Measurement of the

^{140}Ce(n,γ) is a key reaction for slow neutron-capture (s-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty ≈5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.

Formation of intraneuronal iron deposits following local release from nanostructured silica injected into rat brain parenchyma.

Nanostructured materials with controllable properties have been used to cage and release various types of compounds. In the present study, iron-loaded nanostructured sol-gel SiO2-Fe materials were prepared and injected into the rat brain to develop a method for gradual iron delivery into the neurons with the aims to avoid acute iron toxicity and develop an animal model of gradual, metal-induced neurodegeneration. Nanoparticles were prepared by the traditional method of hydrolysis and condensation reactions of tetraethyl orthosilicate at room temperature and subsequent heat treatment at 200 °C. FeSO4 was added in situ during the silica preparation. The resulting materials were characterized by UV-VIS and infrared spectroscopies, X-ray diffraction, and N2 adsorption-desorption. An in vitro ferrous sulfate release test was carried out in artificial cerebrospinal fluid as the release medium showing successful ferrous sulfate loading on nanostructured silica and sustained iron release during the test time of 10 h. Male Wistar rats administered with SiO2-Fe nanoparticles in the substantia nigra pars compacta (SNpc) showed significant intraneuronal increase of iron, in contrast to the animals administered with FeSO4 that showed severe neuronal loss, 72 h post-treatment. Both treatments induced lipid fluorescent product formation in the ventral midbrain, in contrast to iron-free SiO2 and PBS-only injection controls. Circling behavior was evaluated six days after the intranigral microinjection, considered as a behavioral end-point of brain damage. The apomorphine-induced ipsilateral turns in the treated animals presented significant differences in relation to the control groups, with FeSO4 administration leading to a dramatic phenotype, compared to a milder impact in SiO2-Fe administrated animals. Thus, the use of SiO2-Fe nanoparticles represents a slow iron release system useful to model the gradual iron-accumulation process observed in the SNpc of patients with idiopathic Parkinson's disease.

74 Ge( n , γ ) cross section below 70 keV measured at n_TOF CERN.

Neutron capture reaction cross sections on 74 Ge are of importance to determine 74 Ge production during the astrophysical slow neutron capture process. We present new resonance data on 74 Ge( n , γ ) reactions below 70 keV neutron energy. We calculate Maxwellian averaged cross sections, combining our data below 70 keV with evaluated cross sections at higher neutron energies. Our stellar cross sections are in agreement with a previous activation measurement performed at Forschungszentrum Karlsruhe by Marganiec et al., once their data has been re-normalised to account for an update in the reference cross section used in that experiment.

ß-Delayed One and Two Neutron Emission Probabilities Southeast of

The ß-delayed one- and two-neutron emission probabilities (P_{1n} and P_{2n}) of 20 neutron-rich nuclei with N≥82 have been measured at the RIBF facility of the RIKEN Nishina Center. P_{1n} of ^{130,131}Ag, ^{133,134}Cd, ^{135,136}In, and ^{138,139}Sn were determined for the first time, and stringent upper limits were placed on P_{2n} for nearly all cases. ß-delayed two-neutron emission (ß2n) was unambiguously identified in ^{133}Cd and ^{135,136}In, and their P_{2n} were measured. Weak ß2n was also detected from ^{137,138}Sn. Our results highlight the effect of the N=82 and Z=50 shell closures on ß-delayed neutron emission probability and provide stringent benchmarks for newly developed macroscopic-microscopic and self-consistent global models with the inclusion of a statistical treatment of neutron and γ emission. The impact of our measurements on r-process nucleosynthesis was studied in a neutron star merger scenario. Our P_{1n} and P_{2n} have a direct impact on the odd-even staggering of the final abundance, improving the agreement between calculated and observed Solar System abundances. The odd isotope fraction of Ba in r-process-enhanced (r-II) stars is also better reproduced using our new data.

Proficiency of 38 HID-INDELS in kinship analysis and forensic parameters in a Mexican population / Eficiencia de 38 HID-INDELS en análisis de parentesco y parámetros forenses en una población mexicana

Introduction: Insertion–deletions for human identification (HID-INDELs) allow solving peculiar forensic situations when autosomal STRs are insufficient. Although limitations were predicted since the forensic implementation of biallelic markers, formal evaluation of these restrictions is scarce. Particularly, to define the informativity provided by HID-INDELs in kinship analysis is useful to avoid wasting work, resources, and –finally– disappointments.Material and methods: For this reason, we analyzed the 38-plex HID-INDEL system in 25 Mexican families including father, daughter, and mother, whose kinship was previously established with 22 autosomal STRs.Results and discussion: From genotypes of unrelated individuals, we updated allele frequencies and forensic parameters of the Jalisco state (West, Mexico), by increasing the population sample size from 62 to 112. Among the forensic a priori parameters, the Typical paternity index (PI) of the 38plex HID-INDEL system showed important differences regarding the PI and probability of paternity (W) estimated herein from real paternity cases, generally undervaluing the observed informativity of these 38-plex HID-INDEL system. Conversely, the studied HID-INDEL loci offered confident kinship conclusions based on the paternity index (PI ≥10,000) and probability of paternity (W ≥ 99.99%) in 68% of the standard trio cases (18/25), and only 12% of duo paternity cases (6/50) (motherless and fatherless). In fact, 14% of duo paternity cases (7/50) did not reach minimum requirements to stablish paternity (IP < 100; W < 99%).Conclusions: We updated a Mexican population database for 38 HID-INDEL loci, and we described their proficiency from real paternity cases, detailing some limitations non-previously specified. (AU)

Introducción: Las inserciones-deleciones para identificación humana (HID-INDEL), permiten resolver situaciones forenses peculiares cuando los STR autosómicos son insuficientes. Aunque se predijeron sus limitaciones desde la implementación forense de marcadores bialélicos, la evaluación formal de estas restricciones es escasa. Particularmente es útil definir su informatividad en el análisis de parentesco, para evitar desperdiciar trabajo, recursos y –finalmente– decepciones.Material y Métodos: Por este motivo, analizamos el sistema de 38plex HID-INDELs en 25 familias mexicanas entre padre, hija y madre, cuyo parentesco se estableció previamente con 22 STR autosómicos. A partir de los individuos no emparentados, actualizamos las frecuencias alélicas y los parámetros forenses del estado de Jalisco (Oeste, México), aumentando el tamaño de la muestra poblacional de 62 a 112.Resultados y discusión: Entre los parámetros forenses a priori, el índice de paternidad típico (IPT) del sistema 38plex HID-INDEL mostró diferencias importantes con respecto al IP y la probabilidad de paternidad (W) derivados de casos reales de paternidad, generalmente subestimando la informatividad observada de ese sistema. Sin embargo, los 38 HID-INDELs ofrecieron conclusiones de parentesco confiables basadas en el índice de paternidad (IP ≥ 10,000) y la probabilidad de paternidad (W ≥ 99,99%) sólo en el 68% de los casos tríos estándar (18/25), y el 12% de casos de paternidad dúo (6/50) (sin madre y sin padre). De hecho, el 14% de los casos de paternidad dúo (7/50) no alcanzó los requisitos mínimos para establecer la paternidad (IP <100; W < 99%).Conclusiones: En este trabajo actualizamos una base de datos de población mexicana para 38 HID-INDELs y describimos su eficiencia en casos reales de paternidad, detallando algunas limitaciones no especificadas previamente. (AU)

Lipopeptide production by Serratia marcescens SmSA using a Taguchi design and its application in enhanced heavy oil recovery.

Biosurfactant production at reactor level by Serratia marcescens SmSA was optimized and evaluated to enhance the heavy oil recovery on carbonate rocks. Temperature, agitation, and carbon/nitrogen (C/N) ratio were evaluated to optimize biosurfactant production by using a Taguchi (L9) design. The best conditions (C/N ratio: 6, 25 °C, and agitation: 100 rpm) were used to scale up the biosurfactant production with a 3-L bioreactor. The best aeration for biosurfactant production was 0.66 volume of air per volume of liquid per minute (vvm), producing the lowest surface tension (26 mN/m) in 14 h, with a biosurfactant yield of 14.26 g/L as a crude product and 2.85 g/L as a purified product, and a critical micelle concentration of 280 mg/L. The biosurfactant was characterized as a lipopeptide, and it was stable under extreme conditions: pH (2-12), salinity up to 200 g/L, and temperature up to 150 °C confirmed by thermogravimetric analysis. Enhanced oil recovery test was carried out with a carbonate core and heavy oil under reservoir conditions, obtaining an additional recovery of 8%, due to reduced interfacial tension and modified wettability of the rock. These findings highlight the potential application of S. marcescens SmSA biosurfactant in enhanced oil recovery.

Patrones de recaída y respuesta patológica según tipo subrogado en pacientes con cáncer de mama y axila negativa al inicio tratadas con quimioterapia neoadyuvante / Patterns of relapse and pathological response according to surrogate type in breast cancer patients treated with neoadjuvant chemotherapy and negative axillary involvement

Objetivos: Determinar los patrones de recaída y la respuesta patológica en relación con los diferentes tipos subrogados de cáncer de mama tras tratamiento neoadyuvante para analizar supervivencia y optimizar la vigilancia. Material y métodos: Análisis retrospectivo de 112 pacientes con 116 tumores, con axila clínicamente negativa, tratados con quimioterapia neoadyuvante en nuestro Centro entre 2008 y 2014, y operadas posteriormente con cirugía conservadora o radical. Analizamos respuesta patológica en función de los tipos subrogados, tasas de recurrencia y sus patrones, supervivencia libre de enfermedad (SLE) y supervivencia global (SG). Resultados: Se logró una respuesta patológica completa (RPC) en el 52,6%, constatando que estas pacientes tenían mejor supervivencia (p<0,05). En cuanto a los tipos subrogados, observamos RPC en el 85% de los tumores Her-2/neu positivos puros, el 65,6% de los triple negativos, el 43,8% de Luminal B Her-2 positivo, el 40% de Luminal B Her-2 negativo y en el 25% de Luminal A (p<0,05). Con un tiempo medio de seguimiento de 53 meses encontramos una tasa de recaídas del 9%. Los tipos menos agresivos tenían un tiempo a recaída loco-regional de 38,5 meses y a recurrencia sistémica de 74 meses. Los tipos más agresivos mostraron un tiempo medio a recaída loco- regional de 36,2 meses y a recurrencia sistémica de 8 meses. Conclusiones: La quimioterapia neoadyuvante adaptada al tipo subrogado es una estrategia válida para intentar alcanzar una RPC. Las diferencias observadas en el patrón de recurrencia permiten optimizar el seguimiento.(AU)

Purpose: To determine relapse patterns and pathological response in relation to surrogate types of breast cancer after neoadjuvant treatment to analyse survival and optimize surveillance. Material and methods: Retrospective analysis of 112 patients with 116 tumours, with negative axillary involvement, treated with neoadjuvant chemotherapy at our hospital, between 2008 and 2014, who systematically underwent surgery. We analysed pathological response according to surrogate subtypes, rates and patterns of recurrence, disease free survival (DFS) and overall survival (OS). Results: Pathological complete response (pCR) was achieved in 52.6%, finding that these patients had better survival (p<.05). Looking at surrogate subtypes, we observed a pCR in 85% of pure Her-2/neu positive tumours, 65.6% of triple negatives, 43.8% of Her -2 positive Luminal B, 40% of Luminal B and 25% of Luminal A (p<.05). With a median follow-up of 53 months, we found a 9% rate of relapses. The less aggressive types had a median loco-regional relapse time of 38.5 months and a systemic recurrence time of 74 months. The more aggressive types showed a loco-regional relapse time of 36.2 months and systemic recurrence time of 8 months. Conclusions: Neoadjuvant chemotherapy according to surrogate type is a useful strategy to attempt pCR. Loco-regional relapse and systemic recurrence patterns allow surveillance adjustments.(AU)

Localized standing waves induced by spatiotemporal forcing.

Particle-type solutions are observed in out-of-equilibrium systems. These states can be motionless, oscillatory, or propagative depending on the injection and dissipation of energy. We investigate a family of localized standing waves based on a liquid-crystal light valve with spatiotemporal modulated optical feedback. These states are nonlinear waves in which energy concentrates in a localized and oscillatory manner. The organization of the family of solutions is characterized as a function of the applied voltage. Close to the reorientation transition, an amplitude equation allows us to elucidate the origin of these localized states and establish their bifurcation diagram. Theoretical findings are in qualitative agreement with experimental observations. Our results open the possibility of manipulating localized states induced by light, which can be used to expand and improve the storage and manipulation of information.

MRI guided ROLL/SNOLL in breast cancer patients treated with neoadjuvant chemotherapy. / ROLL/SNOLL guiado por resonancia magnética en pacientes con cáncer de mama tratadas con quimioterapia neoadyuvante.

PURPOSE: To describe the results of MRI (magnetic resonance image) guided ROLL (radioguided occult lesion localization) and SNOLL (sentinel node occult lesion localization) in the localization of residual disease after neoadjuvant chemotherapy for breast cancer, as well as assessing the surgical results obtained and disease free survival. METHODS: Prospective observational analysis of 132 patients with 136 tumors, treated with neoadjuvant chemotherapy at our hospital between 2011-2017. Residual disease was located presurgically with MRI guided ROLL/SNOLL technique. We analyzed technical aspects of localization, and variables corresponding to surgical procedures and events occurred during follow-up. RESULTS: The median tumor size was of 20.5mm (interquartilic range [IQR]: 14-28). The majority (96.3%) were invasive ductal carcinomas. Sentinel lymph node detection rate was 98.9%. Complete pathological response (CPR) in the breast was achieved in 58.1% of cases. The rate of affected margins in 89 cases operated by conservative surgery was 2.2%. With a median follow-up of 50 months (IQR: 37-61) we found a 7.4% rate of relapses. Of these, seven were loco-regional and three at distant sites. The estimated mean of disease-free survival time was 83.2 months (Confidence Interval [CI] 95%: 79.6-86.6). CONCLUSIONS: MRI guided ROLL/SNOLL is a great tool for breast cancer residual disease localization following neoadjuvant chemotherapy. In addition, this technique attains good loco-regional control of the diseases and has excellent surgical results.

Neutron Capture on the s-Process Branching Point

The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable ^{171}Tm (t_{1/2}=1.92 yr) is part of the branching around mass A∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of ^{171}Tm at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n_TOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n_TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the ^{171}Yb abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.

Coronavirus Optimization Algorithm: A Bioinspired Metaheuristic Based on the COVID-19 Propagation Model.

This study proposes a novel bioinspired metaheuristic simulating how the coronavirus spreads and infects healthy people. From a primary infected individual (patient zero), the coronavirus rapidly infects new victims, creating large populations of infected people who will either die or spread infection. Relevant terms such as reinfection probability, super-spreading rate, social distancing measures, or traveling rate are introduced into the model to simulate the coronavirus activity as accurately as possible. The infected population initially grows exponentially over time, but taking into consideration social isolation measures, the mortality rate, and number of recoveries, the infected population gradually decreases. The coronavirus optimization algorithm has two major advantages when compared with other similar strategies. First, the input parameters are already set according to the disease statistics, preventing researchers from initializing them with arbitrary values. Second, the approach has the ability to end after several iterations, without setting this value either. Furthermore, a parallel multivirus version is proposed, where several coronavirus strains evolve over time and explore wider search space areas in less iterations. Finally, the metaheuristic has been combined with deep learning models, to find optimal hyperparameters during the training phase. As application case, the problem of electricity load time series forecasting has been addressed, showing quite remarkable performance.

Front propagation steered by a high-wavenumber modulation: Theory and experiments.

Homogeneously driven dynamical systems exhibit multistability. Depending on the initial conditions, fronts present a rich dynamical behavior between equilibria. Qualitatively, this phenomenology is persistent under spatially modulated forcing. However, the understanding of equilibria and front dynamics organization is not fully established. Here, we investigate these phenomena in the high-wavenumber limit. Based on a model that describes the reorientation transition of a liquid crystal light valve with spatially modulated optical forcing and the homogenization method, equilibria and fronts as a function of forcing parameters are studied. The forcing induces patterns coexisting with the uniform state in regions where the system without forcing is monostable. The front dynamics is characterized theoretically and numerically. Experimental results verify these phenomena and the law describing bistability, showing quite good agreement.

Transition to Spatiotemporal Intermittency and Defect Turbulence in Systems under Translational Coupling.

Out of equilibrium systems under the influence of enough energy injection exhibit complex spatiotemporal behaviors. Based on a liquid crystal light valve experiment with translational optical feedback, we observe propagation, spatiotemporal intermittency, and defect turbulence of striped waves. A prototype model of pattern formation with translational coupling shows the same phenomenology. Close to the spatial instability, a local amplitude equation is derived. This amplitude equation allows us to reveal the origin and bifurcation diagram of the observed complex spatiotemporal dynamics. Experimental observations have a qualitative agreement with theoretical findings.

Guía de recomendación ACCHED-SCHGE para el funcionamiento de las unidades de endoscopia durante el brote de coronavirus (COVID-19) / Guideline recommendations ACHED-SCHGE for the endoscopy units during the Coronavirus outbreak (COVID-19)

The outbreak of COVID-19 disease has recently spread from its original place in Wuhan, Hubei province, China, to the entire world, and has been declared to be a pandemic by the World Health Organization in March 2020. All countries in America, in particular Chile, show an important increase in COVID-19 cases and deaths. The clinical manifestations of COVID-19 are a broad spectrum, from asymptomatic mild disease, to severe respiratory failure, shock, multiorgan dysfunction and death. Thus, high clinical suspicion and appropriate structure risk stratification are needed. Health care teams in endoscopy units, are at an increased risk of infection by COVID-19 from inhalation of droplets, mucosae contact, probably contamination due to contact with stools. Endoscopic aerosolized associated infections have also been reported. Different societies' recommendations, have recently placed digestive endoscopy (especially upper) among the high risk aerosol generating procedures (AGPs). In addition, live virus has been found in patient stools. On top of this, the infected health professionals may transmit the infection to their patients. Health care infection prevention and control (HCIPC), has been shown to be effective in assuring the safety of both health care personnel and patients. This is not limited to the correct use of personal protective equipment (PPE), but is based on a clear, detailed and well communicated HCIPC strategy, risk stratification, use of PPE, and careful interventions in patients with moderate and high risk of COVID-19. A conscientious approach regarding limited resources is important, as the simultaneous outbreak in all countries heavily affects the availability of health supplies. The Chilean Gastroenterology Society (SChGE) and Digestive Endoscopy Association of Chile (ACHED) are joining to provide continued updated guidance in order to assure the highest level of protection against COVID-19, for both patients and health care workers. This guideline will be updated online as needed.

El brote de la enfermedad denominada COVID-19, se ha extendido desde su origen en Wuhan, provincia de Hubei, China, a todo el mundo. La Organización Mundial de la Salud lo declaró pandemia en marzo de 2020. Todos los países de América, en especial Chile, presentan incremento de casos y fallecidos. Las manifestaciones clínicas de COVID-19 van desde una enfermedad leve, hasta insuficiencia respiratoria severa, shock, disfunción orgánica y muerte. Se necesita una alta sospecha clínica y una adecuada estratificación del riesgo. El equipo de salud en las unidades de endoscopia, tiene un mayor riesgo de COVID-19 que otras unidades clínicas y de apoyo diagnóstico, dada la mayor exposición a inhalación de gotas, contacto posible con mucosas y contaminación por contacto con deposiciones. Recomendaciones de diferentes sociedades colocan la endoscopia digestiva (especialmente la esofagogastroscopia o endoscopia digestiva alta, EDA) entre los procedimientos generadores de aerosoles (PGA) de alto riesgo. Además, se han encontrado virus viables en las deposiciones de los pacientes. Potencialmente, los profesionales de la salud infectados podrían contagiar a los pacientes. Se ha demostrado que la prevención y control de infecciones asociadas a la atención de salud (IAAS), son efectivos para garantizar la seguridad tanto del personal de salud, como de los pacientes. Esto no es solamente el correcto uso del equipo de protección personal (EPP), sino que se basa en una clara estrategia de IAAS, bien comunicada, con estratificación de riesgo, uso de EPP e intervenciones correctas en pacientes con riesgo moderado y alto. Es relevante un enfoque sobre los limitados recursos, dado la simultaneidad del brote en todos los países, que afecta la disponibilidad de insumos. La Sociedad Chilena de Gastroenterología (SChGE) y la Asociación Chilena de Endoscopia Digestiva (ACHED) publican esta guía actualizada para apoyar las buenas prácticas contra COVID-19, tanto para pacientes como para el equipo de salud. Esta guía podrá tener actualizaciones según avance la información disponible.

Differences in resource use lead to coexistence of seed-transmitted microbial populations.

Seeds are involved in the vertical transmission of microorganisms in plants and act as reservoirs for the plant microbiome. They could serve as carriers of pathogens, making the study of microbial interactions on seeds important in the emergence of plant diseases. We studied the influence of biological disturbances caused by seed transmission of two phytopathogenic agents, Alternaria brassicicola Abra43 (Abra43) and Xanthomonas campestris pv. campestris 8004 (Xcc8004), on the structure and function of radish seed microbial assemblages, as well as the nutritional overlap between Xcc8004 and the seed microbiome, to find seed microbial residents capable of outcompeting this pathogen. According to taxonomic and functional inference performed on metagenomics reads, no shift in structure and function of the seed microbiome was observed following Abra43 and Xcc8004 transmission. This lack of impact derives from a limited overlap in nutritional resources between Xcc8004 and the major bacterial populations of radish seeds. However, two native seed-associated bacterial strains belonging to Stenotrophomonas rhizophila displayed a high overlap with Xcc8004 regarding the use of resources; they might therefore limit its transmission. The strategy we used may serve as a foundation for the selection of seed indigenous bacterial strains that could limit seed transmission of pathogens.

Population data for 21 autosomal STR loci (GlobalFiler kit) in two Mexican-Mestizo population from the northwest, Mexico.

Mexican Mestizos (admixed) have been poorly studied for short tandem repeats (STRs) included for new human identification (HID) kits, such as the GlobalFiler PCR Amplification kit. Therefore, this kit was analyzed in 784 unrelated volunteers from the city of Tijuana (n = 381) and Sonora state (n = 403) in the northwest region of Mexico. Allele frequencies, forensic parameters, Hardy-Weinberg equilibrium, and linkage equilibrium were estimated or evaluated for 21 autosomal STRs, respectively. For this HID kit, the combined power of discrimination (PD) was > 0.99999999999999 (RMP range = 1.23 to 3.0 × 10-25), and the combined power of exclusion (PE) were 0.999999993 and 0.999999997 in Tijuana city and Sonora state, respectively. Interpopulation analyses based on STRs of the GlobalFiler kit was performed, including four Mexican Native American, one Mexican Mestizo, and four ethnic American populations (USA), previously studied. The low-but significant-differentiation observed among Mexican Mestizos (FST = 0.0969%; p = 0.02584) justifies the creation of STR databases for HID purposes in this country. In brief, results allow the confident use of the GlobalFiler kit for HID purposes in Mestizo population from the Northwest region Mexico.

Developing a foot ulcer risk model: what is needed to do this in a real-world primary care setting?

AIM: To determine how routinely collected data can inform a risk model to predict de novo foot ulcer presentation in the primary care setting. METHODS: Data were available on 15 727 individuals without foot ulcers and 1125 individuals with new foot ulcers over a 12-year follow-up in UK primary care. We examined known risk factors and added putative risk factors in our logistic model. RESULTS: People with foot ulcers were 4.2 years older (95% CI 3.1-5.2) than those without, and had higher HbA1c % (mean 7.9 ± 1.9 vs 7.5 ± 1.7) / HbA1c mmol/mol (63 ± 21 vs 59 ± 19) (p<0.0001) concentration [+0.45 (95% CI 0.33-0.56), creatinine level [+6.9 µmol/L (95% CI 4.1-9.8)] and Townsend score [+0.055 (95% CI 0.033-0.077)]. Absence of monofilament sensation was more common in people with foot ulcers (28% vs 21%; P<0.0001), as was absence of foot pulses (6.4% vs 4.8%; P=0.017). There was no difference between people with or without foot ulcers in smoking status, gender, history of stroke or foot deformity, although foot deformity was extremely rare (0.4% in people with foot ulcers, 0.6% in people without foot ulcers). Combining risk factors in a single logistic regression model gave modest predictive power, with an area under the receiver-operating characteristic curve of 0.65 (95% CI 0.62-0.67). The prevalence of ulceration in the bottom decile of risk was 1.8% and in the top decile it was 13.4% (compared with an overall prevalence of 6.5%); thus, the presence of all six risk factors gave a relative risk of 7.4 for development of a foot ulcer over 12 years. CONCLUSION: We have made some progress towards defining a variable set that can be used to create a foot ulcer prediction model. More accurate determination of foot deformity/pedal circulation in primary care may improve the predictive value of such a future risk model, as will identification of additional risk variables.