Formulación de la pregunta de revisión

Presentación del tema: "Formulación de la pregunta de revisión"— Transcripción de la presentación:

1 Formulación de la pregunta de revisión

2 Pasos de una revisión sistemática Cochrane
Formular la pregunta Planificar los criterios de elegibilidad Planificar la metodología Buscar los estudios Aplicar los criterios de elegibilidad Obtener los datos Evaluar el riesgo de sesgo de los estudios Analizar y presentar los resultados Interpretar los resultados y obtener conclusiones Mejorar y actualizar la revisión Defining your review question is the first step in starting your Cochrane systematic review. You begin this process at the title registration stage, but there’s often more work to be done in really thinking through your question in detail.

3 Índice Importancia de una pregunta de revisión bien definida
Componentes de una pregunta de revisión Qué incluir en el protocolo Vea el capitulo 5 del Cochrane Handbook

4 Definir su pregunta Primer paso esencial para su revisión
Guía muchos aspectos de los métodos que se seguirán Criterios de elegibilidad Estrategia de búsqueda Obtención de datos y análisis Piense cuidadosamente con anterioridad Planifique su trabajo Evite sesgos Comparta con su Grupo Cochrane de Revisión (CRG) si modifica la pregunta planteada A well-defined review question is essential to your review. It’s important that you’re clear about what your review will cover, as the question will define many of the subsequent steps of the review: it will determine your eligibility criteria – that is, which studies are included in the review, and which are excluded it will determine how you go about your search strategy, and what kinds of studies you find. If you’re not clear enough about your question at this stage, you may miss papers that are really of interest to you, or find lots of paper that’s not what you wanted. your question will also determine your analysis of the results of the studies – which outcomes do you want to measure, are there specific issues you want to explore, what information do you need to find in the included studies? It’s worth spending time to think this through in some detail at the beginning of the process. Not only can it help you plan your work, but a clear idea of the scope of your review will help you avoid bias later on. By laying down your parameters objectively in advance, you can reduce the risk of making decisions or changing your mind later, on the fly, in a way that might be influenced by the results of particular studies. Your question will be discussed and agreed with your CRG at the title registration stage. It’s not impossible to make changes to the scope of your review later on, but make sure you speak to your CRG if you plan to do so.

5 Planificando su tema y alcance
Aborde una pregunta de importancia y relevancia Impacto de un tema de salud– poblacional e individual Impacto potencial de la intervención Considere todas las partes interesadas importantes: consumidores, profesionales sanitarios y elaboradores de políticas Aborde opciones reales para la toma de decisiones Considere una perspectiva internacional Take some time to think about the importance of your question: who is it relevant to? Does it address an important burden of disease? What is the possible impact of your intervention on that burden? Try to select a question of real importance to consumers and care providers. It’s also important to select a question that addresses the real choices faced in decision-making. What are the intervention options available? What are the outcomes that influence those choices? Cochrane reviews should always consider an international perspective. The burden of specific diseases may vary greatly in different countries or different populations. The intervention options available and the way health systems operate may also be different, as well as the outcomes of importance. Cochrane reviews may be used by people anywhere the world, in contexts very different from yours, so it’s important not to make assumptions when planning or interpreting the results of your review.

6 ¿Una pregunta amplia o restringida?
Ventajas Fácil de redactar Fácil de leer Exhaustiva Generalizable Desventajas Necesita múltiples revisiones Puede ser definida selectivamente Compleja Puede obviar efectos de subgrupos Una revisión de revisiones puede ser preferible Consider whether you wish to answer a narrow question, e.g. looking at one specific intervention in a specific patient group, or a broader question, e.g. looking at all interventions to address a particular health condition, or something more complex like health system or community interventions. A well-focussed systematic review question will be broad enough to answer a useful question, allowing for some of the variations that will always be observed in a field, but not so broad that it doesn’t make sense to consider all those studies together in one review. Narrower reviews are easier to write and easier to read, but you may need to have multiple reviews to answer all the questions relating to a condition or type of intervention. Broad reviews are more comprehensive, but they can be complex, more difficult for authors to write, and can miss some of the detail possible in a narrower review. In some cases what’s most appropriate can change over time. There was once a Cochrane review, ‘Interventions for shoulder pain’, that looked at all possible interventions – steroid injections, physiotherapy, exercise, pain killers. Over time, however, as more and more studies were published, it became unmanageable, and has now been split into a set of reviews looking at one specific intervention. One way that the Cochrane Collaboration manages sets of narrow reviews is to publish Overviews of Reviews – these are brief papers that summarise the findings of multiple related reviews. More information about these Overviews is available in Chapter 22 of the Handbook, if you’re interested in reading more. There’s no right or wrong answer to this - it depends on what you’re interested in. Your Review Group may have a preference based on their experience and how your review fits with other similar reviews already published. Vea el Capitulo 22 del Cochrane Handbook

7 Índice Importancia de una pregunta de revisión bien definida
Componentes de una pregunta de revisión Qué incluir en el protocolo Vea el capitulo 5 del Cochrane Handbook

8 Componentes de una pregunta
Describa los componentes siguientes en detalle Considere variaciones que desea explorar en la revisión P Población I Intervencion C Comparación O Desenlaces (outcomes) You will need to define each aspect of your question very clearly. ASK: Who has seen this PICO format before? It can be used to design a study, or a literature search, and it’s also useful for thinking through the question for your systematic review. You will need to think about each of these components and define in detail: who are you interested in studying in your review? What is the intervention or group of interventions you want to test? What will the interventions be compared to? What outcomes will tell you which intervention is the most effective? Think about what you’re interested in, and what you’re not interested in. Within each component, it’s also important to think about the variations that you would like to explore further, such as different populations for whom the intervention might work differently, or variations on the way the intervention can be applied.

9 Criterios de elegibilidad
Reglas para decidir qué estudios incluir en la revisión Basados en: Algunos o todos de los componentes de la pregunta PICO más definición de los diseños de estudios elegibles Cualquier cambio en los criterios de elegibilidad tras la publicación del protocolo require justificación en la revisión When you have clearly defined your question, and identified in detail the components you would like to investigate, you can then define the eligibility criteria for your review. Eligibility criteria are the essential components, the boundaries, that determine whether a study is included and discussed in the review, or whether it is excluded. Remember that the eligibility criteria for a review may be different from the ideal criteria you might set if you were designing a primary study yourself. For example, you may wish to look specifically at the impact on people with a certain stage of disease, or you might have a preferred model for implementing a complex intervention. However, the body of studies you find in the literature might show considerable variation from your ideal model, or might incorporate a mixture of participants with different stages of disease. If these studies are included in your eligibility criteria, you can explore the effect of these differences within the review. If you rule them out, they will be excluded altogether. It’s important to articulate each component carefully, so that when you come to making decisions about including studies in the review, you are doing so as objectively as possible. Having clear criteria to refer to will help you avoid ad hoc decisions that may introduce bias. We’ll go through each of these components in more detail.

10 Población Definición clara para identificar las personas de interés
Dos aspectos a considerar: Condición de salud ¿Cómo fue diagnosticada?, ¿por quién? Población y contexto Cualquier restricción debe tener una justificación clara: La alternativa es incluir y explorar en el análisis de subgrupos First: the population (sometimes also called the participants, or people). What are the most important characteristics that describe the people you are interested in? The level of precision you need will depend on the topic of your review, but should always be detailed enough to identify which studies you wish to exclude from the review. For example, if you are interested in a specific population with defined diagnostic criteria, e.g. a particular stage of breast cancer, or a particular genetic marker, you will need to describe the criteria in some detail. Keep in mind that your ideal diagnostic criteria may not be universally used, or even available, and older studies may not have access to the newest available tests. Alternatively, if you are looking at a broader group of people with a health condition, e.g. any stage of breast cancer, or even a healthy population with no health condition, less detail will be needed. Whatever limits you place around the group of people should have a clear rationale: if you are limiting to a specific stage of disease, or to a specific age group, is this because you expect this group to react differently to an intervention than other people? Remember: once you have defined your eligibility criteria, you can also identify other differences of interest that you would like to explore in the review.

11 Poblaciones mixtas Estudios en los que solo algunos participantes cumplen los criterios de la revisión: Ejemplo: el criterio es niños hasta 16 años, y se encuentra un estudio que incluye hasta los 18 años ¿Qué es lo más consistente con el objetivo de su revisión? Incluir el estudio completo Puede seleccionar un umbral (ej. 80%, o la mayoria) Incluir solo los participantes que cumplen sus criterios La información separada puede no estar descrita en el artículo Excluir el estudio completo Planificar y justificar en el protocolo cómo se manejarán estos estudios Sometimes a study includes some ‘eligible’ participants and some ‘ineligible’ participants, for example when an age cut-off is used in the review’s eligibility criteria. In this situation, how will you apply your eligibility criteria? Should the study be included or excluded? You have several options for how to treat populations where only a subset meets your criteria: 1. You could include the whole study – although this will mean some participants who don’t meet your criteria will be excluded, it means you won’t lose all the information about those participants who do meet your criteria. You may wish to select a threshold or cut-off point for this – for example, you could decide to include any study in which at least half, or at least 80% of the population meets your criteria. 2. You could decide to only include information on those participants who meet your criteria. This ensures that you don’t include any information from ineligible participants. However, detailed information on which participants met your inclusion criteria and separate results for those participants may not be available. You can try asking the authors of the study for separate information, but you may not be able to obtain it. 3. Finally, you can decide to exclude the whole study. That is, you can decide that the risk of including some inaccurate information from ineligible participants outweighs the benefit of including the study at all. If possible, it is good practice to specify in your protocol how you plan to manage studies where only some of the participants meet your eligibility criteria, particularly where you know there are many mixed studies in your field (such as reviews of joint replacements that often combine kip and knee replacements), or where you have given a cut-off point (such as an age group) that you know will not always match the cut-off points of your included studies. A rationale should be given for why you have chosen a particular approach. Remember that it’s not always possible to predict when this situation will arise, and that in some cases, although post hoc decisions should be avoided, it may be better to consider studies on a case by case basis, rather than stick to an arbitrary rule. When making post hoc decisions, you should consider the overall aims and rationale for defining the scope of your review, and your decisions should be documented in your review. You may wish to conduct a sensitivity analysis on your results to assess the impact of your decisions on the review’s findings.

12 Equidad y poblaciones especiales
Considere si la equidad y la referencia a poblaciones especiales son importantes para la revisión Ejemplo: sexo, edad, etnia, geografía, estatus económico, educación, etc. ¿Por qué? Diferente prevalencia, progreso e impacto de la enfermedad Diferentes efectos o perfil de seguridad de la intervención Diferente relevancia de los desenlaces Cochrane reviews seek to be relevant internationally and across contexts, and it’s important to consider your question in relation to all the different types of people who may be affected. Prevalence and progress – e.g. antibiotics for sore throat – may not be useful in high-income settings, where impact of the disease is not great. In some low-income countries there is a greater likelihood of progression to rheumatic fever, with very serious consequences, such that you might come to a different conclusion about the importance of intervention. Different effects or safety – e.g. some interventions may work differently in different cultural settings (e.g. communication and education interventions), or there may be biological differences in the way interventions work among different ethnic groups, in women compared to men, or in children compared to adults. Different outcomes of importance – e.g. for interventions in children, developmental milestones or attendance at school may be important outcomes that don’t apply to adults. You may need to measure outcomes differently in some populations, e.g. measuring pain in newborn babies. The cost of an intervention may be very important for people without health insurance, or for policy makers planning implementation in resource-poor settings. The duration of treatment required may be important for participants in rural settings who travel long distances to access treatment. Although these may not form part of your eligibility criteria, they will assist you in considering other aspects of your question as you plan your review.

13 Intervención Detallar tanto como sea posible
Formulación Dosis, intensidad Administración Pauta, frecuencia, duración Equipamiento Personal (cualificación, capacitación) Ubicación, contexto Aislada o en combinación con otras intervencion(es) Cualquier restricción debe tener una clara justificación La alternativa es incluir y explorar en el análisis de subgrupos Next, you will need to describe the intervention in enough detail to distinguish your intervention of interest from those interventions that fall outside the scope of the review. So, if your review is looking at a very specific topic, such as a specific dose of a specific drug, you can be very narrow in your definition. If you are looking at a more general topic, such as a class of drugs, or a more complex, multi-component intervention, you can be less detailed in your criteria, allowing for expected variations in the literature. However, you must be able to clearly identify the core or common factors that determine whether each study, each variation, falls within the review, or is so different that it should be excluded – whether this is a minimum clinically effective dose or duration of drug treatment, or essential components of a complex intervention. Based on the objective of your question, think carefully about the advantages and disadvantages of including studies that test your intervention in combination with other interventions. If you are interested in the direct effects, say, of phsyiotherapy for shoulder pain, then a study that looks at physiotherapy in conjunction with painkillers will not answer that question, because the effects of physiotherapy are confounded with those of painkillers . Alternatively, you might be interested in the effects of multi-component interventions, in which case a study of physiotherapy plus painkillers might be appropriate. It is particularly important to be as clear and informative as you can when describing complex interventions, such as multi-component clinical interventions like rehabilitation programs, educational or behavioural interventions, community-based interventions, etc. These are often poorly described in the literature, which makes it difficult to make decisions about inclusion, and difficult for users of the review to implement the intervention if it is found to be effective.

14 Ubicación y contexto Las intervenciones pueden funcionar en algunos contextos pero en otros no Disponibilidad y accesibilidad Equipación Experiencia y pericia del personal disponible Prioridades atendiendo al contexto local Sistema de pago Diversidad cultural y lingüistica Nivel socioeconómico Contexto rural/urbano Again, it’s important to consider your intervention and how it might be applied internationally, and in a variety of contexts. Interventions may work differently in some contexts, or need to be applied differently. Factors you may wish to consider can include: whether the intervention is available in every context, or does it depends on specialised equipment itself that may not be available, where that’s an expensive scanning machine or something simple like running water? are there specific skills or training that the staff implementing the intervention will need? Will different staff be implementing the intervention in different settings? is the intervention acceptable in all cultural contexts, and will it work the same way? is the intervention affordable to people with different incomes, or under different insurance systems? Vea la Sección del Cochrane Handbook

15 Comparación Basada en el objetivo de su revisión
Defina los grupos control activos con tanto detalle como la intervención Sea claro con lo que quiere decir por “no intervención” e.j. no intervención, placebo, atención usual, etc. Puede permanecer abierto a cualquier comparación encontrada, pero sea explícito The comparisons you’re testing against your intervention of interest should be clearly based on the objective of your review question. If you review is comparing the intervention against a specific active alternative (or more than one), e.g. one drug versus another, or health professional versus peer-led interventions for mental illness, the comparisons should be described in as much detail as the intervention. You may be interested in the effects of caffeine compared to any alternative intervention, or no intervention at all. In which case, you don’t need to specify a specific comparison for your eligibility criteria. Even if your objective is to test your intervention against no intervention, remember that may be important differences between inactive comparisons – such as truly doing nothing, or using a placebo, or leaving in place whatever ‘usual care’ is for this population. Remember, too, that ‘usual care’ may vary a lot from study to study, so plan to examine these differences carefully if this applies to your review. Again, remember to consider the real choices available to people making decisions in this area – what are the options currently available in different contexts? Have some intervention options become obsolete (remembering that interventions that are obsolete in high-income countries and large urban hospitals may still be in use in other places)? If your review is broad, you can choose to include studies comparing your intervention to any possible comparison – if that’s the case, make sure you state this clearly.

16 Desenlaces (Outcomes)
Raramente parte de los criterios de elegibilidad Excluir estudios según los desenlaces declarados puede introducir sesgos Los desenlaces pueden ser declarados de forma selectiva por los autores de los ensayos Información adicional puede estar disponible Puede ser apropiado si los desenlaces son importantes para la formulación de la pregunta: Ejemplo: prevención vs tratamiento, intervenciones usadas para más de una condición Sea claro en su protocolo Moving on to outcomes, note that it is not always expected that outcomes will form part of the eligibility criteria for a review. Commonly, studies that do not measure your outcomes of interest are still included and noted in the review, although they cannot contribute to your analysis of those outcomes. It is important to include these studies so that you are presenting a complete picture of the literature. It’s particularly important to consider the possibility of outcome reporting bias. ASK: Can anyone explain the meaning of outcome reporting bias? You are probably familiar with the concept of publication bias – that is, studies with positive or significant findings are more likely to be published than non-significant studies. That also applies within studies to the reporting of results for individual outcomes - outcomes with positive or significant findings are more likely to be fully reported in a paper, which means they’re more available to be included in your review. Given that, it’s important to consider the possibility that your outcomes of interest may have been measured by a study, even if they were not reported. By excluding these studies without exploring further, you run the risk of introducing bias to your review. Don’t forget, also, that it may be possible to contact the authors of a trial and obtain additional information for these studies. In some cases it is appropriate to include the outcomes in your eligibility criteria – for example, if you are interested in prevention, then your included studies must measure prevention, and not only treatment outcomes. For interventions with many applications, you may wish to define your review to cover one particular field – the Cochrane Library currently has separate reviews looking at hormone replacement therapy for menopausal symptoms, for cardiovascular outcomes, and cognitive outcomes. Whether your outcomes are part of the eligibility criteria or not should be clearly stated in your protocol. Fuente: Dwan K, Gamble C, Kolamunnage-Dona R, Mohammed S, Powell C, Williamson PR. (2010) Assessing the potential for outcome reporting bias in a review: a tutorial. Trials. 11:52

17 Desenlaces Identificar desenlaces relevantes
Para consumidores, profesionales de la salud, elaboradores de políticas Incluir efectos adversos Relevantes a diferentes poblaciones Definir puntos temporales clave Mediciones adecuadas (por ejemplo, definiciones, escalas) Evitar desenlaces irrelevantes (por ejemplo, bioquímicos, subrogados, de proceso) Considerar conjuntos de desenlaces clave y desenlaces usados por revisiones relacionadas Planifique cómo seleccionar entre resultados similares Considerar en el protocolo y en la revisión los desenlaces importantes independientemente de la posibilidad de encontrar datos

18 Priorización de desenlaces
Primary outcomes (desenlaces primarios, máx. 3) Usualmente incluir al menos un daño Secondary outcomes (desenlaces secundarios) Desenlaces principales restantes Desenlaces adicionales de menor prioridad Main outcomes (desenlaces principales, máx. 7) Esenciales para la toma de decisiones Base para el análisis y los resúmenes You should specify a small number of primary outcomes, that will form the basis of the conclusions of your review, including at least one potential harm. The rest of your outcomes will be considered secondary outcomes, but keep in mind that the total number of outcomes to be addressed should be kept as small as is reasonable for your question, and focus on those outcomes that are important for decision-making. It’s important to prioritise your outcomes to help you in reporting the results of your review, particularly when it comes to summarising your results. Cochrane reviews have a range of short formats to summarise results, such as the abstract, plain language summary, or Summary of Findings table of your review. You may not be able to report against all your primary and secondary outcomes in each summary, so we recommend that you identify a group of outcomes – including your primary outcomes and perhaps a small number of your secondary outcomes – that can be designated as your main outcomes, and prioritised in any summary of your results. These should be the outcomes that are most important for decision-making, whether or not you expect to find enough data in the literature. Also, try not to duplicate within your main outcomes – avoid including multiple variations on the same outcome (e.g. weight, BMI), or measures of the same outcome at multiple time points, without a clear rationale. Additional variations and time points can be included among your other secondary outcomes.

19 Tipos de desenlaces especiales
Recursos y consejos disponibles: Cochrane Adverse Effects Methods Group Cochrane Patient Reported Outcomes Methods Group Campbell and Cochrane Equity Methods Group Campbell and Cochrane Economics Methods Group Cochrane Qualitative Research Methods Group Ver At these early stages, it’s appropriate to consider whether the important outcomes for your review incorporate some of these outcome types. Cochrane reviews allow for more in-depth consideration of outcome types that are commonly encountered, such as adverse effects and issues of equity. Alternatively, you may wish to incorporate specialised outcome types such as economic or qualitative evidence. Consideration of these topics may require additional systematic literature searching, and more advanced analysis methods. These topics will not be covered in depth in this course, but further information is available in the Handbook, and on the websites of the Methods Groups who contribute to the Cochrane Collaboration in these areas – website details are available on the cochrane.org website. Vea los capitulos 14,15,17,20 del Cochrane Handbook

20 Diseños de estudio Seleccionar el diseño mas apropiado para la pregunta Para la mayoría de las revisiones Cochrane : Ensayos clínicos aleatorizados Previenen diferencias sistemáticas entre grupos A veces también ensayos clínicos controlados (quasi-aleatorizados) ASK: who was under the impression that Cochrane reviews only include randomised trials? In fact, Cochrane reviews mostly include RCTs, but in some cases we do include other study designs. We always aim to include the most appropriate study designs to answer the review question. For straightforward questions about the effects of interventions, that will usually be RCTs. Methodological research tells us that RCTs are the best way to avoid bias introduced by systematic differences between the groups in a study. Usually that’s all you need to specify for your eligibility criteria. In some cases you might want to be specific about an aspect of study design for example if you wish to specifically exclude crossover trials from your review , or in some cases we also include quasi-randomised trials (those trials with methods of allocation that are almost random but not quite, such as alternating allocation).

21 Estudios No-aleatorizados
Acordar con su CRG Justificación clara ECAs inapropiados o improbable en la práctica (e.j. salud pública, temas complejos de sistemas de salud) Medición de desenlaces particulares (e.j. efectos adversos, económicos, cualitativos) No solo porque no hay ECAs disponibles Diseños específicos de elección: e.j. estudios controlados antes y después; series temporales interrumpidas Considerar unos criterios mínimos de diseño Sea consciente del mayor riesgo de sesgos Some Cochrane reviews will look at non-randomised studies. You must have a clear rationale for doing this – that is, why would RCTs not be able to provide this evidence? It is not enough to say that you don’t believe there are any RCTs measuring this outcome. If an RCT is the most appropriate way to measure an effect, and there are none, then Cochrane reviews can conclude that there is no appropriate evidence, and that new studies should be conducted. Unlike a guideline or a local policy, we are not obliged to provide a recommendation if we don’t believe the evidence is sufficient. However, in some cases other study designs are appropriate to answer questions. For example, in some cases RCTs may not be appropriate, e.g. where they might be unethical, or seriously impractical, such as in the case of large-scale changes to health system structures, or public health interventions across whole communities or even countries. There are also some outcomes that RCTs are not able to measure well. RCTs are not always good at measuring adverse effects, particularly rare or long-term effects. In those cases, you might need to look for cohort or case-control studies, perhaps government monitoring data, etc. If you’re incorporating economics or qualitative data in your reviews, these have their own study designs that you may wish to consider. These kinds of studies aren’t usually incorporated in your primary analysis of the effectiveness of the intervention, but can be used to inform and interpret the results. ASK: Is anyone planning to include non-randomised studies in their review? Whenever you plan to include non-randomised studies, you must have the agreement of your CRG – not all CRGs will be happy for you to do this. You should also specify which non-randomised designs you will include. Further advice on this is available from your CRG, including recommended minimum design criteria for non-randomised studies. Whenever you’re including non-randomised studies, you must be aware of the increased risk of bias in the results. Make sure you are familiar with the risks, how to assess them, and how best to analyse the results of these studies. Vea los capitulos 13, 14,15,20, 21 del Cochrane Handbook

22 Convertir una pregunta a título
Los títulos Cochrane tienen formatos estándar ‘intervention’ for ‘issue’ Antibiotics for acute bronchitis Community-wide Interventions for increasing physical activity También pueden incluir otros detalles: Immediate versus delayed treatment for cervical intraepithelial neoplasia Inhaled nitric oxide for respiratory failure in preterm infants Pool fencing for preventing drowning in children The titles of Cochrane reviews are usually based on the standard format: ‘intervention’ for ‘population’. In some cases there are variations, for example if you wish to include a specific comparison, a specific population, or if yours is a review of a prevention rather than treatment intervention. This will be agreed with your CRG at the title registration stage.

23 Índice Importancia de una pregunta de revisión bien definida
Componentes de una pregunta de revisión Qué incluir en el protocolo Vea el capitulo 5 del Cochrane Handbook

24 ¿Qué incluir en el protocolo?
Antecedentes Descripción detallada de la condición y de la intervención Métodos “Criteria for considering studies for this review” Describir claramente los criterios de elegibilidad Listar los desenlaces planificados “Data collection and analysis” Listar los análisis de subgrupos planificados There are several places in your protocol where the details of your question are explained. In the Background, you can give your detailed descriptions of the condition of interest, including the burden of disease, the population, and how the condition affects people. In the Methods section, your eligibility criteria are listed in the section called ‘Criteria for considering studies for this review’. Your list of outcomes to be reported is also included here, even if they are not part of your eligibility criteria. Finally, those additional factors and variations that you want to explore within your review can be planned as subgroup analyses in the section called ‘Data collection and analysis’. We’ll be talking in more detail about analysis methods in separate sessions.

25

26

27

28

29 Mensaje clave Reflexionar en detalle sobre el alcance de la revisión antes de comenzarla (e.j. usando el modelo PICO ) Usar esta información para definir criterios de elegibilidad específicos y claros Esta información también ayudará a definir la estrategia de búsqueda, la obtención de datos y el análisis

30 Referencias Reconocimientos
O’Connor D, Green S, Higgins JPT (editors). Chapter 5: Defining the review question and developing criteria for including studies. Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version [updated March 2011]. The Cochrane Collaboration, Available from Reconocimientos Compilado por Miranda Cumpston. Basado en el material del Australasian Cochrane Centre . Aprobado por Cochrane Methods Board Traducido por Nelcy Rodríguez, Virginia Rodríguez y Jesús López-Alcalde