Regresión logística / Logistic regression

La regresión logística es un grupo de técnicas estadísticas que tienen como objetivo comprobar hipótesis o relaciones causales entre una variable dependiente categórica y otras variables independientes que pueden ser categóricas y cuantitativas. Mediante este modelo pretendemos estudiar la probabilidad de que ocurra el evento estudiado en función de unas variables que suponemos que son relevantes o influyentes. En este método es necesario detectar las variables modificadoras de efecto y las de confusión. Sus parámetros se estiman con el método de la máxima verosimilitud a través de un proceso con sucesivas iteraciones (AU)

Logistic regression is a group of statistical techniques that aim to test hypotheses or causal relationships between a categorical dependent variable and other independent variables that can be categorical and quantitative. Through this model we intend to study the probability that the event studied will occur based on some variables that we assume are relevant or influential. In this method it is necessary to detect effect modifier and confounding variables. Its parameters are estimated with the maximum likelihood method through a process with successive iterations (AU)

[Logistic regression]. / Regresión logística.

Logistic regression is a group of statistical techniques that aim to test hypotheses or causal relationships between a categorical dependent variable and other independent variables that can be categorical and quantitative. Through this model we intend to study the probability that the event studied will occur based on some variables that we assume are relevant or influential. In this method it is necessary to detect effect modifier and confounding variables. Its parameters are estimated with the maximum likelihood method through a process with successive iterations.

Análisis de supervivencia / Survival analysis

El análisis de supervivencia es un método estadístico que valora el tiempo entre un evento inicial (inclusión del sujeto en el estudio) y uno final, que sucede cuando este presenta una característica definida con anterioridad (evento). Su objetivo es estimar, teniendo en cuenta la variable tiempo, la probabilidad de que ocurra un suceso determinado. Tiene la particularidad de aceptar tiempos incompletos de participación y asumir que todos los factores implicados en el estudio son homogéneos. Existen varios métodos para calcular la probabilidad de supervivencia; los más utilizados son los de Kaplan-Meier y el actuarial (AU)

Survival analysis is a statistical method that assesses the time between an initial event (inclusion of the subject in the study) and a final event, which occurs when the subject presents a previously defined characteristic. Its objective is to estimate, taking into account the time variable, the probability of a certain event occurring. It has the particularity of accepting incomplete participation times and assuming that all the factors involved in the study are homogeneous. There are several methods to calculate the probability of survival, the most used are the Kaplan-Meier and the actuarial (AU)

[Survival analysis]. / Análisis de supervivencia.

Survival analysis is a statistical method that assesses the time between an initial event (inclusion of the subject in the study) and a final event, which occurs when the subject presents a previously defined characteristic. Its objective is to estimate, taking into account the time variable, the probability of a certain event occurring. It has the particularity of accepting incomplete participation times and assuming that all the factors involved in the study are homogeneous. There are several methods to calculate the probability of survival, the most used are the Kaplan-Meier and the actuarial.

Coeficiente de correlación intraclase / Intraclass correlation coefficient

El coeficiente de correlación intraclase permite medir la concordancia general entre dos o más mediciones que implican variables de carácter cuantitativo, obtenidas estas con diferentes instrumentos de medida o evaluadores. Se basa en un modelo de análisis de varianza con medidas repetidas. Su uso solo es posible si existe normalidad de las distribuciones de las variables, igualdad de varianzas e independencia entre los errores producidos por los observadores (AU)

The intraclass correlation coefficient makes it possible to measure the general concordance between two or more measurements that involve variables of a quantitative nature, obtained with different measuring instruments or evaluators. It is based on an analysis of variance model with repeated measures. Its use is only possible if there is normality of the distributions of the variables, equality of variances and independence between the errors produced by the observers (AU)

La curva ROC / ROC curve

La curva ROC es una herramienta estadística que se utiliza para evaluar la capacidad discriminativa de una prueba diagnóstica dicotómica. Se trata de curvas en las que se presenta la sensibilidad en función de los falsos positivos (complementario de la especificidad) para distintos puntos de corte. Son útiles para elegir el punto de corte más adecuado de una prueba, conocer el rendimiento global de esta y comparar la capacidad discriminativa de 2 o más pruebas diagnósticas. (AU)

The ROC curve is a statistical tool used to evaluate the discriminative capacity of a dichotomous diagnostic test. These are curves in which sensitivity is presented as a function of false positives (complementary to specificity) for different cut-off points. They are useful for choosing the most appropriate cut-off point for a test, knowing its overall performance and comparing the discriminative capacity of 2 or more diagnostic tests. (AU)

[Intraclass correlation coefficient]. / Coeficiente de correlación intraclase.

The intraclass correlation coefficient makes it possible to measure the general concordance between two or more measurements that involve variables of a quantitative nature, obtained with different measuring instruments or evaluators. It is based on an analysis of variance model with repeated measures. Its use is only possible if there is normality of the distributions of the variables, equality of variances and independence between the errors produced by the observers.

[ROC curve]. / La curva ROC.

The ROC curve is a statistical tool used to evaluate the discriminative capacity of a dichotomous diagnostic test. These are curves in which sensitivity is presented as a function of false positives (complementary to specificity) for different cut-off points. They are useful for choosing the most appropriate cut-off point for a test, knowing its overall performance and comparing the discriminative capacity of 2 or more diagnostic tests.

Tuberculosis in a Spanish cohort of children living with HIV: the CHOTIS study (Childhood HIV & TB study).

BACKGROUND: Tuberculosis (TB) is the leading opportunistic infection in children with human immunodeficiency virus (HIV), but is uncommon in low prevalence regions. We aim to describe the changing epidemiology and clinical presentation of TB-HIV co-infection in a cohort of HIV-infected children in Spain.METHODS: Children diagnosed with TB between 1995 and 2016 in the paediatric HIV cohort were identified. The incidence and clinical presentation were compared in three periods: 1995-1999 (P1, before initiation of combined antiretroviral therapy, cART), 2000-2009 (P2, increase in immigration), and 2010-2016 (P3, decrease in immigration).RESULTS: We included 29 TB cases among 1183 children aged <18 years (2.4%, 243/100 000 person-years). The proportion was stable in P1 and P2 (1.3%), but decreased in P3 (0.8%). The median age at TB diagnosis was 6.4 years (IQR 4-10.6); most children in P3 were aged >10 years (20% vs. 23.1% vs. 83.3%, P = 0.01). TB was diagnosed at HIV presentation in 11/29 children (37.9%). Foreign-born children accounted for respectively 0%, 8% and 67% of the total number of children in each period (P ≤ 0.0001). One third had extrapulmonary TB; four children died (13.8%).CONCLUSION: In our cohort, the incidence of TB-HIV co-infection decreased with decline in immigration. In regions with adequate cART coverage and low TB transmission, paediatric TB-HIV coinfection is uncommon, but associated with significant morbidity. Strategies for TB surveillance, diagnosis and treatment in this vulnerable population should be reinforced.

Serological detection of Ascaris suum at fattening pig farms is linked with performance and management indices.

The aim of the present study was to determine the association between the presence of Ascaris suum at fattening pig farms, using different serological methods and the percentage of affected livers at slaughter, with performance and management indices. In total, 21 fattening pig farms from the North of Spain were included in the study. Serum samples were collected from pigs at slaughter and analysed for the presence of anti-Ascaris antibodies. For this, two different ELISAs were used. The first was based on the antibody recognition of the A. suum haemoglobin (As-Hb) molecule whereas the second test used the total extract of A. suum lung stage L3. The serological results were subsequently correlated with the percentage of condemned livers at slaughter, management practices and technical performance parameters including average daily gain (ADG) and feed conversion ratio (FCR). According to the data from the slaughterhouse, 12 out of the 21 farms had livers condemned due to liver white spots. A total of 10 farms (48%) had an average optical density ratio (ODr) exceeding the test cutoff when the As-Hb ELISA was used. This number increased to 18 farms (81%) when using the As-Lung-L3 ELISA. The average ODr of the farms on both ELISAs correlated positively with the percentage of affected livers (P<0.01). Only the average ODr values obtained with the As-Lung-L3 ELISA were positively correlated with the FCR (P<0.01). No correlation was found between percentage of affected livers or serology and the ADG. In relation to management practices, farms with greater than or equal to 50% slatted flooring and that applied the 'all-in/all-out' flow system showed a lower percentage of liver condemnations (P<0.01), lower average ODr results on the As-Lung-L3 ELISA (P<0.05) and lower FCR (P<0.01) compared with those with less than 50% slatted flooring. This study emphasizes that serology is a promising diagnostic tool for diagnosing ascariasis at fattening pig farms. It also supports earlier findings that the presence of A. suum can have a significant negative impact on farm productivity and that stable infrastructure or management practices can have a considerable impact on the control of this parasite.

Comparison of the Allometry Coefficient of the Length-Weight and Length-Length Relationship between Selene brownii, S. vomer and S. setapinnis Caught in the Gulf of Mexico / Comparación del Coeficiente de Alometría de la Relación Talla-Peso y Longitud-Longitud entre Selene brownii, S. vomer y S. setapinnis Capturados en el Golfo de México

This work presents a comparison of the length-weight and length-length allometric relationships between six measurements: length pattern (LP), cephalic length (CL), maximum depth (MA), caudal peduncle depth (CPD) ocular diameter (OD) and weight (W) of three species of the genus Selene (S. brownii, S. vomer and S. setapinnis) caught in the port of Veracruz, Mexico, using a beach seine of 800 m. The results show certain relationships between all measurements of S. brownii (an isometric relationship and four negative allometric relationships); S. vomer showed only four relationships (two isometric and two negative allometric); and S. setapinnis showed three relationships (all negative allometric); the results of S. vomer and S. setapinnis are consistent with those reported by Muto et al. (2010). The comparison of the coefficients of allometry between the three species allowed us to determine that S. brownii and S. vomer differed significantly in two of the four allometric coefficients of length-weight relationships common to them, and in three of the four allometric coefficients of length-length relationships common to them. S. brownii and S. setapinnis differed significantly in two of the three allometric coefficients of length-weight relationships common to them and in the only allometric coefficient of length-length relationships common to them. Finally, S. vomer and S. setapinnis differed significantly in the three common allometric coefficients of length-weight relationships, and in the only common allometric coefficient of length-length relationship.

En este trabajo se presentan las comparaciones de las relaciones alométricas de longitud- peso y longitud-longitud de seis medidas (longitud patrón (LP), longitud cefálica (LC), amplitud máxima (AM), amplitud del pedúnculo (AP), diámetro ocular (DO) y Peso (W) de tres especies del género Selene (S. brownii, S. vomer y S. setapinnis) capturados en el puerto de Veracruz México, mediante el uso de un chinchorro playero de 800 m. Los resultados obtenidos muestran que S. brownii posee relaciones entre todas sus medidas (una isométrica y cuatro alométricas negativas), S. vomer posee solo cuatro relaciones (dos isométricas y dos alométricas negativas) y S. setapinnis posee tres relaciones (todas alométricas negativas), los resultados de S. vomer y S. setapinnis concuerdan con los reportados por Muto et al. (2010). Al comparar los coeficientes de alometría entre las tres especies se pudo determinar que S. brownii y S. vomer difieren significativamente en dos de los cuatro coeficientes alométricos comunes en las relaciones longitud-peso, y tres de los cuatro coeficientes alométricos comunes en las relaciones longitud-longitud; S. brownii y S. setapinnis difieren significativamente en dos de los tres coeficientes alométricos comunes en las relaciones longitud-peso y en el único coeficiente alométricos común en las relaciones longitud-longitud; por último S. vomer y S. setapinnis difieren significativamente en los tres coeficientes alométricos comunes en la relaciones longitud-peso, y en el único coeficiente alométrico común en las relaciones longitud-longitud.

Resistance of gastrointestinal nematodes to the most commonly used anthelmintics in sheep, cattle and horses in Spain.

The objective of this study was to evaluate the status of anthelmintic resistance (AR) in ruminants and horses in Spain. The efficacy of commonly used macrocyclic lactones (MLs) - ivermectin (IVM) and moxidectin (MOX) - was measured in sheep, cattle and horses. In addition, albendazole (ABZ) and levamisole (LEV) were evaluated in sheep and oxibendazole (OXI) and pyrantel (PYR) in horses. Efficacy was evaluated based on the difference between the arithmetic mean pre- and post-treatment faecal egg count (in cattle and horses), or compared to an untreated control group (in sheep). AR was present when the percentage reduction in egg count was <95% and the lower 95% confidence interval (CI) was <90%; if only one of these two criteria was met, the finding was recorded as suspected AR (SAR). In horses, AR-PYR and OXI was considered when the percentage reduction in egg count was ≤ 90% and the lower 95% CI was ≤ 80%. For each animal species, at least 10 study sites were selected. AR to at least one of the drugs was detected in all 10 sheep flocks; the main parasite identified after treatment was Teladorsagia circumcincta. Moreover, in 5 flocks multidrug resistance was identified, on 4 farms to drugs from different families, on one farm to both MOX and IVM and on another farm to all drugs tested. In cattle, the efficacy of both MOX and IVM was 100% on 4 and 3 farms, respectively, and therefore 60% of these farms were considered to have AR or SAR to both MLs. The most frequent parasite identified after treatment was Trichostrongylus spp., although Ostertagia ostertagi was also identified after treatment on one farm. In contrast to ruminants, the 4 drugs evaluated in horses were highly efficacious against strongyles, with efficacies for the MLs and OXI between 95 and 100% and between 94 and 100% for PYR, although 3 herds were SAR against PYR. In conclusion, AR to at least one of the commonly used drugs was identified on all sheep flocks investigated in the northwest of Spain. The occurrence of AR to MLs in cattle was higher than expected but consistent with what was observed in sheep. In horses, all currently used drugs were confirmed as effective against strongyles.

Analysis of genetic variability of Fasciola hepatica populations from different geographical locations by ISSR-PCR.

Inter-simple sequence repeats markers were used to determinate the genetic variability of Fasciola hepatica populations recovered from sheep and cattle from Spain (Sp1, Sp2, Sp3 and Sp4), UK (Eng), Ireland (Ir) and Mexico (Mex). Twenty five primers were tested but only five produced 39 reproducible bands, being 71.79% polymorphic bands. This percentage ranged from 10.26% in Sp4 to 48.72% in Sp1, and per host between 28.21 and 48.72% in sheep and between 10.26 and 38.46% in cattle. This relatively low range of genetic diversity within populations, with a mean of 34.40%, implies that a large proportion of variation resided among populations. The population differentiation (Gst = 0.547) indicated that 54.7% of variation is due to differences between populations and 45.3% due to differences within population. The Nei's distance ranged between 0.091 and 0.230 in sheep and between 0.150 and 0.337 in cattle. The genetic relationships between populations and individuals were shown by a UPGMA dendrogram and a principal coordinate analysis; both grouped all populations separately from Sp4, a population of from the Midwest of Spain with the lowest level of diversity. Small genetic distances were observed between Eng and Ir, on the one hand, and Sp1, Sp2, Sp3, from the Northwest of Spain, together with Mex, on the other.

Immunological features of LPS from Ochrobactrum intermedium on sheep experimentally infected with Fasciola hepatica.

The effects of the lipopolysaccharide (LPS) from Ochrobactrum intermedium in sheep with fasciolosis was reported previously, resulting in lower fecal egg counts and fluke burden. In the current study, we analyzed its immunological effects in two groups of sheep, treated (T) and controls (C). Fasciolosis induces a T helper (Th) type-2 response, characterized by IL-4 and IL-10 production; however, at the beginning of the infection, the IFN-γ production predominates (Th type-1 response). Although we did not find differences in IL-4 production or in the expression level of this gene in the hepatic lymph nodes, the expression level of IL-10 was higher (P < 0.05) in the T group at 4 wpi. The IFN-γ production was higher (P < 0.01) at 12 wpi as well as its level of expression at 4 wpi (P < 0.05) in the T group. We found a higher expression level of TGF-ß at 4 wpi in the T group (P < 0.05), associated with the previous report of thicker fibrous tracks in a treated group. Immunoglobulin G1, related with a Th type-2 response, was higher (P < 0.01) in the T group at 4 and 12 wpi. In conclusion, the effects of LPS from O. intermedium could have resulted from a predominant Th type-2 immune response.

Effect of dietary supplementation with flaxseed oil or vitamin E on sheep experimentally infected with Fasciola hepatica.

The effects of two diets supplemented with flaxseed oil (FO) or vitamin E (VE) were studied in sheep infected with Fasciola hepatica. The control group (CO), not supplemented, had higher weight gain and faecal egg count (P < 0.05) at the end of the study. At necropsy, the number (71.2 ± 26.5) and size of flukes were lower in the FO group (P < 0.01), probably due to the higher levels of white blood cells and lymphocytes (P < 0.01). This group also had higher red blood cell and haematocrit values (P < 0.01). The CO group had more severe hypoproteinaemia and hypoalbuminaemia, due to having the highest fluke burden (123.0 ± 35.2), and also the highest IgG1 titre (P < 0.01). The diet did not affect production or gene expression levels of IFN-γ and IL-4. On the other hand, the supplementation with VE led to a reduction in adult fluke burden (97.7 ± 39.9) and lower lipid oxidation in the liver (P < 0.001).

Development of an egg hatch assay for the detection of anthelmintic resistance to albendazole in Fasciola hepatica isolated from sheep.

The aim of this study was to develop an egg hatch assay (EHA) to detect the resistance of Fasciola hepatica to albendazole (ABZ). With this purpose, two different F. hepatica isolates were tested: (i) susceptible (Shrewsbury/South Gloucester strain) to ABZ (SA); (ii) resistant to ABZ (RA). A commercial formulation of ABZ (Sinvermin) diluted in dimethyl sulfoxide (DMSO) was used at concentrations of 0.0002, 0.002, 0.02, 0.2, and 2 µg/ml. In the SA isolates, eggs from feces exposed to ABZ at the three highest concentrations showed significantly lower hatching percentages than the control well (P<0.01); also for the two highest concentrations, the percentage of development was significantly lower than the control (P<0.01). However, in the RA isolate, no differences among treatments and control were found in the percentage of hatched or developed eggs. On the other hand, the EHA was conducted over a 15 day period following treatment with ABZ for sheep infected by the RA isolate. On day 7 post-treatment (pt), no differences among treatments and controls were observed. On day 15 pt, the development and hatching rates exposed to the highest ABZ concentration were lower than at lower concentrations, suggesting susceptibility. The ovicidal effect of ABZ and the potential use of EHA to differentiate between ABZ susceptible and resistant isolates are confirmed in the current study. However, the use of this technique should be confirmed with a higher number of isolates.

[Epidemiology of parkinsonism in the Guadalajara Health Area]. / Epidemiología del parkinsonismo en el Área de Salud de Guadalajara.

OBJECTIVES: 1) To determine the prevalence of Parkinson syndromes in the Guadalajara Health Area and its Basic Health Zones, as well as the typology of the Parkinson's disease; 2) to determine the distribution of antiparkinsonian medication use in the whole Area, and 3) to evaluate the cost per person and per year of this use according to the criteria of sex and age. MATERIAL AND METHOD: A descriptive cross-sectional study including 1,352 subjects affected by parkinsonism in the Guadalajara Area of both sexes and all ages. The variables measured were age, sex, environment, diagnosis, typology of the Parkinson's disease using the Hoehn and Yahr index, treatment, total cost and mean cost of the treatment per person per year. Prevalences were calculated, and the appropriate descriptive statistics were used. RESULTS: The prevalence of parkinsonism was 585/10(5) inhabitants, being higher in a rural environment (P<.05), in females (P<.01) and in subjects over 90 years (P<.01). The majority suffered from Parkinson's disease (P<.001), of whom 43.4% had symptoms equivalent to Yahr grade II (P<.001). The active ingredient most used was levodopa/carbidopa (51.3%) (P<.001) and the mean drug cost per person was 514.37€. CONCLUSIONS: The prevalence of parkinsonism is similar to that in the rest of the country, although in our study there is a predominance of females and it is in a rural environment. Levodopa is the drug most used, and the mean therapeutic cost per person is similar to the rest of Spain.

The diagnosis of fasciolosis in feces of sheep by means of a PCR and its application in the detection of anthelmintic resistance in sheep flocks naturally infected.

The aim of this study was to develop a PCR for the diagnosis of Fasciola hepatica infection in feces of sheep based on the ribosomal internal transcribed spacer. Detection of infection was possible from the second week post-infection in experimentally infected sheep by amplification of a 292bp fragment. This PCR was employed for the detection of anthelmintic resistance (AR) in naturally infected sheep flocks, and results were compared with techniques such as the fecal egg count reduction test (FECRT) and the copro-antigen reduction test (CRT). The FECRT was carried out in two flocks, Santillan de la Vega (SV) and Corullón (CR), with sheep treated with albendazole (ABZ), clorsulon (CL), or triclabendazole (TCBZ). Feces were collected from individuals on days 0, 7, 15, and 30 post-treatment (pt). The FECRT showed adult F. hepatica to be resistant to ABZ and CL in both flocks. All parasite stages in the SV flock were susceptible to TCBZ, while in the CR flock, adult flukes showed resistance and immature forms were susceptible to the treatment. To compare FECRT and the PCR results, we calculated the percent of positive sheep on day 1 pt. In both flocks, the percent positive sheep was consistently higher by PCR than by sedimentation, confirming that the PCR is a more sensitive method of diagnosing infection and therefore to detect the resistance in infected animals. The CRT was carried out in the SV flock using a sandwich ELISA kit. The percent of sheep found positive by PCR was higher than with ELISA. Comparison of FECRT, CRT, and PCR for the detection of AR showed PCR to be the most sensitive.