EBD RESEARCH DESIGN II

what is a systematic review (what does it aim to do)

systematic review: aims to identify, select and synthesise all research published on a particular question or topic

systematic reviews adhere to… based on…

ideally they provide… about…

• systematic reviews adhere to a strict scientific design based on pre-specified and reproducible methods

• ideally they provide reliable estimates about the effects of interventions (prevention/ treatments)

not all systematic reviews include a ____-________

not all systematic reviews include a meta-analysis

not all systematic reviews only include __________ ___________ ______

not all systematic reviews only include randomised control trials (unavailable/ inappropriate)

why are systematic reviews useful

• find results of research (fairly) quickly - long procedure

• assess validity, applicability and implications of results

• guides reviewers to report work explicitly and concisely

advantages of systematic reviews

• structured

• rigorous

• well-defined

• each stage is peer reviewed

• kept up to date

hence a key tool in EBD

which organisations undertake high quality reviews

• Cochrane

• Centre for Reviews and Dissemination (CRD)

• York University

• others e.g. Campbell (Canada)

how are systematic reviews undertaken

independently - not as stringent as organisational ones

Cochrane

Cochrane background

• founded in memory of Archie Cochrane (British epidemiologist)

• Cochrane centre opened in Oct 1992

• 52 specialist groups

• Oral Health Group started June 1994

• currently based at Manchester University

what is the aim of the Cochrane Oral Health Group

• the COHG aims to produce systematic reviews which primarily include all randomised controlled trials (RCTs) of oral health

what does ‘oral health’ include

• prevention, treatment and rehabilitation of oral, dental and craniofacial diseases and disorders

there are currently how many completed systematic reviews related to dentistry and oral health

219 completed systematic reviews related to dentistry and oral health

there are currently how many protocols related to dentistry and oral health

41 protocols related to dentistry and oral health

Cochrane systematic review order of sections

what does the ‘Text of review’ section include (12)

what does PRISMA stand for

Preferred Reporting in Systematic Reviews and Meta-Analysis

what is PRISMA

• a method of ‘Search strategy for identification of studies’ (included in ‘Text of review’)

• very strict

what figure appears in the ‘Results’ section of a systematic review

forest plots

what is a forest plot

forest plot: a graphical representation of the findings of multiple studies that investigated the same scientific question and measured the same outcome

what is the significance of the line of null effect

when comparing two things if the result is on/ around this line there is no difference between them

what do the numbers in [ ] on the right hand side signify

the confidence interval in numerical form

label the point estimate and the horizontal line

• point estimate = purple lines

• horizontal line = red line

what does the point estimate represent

point estimate

• the effect size identified in each study

• the size of the box represents the size of the study in terms of participants

what does the horizontal line represent

horizontal line

• 95% confidence interval of the study result

• i.e. the range of values within which you can be 95% certain the true value lies

• the longer this line the less precise the findings are

if a line crosses the line of null effect what does it say about the result

the result is not statistically significant

the ______ the study the _______ the confidence interval and the ______ the point estimate

the bigger the study the smaller the confidence interval and the bigger the point estimate (greater precision of results)

the ______ the study the _______ the confidence interval and the ______ the point estimate

the smaller the study the larger the confidence interval and the smaller the point estimate (less precision of results)

what is a meta-analysis

meta-analysis: the statistical combination of results from two or more separate studies

what are advantages of meta-analyses

• improvement in precision

• ability ot answer questions not posed by individual studies

• opportunity to settle controversies arising from conflicting claims

what are most methods of meta-analyses

most methods of meta-analyses are variations on a weighted average of the effect estimates from different studies

when was fluoridated toothpaste introduced

1974

which demographic do most studies of benefits of water fluoridation target

children

what do studies on water fluoridation show

• water fluoridation is effective in preventing decay in children

• ^ studies are mainly before 1975 - still relevant today?

  • update confirms the effect is smaller now (Iheozor-Ejiofor et al. 2024)

• there is no credible evidence of adverse effects other than dental fluorosis (Systematic Review of Public Water Fluoridation done by the University of York)

what are other adverse effects of water fluoridation patients may be worried about

• bone cancer - osteosarcoma

• damage to the brain - affects the pineal gland

• causes arthritis problems

• increase risk of hip fractures and other bones

• lowers IQ

• reproductive problems

• affects thyroid function

• damage to bone

• non-IQ neurotoxic effects

when would it be inappropriate to do a meta-analysis

• different methods are used in studies

• different outcome measures are used

» heterogeneity of methods and outcomes

if it was inappropriate to do a meta-analysis what should be done instead

• narrative synthesis - summarise and aggregate findings where possible

• highlights weaknesses in evidence

• makes recommendations for future research

what is the checklist for systematic reviews

Critical Appraisal Skills Programme (CASP)