W7-L7 (DSA 458) Case-Control and Cohort Studies (5.10.2023) PDF

Research Methodology (DSA 4580) Step 2: Selecting a Study Approach Case-Control and Cohort Studies Academic Year: 2023-2024 Fifth Year DSA 4580 WEEK 7 LECTURE 7 Abdulhamid Al Ghwainem, BDS, MSc, DClinDent Pediatric Dentistry Assistant Professor in Pediatric Dentistry [email protected] Thu...

Research Methodology (DSA 4580) Step 2: Selecting a Study Approach Case-Control and Cohort Studies Academic Year: 2023-2024 Fifth Year DSA 4580 WEEK 7 LECTURE 7 Abdulhamid Al Ghwainem, BDS, MSc, DClinDent Pediatric Dentistry Assistant Professor in Pediatric Dentistry [email protected] Thursday, 5 October 2023 Copyright © 2023 by PSAU, Abdulhamid Al Ghwainem Disclaimer DISCLAIMER The information presented in this lecture is offered for educational and informational purposes and should not be construed as medical, dental, or research advice. While the amount of information in this handout is vast, and I make every effort to be as current and thorough as possible, the information cannot be taken as a reference manual or textbook. Please note that you should read the required textbooks as specified in the course curriculum and lecture references. 2 Notice WARNING Materials used in connection with this course or lecture may be subject to copyright protection. 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Do not remove this notice 3 Outline § Classifications of research designs. § How to choose a research design. § Case-control studies. § Cohort studies. 4 Lecture Objectives By the end of this session, you should be able to: § Identify and relate different studies approaches and designs for health research. § Select most appropriate research approaches and designs. § Define case-control study design and highlight its importance, key features, advantages and disadvantages. § Define cohort study design and types and highlight its importance, key features, advantages and disadvantages. § Understand and differentiate between odds ratio and rate ratio in case-control and cohort studies. § Differentiate between cross-sectional,case-control and cohort studies. 5 Research Process/Steps Research: answering questions in logical and systematic ways Question Answer Research methodology: how to get from Question to Answer 6 Research Process/Steps Research: answering questions in logical and systematic ways Question Answer Research methodology: how to get from Question to Answer Identify study question Select study approach Design study and collect data 7 Analyse data Report findings Research Process/Steps Research: answering questions in logical and systematic ways Identify study question Select study approach Design study and collect data 8 Analyse data Report findings Research Approaches and Designs § Study design refers to the methods and methodologies used in research to gather the data needed to explore a specific question. § Some research questions are best approached by statistical analysis of data. This is quantitative research. § Others are better answered by looking for patterns, features or themes in the data. This is qualitative research. Illustrates how research methodology and research method relate to each other. Source: Andiappan and Wan (2020) 9 Research Approaches and Designs Study designs in medical research have similar components (as we’d expect from the PICO): • A defined population (P) from which groups of subjects are studied • Outcomes (O) that are measured And for experimental and analytic observational studies: • Interventions (I) or exposures (E) that are applied to different groups of subjects 10 Research Approaches and Designs Algorithm for classifying the types of research, this scheme is intended to classify the study types as clearly as possible. Medical Research Primary Research Epidemiological Research Basic Research Theoretical § § § § Method development § (physics, chemistry § biology, § bioinformatics) § Analytical § measurement procedure Imaging procedure Test development assessment procedure Weaker evidence Secondary Research Applied Cell research Animal research Stem cell research Genetics Tissue banking Clinical Research Descriptive Case Report A report on a single patient with an outcome of interest Case Series A report on a series of patients with an outcome of interest. No control group is involved Analytical Surveillance Study Report obtained from the databases that follow and record a health problem for a certain time Qualitative Ecological Cross-sectional Examines the relationship between exposure and outcome by examining population-level data rather than individuallevel data 11 Exposure and Exposure ← Outcome outcome are at the same time Meta-analysis QuasiExperimental Research Randomised Controlled Trial Case-control Systematic Review Cohort Exposure → Outcome Stronger evidence Research Approaches and Designs Study Designs Decision Tree is not completely exhaustive but covers most basics designs All Types Of Research Designs And Approaches Secondary Research All Types of Reviews Systematic Review Metaanalysis Is it a primary research (collecting new data) or a secondary research (synthesizing already published research)? Primary Research Basic Is it a basic research (e.g.: laboratory research) or clinical research (e.g.: involving human subjects)? Clinical Is there an intervention or experimental group? Yes Yes No Analytical Study Is there a comparison or Interventional/Experi Observational Study mental Study control group? No What is the starting point for research? Randomised Controlled Trial Non-randomised Controlled Trial Descriptive Study Exposure and Outcome at the same time Survey (Crosssectional) Outcome Exposure Case-control Study Cohort Study Case Report Case Series Analytical Crosssectional Study Qualitative Study Based on the work of Grimes et al., (2002). Grimes, D. A., & Schulz, K. F. (2002). “An overview of clinical research: The lay of the land”. The Lancet, 359(9300), 57-61 12 Case-Control Studies: overview Case–control study: a study that compares the exposure histories of people with disease (cases) and people without disease (controls) – Case: a study participant with a disease (e.g.: noncommunicable disease, neuropsychiatric condition, injury, or other disease, disorder, disability, or health condition of interest to the researcher) – Control: a participant who does not have the disease being examined A case-control can be used in the following instances: § The outcome of interest is rare § Multiple exposures may be associated with a single outcome § Funding or time is limited 13 Case-Control Studies: overview Which clinical questions does Case-Control studies best answer? § Particularly useful for rare conditions, it’s often the only option as it’s not appropriate to try to cause a disease using RCTs. § Can be used to identify point of outbreak, looking into the past to see common exposure in the Case histories. § Can look at many exposure factors of the patient’s environment, medical history, diet. This is useful where no single aspect of the patient’s life has been narrowed down as a potential cause. 14 Case-Control Studies: overview § Individual participants in a case–control study are selected for inclusion in the study based on their disease status, then both cases and controls are asked the same set of questions about past exposures § A case–control study is often the best study approach for identifying possible risk factors for a disease participant who does not have the disease being examined 15 Case-Control Studies: overview § Case-control Study identifies patients with a particular outcome (cases) and control patients without the outcome. Looks back and explores exposures and possible links to outcome. Past Retro- Exposed Present Population Future Pro- Cases Exposed Controls Sample Unexposed Unexposed Data always collected retrospectively at one time point on one representative sample Direction of time Starting point in time 16 Case-Control Studies: overview 17 Case-Control Studies: overview Key Features Of Case-Control Studies Aim/Objective Compare exposure histories of a people with a disease (cases) and people without that disease (controls) Research Question Do cases and the controls have different exposure histories? Case/Sample/Population Cases and controls MUST be similar ECXCEPT for their disease status When you use this design The disease is relatively uncommon, but a source of cases is available Requirement/Resources An appropriate source of cases Steps 1. 2. 3. 4. What to look for Recall bias Key statistical measure Odds ratio (OR) Identify a source of cases Define and assign a case definition Decide what type of control population will be appropriate for the study Decide whether cases and controls will be matched 18 Advantages and Disadvantages of Case-Control Studies § Advantages: § Disadvantages: • Relatively quick and inexpensive. • May include researcher bias (selection bias). • Results can easily be tainted by recall bias, where people with the disease or condition are more likely to remember past details compared to people who don’t have the disease or condition. • Control groups can be difficult to find. • Confounding bias. • Cannot tell us about causal relationships (no cause and effect), only calculates the odds. • Can't always be generalised to the general population. • Optimal choice for rare conditions. • Multiple risk factors can be studied at the same time. • Quickly establishes associations between risk factors and disease. This can be especially useful with disease outbreaks, as causes can be identified with small sample sizes. • Few ethics issues as the cases already have the condition. 19 Case-Control Studies: data collection § The first step in designing a case–control study is to identify an appropriate and accessible source of individuals who have the disease or disorder of interest § Hospitals, specialty clinics, physicians’ offices, public health agencies, disease registries, and disease support groups may be able to assist researchers in identifying individuals who are likely to meet the study’s case definition 20 Case-Control Studies: data collection § Case definition: a list of the inclusion and exclusion criteria that must be met for an individual to be classified as a person with the disease of interest in a case series, a case–control study, or another type of study § The first step in defining a case definition is clarifying what constitutes the disease or disorder of interest –Sign: an objective indication of disease that can be clinically observed, such as a rash, cough, fever, or elevated blood pressure –Symptom: a subjective indication of illness that is experienced by an individual but cannot be directly observed by others 21 Case-Control Studies: data collection After defining the disease or procedure of interest, then other important step in establishing a case definition is selecting the relevant PPTs, the person, place, and time characteristics üThe characteristics of the population (person) üThe place where the person lived, worked etc (place) üThe date when the disease or death occurred (time) 22 Case-Control Studies: data collection § Next, an appropriate source of controls must be selected, such as friends and relatives of cases, hospital or clinic patients without the disease of interest, or members of the general population § Control definition: a list of all of the eligibility criteria for inclusion in a comparison population - Controls must be similar to cases except for their disease status, so the inclusion and exclusion criteria for cases that do not specifically relate to the disease must also apply to controls 23 Case-Control Studies: data collection • Matching: the process of recruiting one or more controls who are demographically similar to each case – Frequency matching (also called group matching): ensures that cases and controls in a case–control study have similar group-level demographic characteristics – Matched-pairs matching (also called individual matching) links each case to controls with key variables or similar characteristics, such as genetic siblings 24 Case-Control Studies: data collection § Many case–control studies use no matching § Undermatching: results from matching few characteristics of the cases and controls (or exposed and unexposed participants) -If the Control group is under-matched and there aren’t enough comparable factors to differentiate what is specific to the Case population -For example, if you could not find female Controls to match female Cases, then you cannot assess whether gender is or isn’t a contributing risk factor. 25 Case-Control Studies: data collection § Overmatching: results from matching too many characteristics of the cases and controls -If the Control group is overmatched with exposure and NOT to the cases. -For example, if you overmatched female Controls to female Cases, then you will wrongfully assume that the gender is a contributing risk factor. 26 Case-Control Studies: data collection § Matching should therefore be selected very carefully, and ONLY those that are known to be associated with both exposure and disease should be considered. § The number of matching variables SHOULD also be reduced to as few as possible. § As the number of matching variables grows, the cases and controls will become increasingly similar with respect to the exposure of interest, and the study may produce a misleading result or provide no information. § Additionally, when matching on more than one variable, matching variables should not be strongly correlated with each other. 27 Case-Control Studies: ethics § Researchers conducting case-control studies must be extremely careful about protecting patient privacy and confidentiality. § Consent? § Ethical approval? 28 Case-Control Studies: analysis § Measure of association: a number that summarizes the relationship between an exposure and a disease outcome § Odds ratio (OR): refers to the odds in favour of exposure to a particular factor in cases divided by the odds in favour of exposure in controls. § Case–control studies are able to examine odds of exposure among the diseased and the not diseased § Because the study population is usually not representative of the community as a whole (because cases are preferentially recruited), case–control studies are unable to estimate rates of disease among the exposed and unexposed 29 Case-Control Studies: analysis § Contingency table (also called a crosstab): a row-by-column table that displays the counts of how often various combinations of events happen § Two-by-two (2×2) table: a contingency table displaying two variables that have been divided into dichotomous (yes/no) categories -In the 2×2 table for an unmatched case–control study, the columns are for disease status (case = yes, and control = no) and the rows are for exposure status (exposed = yes, and unexposed = no) Exposure Yes No Total Cases a c a+c Exposure odds ratio (OR) Odds of being exposed among the cases = a/c Odds of being exposed among the controls = b/d Exposure odds ratio = (a/c)/(b/d) = (a*d)/(b*c) Controls b d b+d 30 Total a+b c+d a+b+c+d Case-Control Studies: : analysis For a case–control study, the OR is the ratio of the odds of exposure among cases to the odds of exposure among controls 31 Case-Control Studies: analysis: example Exposure Yes No Total Cases 17 83 100 Controls 13 87 100 Total 30 170 200 Exposure odds ratio (OR) Odds of being exposed among the cases = a/c = 17/83 = 0.205 Odds of being exposed among the controls = b/d = 13/87 = 0.149 Exposure odds ratio = (a/c)/(b/d) = 0.205/0.149 = 1.37 Exposure odds ratio =(a*d)/(b*c) = (17*87)/(13*83)=1479/1079= 1.37 32 Case-Control Studies: : analysis OR = ad/bc § OR = 1 (or close to 1): the odds of exposure were the same (or about the same) for cases and controls § OR > 1: cases had greater odds of exposure than controls, implying that the exposure was risky § OR < 1: cases had lesser odds of exposure than controls, implying that the exposure was protective 33 The Sources of Bias in Case-Control Studies Bias can be introduced because of any systematic errors in the design, conduct, or analysis of research 1. Selection Bias: occurs when individuals or groups in a study differ systematically from the population of interest leading to a systematic error in an association or outcome 2. Misclassification bias: bias that occurs when participants are not correctly categorized, such as when some controls in a case–control study are incorrectly classified as cases or some cases are incorrectly classified as controls due to a systematic problem with the case definition or the control definition 3. Recall bias: bias that occurs when cases and controls systematically have different memories of the past 34 The Sources of Bias in Case-Control Studies Bias can be introduced because of any systematic errors in the design, conduct, or analysis of research 4. Information Bias: arises from systematic differences in the collection, recall, recording or handling of information used in a study. 5. Measurement Bias: occurs when information collected is inaccurate. 6. Confounding: A situation in which the effect or association between an exposure and outcome is distorted by the presence of another variable which can confuse the association between an exposure and an outcome. 35 Critical Appraisal Tools and Checklists of Case-Control Studies: § STrengthening the Reporting of OBservational studies in Epidemiology ( STROBE Checklist): https://www.strobe-statement.org/checklists/ § Critical Appraisal Skills Programme ( CASP): https://casp-uk.net/ § Joanna Briggs Institute (JBI checklist): https://jbi.global/critical-appraisal-tools § The Center for Evidence-Based Management (CEBMa checklist): https://cebma.org/resources-and-tools/what-is-critical-appraisal/ § SIGN Critical Appraisal Notes and Checklists: https://www.sign.ac.uk/what-we-do/methodology/checklists/ § NCCEH https://www.ncceh.ca/sites/default/files/Critical_Appraisal_Case-Control_Studies_2016.pdf 36 Critical Appraisal Tools and Checklists of Case-Control Studies: • Factors to look for: § Selection, recall bias § Inclusion and exclusion criteria § Poorly matched or over-matched controls § Confounding § Data collection § Appropriate statistical analysis § Presentation of results (clear, precise) § Applicability to local and general population 37 Case-Control Study: example Quandalle, C., Boillot, A., Fournier, B., Garrec, P., DE LA Dure-Molla, M., & Kerner, S. (2020). Gingival inflammation, enamel defects, and tooth sensitivity in children with amelogenesis imperfecta: a case-control study. Journal of applied oral science : revista FOB, 28, e20200170. https://doi.org/10.1590/1678-7757-2020-0170 38 Break Out Session Instructions: Scan the following QR code: § Identify and explain the design of the research § Identify cases and controls § What is the Odds Ratio (OR),and what does it mean? 39 Break Out Session Feedback 40 Cohort Studies: overview § Cohort: a group of similar people followed through time together § Cohort study: an observational study that follows people forward in time so that the rate of incident (new) cases of disease can be measured -For simplicity, this lecture will group cohort study designs into three categories: prospective, retrospective, and longitudinal A cohort study can be used in the following instances: § The outcome of interest is common § When there is a link between an exposure and an outcome § The time between exposure and outcome is not too long (adding to the study costs and increasing the risk of participant attrition) 41 Cohort Studies: overview Which clinical questions does Cohort studies best answer? § Risks: What risk factors predict disease? § Aetiology: What factors cause this outcome? § Prognosis: What happens with this disease over time? § Diagnosis: If the test is positive, what happens to the patient? 42 Cohort Studies: overview § All cohort studies have at least two measurement times: -an initial survey determines the baseline exposure and disease status of all participants -then follow-up assessments that identify incident cases of disease § Because all cohort studies examine incident (new) disease, they must be able to demonstrate that the outcome of interest was not present in any members of the cohort at baseline 43 Cohort Studies: overview 44 Cohort Studies: overview § Prospective Cohort study: identifies two groups (cohorts) of patients, one which received the exposure of interest and one which did not. Follows these cohorts forward for the outcome of interest. Very useful in causation as well as prognosis research Past Retro- Present Population Future Pro- Outcome Exposed Unexposed Sample No outcome Outcome No outcome Data collected prospectively at multiple time points on one representative sample Direction of time Starting point in time 45 Cohort Studies: overview § Prospective cohort study: a cohort study that recruits participants because they have or do not have an exposure of interest at the time of the baseline survey, and then follows both exposed and unexposed people forward in time to look for incident cases of disease § Prospective cohort studies collect baseline data about exposures and outcomes in the present and follow the cohort to some point in the future 46 Cohort Studies: overview § Retrospective Cohort Study: identifies two groups (cohorts) of patients to examine the relationship between the exposure and the outcome. Follows thesecohorts backwards for theoutcome of interest. No outcome Present Population Exposed Hospital/Clinical notes/records Outcome Future Pro- Unexposed Sample Past Outcome Retro- No outcome Data always collected retrospectively from Hospital/Clinical notes/records on one representative sample Direction of time Starting point in time 47 Cohort Studies: overview § Retrospective cohort study (sometimes called a historic cohort study): a cohort study that recruits participants based on data about their exposure status at some point in the past and typically also measures outcomes that have already occurred (but happened after the baseline exposures were established) § Retrospective cohort studies use documented baseline data collected at some point in the past and follow the cohort to another point in the past or to the present 48 Cohort Studies: overview § Longitudinal cohort study: a cohort study that follows a group of individuals who are representative members of a selected population forward in time. Exposures and outcomes aredetermined simultaneously in future.h Present Future Pro- Population Sample Past Retro- Data collected prospectively at multiple time points on one representative sample Direction of time Starting point in time 49 Look for: Exposed with disease Exposed without disease Unexposed with disease Unexposed without disease Cohort Studies: overview § Longitudinal studies do NOT recruit participants based on exposure status – instead, participants are recruited based on a defining characteristic, typically those who experienced a common event in a selected period, such as birth or graduation), performing a cross-section at intervals through time § Longitudinal studies may use a fixed population in which all participants start the study at the same time and no additional participants are added after the study’s start date § Alternatively, longitudinal studies may use a dynamic population (also called an open population) with rolling enrollment that allows new participants to be recruited after the study team begins collecting data 50 Cohort Studies: overview 51 Cohort Studies: overview Key Features Of Cohort Studies Approach Prospective or Retrospective Cohort Longitudinal Cohort Aim/Objective Compare rates of a new (incident) disease over time in people with and without a particular welldefined exposure Follow representative sample of a well-defined population forward in time to look for a new (incident) disease associated with a diversity of exposures Research Question Is exposure associated with an increased risk incidence of disease? Is exposure associated with an increased risk incidence of disease? Case/Sample/ Population The study participants MUST be similar EXCEPT for exposure status The study participants MUST NOT have the outcome at the start of the study The study participants MUST be available for followups in months or years after they enrolled The study participants MUST be representative When you use An exposure is relatively uncommon, but a source this design of exposed individuals is available To examine multiple exposures and multiple outcomes, and the time is not a concern Requirement/ A source of exposed individuals is available Resources The research team has adequate time and money for the study 52 Cohort Studies: overview Key Features Of Cohort Studies Approach Prospective or Retrospective Cohort Longitudinal Cohort Steps 1. Identify a source of exposed individuals 2. Decide what type of unexposed individuals will be appropriate for the study 1. Identify a source population 2. Select the exposures and outcomes that will be addressed 3. Decide how long the data will be collected 4. Develop a strategy for increasing participation and reducing attrition What to look for Loss to follow-up (prospective) or missing records (retrospective) Information bias, in which the exposed participant are more thoroughly examined for the disease than that and exposed participant Loss to follow-up Potential data management challenges if a lot of information is collected at many points in time Key statistical measure Incidence rate ratio (RR, also called relative risk) Incidence rate ratio (RR, also called relative risk) 53 Advantages and Disadvantages of Cohort Studies § Advantages: § Disadvantages: • Can estimate incidence of an outcome of interest. • Good choice for rare exposure and common outcome. • Many outcomes can be assessed. • Subjects can be matched. • Can establish timing and directionality of events. • Eligibility criteria and outcome assessments can be standardised. • Administratively easier and cheaper than RCT. • Can tell us about causal relationships (cause and effect). • Ethically safe. • Relatively expensive and time consuming. • Sample size requirements may be very large (especially when looking at rare exposures). • Not suitable for studying rare diseases. • Potential for selection bias. information bias, attrition bias and confounding. • Generalizability limited by sampled population and population definition. 54 Cohort Studies: data collection § All participants must complete the same assessments in order to prevent the information bias that might result when exposed participants are more thoroughly examined for disease than unexposed participants § A strong data management system must be established to link baseline and follow-up data while maintaining the confidentiality of the information provided by participants 55 Cohort Studies: data collection § For prospective and longitudinal cohort studies, decisions must be made about how often follow-up data collection will take place and how long the study (or at least the first wave of the study) will continue § Researchers must develop strategies that minimize the burden of participation while maximizing interest in continuing to participate – Loss to follow-up (Attrition Bias) is the inability to continue tracking a participant in a prospective or longitudinal study because the person drops out, relocates, dies, or stops responding to study communication for another reason 56 Cohort Studies: ethics § Researchers conducting case-control studies must be extremely careful about protecting patient privacy and confidentiality. § Consent? § Ethical approval? 57 Cohort Studies: analysis § Incidence = the number of new cases of a disease occurring in a specific population over a particular period of time. § Two types of incidence are commonly used: ‘incidence proportion’ and ‘incidence rate’. § Incidence proportion, risk or cumulative incidence refers to the number of new cases in your population during a specified time period. It can be calculated using the following equation: § Incidence rate incorporates time directly into the denominator and can be calculated as follows: Person years at risk means the total amount of time (in years) that each person of the study population is at risk of the disease 58 during the period of interest. Cohort Studies: analysis § Incidence = the number of new cases of a disease occurring in a specific population over a particular period of time. Total =30 Incidence proportion, risk or cumulative incidence = 4/30=0.13 Number at risk of the disease during the study period= 30-2=28 Incidence rate= 4/28=0.142= 142 per 1000 No disease=24 Disease= 2 New disease= 4 59 Cohort Studies: analysis 60 Cohort Studies: analysis -In the 2×2 table for a cohort study, the columns are for disease status (disease = yes, and no disease = no) and the rows are for exposure status (exposed = yes, and unexposed = no) Exposure Yes No Total Disease a c a+c No disease b d b+d Total a+b c+d a+b+c+d Incidence rate ratio: a ratio that compares the incidence rate among the exposed to the incidence rate in the unexposed. Can be called rate ratio (RR), relative rate or sometimes as the risk ratio or relative risk, is a generic one that describes any ratio of two rates with the reference (comparison) group in the denominator The point estimate for the RR in a cohort study is RR = [a/(a+b)]/[c/(c+d)] Incidence rate in the exposed = a/a+b Incidence rate in the unexposed =c/c+d 61 Cohort Studies: analysis For a cohort study, the RR is the ratio that compares the incidence rate among the exposed to the incidence rate in the unexposed 62 Cohort Studies: analysis: example Exposure Yes No Total Disease 17 83 100 No disease 13 87 100 Incidence rate ratio (RR)= [a/(a+b)]/[c/(c+d)] Incidence rate in the exposed = a/a+b= 17/30= 0.567 Incidence rate in the unexposed =c/c+d= 83/170= 0.488 Incidence rate ratio (RR)= [a/(a+b)]/[c/(c+d)] = 0.567/0.488 = 1.16 63 Total 30 170 200 Cohort Studies: analysis RR provides an initial interpretation for the incidence rate ratio: • RR = 1 (or close to 1): the incidence rate was the same (or about the same) in the exposed and in the unexposed • RR > 1: the incidence rate was greater in the exposed than in the unexposed, suggesting that the exposure was risky • RR < 1: the incidence rate was lesser in the exposed than in the unexposed, suggesting that the exposure was protective 64 The Sources of Bias in Cohort Studies Bias can be introduced because of any systematic errors in the design, conduct, or analysis of research 1. Selection Bias: occurs when individuals or groups in a study differ systematically from the population of interest leading to a systematic error in an association or outcome § Sampling bias: sample is not representative § Prevalence-incidence bias (Neyman bias): It arises when a gap in time occurs between exposure and selection of study subjects 2. Misclassification bias: previously mentioned 3. Recall bias: when exposed participants are more thoroughly examined for disease than unexposed participants 4. Attrition bias: Loss to follow-up is the inability to continue tracking a participant in a prospective or longitudinal study because the person drops out, relocates, dies, or stops responding 65 The Sources of Bias in Cohort Studies Bias can be introduced because of any systematic errors in the design, conduct, or analysis of research 5. Information Bias: arises from systematic differences in the collection, recall, recording or handling of information used in a study. 6. Measurement Bias: occurs when information collected is inaccurate. 7. Confounding: A situation in which the effect or association between an exposure and outcome is distorted by the presence of another variable which can confuse the association between an exposure and an outcome. 66 Critical Appraisal Tools and Checklists of Cohort Studies: § STrengthening the Reporting of OBservational studies in Epidemiology ( STROBE Checklist): https://www.strobe-statement.org/checklists/ § Critical Appraisal Skills Programme ( CASP): https://casp-uk.net/ § Joanna Briggs Institute (JBI checklist): https://jbi.global/critical-appraisal-tools § The Center for Evidence-Based Management (CEBMa checklist): https://cebma.org/resources-and-tools/what-is-critical-appraisal/ § SIGN Critical Appraisal Notes and Checklists: https://www.sign.ac.uk/what-we-do/methodology/checklists/ 67 Critical Appraisal Tools and Checklists of Cohort Studies: • Factors to look for: § Selection, recall and attrition bias § Inclusion and exclusion criteria § Matching controls • Participants may move between exposure/non-exposure categories or not properly comply with methodology requirements • Being in the study may influence participants’ behaviour § Confounding § Data collection § Appropriate statistical analysis § Presentation of results (clear, precise) § Applicability to local and general population 68 Cohort Studies: examples Pitchika, V., Pink, C., Völzke, H., Welk, A., Kocher, T., & Holtfreter, B. (2019). Long-term impact of powered toothbrush on oral health: 11-year cohort study. Journal of clinical periodontology, 46(7), 713–722. https://doi.org/10.1111/jcpe.13126 Alajmi, S., Shaban, A., & Al-Azemi, R. (2020). Comparison of Short-Term Oral Impacts Experienced by Patients Treated with Invisalign or Conventional Fixed Orthodontic Appliances. Medical principles and practice : international journal of the Kuwait University, Health Science Centre, 29(4), 382–388. https://doi.org/10.1159/000505459 69 Break Out Session Instructions: Scan the following QR codes: § Identify and explain the design of the research § What are the population, sampling technique, and inclusion and exclusion criteria? § What are the main findings? 70 Break Out Session Feedback 71 Putting all this together 72 Research Approaches and Designs Algorithm for classifying the types of research, this scheme is intended to classify the study types as clearly as possible. Medical Research Primary Research Epidemiological Research Basic Research Theoretical § § § § Method development § (physics, chemistry § biology, § bioinformatics) § Analytical § measurement procedure Imaging procedure Test development assessment procedure Weaker evidence Secondary Research Applied Cell research Animal research Stem cell research Genetics Tissue banking Clinical Research Descriptive Case Report A report on a single patient with an outcome of interest Case Series A report on a series of patients with an outcome of interest. No control group is involved Analytical Surveillance Study Report obtained from the databases that follow and record a health problem for a certain time Qualitative Ecological Cross-sectional Examines the relationship between exposure and outcome by examining population-level data rather than individuallevel data 73 Exposure and Exposure ← Outcome outcome are at the same time Meta-analysis QuasiExperimental Research Randomised Controlled Trial Case-control Systematic Review Cohort Exposure → Outcome Stronger evidence Research Approaches and Designs Study Designs Decision Tree is not completely exhaustive but covers most basics designs All Types Of Research Designs And Approaches Secondary Research All Types of Reviews Systematic Review Metaanalysis Is it a primary research (collecting new data) or a secondary research (synthesizing already published research)? Primary Research Basic Is it a basic research (e.g.: laboratory research) or clinical research (e.g.: involving human subjects)? Clinical Is there an intervention or experimental group? Yes Yes No Analytical Study Is there a comparison or Interventional/Experi Observational Study mental Study control group? No What is the starting point for research? Randomised Controlled Trial Non-randomised Controlled Trial Descriptive Study Exposure and Outcome at the same time Survey (Crosssectional) Outcome Exposure Case-control Study Cohort Study Case Report Case Series Analytical Crosssectional Study Qualitative Study Based on the work of Grimes et al., (2002). Grimes, D. A., & Schulz, K. F. (2002). “An overview of clinical research: The lay of the land”. The Lancet, 359(9300), 57-61 74 References Required: Neale, J., 2020. Research methods for health and social care. Bloomsbury Publishing. Jacobsen, K.H., 2020. Introduction to health research methods: A practical guide. Jones & Bartlett Publishers. Additional: Bowling, A., 2014. Research methods in health: Investigating health and health services. Maidenhead, United Kingdom: Open University Press. Creswell, J.W. and Creswell, J.D., 2018. Research design: Qualitative, quantitative, and mixed methods approaches. Sage publications. World Health Organization. Regional Office for the Western Pacific, 2001. Health research methodology : a guide for training in research methods. 2nd ed.. WHO Regional Office for the Western Pacific. https://apps.who.int/iris/handle/10665/206929 World Health Organization. Regional Office for the Eastern Mediterranean. (2004). A practical guide for health researchers. https://apps.who.int/iris/handle/10665/119703 References Cited references: § Andiappan, V., Wan, Y.K. Distinguishing approach, methodology, method, procedure and technique in process systems engineering. Clean Techn Environ Policy 22, 547–555 (2020). § Grimes, D. A., & Schulz, K. F. (2002). “An overview of clinical research: The lay of the land”. The Lancet, 359(9300), 57-61 Next Lecture: Step 2: Selecting a Study Approach Randomized Controlled Trials Identify study question Select study approach Design study and collect data Thank you! Any questions [email protected] Analyse data Report findings