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What Is A Critically Appraised Topic (CAT) – A Guide With Examples

Published by at December 28th, 2023 , Revised On May 9, 2024

A Critically Appraised Topic concisely synthesises the best available evidence on a specific clinical question. It goes beyond a mere summary, involving a meticulous appraisal of the methodology, results, and relevance of research studies. CATs act as pragmatic tools, offering healthcare professionals a structured pathway to assimilate and apply evidence to their day-to-day decision-making.

In the contemporary healthcare milieu, where information burgeons ceaselessly, the significance of Evidence-Based Practice cannot be overstated. CAT serves as a linchpin in this process, crucial in transforming raw research data into actionable insights for practitioners.

From traditional literature reviews and critically appraising evidence, CAT empowers healthcare professionals to navigate the complexities of medical literature, ensuring that decisions are grounded in the most current and reliable information available.

Key Components Of A CAT

These key components encompass the entire process, from formulating a precise clinical question to critically appraising the evidence and analysing sources that will inform clinical decision-making.

Formulating A Focused Clinical Question

PICO(T) Framework

Formulating a focused and answerable clinical question is the cornerstone of a successful CAT. The PICO(T) framework provides a structured approach, breaking down the question into its essential components:

  • P – Patient/Population: Who is the patient or population of interest?
  • I – Intervention: What is the intervention or exposure being considered?
  • C – Comparison: Is there a relevant comparison to consider?
  • O – Outcome: What are the desired outcomes or effects?
  • T – Time: Is there a specific time frame for the intervention and outcomes?

This framework not only guides the development of a clear question but also facilitates a targeted search for evidence.

Systematic Literature Review

While there are many different reviews, including scoping review and rapid review, systematic literature review plays an important role in CATs.

Search Strategy

Crafting a comprehensive search strategy is paramount in identifying all relevant literature. This involves selecting appropriate keywords, using Boolean operators, and considering synonyms to cast a wide net. The goal is to leave no stone unturned in pursuing evidence that directly addresses the formulated clinical question.

Inclusion And Exclusion Criteria

Systematic literature reviews must adhere to strict criteria to ensure the selected studies align with the research question. Inclusion criteria define a study’s characteristics to be considered, while exclusion criteria delineate factors that render a study unsuitable. This meticulous selection process ensures the relevance and applicability of the chosen evidence.

Critical Appraisal

Validity And Reliability Assessment

Rigorous critical appraisal is the linchpin of a CAT. Validity and reliability assessments scrutinise the methodological robustness of selected studies. Validity ensures that the study measures what it claims to measure, while reliability assesses the consistency of its results. Thorough evaluation in these domains provides that the evidence base is trustworthy and applicable to clinical scenarios.

Bias Evaluation

Systematic biases can compromise the integrity of study findings. CATs meticulously assess potential biases such as selection bias, performance bias, and detection bias. Identifying and understanding these biases is integral to gauging the overall quality and reliability of the evidence.

Applicability To Clinical Practice

Beyond methodological rigour, CATs evaluate the practical applicability of the evidence to real-world clinical scenarios. This involves considering the patient population, intervention specifics, and outcomes, ensuring that the synthesised evidence aligns with the nuances of diverse clinical settings.

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Steps To Create A CAT

Creating a Critically Appraised Topic (CAT) involves a systematic and meticulous process, guiding healthcare professionals from identifying a clinical issue to synthesising findings. Let’s dive deeper into the sequential steps that constitute the construction of a robust and informative CAT.

Step 1: Identifying A Clinical Issue

The inception of a CAT lies in recognising a pertinent clinical issue or question. This may stem from challenges encountered in daily practice, uncertainties about the efficacy of interventions, or gaps in existing knowledge. Healthcare professionals lay the foundation for a targeted exploration through the CAT methodology by pinpointing a specific clinical concern.

Step 2: Formulating A Specific Question

Once the clinical issue is identified, the next step is formulating a clear and focused clinical question. Utilising the PICO(T) framework (Patient/Population, Intervention, Comparison, Outcome, Time), practitioners can articulate a question that is answerable and guides subsequent steps in the CAT process.

The precision of the question ensures that the ensuing literature search and evidence appraisal are tightly aligned with the clinical inquiry.

Step 3: Conducting A Comprehensive Literature Search

A comprehensive literature search is the backbone of evidence-based practice and, by extension, the creation of a CAT. Employing the search strategy developed from the formulated question, healthcare professionals delve into databases, journals, and other reputable sources. The goal is to cast a wide net, capturing studies that contribute relevant insights to the targeted clinical issue.

Step 4: Selecting Relevant Studies

The literature search yields a plethora of studies, but not all are equally relevant or reliable. Rigorous inclusion and exclusion criteria guide the selection process, ensuring that only studies meeting predefined standards contribute to the critically appraised topics. This step demands a discerning eye to filter out studies that may introduce bias or lack applicability to the clinical context.

Step 5: Appraising The Evidence

Critical appraisal is the crux of a CAT, demanding a thorough evaluation of selected studies. Validity and reliability assessments, scrutiny of biases, and consideration of applicability to clinical practice form the core of this step. The goal is to sift through the evidence, identifying high-quality studies that withstand methodological scrutiny and contribute robust insights to address the clinical question.

Step 6: Synthesising The Findings

With a curated selection of appraised evidence, the final step involves synthesising the findings into a coherent and digestible summary. This synthesis not only presents the key results of the selected studies but also highlights patterns, inconsistencies, or gaps in the existing evidence.

The synthesised information becomes the essence of the CAT, serving as a valuable resource for informed decision-making in clinical practice.

Examples Of Critically Appraised Topics

As we explore the practical application of Critically Appraised Topics (CATs), it’s essential to talk about some concrete examples that showcase the versatility of this evidence-based practice methodology. CATs can be tailored to developing a research strategy, each offering unique insights into clinical questions. 

A. Case Studies

CAT Example: “Assessing the Efficacy of a Novel Rehabilitation Approach in Stroke Patients: A Case Study Analysis”

In this CAT, a clinical issue surrounds the rehabilitation of stroke patients using a newly proposed intervention. The focused clinical question may revolve around the effectiveness of the novel approach in improving motor function and quality of life. The CAT would involve a comprehensive search for case studies exploring similar interventions, followed by a critical appraisal of each case’s methodology and outcomes. The synthesis would then present a nuanced understanding of the intervention’s impact based on the collective evidence from the case studies.

B. Clinical Trials

CAT Example: “Comparative Analysis of Antihypertensive Medications in Controlling Blood Pressure: A Critical Appraisal of Randomised Clinical Trials”

This CAT addresses the clinical issue of hypertension management by comparing the efficacy of different antihypertensive medications. The formulated question may inquire about the comparative effectiveness in achieving blood pressure control and minimising side effects. The literature search would focus on randomised clinical trials (RCTs) evaluating these medications. Critical appraisal would assess the validity and reliability of each trial, and the synthesis would present a comprehensive overview of the evidence, guiding healthcare professionals in selecting optimal antihypertensive strategies.

C. Systematic Reviews And Meta-Analyses

CAT Example: “The Impact of Physical Activity on Mental Health: A Systematic Review and Meta-Analysis Critically Appraised”

In this CAT, the clinical issue centers around the relationship between physical activity and mental health. The formulated question may explore the overall impact of physical activity on anxiety and depression. The literature search would prioritise systematic reviews and meta-analyses, ensuring a comprehensive overview of the existing evidence.

The critical appraisal would assess the methodological rigor of the reviews/meta-analyses, and the synthesis would distill the key findings, providing a synthesised perspective on the association between physical activity and mental well-being.

Challenges And Considerations In CAT

While Critically Appraised Topics (CATs) provide a robust framework for evidence-based decision-making, several challenges and considerations arise during their creation. Navigating these challenges is integral to ensuring the reliability and applicability of the synthesised evidence.

Limited Availability Of High-Quality Evidence

One of the primary challenges in creating a CAT lies in the availability of high-quality evidence. In certain clinical scenarios, particularly emerging or niche fields, the literature may be sparse or dominated by lower-quality studies. This paucity of robust evidence can hinder the creation of a comprehensive and well-informed CAT.

Healthcare professionals must grapple with the balance between synthesising the available evidence and acknowledging the limitations imposed by a scarcity of high-quality studies.

Variability In Study Designs

The landscape of healthcare research encompasses many study designs, each with its strengths and limitations. Ranging from randomised controlled trials (RCTs) to observational studies and case reports, the variability in study designs poses a challenge during the critical appraisal stage of a CAT.

Appraising evidence from diverse study types demands a nuanced understanding of each design’s inherent biases and limitations. Healthcare professionals must carefully consider the hierarchy of evidence and interpret findings in the context of the study design to draw meaningful conclusions.

Applicability To Diverse Patient Populations

The generalisability of research findings to diverse patient populations is a crucial consideration in evidence-based practice. Clinical heterogeneity across different patient groups may impact the applicability of evidence to specific demographics or conditions. 

This challenge is particularly pronounced when applying evidence derived from homogeneous study populations to a more diverse real-world clinical setting. Healthcare professionals must critically evaluate the study participants’ demographic characteristics and consider the findings’ relevance to their patient population’s unique characteristics.

Benefits Of Using CAT In Clinical Practice

The integration of Critically Appraised Topics (CATs) into clinical practice offers a myriad of advantages, empowering healthcare professionals with evidence-based insights that directly impact decision-making and patient outcomes. Here, we explore the key benefits that CATs bring to the forefront of modern healthcare.

  1. Informed Decision-Making

CATs serve as invaluable tools for healthcare professionals seeking to make informed and evidence-based decisions in the complex landscape of patient care. By synthesising the best available evidence on a specific clinical question, CATs distil complex research findings into digestible insights.

This process enables practitioners to navigate the vast sea of medical literature with precision, ensuring that decisions are grounded in the most current and reliable evidence. Informed decision-making, facilitated by CATs, contributes to a higher quality of care and enhances patient safety.

  1. Enhancing Patient Outcomes

The ultimate goal of any healthcare intervention is to enhance patient outcomes, and critically appraised topics play a pivotal role in achieving this objective. By critically appraising and synthesising evidence, healthcare professionals can tailor their interventions to align with the most effective and evidence-supported approaches.

This personalised approach, informed by the findings of CATs, has the potential to optimise treatment plans, improve patient satisfaction, and contribute to better overall health outcomes. 

Whether in diagnosis, treatment, or preventive measures, integrating CATs into clinical practice fosters a patient-centred approach that resonates with the principles of evidence-based care.

  1. Keeping Practice Up-to-Date With Current Evidence

The field of healthcare is dynamic, with new research emerging continuously. Staying abreast of the latest evidence is a perpetual challenge for healthcare professionals. CATs, by nature, necessitate a systematic review of the most recent literature, ensuring that practitioners remain up-to-date with current evidence in their respective fields.

This commitment to currency is vital in a rapidly evolving healthcare landscape, where outdated practices can lead to suboptimal patient care. CATs, therefore, serve as a bridge between the latest research and everyday clinical practice, fostering a culture of continuous learning and improvement.

Tools And Resources For Creating CATs

Creating Critically Appraised Topics (CATs) demands a robust toolkit for managing resources and navigating the complexities of evidence-based practice. Here, we explore key tools and resources that empower healthcare professionals in the meticulous creation of critically appraised topics.

Online Databases And Libraries

Some of the top online databases and libraries include the following.


A comprehensive biomedical literature database, PubMed facilitates the systematic literature review phase of CAT creation. Its vast repository includes a diverse range of studies, from clinical trials to systematic reviews.

Cochrane Library

A goldmine for evidence synthesis, the Cochrane Library specialises in systematic reviews and meta-analyses. It offers a wealth of high-quality, peer-reviewed studies critical for the robust appraisal of evidence.


Particularly useful for pharmacological and biomedical research, Embase complements PubMed by indexing a broader range of drug and pharmaceutical literature.

Journals And Speciality Databases

Speciality journals and databases relevant to the specific clinical area of interest provide targeted insights. Evaluating sources can contribute to a more focused and thorough literature search.

Critical Appraisal Checklists

CASP (Critical Appraisal Skills Programme)

CASP provides a suite of critical appraisal checklists tailored to different study designs. These tools guide healthcare professionals in systematically evaluating the methodological rigour of studies.

Joanna Briggs Institute (JBI) Critical Appraisal Tools

JBI offers a collection of critical appraisal tools designed for various types of research, supporting a comprehensive and systematic evaluation of evidence.

AMSTAR 2 (A Measurement Tool To Assess Systematic Reviews)

Specifically designed for appraising systematic reviews and meta-analyses, AMSTAR 2 provides a structured approach to assess the methodological quality of these types of studies.

Training Programs And Workshops

Centre For Evidence-Based Medicine (CEBM) – University Of Oxford

CEBM provides a range of training programs, including workshops and online courses, offering healthcare professionals the skills and knowledge needed to engage in evidence-based practice and create CATs.

Evidence-Based Medicine And Critical Appraisal Courses

Institutions and organisations often offer courses in evidence-based medicine and critical appraisal. These programs equip healthcare professionals with the foundational skills to create robust CATs.

Workshops By Professional Associations

Professional associations in healthcare frequently organise workshops and training sessions focusing on evidence-based practice. These sessions may include hands-on guidance in creating CATs.

Frequently Asked Questions

A Critically Appraised Topic (CAT) is a concise summary and evaluation of the best available evidence on a specific clinical question. It involves a systematic literature review, critical appraisal of studies, and synthesis of findings, providing healthcare professionals with a distilled and evidence-based understanding for informed decision-making in clinical practice.

In occupational therapy (OT), Critically Appraised Topics (CATs) focus on synthesising evidence relevant to specific clinical questions. These concise summaries and evaluations help occupational therapists stay informed about the latest research, enabling evidence-based decision-making to enhance the effectiveness of interventions and strategies in occupational therapy practice.

Critical appraisal in research involves systematically evaluating the validity, reliability, and relevance of a study’s methodology and results. For example, in a clinical trial, critical appraisal may assess the randomisation process, blinding, and statistical methods to determine the study’s reliability, informing healthcare professionals about the evidence’s trustworthiness and applicability.

To write an appraisal for a topic, employ a systematic approach. Critically evaluate the quality, validity, and relevance of evidence, considering study design, methodology, and results. Summarise key findings, highlight limitations, and assess applicability to inform readers about the topic’s credibility and implications for practice.

Critical appraisal involves assessing three main factors: validity (whether the study measures what it claims), reliability (consistency of results), and relevance (applicability to the clinical context). Evaluating these factors ensures a thorough understanding of the quality and applicability of research evidence in evidence-based practice.

No, a Critically Appraised Topic (CAT) is distinct from a systematic review. While both involve a systematic approach to evaluating evidence, a CAT is a concise summary and appraisal of a single study or a few studies, whereas a systematic review comprehensively synthesises evidence from multiple studies on a particular topic.

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