HAHP 3100 Test 1

primary research approach

collect and analyze new data

secondary research approach

analyze existing data

tertiary research approach

review and synthesize existing literature

research question

A statement including the specific exposure, disease, or outcome, and the population which research is focused on

study objectives

takes a form of a measurable question or a 'to' statement. Represents a step towards answering the main research question

lead researcher

first author, does the majority of the work

senior researcher

last author, most experienced and guides the work of others

Coauthors

most papers have between four to dozens

International Committee of Medical Journal Editors (ICMJE): Authorship Criteria

1. Substantial contributions to conception and design and/or acquisition of data and/or analysis and interpretation of data

2. Drafting the article and/or revising it critically for important intellectual content

3. Final approval of the version to be published

correlational studies

uses population level (group) data to examine the relationship between exposure rates and disease rates

ecological fallacy

assuming from a population that there is a high level of something, everyone will experience that same thing

correlational analysis

the use of statistical correlation to evaluate the strength of the relations between variables

correlational analysis for continuous variables

Pearson correlation co-efficient (r)

correlational analysis for rank/categorial variables

Spearman rank-order correlation

linear regression

used when comparing more than two variables with a goal of understanding the relationship between the two

case series

describes two or more patients who have the same condition/have undergone the same procedures. identifies new symptoms, refines diagnosis, develops hypotheses for future research etc.

atomistic fallacy

Wrongly assuming from observations causing the disease in individuals applies to all populations. prone to the opposite of the ecological fallacy

cross sectional studies

an observational study where exposure and disease are determined simultaneously in a given population. A temporal relationship between exposure and disease can not be determined

case controlled studies

used when the disease is uncommon and the general population is unlikely to yield enough cases. compares two preexisting groups to identify possible etiologies

case control analysis

used to find the proportion of individuals exposed in the cases (a/a+c) and controls (b/b+d)

odds ratio

ratio of odds of exposure in cases to that of controls

OR = 1

odds of exposure are the same for cases and controls

OR > 1

cases have higher odds of exposure than controls, exposure is risky to health

OR < 1

cases have lower odds of exposure than controls, exposure is protective to health

OR statistically significant

95% CI is greater than 1, and the exposure is deemed risky 95% CI is less than one, and the exposure is deemed protective

OR not statistically significant

95% confidence interval overlaps OR = 1 exposure and disease have no association

Matching

the process of selecting controls in a case-control study so that controls are similar to cases

no matching

assumes similar inclusion and exclusion criteria will result in case and control populations having similar distributions

frequency matching

control population is recruited similar to the case population, individual cases are not tied to individual controls

matched pairs

each case is personally linked to an individual control for all characteristics that are not disease specific

Limiting misclassification bias

all participants meet inclusion and exclusion criteria.

adherence to strict definitions of cases and controls

recall bias

information on past exposures depends on the memory of events from all people (oftentimes inadequate and limited)

occurs when the memory is better among cases than controls due to the disease

cohort

a group of individuals with similar characteristics followed along a timeline

cohort study

follows participants along a timeline to calculate the rate where a new disease occurs, identifies disease risk factors

baseline

exposure status of the participants

follow-up assessments

determine the number of participants who have developed a new disease since the initial examination

rate ratio

the incidence of disease for exposed (a/a+b) and control (c/c+d)

RR = 1

incidence rate was the same in exposed and not exposed groups, exposure is not associated with disease

RR > 1

the incidence rate was higher in the exposed group than non-exposed, exposure is risky

RR < 1

the incidence rate was lower in the exposed than non-exposed, exposure is protective

CI overlaps RR = 1

RR is not significant, no association

rate ratio CI > 1

RR is statistically significant, exposure is a risk factor

rate ratio CI < 1

RR is statistically significant, exposure is protective

Prospective (longitudinal) cohort studies

This study follows a population over time to track the development of the disease. Begins with the identification of the population and exposure status. It takes a long time to complete

retrospective cohort studies

existing data from the past is used to identify the population and exposure status. Determines the present status of the disease, no future follow-up is needed. Relatively quick

Combined prospective and retrospective cohort study

Past data is used to identify the population and exposure status. Quick to assemble using the study populations past data and follows the population into the future for development of disease.

Framingham Heart Study

one of the longest research studies. Began in 1948 using participants from 30-62 years old. For each possible exposure they made a hypothesis and identified the exposed and not exposed subjects were followed every two years to see the development of disease

Selection bias

selecting participants into exposed and non-exposed based on characteristics that could affect the outcome

information bias

collecting different quality and quantity of information for the exposed and non exposed

misclassification bias

misclassify exposure status and diseases status

observational study

investigators use the data observed in the population to make inferences on the relationship between the variables

experimental study

investigators intervene in the natural history by actively altering one variable and making inferences on the relationship between the variables based on the outcome

comparison groups in an experimental study

therapy/no therapy, therapy/placebo, therapy A/therapy B

randomization

the process where allocation of patients into treatment groups is done by chance and without the ability to predict who is in what group

clinical trial

a controlled experiment that has a clinical event as well as an outcome measure. Done in a clinical setting with subjects with a specific disease or health condition

randomized clinical trial

a clinical trial where patients are randomly assigned to specific groups comparing different treatments

stratified randomization

the random assignment within group defined by the participants' characteristics like age or disease severity. Ensures a good balance of factors across intervention groups

primary purpose of randomization

prevents bias within allocating participants to treatment groups

secondary purpose of randomization

achieve compatibility between groups

single blind study

subjects are unaware of their exposure status

double blind study

subjects and researchers are unaware of who is in the research and control groups

Hawthorne bias

subjects may change their behaviour because they know what is being observed. Can interfere with the accurate measurement of the impact of interventions

Parallel treatment

participants are randomized into A and B groups. Group A is the variable and B is control, the outcomes are then followed

Planned crossover treatment

participants are randomized into A and B groups. Group A is the variable, and B is the control. Halfway through the study, both groups "washout" and switch, A becomes the control, and B becomes the variable.

Unplanned crossover treatment

participants are randomized into groups A and B, some participants in A may refuse treatment and switch into B. Some from B require different care and are switched into A

treatment received approach

limits analysis to participants who were fully compliant with their assigned intervention (ideal world scenario)

treatment assigned approach

includes all participants even if they were not fully compliant with their assigned intervention (real world)

efficiency

The proportion of subjects in the control group who experienced an unfavourable outcome that could have had favourable outcome if they were in the treatment group instead. High efficacy is an indicator that an intervention is successful.

number needed to treat

the expected number of subjects needed to treat to achieve a favourable outcome in one person. Smaller number indicates a more effective intervention.

efficiency = (rc - ri)/rc

efficiency equation

NNT = 1/(rc - ri)

Number needed to treat equation

equipoise

experimental research should be conducted. only when there is uncertainty about which treatment will work better

distributive justice

infers the source population must be appropriate and non-exploitative

beneficence (do good) and non-maleficence (do no harm)

research must balance benefits and risks of the study

respect for participants

subjects must volunteer without being coerced or unduly influenced by their compensation

cross sectional analysis: prevalence of exposure

a/(a+c) vs. b/(b+d)

cross sectional analysis: prevalence of disease

a/(a+b) vs c/(c+d)

exposure

a personal characteristic, behaviour, environmental encounter, or intervention that may change the likelihood of developing a health condition

risk factor

an exposure increasing an individual's likelihood experiencing a particular disease or outcome

protective factor

an exposure reducing an individuals likelihood of experiencing a disease or outcome

non modifiable risk factor

a risk factor for a disease that cannot be changed through health interventions

modifiable risk factor

a risk factor for a disease that can be avoided or mitigated

feasibility study

an evaluation of the likelihood that a task can be completed with resources available

external funding

funding from private foundations, corporations, government agencies, etc.

internal funding

funding through universities or employers

research proposal

usually a request for funding or supervisory support

principal investigator

the primary investigator accepting responsibility for the study

research protocol

a detailed handbook describing all actions that will be taken during the study implementation