to determine study characteristics influencing a trial's impact such as type of sponsor and place of conduct. In this article, we describe the rationale and design of this project and present the characteristics of the trials included in our study cohort. METHODS: The research impact of the following sub-cohorts was compared: German IITs (funded by DFG and BMBF or by other German non-commercial organizations), international IITs (without German contribution), German ISTs, and international ISTs. Trials included were drawn from the DFG-/BMBF-Websites, the German Clinical Trials Register, and from ClinicalTrials.gov . Research impact was measured as follows: 1) proportion of published trials, 2) time to publication, 3) proportion of publications appropriately indexed in biomedical databases, 4) proportion of openly accessible publications, 5) broadness of publication's target group, 6) citation of publications by systematic reviews or meta-analyses, and 7) appearance of publications or citing systematic reviews or meta-analyses in clinical practice guidelines. We also aimed to identify study characteristics associated with the impact of trials. RESULTS: We included 691 trials: 120 German IITs, 200 International IITs, 171 German ISTs and 200 International ISTs. The median number of participants was 150, 30% were international trials and 70% national trials, 48% drug-trials and 52% non-drug trials. Overall, 72% of the trials had one pre-defined primary endpoint, 28% two or more (max. 36). CONCLUSIONS: The results of this project deepen our understanding of the impact of biomedical research on clinical practice and healthcare policy, add important insights for the efficient allocation of scarce research resources and may facilitate providing accountability to the different stakeholders involved.

Discovery of a novel thermostable Zn2+ -dependent alcohol dehydrogenase from Chloroflexus aurantiacus through conserved domains mining.

AIMS: The purpose of the study was to demonstrate feasibility of the Conserved Domains Database (CDD) for identification of novel biocatalysts with desirable properties from a class of well-characterized biocatalysts. METHODS AND RESULTS: The thermostable ADH from Sulfolobus solfataricus with a broad substrate range was applied as a template for the search for novel thermostable ADHs via CDD. From the resulting hits, a putative ADH gene from the thermophilic organism Chloroflexus aurantiacus was cloned and expressed in Escherichia coli. The resulting enzyme was purified and characterized. With a temperature activity optimum of 70°C and a broad substrate spectrum especially for diketones, a versatile new biocatalyst was obtained. CONCLUSIONS: Database-based mining in CDD is a suitable approach to obtain novel biocatalysts with desirable properties. Thereby, the available diversity of similar but not equal enzymes within this class can be increased. SIGNIFICANCE AND IMPACT OF THE STUDY: For industrial applications, there is a demand for larger diversity of similar well-characterized enzymes in order to test them for a given process (biodiversity screening). For fundamental science, the comparison of enzymes with similar function but different sequence can provide insight into structure function relationships or the evolution of enzymes. This study gives a good example on how this demand can be efficiently met.

Relevance of osteoclast-specific enzyme activities in cell-based in vitro resorption assays.

Cell-based in vitro resorption assays are an important tool to simulate the in vivo biodegradation of resorbable bone graft materials and to predict their clinical performance. The present study analyses the activity of osteoclast-specific enzymes as potential surrogate measures for classical pit assay, which is not applicable on irregular structured materials. Osteoclasts derived from human peripheral blood mononuclear cells were cultivated on different surfaces: calcium phosphate bone cements (CPC), dentin discs, osteoblast-derived extracellular matrix (ECM) and tissue culture polystyrene as control. Pit formation on the resorbable materials was investigated and correlated with the activity of tartrate resistant acid phosphatase (TRAP), carbonic anhydrase II (CAII) and cathepsin K (CTSK). Furthermore, the relation between intra- and extracellular enzyme activities was examined for TRAP and CTSK during resorption of the different materials. Resorbed area of CPC correlated with intracellular TRAP activity and intracellular CAII activity. Highest resorption was detected at around pH 7.2. Resorbed area on dentin correlated with the extracellular CTSK activity and extracellular TRAP activity and was maximal at around pH 6.8. Osteoclasts cultivated on cell-derived mineralised ECM showed a good correlation between both extracellular TRAP and CTSK activity and the release of calcium ions. Based on these data a different regulation of TRAP and CTSK secretion is hypothesised for the resorption of inorganic calcium phosphate compared to the resorption of collagenous mineralised matrix.

Student outbreak response teams: lessons learned from a decade of collaboration.

OBJECTIVES: Student response teams within colleges of public health effectively address important concerns for two stakeholders. For universities, students learn the fundamentals of field epidemiology and provide popular training and networking opportunities. For health departments, students serve as surge capacity as trained workforce available during outbreak investigations and potentially for routine tasks. STUDY DESIGN: This paper describes the interaction between a student response team and several health departments utilizing specific examples to demonstrate the various roles and activities students can fulfill. Lessons learned from both University team leaders and the various health departments are also included. METHODS: The program evolved over time, beginning with a needs assessment of local health departments and a determination of student training needs, collection, and confidential transmission of data, and interviewing techniques. Over the last decade students have worked on outbreak investigations, case-control studies, program evaluations, and in-field responses. RESULTS: Since 2005, over 200 public health graduate students have contributed more than 1800 h investigating 62 separate disease outbreaks in Arizona. In addition, over the past four years students also worked an additional 2500 h to assist county health departments in routine enteric investigations, specifically for Campylobacter and Salmonella. Best practices and lessons learned found that communication, preplanning and a willingness to collaborate increased the learning opportunities for students and ability for health departments to increase their capacity both during an emergency and for routine work. CONCLUSIONS: Establishment of a student response team (1) trains students in field experiences; (2) creates trained surge capacity for health departments; (3) increases collaboration between schools of public health and state/local health departments; (4) establishes a way to share funding with a local health department; and (5) increases the number of students being placed in health departments for projects, internships, and jobs following graduation.

[Development of Endothelial Cell Density after Penetrating Keratoplasty in Patients with Fuchs Dystrophy or Keratoconus - Comparison of Excimer Laser and Mechanical Trephination]. / Entwicklung der Endothelzelldichte nach perforierender Keratoplastik bei Patienten mit Fuchs-Dystrophie oder Keratokonus ­ Vergleich von Excimer-Laser- und mechanischer Trepanation.

Purpose The aim of this retrospective study was to compare the development of endothelial cell density (ECD) after penetrating keratoplasty (PKP) in patients with Fuchs dystrophy (FD), keratoconus (KC) or "other diagnoses" (OD), depending on the type of trephination. Patients and Methods In 104 eyes with Fuchs dystrophy, keratoconus or "other diagnoses", the ECD after PKP using either excimer laser (EXC) or mechanical trephination (MECH) was registered after 1.5, 6, 12, 18 and 24 months. With linear and exponential regression models, the endothelial cell loss (ECL) was determined as absolute and percentage cell loss per year. Results For the entire group of patients, ECD was significantly higher after EXC-PKP during the full range of follow-up (except 6 months). With a linear regression model, there was no significant difference in the absolute ECL per year (p = 0.084), but with an exponential regression model, there was a significant difference in the percentage ECL per year (p = 0.021) in favour of EXC trephination. For keratoconus (n = 33), except for the 24-month-follow-up (p = 0.035), ECD was not significantly different on the basis of EXC vs. MECH. With a linear regression model, there was a significant difference in the absolute ECL per year (p = 0.015) in favour of EXC-trephination, but with an exponential regression model there was no significant difference in the percentage ECL per year (p = 0.088) between the two types of threphination. In patients with FUCHS (n = 35) - except for the 6-week-follow-up (p = 0.024) - ECD was not significantly different for EXC vs. MECH. With linear/exponential regression model, the ECL per year was not significantly different in favour of any type of trephination (p = 0.287/p = 0.121). In patients with OD (n = 36), ECD was not significantly different for EXC vs. MECH. With a linear/exponential regression model, the ECL per year was not significantly different in favour of any type of trephination (p = 0.494/p = 0.787). Conclusion During the first 24 months after PKP, a significantly higher ECD and a significantly lower percentage of ECL per year was observed after EXC trephination for the entire group of patients. For the different diagnostic groups KC, FD and OD, no significant difference in ECD or ECL loss was noticed over a range of follow-up intervals. This may most likely be attributed to the small number of patients in the three subgroups.

Distribution of internal carotid artery plaque locations among patients with central retinal artery occlusion in the Eagle study population.

PURPOSE: Arterial emboli in the internal carotid artery (ICA) mainly cause cerebral ischemia; only 10 % of emboli reach the retinal arteries. Computational blood flow studies suggest that plaques situated in the ICA siphon may be a source of embolism to the ophthalmic artery (OA). To validate these calculated probabilities in patients with central retinal artery occlusion (CRAO), we reanalyzed digital subtraction angiography (DSA) images from the Multicenter Study of the European Assessment Group for Lysis in the Eye (EAGLE) study, a multicenter randomized study in patients with nonarteritic CRAO. METHODS: A reevaluation of 34 DSA studies was done from the interventional arm of the EAGLE study with regards to distribution of arterial plaques at specific ICA siphon locations and ICA stenosis. A comparison was made of plaque distribution to calculated probabilities for emboli reaching the OA from a computational fluid dynamics (CFD) model of a patient-specific ICA siphon. RESULTS: Most of the ICA plaques near the OA's origin were located in the cavernous ICA portion (31.3%). Of these, 12.5 % had plaques in the curvature opposite the OA origin, a location carrying the highest risk for embolization into the OA (according to the CFD model 12.6-13.2 % probability of embolisation into the OA). Also, 15.6 % had plaques in the paraclinoid ICA portion distal to the OA origin. CONCLUSIONS: There were 40.6% of the patients that had plaques in the cavernous and clinoid ICA portions presenting possible sources for embolic material generating RAO.

Risk of cancer incidence before the age of 15 years after exposure to ionising radiation from computed tomography: results from a German cohort study.

The aim of this cohort study was to assess the risk of developing cancer, specifically leukaemia, tumours of the central nervous system and lymphoma, before the age of 15 years in children previously exposed to computed tomography (CT) in Germany. Data for children with at least one CT between 1980 and 2010 were abstracted from 20 hospitals. Cancer cases occurring between 1980 and 2010 were identified by stochastic linkage with the German Childhood Cancer Registry (GCCR). For all cases and a sample of non-cases, radiology reports were reviewed to assess the underlying medical conditions at time of the CT. Cases were only included if diagnosis occurred at least 2 years after the first CT and no signs of cancer were recorded in the radiology reports. Standardised incidence ratios (SIR) using incidence rates from the general population were estimated. The cohort included information on 71,073 CT examinations in 44,584 children contributing 161,407 person-years at risk with 46 cases initially identified through linkage with the GCCR. Seven cases had to be excluded due to signs possibly suggestive of cancer at the time of first CT. Overall, more cancer cases were observed (O) than expected (E), but this was mainly driven by unexpected and possibly biased results for lymphomas. For leukaemia, the SIR (SIR = O/E) was 1.72 (95 % CI 0.89-3.01, O = 12), and for CNS tumours, the SIR was 1.35 (95 % CI 0.54-2.78, O = 7). Despite careful examination of the medical information, confounding by indication or reverse causation cannot be ruled out completely and may explain parts of the excess. Furthermore, the CT exposure may have been underestimated as only data from the participating clinics were available. This should be taken into account when interpreting risk estimates.

HLA-A*31:01 and different types of carbamazepine-induced severe cutaneous adverse reactions: an international study and meta-analysis.

HLA-A*31:01 was reported to be associated with carbamazepine (CBZ)-induced severe cutaneous adverse reactions (SCAR), including drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). We conducted an international study using consensus diagnosis criteria to enroll a total of 93 patients with CBZ-SCAR from Europe or Asia. We found that HLA-A*31:01 showed a significant association with CBZ-DRESS in Europeans (P<0.001; odds ratio (OR) (95% confidence interval (CI))=57.6 (11.0-340)), and the strong association was also found in Chinese (P<0.001; OR (95% CI)=23.0 (4.2-125)). However, HLA-A*31:01 had no association with CBZ-SJS/TEN in neither Chinese nor Europeans. By comparison, HLA-B*15:02 showed a strong association with CBZ-SJS/TEN in Chinese (P<0.001, OR (95% CI)=58.1 (17.6-192)). A meta-analysis of this and other published studies confirmed that in all populations, HLA-A*31:01 had an extremely strong association with CBZ-DRESS (P<0.001, a pooled OR (95% CI)=13.2 (8.4-20.8)), but a much weaker association with CBZ-SJS/TEN (P=0.01, OR (95% CI)=3.94 (1.4-11.5)). Our data revealed that HLA-A*31:01 is a specific predictor for CBZ-DRESS but not for CBZ-SJS/TEN. More studies are needed to investigate the genetic determinant of CBZ-SJS/TEN in Europeans. Considering the potential clinical utility, the cost-effectiveness of the combined HLA-A*31:01 and HLA-B*15:02 genetic test to prevent CBZ-SCAR in Chinese needs further investigation.

Biocatalytically active silCoat-composites entrapping viable Escherichia coli.

Application of whole cells in industrial processes requires high catalytic activity, manageability, and viability under technical conditions, which can in principle be accomplished by appropriate immobilization. Here, we report the identification of carrier material allowing exceptionally efficient adsorptive binding of Escherichia coli whole cells hosting catalytically active carbonyl reductase from Candida parapsilosis (CPCR2). With the immobilizates, composite formation with both hydrophobic and hydrophilized silicone was achieved, yielding advanced silCoat-material and HYsilCoat-material, respectively. HYsilCoat-whole cells were viable preparations with a cell loading up to 400 mg(E. coli) · g(-1)(carrier) and considerably lower leaching than native immobilizates. SilCoat-whole cells performed particularly well in neat substrate exhibiting distinctly increased catalytic activity.

Cholinergic nerve fibers in bone defects of a rat osteoporosis model and their regulation by implantation of bone substitution materials.

OBJECTIVES: Bone is innervated by autonomic nervous system that consists of sympathetic and parasympathetic nerves that were recently identified in bone. Thus we asked whether parasympathetic nerves occur in bone defects and at the interface of substitution materials that were implanted for stabilization and improvement of healing in an osteoporosis animal model. METHODS: Osteoporosis was induced in rats by ovariectomy and deficiency diet. A wedge-shaped osteotomy was performed in the metaphyseal area of femur. Eight different implants were inserted that were based on calcium phosphate cement, iron, silica-mineralized collagen, and modifications with strontium. Nerves were identified by immunohistochemistry with antibodies against vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH) and protein gene product 9.5 (PGP 9.5) as neuronal marker. RESULTS: Cholinergic nerves identified with VAChT immunostaining were detected in defects filled with granulation tissue and in surrounding mast cells. No immunolabeling of cholinergic nerves was found after implantation. The general presence of nerves was reduced after implantation as shown by PGP 9.5. Sympathetic nerves identified by TH immunolabeling were increased in strontium functionalized materials. CONCLUSION: Since cholinergic innervation was diminished after implantation a further increase in the compatibility of substitution materials to nerves could improve defect healing especially in osteoporotic bone.

Echocardiographic measurements of cardiac dimensions correlate better with body length than with body weight or body surface area.

Looking after children means caring for very small infants up to adult-sized adolescents, with weights ranging from 500 g to more than 100 kg and heights ranging from 25 to more than 200 cm. The available echocardiographic reference data were drawn from a small sample, which did not include preterm infants. Most authors have used body weight or body surface area to predict left ventricular dimensions. The current authors had the impression that body length would be a better surrogate parameter than body weight or body surface area. They analyzed their echocardiographic database retrospectively. The analysis included all available echocardiographic data from 6 June 2001 to 15 December 2011 from their echocardiographic database. The authors included 12,086 of 26,325 subjects documented as patients with normal hearts in their analysis by the examining the pediatric cardiologist. For their analysis, they selected body weight, length, age, and aortic and pulmonary valve diameter in two-dimensional echocardiography and left ventricular dimension in M-mode. They found good correlation between echocardiographic dimensions and body surface area, body weight, and body length. The analysis showed a complex relationship between echocardiographic measurements and body weight and body surface area, whereas body length showed a linear relationship. This makes prediction of echo parameters more reliable. According to this retrospective analysis, body length is a better parameter for evaluating echocardiographic measurements than body weight or body surface area and should therefore be used in daily practice.

Wall shear stress distribution at the carotid bifurcation: influence of eversion carotid endarterectomy.

OBJECTIVES: To test the feasibility of four-dimensional (4D) flow MRI to quantify the systolic wall shear stress (WSSsystole) and oscillatory shear index (OSI) in high-grade internal carotid artery (ICA) stenosis before and after endarterectomy (CEA). METHODS: Twenty patients with ≥60 % ICA stenosis were prospectively and consequently included. Four-dimensional flow MRI was used to measure individual time-resolved 3D blood flow velocities. Segmental WSSsystole and OSI were derived at eight wall segments in analysis planes positioned along the ICA, common (CCA) and external carotid artery (ECA). RESULTS: Regional WSSsystole of all patients decreased after CEA (P < 0.05). Changes were most prominent at the ICA bulb but remained unchanged in the CCA and ECA. OSI was significantly lower after CEA in the lateral vessel walls (P < 0.05). For analysis planes at the stenosis in- and outlet, a reduction of mean WSSsystole by 32 % and 52 % (P < 0.001) and OSI distal to the stenosis (40 %, P = 0.01) was found after CEA. CONCLUSIONS: Our findings show the potential of in vivo 4D flow MRI to quantify haemodynamic changes in wall shear stress even in patients with complex flow conditions.

Tailoring sparse multivariable regression techniques for prognostic single-nucleotide polymorphism signatures.

When seeking prognostic information for patients, modern technologies provide a huge amount of genomic measurements as a starting point. For single-nucleotide polymorphisms (SNPs), there may be more than one million covariates that need to be simultaneously considered with respect to a clinical endpoint. Although the underlying biological problem cannot be solved on the basis of clinical cohorts of only modest size, some important SNPs might still be identified. Sparse multivariable regression techniques have recently become available for automatically identifying prognostic molecular signatures that comprise relatively few covariates and provide reasonable prediction performance. For illustrating how such approaches can be adapted to the specific features of SNP data, we propose different variants of a component-wise likelihood-based boosting approach. The latter links SNP measurements to a time-to-event endpoint by a regression model that is built up in a large number of steps. The variants allow for strategic choices in dealing with SNPs that differ in variance because of their variation in minor allele frequencies. In addition, we propose a heuristic that allows computationally efficient handling of millions of covariates, thus opening the door for incorporating SNP × treatment interactions. We illustrate this using data from patients with acute myeloid leukemia. We judge the resulting models according to prediction error curves and using resampling data sets. We obtain increased stability by moving interpretation from the SNP to the gene level. By considering these different aspects, we outline a more general strategy for linking SNP measurements to a time-to-event endpoint by means of sparse multivariable regression models.

Initially fewer bloodstream infections for allogeneic vs. autologous stem-cell transplants in neutropenic patients.

Chemotherapy and/or radiotherapy used as conditioning regimens before autologous or allogeneic haematopoietic cell transplantations (HCTs) cause neutropenia, which is the main reason for bloodstream infections. Autologous HCTs are considered to be superior to allogeneic HCTs in terms of infection outcome. A previous analysis suggested that patients with allogeneic HCTs are exposed to a reduced infection hazard and that an unfavourable infection outcome of allogeneic HCTs may be mediated through prolonged neutropenia. Therefore, we investigated whether allogeneic HCTs initially lead to fewer infections. We evaluated data from a prospective non-randomized multi-centre cohort study, with a total of 1616 patients. Of these, 703 patients received autologous and 913 patients received allogeneic HCTs from January 2000 to June 2004. The retrospective analysis used simultaneous confidence bands for the cumulative infection probability in the presence of competing risks. Patients with allogeneic HCTs experienced fewer infections during the early phase of neutropenia. As patients with autologous HCTs are not necessarily subject to antibiotic prophylaxis, a future study should investigate this policy. A limitation of the analysis is that it did not find the effect of crossing cumulative infection probabilities to be significant.

Motor functions in trumpet playing-a real-time MRI analysis.

INTRODUCTION: The function of the orofacial and pharyngeal musculature for sound generation in brass instruments is insufficiently investigated. The contribution of muscles defying direct observation remains poorly understood. Time-resolved magnetic resonance imaging (MRI) allows visualization of muscle function as well as changes of the oropharyngeal cavities during muscle activation. METHODS: We used fast 3-T MRI imaging to analyze motor activation during sound generation in brass instruments. Twelve professional trumpeters were analyzed at different pitch, loudness and dynamic. MR images were analyzed for position of the mouthpiece to lips and teeth, pivoting, nasopharyngeal closure and changes in the area of oral and pharyngeal cavity. RESULTS: Of the 12 subjects, eight positioned the mouthpiece mainly to the upper lip, three in equal parts to upper and lower lip, and only one mostly to the lower lip. The last turned out to be the only subject with upward pivoting. All subjects had a complete velopharyngeal closure. Measurements of the oral and pharyngeal cavities showed an increase when subjects were playing higher pitches. The increase in areas of oral and pharyngeal cavity was present also when switching from lower to higher loudness and when performing crescendo to decrescendo. Enlargement of the oral and pharyngeal cavity was less pronounced with increasing loudness. But no general difference in change of oral and pharyngeal cavity could be observed. CONCLUSIONS: The present study shows that it is possible to measure motor function and its implications on oral as well as pharyngeal cavities during sound generation in brass instruments. These changes seem to follow a reproducible pattern.

Venous Leak Embolization in Patients with Venogenic Erectile Dysfunction via Deep Dorsal Penile Vein Access: Safety and Early Efficacy.

PURPOSE: This all-comers registry aimed to assess safety and early efficacy of venous embolization in patients with venogenic erectile dysfunction due to venous leak in an unselected cohort. METHODS: Between October 2019 and September 2022, patients with venogenic erectile dysfunction resistant to phosphodiesterase-5-inhibitors were treated with venous embolization using ultrasound-guided anterograde access via a deep dorsal penile vein in a single center. A mix of ethiodized oil and modified cyanoacrylate-based glue n-butyl 2 cyanoacrylate (NBCA) monomer plus methacryloxy-sulpholane monomer (Glubran-2, GEM, Italy) was used as liquid embolic agent. Prior to embolization, venous leak had been verified based on penile duplex sonography and computed tomography cavernosography. Procedural success was defined as technically successful and complete target vein embolization. The primary safety outcome measure was any major adverse event 6 weeks after the procedure. The primary feasibility outcome measure was IIEF-15 (International Index of Erectile Function-15) score improvement ≥ 4 points in ≥ 50% of subjects on 6 weeks follow-up post intervention. RESULTS: Fifty consecutive patients (mean age 61.8 ± 10.0 years) with severe erectile dysfunction due to venous leak underwent venous embolization. Procedural success was achieved in 49/50 (98%) of patients with no major adverse events on follow-up. The primary feasibility outcome measure at 6 weeks was reached by 34/50 (68%) of patients. CONCLUSION: Venous leak embolization via deep dorsal penile vein access using a liquid embolic agent was safe for all and efficacious in the majority of patients with severe venogenic erectile dysfunction on 6 weeks follow-up.

Performance of a novel microarray multiplex PCR for the detection of 23 respiratory pathogens (SYMP-ARI study).

Symptoms of acute febrile respiratory tract infection are often unspecific, but the rapid identification of pathogens allows optimised patient management. The objective of this study was to evaluate a novel multiplex polymerase chain reaction (PCR) suspension microarray which detects 19 viral and four atypical bacterial targets. A comprehensive set of sensitive monoplex real-time PCR assays was used for each pathogen as the gold standard. A panel of archived as well as 300 prospectively collected clinical samples was analysed by both methods. At least one target was detected in 165/300 (55 %) samples by monoplex PCR and in 140/300 (46 %) samples by multiplex PCR, respectively. The positivity rate was significantly higher in paediatric patients compared to adults [126/154 (82 %) vs. 39/146 (27 %) by monoplex and 114/154 (74 %) vs. 26/146 (18 %) by multiplex PCR, respectively]. Among all samples, 17/300 (5.6 %) were positive for atypical bacteria by monoplex and 8/300 (2.6 %) by multiplex PCR, respectively. Multiple detections were recorded in 35/300 (11.6 %) samples by monoplex and 26/300 (8.7 %) by multiplex PCR. For the most common pathogens, the sensitivity ranged from 57 to 93 % and the specificity ranged from 95 to 100 %. The overall concordance between both methods was 77 % [95 % confidence interval (CI) 72-81 %]. False-negative results by multiplex PCR were mainly due to the low target concentration. Compared to monoplex PCR, the novel microarray assay proved its principle but displayed overall lower sensitivities, potentially restricting its use to paediatric patients. For some targets, only small numbers of positive samples were available, requiring larger studies to firmly assess the sensitivity and specificity.