Medical Research methodology
Dr. Waled Al-DubaiAssociate professor Sanaa University1437-2016
Definition of research
Research is a Systematic and an Organized method to Finding Answers to QuestionsOR:Research is a systematic investigation into a subject in order to discover new information or new fact or reach a new understandingortocollect informationonasubject
Research consist of the previx Re which means ( again , or a new ) And Search (verb) means ( to examine, or to try )
Definition of research RESEARCH IS IS SYSTEMATIC because there is a definite set of procedures and steps which you will follow in order to get the most accurate results .
Research is ORGANIZED because there is a structure of research
Definition of researchFINDING ANSWERS
Finding answers to a hypothesis or to the question of the research is the end of all research, because, research is successful when we find answers. Sometimes the answer is no association or no corelation or no significant differences , but it is still an answer.QUESTIONS
Question is central to research , because research with-out a question, has no aims.
The researcher Should be patientShould be ambitiousRemember it is research
Classification of Medical Research
Medical research 1-Primary research Primary research is a research which involves the collection of data that does not yet exist
2-Secondary research Secondary research is a research which involves the collection of data from studies of other researchers
Classification of Experimental Medical Research
Classification of Observational Medical Research
Notes1-Descriptive study is an observational study which describes the distribution of characteristics of a disease or outcome, like percentage of (male , female) or (children, adult) in acute leukemia, etc
2-Analytical study is an observational study which is looking for associations between exposure and outcome and analyze them for possible causes and effects by using case and control groups.3-The best feature that distinguishes an analytic study from a descriptive study is a using comparison Group in analytic study
Descriptive study1-Case report ( on one patient)Case reports often describe new case that cannot be explained by known diseases or syndromes or describe case that show an important variation of a disease or condition. Advantages1-Can help in the identification of new syndrome or disease 2Help in detecting new drug side effects and (adverse or potential uses beneficial) Disadvantages 1-Cases may not be generalizable 2-Not based on systematic studies(consider as non-resaerch by most epidemiologist. 3-Causes or associations may have other explanations
Example of case report Haemorrhagic-fever-like changes and normal chest radiograph in a doctor with SARS. Wu EB1, Sung JJ.Lancet. 2003 May 3;361(9368):1520-1.AbstractA 33-year-old doctor contracted severe acute respiratory syndrome presenting with features of disseminated intravascular coagulopathy without changes in the chest radiograph initially. A CT scan of his chest showed marked lung changes. His condition improved with intravenous methylprednisolone 500 mg daily and ribavirin 1.2 g orally thrice daily. The case illustrates the importance of a break in fever between the viraemic and lung inflammatory phases of the illness that occurs before radiographic changes and which may obscure diagnosis. Careful quarantine and follow-up of these patients are necessary. Coagulopathy is usually uncomplicated and early CT of the chest may elucidate hidden lung changes and facilitate a rapid diagnosis.
2-Case series Case series are the same of case report in advantages and disadvantages but Case series are collections of different case reports of different patients of the same case or condition or disease or syndrome.
3-Discreptive cross-sectional studyA descriptive cross-sectional study may be purely descriptive and used to assess the prevelance and distribution of a particular disease in a defined population,It also called prevalence study or Cross-sectional survey They may cover, for example:1-Physical characteristics of people (weight, height), or the environment (everything about environment , like temperature), as ina- prevalence surveys (of bilharzia, leprosy, HIV), b- evaluation of coverage of immunization, 2-Socio-economic characteristics of people such as their age, education, marital status, number of children and income,If a cross-sectional study covers the total population it is called a. census.
3-Discreptive cross-sectional studyAdventage1-provides snap shot about outcome 2-Simple and quick3-Is first line of epidemiological research4-It estimates the prevalence of diseasePrevalence is the total number of new and old cases in defined population5-Good for common and chronic diseases(hypertension, diabetes) Disadventage1-We can not establish causality because we do not know whether the agent causes the outcome or not (We do not know who come first)
Example of descriptive cross sectional studyType II Diabetes Mellitus and impaired glucose tolerance in Yemen: prevalence, associated metabolic changes and risk factors
Al-Habori M1, Al-Mamari M, Al-Meeri A
Diabetes Res Clin Pract. 2004 Sep;65(3):275-81.
AbstractOBJECTIVE: To investigate the prevalence of type II Diabetes Mellitus (DM) and impaired glucose tolerance (IGT) and identify the metabolic abnormalities and risk factors associated with these conditions in an urban city of Yemen.RESEARCH DESIGN AND METHODS: Cross-sectional, population-based study investigating 498 adults (245 males and 253 females) aged 25-65 years. The 1999 modified World Health Organization criteria were adopted for the diagnosis of Diabetes Mellitus and IGT. A standard questionnaire was applied and blood lipids, blood pressure, body mass index (BMI) and waist/hip ratio (WHR) were determined.RESULTS: The overall prevalence of type II Diabetes Mellitus was 4.6% (7.4% in males and 2% in females). Impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) were found in 2% and 2.2% of the study population. Factors independently related to any abnormality in glucose tolerance, using logistic regression analysis, were sex, hyperlipidaemia, hypertriglyceridaemia, and hypertension; whereas sex and age related to DM. More than 80% of the type II diabetics were over the age of 40, 35% being hyperlipidaemic, 22% being hypertensive and 18% obese. Sixty percent of IGT subjects were hyperlipidaemic and 20% were obese. Approximately 78% of obese individuals (>/=30 kg/m(2)) had normal glucose tolerance.CONCLUSION: The prevalence of type II DM and its potential increase reflected by the high prevalence of obesity in normal glucose tolerance subjects in the Yemeni population constitutes a major public health problem.
1-Outecome means disease or dependent variable2-Exposure means risk factors or independent variable3-Case : A person with the disease or outcome of interest. 4-Control:A person who does not have the disease or outcome.5-Independent variable is a variables which may cause or affect the outcome ( disease or dependent variable) .e.g independent variable is smoking but the outcome or dependent variable is lung cancer.6-Dependent variable is the outcome in the study which undergoes to the effect of independent variable. 7-Risk factor is any factor whose presence is associated with an increased risk of adisease or condition
Notes1-Non-intervention study is study (observational study) in which the researcher just observes and analyses researchable objects or situations but does not intervene;2-Intervention study is study(Expermental study) in which the researcher manipulates objects or situations and measures theoutcome of his manipulations
Classification of Observational Medical Research
Analytical studiesAnalytical study is study attempts to establish causes or risk factors for certain problems.This is done by comparing two or more groups, some of which have or develop the problem and some of which have not
1-Analytical comparative Cross-sectional studyAnalytical comparative Cross-sectional study investigate the association between the putative risk factors and the outcome in the same time by both describing and comparing between groups .
Example of analytical comparative cross- sectional studyPrevalence and factors associated with low birth weight in Axum and Laelay Maichew Districts, North Ethiopia:A comparative cross sectional study
Negassi Teklehaimanot1, Tesfay Hailu2, Huruy Assefa2, *International Journal of Nutrition and Food Sciences2014:3(6):560-566
Differences between descriptive cross-sectional study and analytical comparative cross-sectional study Descriptive cross-sectional study1-Collected number of cases and number of total population.
2-Can assess only prevalence of disease or other health eventsAnalytical comparative cross-sectional study1-Exposer and outcome are assessed at the same time by using compare groups 2-Can determine association between exposure and disease by using Prevalence odds ratio
Case Control StudyCase control study is a retrospective study which compares patients who have a disease or outcome of interest (cases) with persons who do not have the disease or outcome (controls), and looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between the ri