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Critical Appraisal Skills- 1 Cohort studies Clinical Research FelloProgramme  Introduction  ClinicalAppraisal Skills as part of Evidence Based Medicine (EBM)  Cohort studies  Understanding of Core Concept  Confounding factors  Bias  Risk difference  Hazar ratio  Confidence Interval  Questions 19/11/2024Dr Aybaniz IsmayilliIntroduction Critical Appraisal Critical appraisalskills are the ability to systematically evaluate research studies to determine their validity, reliability, and applicability to a specific context. Cohort Studies Follows a group of people (prospectively/retrospectively) over a period of time to see how things change ex: Monitoring a group of healthy individuals in 2024 to track who develops diabetes by 2030 based on diet and lifestyle factors. (prospective) ex: Using medical records from 2001 to 2005 to evaluate whether patients who took a specific medication developed heart disease compared to those who did not. (retrospective) Incidence, nature of history of certain conditions, analysing associations, diagnosis 19/11/2024 3 Appraisal Formulated research question Introduction Credibility Hypothesis Valid study design Methods Valid outcome measure Bias Results Statistically significant Measuring tests Discussion Conclusion Generalizability Limitations 19/11/2024 4Critical Appraisal Framework CASP Checklists - CriticalAppraisal Skills Programme 19/11/2024 5 In adults aged 65 years and older, does a history of COVID infection compared to no prior infection increase the risk of developing persistent or new clinical sequelae during the post-acute phase ? 19/11/2024 Pitch deck title 6 INTRODUCTION 19/11/2024 Pitch deck title 720XX Pitch deck title 920XX Pitch deck title 10 Does the article can answer the same question as your clinical question? Answer: Yes  Is the article recently published (within 5 years) Answer: Yes, 2022  Do the authors present a hypothesis? Answer: Yes The hypothesis is that adults aged 65 years and older who had SARS-CoV-2 infection are at an increased risk of developing persistent or new clinical sequelae in the post-acute phase compared to those without prior infection. 19/11/2024 11 METHODS 19/11/2024 Pitch deck title 1220XX Pitch deck title 13 Is the study design valid for your question? Answer: Yes A cohort study is suitable because it compares outcomes (persistent or new clinical sequelae) in exposed (SARS-CoV-2 infected) and non- exposed (non-infected) groups over time, effectively addressing the question of association. 19/11/2024 14 CONFOUNDING F ACTORS Confounding factors are variables that can distort the apparent relationship between an exposure and an outcome because they are associated with both. They can lead to incorrect conclusions if not accounted for in the study design or analysis. 20XX Pitch deck title 15 Older individuals are more likely to have severe COVID-19 due to weaker immune Ensuring both groups were similar Age systems. in age (matching). Age is also linked to an increased risk of Analyzing results separately for long-term health problems, even without different age ranges (stratification). COVID-19. Ensured that both the SARS-CoV-2 Men and women may experience COVID- distribution of males and females Sex 19 differently due to biological factors Analyzed the results separately Balanced the prevalence of pre- People with conditions like hypertension, existing conditions between the Pre- diabetes, or dementia are more likely to have SARS-CoV-2 and control groups. existing severe COVID-19. condition These conditions can also independently 30% of the infected group had increase the risk of long-term health issues, diabetes, the control group also had a similar percentage with regardless of COVID-19. diabetes. 20XX 16 Selection Bias Selection bias occurs when the participants in the study are not representative of the target population, which can affect the generalizability of the findings. • The study used a large Medicare database, ensuring a representative sample of adults aged 65 and older in the U.S. • Multiple comparison groups were included (non-infected individuals from 2020, 2019, and viral respiratory infection cohorts) to enhance robustness. 20XX Pitch deck title 17 Measurement Bias Measurement bias occurs when the exposure, outcomes, or confounders are inaccurately measured or classified, leading to systematic errors.  Determined using objective PCR test results and ICD-10 codes, minimizing misclassification.  All participants were classified into exposure and outcome groups using the same procedures 20XX Pitch deck title 18 Hazard Ratio Compare the risk of an event (like developing a disease or experiencing an outcome) happening in two groupsover time. It indicates how much more (or less) likely an event is to occur in one group comparedto another. • HR = 1: No difference in risk betweenthe two groups. • HR > 1: The event is more likely to occur in the exposedgroup. For example, HR = 2 means the risk is twice as high. • HR < 1: The event is less likely to occur in the exposedgroup. For example, HR = 0.5 means the risk is half as likely. "How much faster/sloweris the risk of the outcome?" 20XX Pitch deck title 19 Risk Difference Risk difference is the absolute difference in the proportion of individuals experiencing an outcome between two groups. RD = Risk in Exposed - Risk in Unexposed • risk difference of 8%, COVID infection is associated with an additional 8 % absolute risk of developing respiratory failure. • "How many more/fewer people experience the outcome?" 20XX Pitch deck title 20 Confidence Interval The confidence interval provides a range within which the true value (e.g., risk difference, mean, or odds ratio) is likely to lie, with a certain level of confidence, typically 95%. A 95% CI means that if the study were repeated 100 times, the true effect would lie within the interval in 95 of those repetitions. 20XX Pitch deck title 2120XX Pitch deck title 2220XX Pitch deck title 23 What are the results of this study? The study found that adults aged 65 years and older with a history of SARS-CoV-2 infection had a significantly higher risk of persistent and new clinical sequelae during the post-acute phase compared to non-infected individuals. Increased risks for conditions like respiratory failure (7.55 times higher risk), fatigue (1.59 times higher), and hypertension (1.27 times higher). 32% of participants in the SARS-CoV-2 group experienced at least one sequela. 20XX 24 Summary Positive/Methodologically Sound: • Large Sample Size: • Medicare data provided a robust, representative cohort of older adults. • Propensity Score Matching: • Balanced confounding variables like age, sex, and pre-existing conditions. • Multiple Comparison Groups: • Included controls from 2020, 2019, and other respiratory infections. • Validated Data Sources: • Used ICD-10 codes and claims data, ensuring consistency and accuracy. 19/11/2024 25 Summary Negative/Relatively Poor Methodology: • Residual Confounding: • Despite adjustments, unmeasured confounders (e.g., lifestyle factors) may remain. • Retrospective Design: • Relies on historical data, which may include inaccuracies or incomplete records. Unknowns: • Generalizability Beyond the Elderly: • The findings may not apply to younger populations or those outside the Medicare system. • Unmeasured Variables: • Factors like socioeconomic conditions or healthcare access differences might not be fully accounted for. 19/11/2024 26 Questions? 19/11/2024 2719/11/2024