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RANDOMISED
CONTROLLED TRIAL
SUMIT KUMAR DAS
Experimental Studies
• In 1920s “Experimental Epidemiology” meant the study of epidemics among the
colonies.
• In modern u...
Select suitable population
(Reference or target population)
Select suitable sample
(Experimental or study population)
Make...
Basic steps of Randomized Controlled Trials
1. The Protocol :-
- It is the feature of the RCT is the study is conducted un...
Basic steps of Randomized Controlled Trials
2. Selecting reference and experimental population :-
a) Reference or target p...
Basic steps of Randomized Controlled Trials
b) Experimental or study population – (Cont…)
- The participants must fulfill ...
Basic steps of Randomized Controlled Trials
4) Manipulation:-
- After forming the study and control group manipulation in ...
Basic steps of Randomized Controlled Trials
6) Assessment:- (Cont…)
- Bias may occur from three sources
first, from the pa...
Schematic diagram of the design of concurrent parallel controlled trials
Patients
Random
Assignment
Exposed to
specific Ri...
Schematic diagram of the design of cross-over controlled trials
Patients
Random
Assignment
Exposed to
specific Risk
Unexpo...
Types of Randomized control trials
1. Clinical Trial:-
It is done for various purposes like
prophylactic trials( e.g. immu...
Types of Randomized control trials
3. Risk factor Trial:-
- The investigator intervenes to interrupt the usual sequence in...
Types of Randomized control trials
5. Trial of aetiological agent:-
it is done to confirm or refute aetiological hypothese...
A randomized controlled trial to prevent childhood obesity
through early childhood feeding and parenting guidance:
rationa...
• Hypotheses
i) children within intervention group will have normal growth and control group would
increase the height and...
Study group:-
• intervention group:- bilingual worker starts from 36 months of pregnancy, then 3
days, 2 weeks then 2,4,6,...
• Discussion and conclusion:-
Although this is study design the authors intention was only to know
about the hispanic comm...
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Randomized Controlled Trial

  1. 1. RANDOMISED CONTROLLED TRIAL SUMIT KUMAR DAS
  2. 2. Experimental Studies • In 1920s “Experimental Epidemiology” meant the study of epidemics among the colonies. • In modern usage it is often equated as “Randomized Controlled Trial”. • The main difference between observational and experimental is that it is under the direct control of the investigator. • Historically , in 1747, James Lind first performed the experimental studies. • Experimental Studies are of two types 1. Randomized Controlled trial (Those involving a process of random allocation) 2. Non-randomized or “Non-experimental” trials (i.e. those departing from strict process of randomization).
  3. 3. Select suitable population (Reference or target population) Select suitable sample (Experimental or study population) Make necessary exclusions RANDOMIZE Experimental group Control group Manipulation & follow-up ASSESMENT Those who do not wish to Give consent Those not eligible Design of a randomized controlled trial
  4. 4. Basic steps of Randomized Controlled Trials 1. The Protocol :- - It is the feature of the RCT is the study is conducted under a strict protocol. - it fixes the aim and the objective of the study. - criteria for selection of study and control group , sample size . - treatment to be applied to where, when, how and what kind of patients. - it is essential when a number of centers is participating in the trial. - sometimes before a protocol completed, a preliminary (pilot) studies have to be made to find out operational efficiency, procedural flaws, unknown effect, acceptability of certain effect . - it should be agreed upon all concerned before the trials begins. - The protocol aims at preventing bias and reduce the sources of error in the study.
  5. 5. Basic steps of Randomized Controlled Trials 2. Selecting reference and experimental population :- a) Reference or target population- - it is the population to which the finding of the trial, if found successful, then expected to applicable( e.g drug, vaccine, or other procedures) - it may be geographically limited or limited to persons in specific age, sex, occupation and social group. - it may be population of whole city, industrial workers, obstetric population as according to the nature of the study. b) Experimental or study population- - it is derived from the reference population. - it should be randomly chosen. - it should be representative of the reference population
  6. 6. Basic steps of Randomized Controlled Trials b) Experimental or study population – (Cont…) - The participants must fulfill following criteria i) They must give “informed consent” , after having been informed about the purpose, procedure and possible dangers. ii) They should be qualified or eligible for the trial. e.g.- if we are testing for anaemia, if the persons are not anaemic then they are not eligible. 3. Randomization :- - it is a statistical procedure, by which we allocate ‘study’ and ‘control’ group. - It eliminates “bias” and allow for comparability, though theoretically elimination is possible by matching. - It can be best done using random number table.
  7. 7. Basic steps of Randomized Controlled Trials 4) Manipulation:- - After forming the study and control group manipulation in done by deliberate application or withdrawal or reduction of suspected causal factor. - it creates an independent variable (e.g.- drug, vaccine) whose effect is the determined by final outcome which constitute dependent variable (e.g. incidence of disease, survival time, recovery perid). 5) Follow up :- - it implies examination and control group subjects at different interval of time. - losses of follow due to inevitable(death, migration, loss of interest). It is called attrition. If it substantial , it should be minimized. 6) Assessment :- - it is assessment of trial in terms of positive and negative result.
  8. 8. Basic steps of Randomized Controlled Trials 6) Assessment:- (Cont…) - Bias may occur from three sources first, from the participant, if he reports that feeling better knowing that he is getting new form of treatment. i.e. “Subject Variation” Secondly, investigator measuring the outcome with influence if he knows the result beforehand. i.e. “Observer bias” Thirdly, “Bias in evaluation” i.e. investigator subconsciously give favorable result of the outcome. to avoid first bias “single Blind Trial” is done that the participant is not know. “Double Blind Trial” is done that the doctor as well as the participant are not aware. “Triple Blind Trial” i.e. participant, investigator and the person analyzing the data are not aware the fact.
  9. 9. Schematic diagram of the design of concurrent parallel controlled trials Patients Random Assignment Exposed to specific Risk Unexposed to specific risk COMPARE OUTCOME Time Concurrent parallel study designs • comparison are made between two randomly assigned group, one is exposed and other is not-exposed • Patients remain in the study or the control group for the duration of investigation. Observation Study Designs
  10. 10. Schematic diagram of the design of cross-over controlled trials Patients Random Assignment Exposed to specific Risk Unexposed to specific risk COMPARE OUTCOME EXPOSED AND UNEXPOSD TO RISK Time Cross-over type of study designs Observation • Patients randomly assigned for study and control group. • study group receives treatment under consideration and control receives placebo/ alternative. • after observation groups are taken off for elimination of any medication effect and “carry over” effect. • then those who were cases are kept in control and those who were in control are kept in cases. • in economize the total number of patient required. But, it is not suitable if the drug of interest cures a disease. Study Designs
  11. 11. Types of Randomized control trials 1. Clinical Trial:- It is done for various purposes like prophylactic trials( e.g. immunization, contraception) therapeutic trials (e.g. drug treatment, surgical procedure) safety trials (e.g. side effects of oral contraceptive and injectibles ) 2. Preventive Trials:- -synonymous with “primary Prevention”. - purported to prevent or eliminate disease on an experimental basis. - its analysis must result a clear statement like how it will be benefitted for the community, the cost and risk involved. since preventive trial involved larger number of subjects and sometimes a longer time span to obtain results, there may be greater number of practical problems in their organization and execution.
  12. 12. Types of Randomized control trials 3. Risk factor Trial:- - The investigator intervenes to interrupt the usual sequence in the development of the disease for those who have “risk factor” for developing disease; often this involves risk factor modification. eg. Risk factors for CHD are cholesterol, smoking, hypertension and sedentary habit. Risk factor trials can be single factor or multifactor. Both the approaches are complementary and both are needed. 4. Cessation Experiment:- an attempt is made to evaluate the termination of a habit (or removal of a suspected agent.) which is considered to be causally related to a disease. ex: for Smoking and lung cancer if in a RCT one group of cigarette smoker continue to smoke and another has given up, the demonstration of the decrease in a incidence of lung cancer in the study group strengthen the hypothesis of a causal relatioship.
  13. 13. Types of Randomized control trials 5. Trial of aetiological agent:- it is done to confirm or refute aetiological hypotheses, since most diseases are fatal, disabling or unpleasant, human experiment to confirm an aetiological hypothesis are rarely possible. Ex. Retrolental Fibroplasia as a cause of blindness. But it was happening due to oxygen therapy 6. Evaluation of health service:- it is somewhat extended part of randomized control trial to asses the effectiveness and efficiency of health services. Often , choices have to be made from tow alternative policies of health care delivery. This can be done by this.
  14. 14. A randomized controlled trial to prevent childhood obesity through early childhood feeding and parenting guidance: rationale and design of study Elizabeth Reifsnider, David P McCormick, Karen W Cullen, Laura Szalacha, Michael W Moramarco, Abigail Diaz and Lucy Reyna (2013) • AIM OF THE STUDY:- effectiveness of well structured health service in preventing over weight obesity in early 2 years of infants. • METHOD:- will Randomize two group design : Intervention group and control group, each having 70 pregnant women third trimester, IG received full intervention by CHW , with home visit with backup by public nurses. CG received only measurement visit , no intervention
  15. 15. • Hypotheses i) children within intervention group will have normal growth and control group would increase the height and weight more rapidly ii) fewer children will have BMI>95 percentile in intervention group as compared to control group iii) intervention group will have exclusively breastfed than control group iv) intervention will have more fruit, vegetables than sweetened beverage, but control group will get opposite v) The parents of intervention will be more responsive to infant feedings than control group. • Participant’s recruitment it occurred at WIC clinic sponsored by the Houston Department of human and health services. • Study criteria and follow up maternal included criteria if Mexican, English or Spanish ,bmi >25, age 18-40, and excluded if type I diabetes, high risk pregnancy, hospitalized after discharge of infant ), infant included if weight > 2500 gm, without disorder that could intervene the growth and excluded if infant are not discharged with mother due to severe illness which could resist the growth.
  16. 16. Study group:- • intervention group:- bilingual worker starts from 36 months of pregnancy, then 3 days, 2 weeks then 2,4,6,9,12,18,24. provide images and texts. Report taken according to the hypothesis i.e. weight, food habit, sleep. Also receive measurement visit from a bilingual research assistant. • control group:- receives only 8 visits from RA. And monthly breastfeeding's call. Measurement:- length of child is measured by a portable recumbent. sleep assess by Brief Infant Sleep Questionnaire(BISQ) questionnaire like excessive sleepiness, sleep disorder. Feeding Infants and Toddlers Study (FITS) is the guiding framework for the dietary data collection Demographics parental age, educational level, employment status Data collection:- data is to be taken by Research Assistant. And REDCap, ASA24, and for analyise REDCap, SPSS is to be used.
  17. 17. • Discussion and conclusion:- Although this is study design the authors intention was only to know about the hispanic community as it has been told they are more prone to infant obesity. That they have deliberately choose the study population. In has been mentioned in the discussion that it will give a good quality of data and it will useful for further study for cardio-metabolic disease in adulthood. this is a good protocol. And it will definite give a good data, that most of the study have been conducted to prevent the obesity in elder age. But obesity can not be controlled after 5 years of age. That’s why they will intervene from early age. According to the study prospective cohort study can also be useful if their purpose of the study would have been something different like how the obesity occurring to those children having special life style and other factor. case-control study can also be done like after consequences those who are having obesity what were there lifestyle , how they were connected with health workers.
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it is a general overview about randomized controlled trial

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