PHA 335 - Research Design L3

What are the highest levels of evidence in research design?

Systematic review; Meta-analysis; Randomized Controlled Trial (RCT)

What is a systematic review?

A structured qualitative review of multiple studies addressing a single well-defined question

What type of data does a systematic review use?

Qualitative (non-numerical data)

What framework is used in systematic reviews?

PICOTS

What is a meta-analysis?

A study that statistically combines results from multiple studies into one quantitative result

What type of data does a meta-analysis use?

Quantitative (numerical data)

What is the main output of a meta-analysis?

A single pooled quantitative result

What visual is commonly used in meta-analysis?

Forest plot

What is a major benefit of meta-analysis?

Increases statistical power by combining studies

What is a major limitation of meta-analysis?

Publication bias

What is publication bias?

Studies with significant results are more likely to be published

What is a randomized controlled trial (RCT)?

A prospective study with random assignment to treatment groups

Why are RCTs considered the gold standard?

They reduce bias and establish cause-and-effect

Are RCTs prospective or retrospective?

Always prospective

What type of validity is high in RCTs?

Internal validity

What type of validity is low in RCTs?

External validity

Why do RCTs have low external validity?

They are conducted in controlled settings and may not reflect real-world conditions

What is the main threat to internal validity in RCTs?

Experimental mortality (loss of participants)

What is a superiority trial?

A study designed to determine if one treatment is better than another

What is a non-inferiority trial?

A study designed to show a new treatment is not worse than an existing treatment

What does a superiority trial aim to show statistically?

A significant difference between treatments

What does a non-inferiority trial aim to show statistically?

No significant difference (treatments are equivalent)

In non-inferiority trials, what may be adjusted?

The significance line (e.g., from 1.0 to another value like 1.3)

What does PICOTS stand for?

Population; Intervention; Comparator; Outcome; Timing; Setting

What does Population mean in PICOTS?

Characteristics of the study population

What does Intervention mean in PICOTS?

The treatment or exposure being studied

What does Comparator mean in PICOTS?

The control or comparison group

What does Outcome mean in PICOTS?

The clinical result measured

What does Timing mean in PICOTS?

When and how long outcomes are measured

What does Setting mean in PICOTS?

Where the study takes place

What is a cohort study?

A study that starts with exposure and looks for outcomes

What measure is commonly used in cohort studies?

Relative Risk (RR)

Can cohort studies be prospective or retrospective?

Yes

What is a case-control study?

A study that starts with disease and looks backward for exposure

Are case-control studies prospective or retrospective?

Retrospective

What is compared in case-control studies?

Exposure in cases vs controls

What is a key advantage of case-control studies?

Good for rare diseases

What is a key advantage of cohort studies?

Good for studying multiple outcomes

What is a cross-sectional study?

A study that examines data at one point in time

Can cross-sectional studies determine cause and effect?

No

What is a limitation of cross-sectional studies?

Cannot establish temporality

What is a crossover study?

A study where participants receive multiple treatments sequentially

What is unique about crossover studies?

Subjects serve as their own control

Are crossover studies prospective or retrospective?

Always prospective

What is a washout period?

A time with no treatment to remove prior drug effects

What is a pre-post study?

A study comparing outcomes before and after an intervention

Are pre-post studies dependent or independent?

Dependent (same subjects)

What is a database study?

A study using existing data repositories

Are database studies usually prospective or retrospective?

Retrospective

What is a descriptive study?

A study that describes a disease or phenomenon

Can descriptive studies determine cause and effect?

No

What is a survey study?

A study that collects data using questionnaires

What is a major advantage of surveys?

Quick and can be anonymous

What is a major limitation of surveys?

Response bias and non-response bias

What is non-response bias?

Failure to collect data from all participants

What is response bias?

Participants give inaccurate answers

What is reliability?

The consistency or reproducibility of results

What is validity?

The accuracy of results

What is internal validity?

The extent to which results are free from bias within the study

What is external validity?

The extent to which results can be generalized

What is bias?

A systematic error that affects study results

What is selection bias?

Error due to how participants are selected

What is detection bias?

Differences in how outcomes are assessed between groups

What is measurement (information) bias?

Differences in how data are collected or reported

What is recall bias?

Participants do not accurately remember past information