What is research, Types of research, Requisites of good research, Concept in epidemiology, Epidemiologic studies , Literature search, Protocol designing, Ethical issues, Dissertation writing , Research paper writing , Reviewing a research paper
2. What is research
Types of research
Requisites of good research
Concept in epidemiology
Epidemiologic studies
Literature search
Protocol designing
Ethical issues
Dissertation writing
Research paper writing
Reviewing a research paper
3. RESEARCH = ‘Re’ + ‘Search’
- Means ‘to search again’
or
- To search for new facts
or
- To modify older ones
Obvious function of research is to add
new knowledge
4. Oral health research refers to laboratory, clinical
and field investigations that lead to improvement
in the control of oral diseases and health care
delivery.
The ultimate goal is to improve the quality of life
for the population.
5. Basic and applied research
Empirical and theoretical research
Quantitative (numeric )or qualitative (non-
numeric)
Conceptual and Empirical research
6. To promote oral health of the public.
Contribute new knowledge or reevaluate current
knowledge.
To improve the techniques and practices of
identifying, preventing and treating oral disease.
7. To develop and test theories related to oral health
care and oral disease process.
To identify and solve problems indigenous to
advancement, decision making and change in oral
health care delivery.
8. FOCUS: area of interest/expertise
:meaningful progress
RATIONALE: clinically relevant
: proof of concept
: challenge/change current treatment
methods
VALIDITY: will the results be useful and to whom
9. FEASIBILITY: time
: study population/sample
: infrastructure
: skill/aptitude
ETHICS: do unto other what you would do unto
you
BUDGET: materials
: manpower
: equipment
10. Epidemiology is derived from the word epidemic
(epi=among; demos=people; logos=study) which
is a very old word dating back to the 3rd Century
B.C.
Epidemiology has been defined as “ The study of
the distribution and determinants of health related
states or events in specified populations, and the
application of this study to the control of health
problems.”
11. “I keep six honest serving men ; they taught
me all I know. Their names are :-
What , When, Where ,Who, How and Why”
- Rudyard kipling
13. These studies are concerned with observing the
distribution of disease or health-related
characteristics in human population and identifying
the characteristics with which the disease in
question seems to be associated.
14. I. Defining the population to be studied
II. Defining the disease under study
III. Describing the disease under study
Time distribution
Short term
fluctuation
Periodic
fluctuation
Long term
fluctuation
15. Place distribution
Person distribution
International
variation
National
variation
Rural-
urban
differences
Local
distribution
Age
Gender
Bimodality
Ethnicity
Marital status
Occupation
Social class
Behavior
16. IV. Measurement of disease
V. Comparing with known indices
VI. Formulation of a hypothesis
Cross-sectional
study Longitudinal study
17. “Smoking 40-50 bidids per day, will
result in leukoplakia among 4% of
beedi smokers after 10 yrs”
Population-
beedi
smokers
dose response
relationship-
40-50 bidis
per day
expected
effect- disease
that is
leukoplakia
Time response
relationship
– 10 yrs
cause-
smoking
18. Provides data with regard to disease problem.
Provides information about etiology of disease.
Provides background data for planning, organizing
and evaluating preventive and curative services.
Describing variations in disease occurrence by
time,place and person.
19. In contrast to descriptive studies that look at entire
population, in analytical studies, the subject of
interest is the individual within the population.
Comprises of : 1) case control study
2) cohort study
20. From each of the study design, one can determine:
1) Whether or not association exists between a
disease and factor
2) If one exists, the strength of the association
22. 3 distinct features:
Both exposure and outcome have occurred before
the start of the study.
The study proceeds backwards from effect to cause.
It uses a control or comparison group to support or
refute an inference.
23. I. Selection of cases and controls
Case : Diagnostic criteria
: Eligibility criteria
Sources of case: hospitals
: general population
Sources of control: hospitals control
: relatives
: neighbourhood controls
: general population
Specifications
24. II. Matching:
It is defined as the process by which we select
controls in such a way that they are similar to
cases with regard to certain pertinent selected
variables (eg age) which are known to influence
the outcome of disease and which, if not
adequately matched for comparability could
distort or confound the results.
25. III. Measurement of exposure
IV. Analysis and interpretation
Exposure rate
Estimation of disease risk associated with
exposure (odds ratio)
26. Exposure rate-cases: a/(a+c) =33/35 =94.2%
controls: b/(b+d) = 55/82= 67%
Cases ( with oral
cancer)
Controls (without
oral cancer)
Tobacco
chewers(atleast 5
times a day)
( a) 33 (b) 55
Non tobacco
chewers
(c ) 2 (d) 27
Total (a+c) 35 (b+d) 82
27. Odds ratio= ad/bc
=33*27 / 55*2
=8.1
This implies that the risk of oral cancer was 8.1
times greater in individuals who chewed tobacco
than in those who did not chew tobacco.
28. Bias is any systemic error in the determination of
the association between the exposure and disease.
Bias due to confounding
Memory or recall bias
Selection bias
Berkesonian bias
Interviewer bias
29. 1) Easy to carry
2) Rapid and inexpensive
3) Investigate rare disease
4) No risk to subjects
5) Allows study of several
different etiological
factors
6) Do not require follow up
7) Ethical prob minimal
8) Rational prevention and
control programmes
1) Problem of bias
2) Selection of appropriate
control grp not possible
3) Cannot measure
incidence
4) Not suited to evaluation of
therapy or prophylaxis of
disease
30. It is usually undertaken to obtain additional
evidence to refute or support the existence of an
association between suspected cause and disease.
Prospective study, longitudinal study, incidence
study, forward looking study
31. Distinguishing features are:
Cohorts are identified prior to the appearance of the
disease
Study grp are observed over a period of time to
determine the frequency of disease among them.
The study proceeds from cause to effect.
32. The term cohort is defined as a group of people who
share a common characteristic or experience within
a defined time period.
TIME
DIRECTION OF
ENQUIRY
COHORT STUDY
TIME
DIRECTION OF
ENQUIRY
CASE CONTROL
STUDY
34. I. Selection of study subjects:
General population
Special groups
II. Obtaining data on exposure
Cohort members
Review of records
Special tests
Environmental survey
III. Selection of comparison groups
36. Tobacco
chewing
Developed oral
cancer
Did not
develop oral
cancer
Total
Yes 45 (a) 9955 (b) 10000 (a+b)
No 5 (c) 9955 (d) 10000 (c+d)
Incidence rate among tobacco chewers = a/(a+b)=
45/10000= 4.5 per 1000
among non tobacco chewers = c/(c+d)=
5/10000= 0.5 per 1000
37. RR= incidence of disease among exposed
incidence of disease among non-exposed
= 4.5/0.5= 9
AR= incidence of disease among exposed-
incidence of disease among non-exposed
incidence rate among exposed
=(4.5-0.5)/4.5 * 100
= 88.9%
38. 1) Incidence can be
calculated
2) Several possible
outcomes can be
studied
3) Estimate of relative risk
4) Dose-response ratio can
be calculated
5) Bias can be minimized
1) Involve large no. of
people
2) Long time to complete
the study
3) Expensive
4) Ethical problems
5) Administrative
problems
6) Changes in diagnostic
criteria over prolonged
followup
7) May alter peoples
behaviour
39. 2 types: a) Randomized controlled trials
b) Non-randomized or “non-experimental”
trials
For new programmes or new therapies, the RCT is
the No.1 method of evaluation.
40. Select suitable population
Select suitable
sample
Make necessary
exclusions
RANDOMISE
Experimental
grp
Control grp
Manipulation
& follow up
Assessment
Those not
eligible
Those who do
not wish to give
consent
Design of
a RCT
41. I. Drawing up a protocol
II. Selecting reference and experimental population
III. Randomization
IV. Manipulation or intervention
V. Follow up
VI. Assessment of outcome
42. Blinding can be done in 3 ways:
Single blind trial- participant is not aware
Double blind trial- neither doctor nor participant is
aware
Triple blind trial- neither investigator, participant
and person analysing data are all “blind”.
45. Systematic review
Randomized controlled trial
Non- RCT
Cohort study
Case control study
Cross sectional
study
Case series
Isolated
case
report
Hierarchy of
evidence
46. Taste alteration and impact on quality of life
after head and neck radiotherapy.
A clinicopathological study of 338 dentigerous
cyst.
A new topical treatment protocol for oral hairy
leukoplakia.
47. Genotoxic effects of panoramic radiation by
assessing the frequency of micronuclei
formation in exfoliated buccal epithelium
Remodeling of the antegonial angle region in
the human mandible: A panoramic
radiographic cross–sectional study
48. Role of dermatoglyphics as an indicator of
precancerous and cancerous lesions of the oral
cavity.
Analgesic efficacy of diazepam and placebo in
patients with temporomandibular disorders: A
double blind randomized clinical trial
Hinweis der Redaktion
1) Basic research is search for knowledge without any specific purpose. Applied research is problem oriented- finding solu to an existing prob
2) Empirical means that it is based on observation an dexperience more than upon theory and abstraction.
What is the purpose of health research? 1) by improving education, service, practice & delivery.
2) To improve all phases of oral health care 3) in individuals and in grps
Indigenous- occuring naturally in a particular place
Rationale – set of reasons
Feasibility means smethng which can be easily done. Infrastructure means facilities.
Ecological or corelational ; cross sectional study or prevalence; case control or case reference; cohort or followup. Decriptive study is limited to description of a disease in apopulation i.e pattern of occurrence of disease. Analytical study goes by analysing the relationship between health status and other variables.
Meticulous observations made in africa by Burkitt led to the eventual incrimination of Epstein barr virus as the etiological factor of the type of cancer known as Burkitts lymphoma. It was the epidemiological study in New Guinea of “kuru” , a herediatary neurological disorder that led to the discovery of slow virus infections as the cause of chronic degenerative neurological disorders in human beings.
Define the population not only in terms of total number but also its composition in terms of age, sex, occupation. Helps to determine pop at risk.Once the population has been defined, one needs to define the disease to be investigated. It should be both valid nd precise to enable to identify those who have d disease from those who do not hve d disease. The primary objective of descriptive epidemiology is to describe the distribution of disease by time,place nd person & identifying those characteristics associated with presence or absence of disease in individuals.
Measurement of disease in terms of mortility and morbidity…cross sectional or prevalence study cross sectional- both exposure nd outcme at sme time. Longitudinal is cross sectional study done for a longer duration. Comparision is done to find out which population is at risk.
Analytical studies are the second majot type of epidemiological study
Also known as retrospective study
Control must be free form the disease. They must be as similar to cases as possible, except for the absence of disease under study.
hospital controli sbias bcoz may be dey hve sme disease which is influenced by factor under study. Eg oral cancer nd smoking. Nd lung cancer
Confounding factor is one which is associated with both exposure and disease and is distributed unequally in study and control grp. Example of age
Measurement of exposure by interview, questionnaire, past record , clinical or laboratory investigation
Relative risk
Berkesonian bias is termed after Dr Joseph Berkson who recognize this problem. Occurs in hospital based studies.
Cohort must be free from the disease under study.
Relative risk implies 9 times higher risk of development of oral cancer in tobacco chewers compared to non-chewers. RR of 1 indicates no association, >1 indicates positive association .. AA- out of the total risk of development of cancer in chewers, 88.9% is attributed to tobacco chewing.
Protocol specifies the aims and objectives of the study, criteria for the selection of study and control grps, sample size, allocation of study subjects into study and control grp.treatment to be apllied and upto the stage evaluation.
Assessment of outcme- positive and negative results
2 sources of bias- on part of participants- feel bttr when they cme to know they receivng sme new treatment. Observer bias- investigatir may be influenced if he knows beforehand the particular therapy to which pt is subjected.
The hierarchy of evidence that is generated from various studies is shown in following figure
