Week 5 ILAs Flashcards by Mary Faragalla

a type of descriptive study, detailed report on ONE patient, often used to describe unique cases or cases that show important variations of a disease

case report

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a type of descriptive study, a series of group of cases reports on MULTIPLE patients who received a similar treatment, experienced a similar disease, or had a similar exposure; cannot show risk factor association with disease

case series

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a type of descriptive study, frequency of disease and frequency of related factors are assessed in the present among INDIVIDUALS; measures disease prevalence; cannot show risk factor association DOES NOT ESTABLISH CAUSALITY

cross sectional

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a type of descriptive study, compares frequency of disease and frequency of risk related factors across POPULATIONS

ecological

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a type of analytical observational study, collecting data from filtered target audiences to understand issues particular to them

community surveys

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a type of analytical observational study, compares a group of people with a disease to a group of people without a disease; attempts to identify risk factors and exposures that contribute to development of outcome of interest, measures are odds ratios

case-controls

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a type of analytical observational study, compares a group with a given exposure or risk factor to a group without such risk factor/exposure; looks to see if risk factor is associated with later development of disease, can be retrospective or prospective, but risk factor MUST be present BEFORE disease development

cohort

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a type of cohort, individuals are sampled and data collected about their past (useful to study rare diseases

retrospective

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a type of cohort, individuals are followed over time and data is collected. No participants have disease at time of study onset (ex. Framingham Heart Study)

prospective

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experimental studies involving humans, compares therapeutic benefits of >= 2 interventions, study quality improves when clinical trial is randomized, controlled, double blinded

clinical trials

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a type of clinical trial, measures an intervention’s effect by randomly assigning individuals to an intervention group or control arm. considered “gold standard”

randomized controlled trial

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a type of clinical trial, neither subject nor researcher knows whether the subject is in treatment or control group until clinical trial is over; makes results of study less likely to be biased

double blind

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a type of clinical trial, trial of 2+ groups, one group gets active treatment, others get placebo, but everything else is same between groups, so that any difference in their outcome can be attributed to the active treatment

placebo-controlled trial

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a type of clinical trial, test whether a new experimental treatment is not unacceptably less effective than an active control treatment already in use (no worse than standard treatment); underlying hypothesis is that the investigation treatment may not provide additional efficacy but may benefit patients or society regarding quality of life and/or cost

noninferiority trials

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a type of clinical trial, similar to noninferiority, aims to show that a new treatment is no better and no worse than standard treatment

equivalence trials

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a type of clinical trial, compares effect of series of 2 or more treatments on a subject, order of treatments is randomized, washout periods between treatments so subjects can act as own controls

crossover clinical trials

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a type of clinical trial, all subjects analyzed according to original, randomly assigned treatment; no one excluded, tries to avoid various bias but may dilute true intervention effect in doing so

intention to treat analysis

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phase of clinical trial, very small number of healthy volunteers or patients with disease of interest, open label, initial pharmacokinetic assessments via microdosing

phase 0

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phase of clinical trial, small number of healthy volunteers or patients with disease of interest, open label, safety assessment via dose escalation to determine max tolerated dose

phase I

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phase of clinical trial, moderate number of patients with disease of interest; randomized, controlled, anonymized, efficacy assessment and provides additional data on short term adverse side effects

phase II

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phase of clinical trial, large number of patients with disease of interest

phase III

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phase of clinical trial, postmarketing surveillance of patients after treatment is approved

phase IV

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type of analytical interventional studies, evaluate the effects of interventions on health outcomes within a group that may be defined geographically or socially; can be randomized- groups, can be longitudinal cohort or cross sectional studies, if number of group is too small it can result in weak statistical power, ex) Kingston Newburgh Fluoride Trial

community interventions

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considered highest quality evidence on research topic because their study design reduces bias and produces more reliable findings

systematic reviews and meta analyses

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attempt to gather all research using defined methods to answer a specific question; entire process of selecting, evaluating, and synthesizing all available evidence

systematic reviews

method of statistical analysis that pools summary data (ex. means) from multiple studies to obtain a more precise estimate of the size of an effect; combining data from a systemic review

meta-analysis

when publication of a study results is based on direction, strength, or significance of the findings ex) positive findings more likely to be published, negative findings are not accepted

publication bias

helps determine if statistically significant results are meaningful; measures strength of relationship between 2 variables = (mean of treatment group-mean of control group)/ standard deviation of control group larger, the stronger the relationship between 2 variables

effect size

the extent of variability in study outcomes; estimated by meta analyses

heterogeneity

display of results from multiple studies on set of axes to check for heterogeneity

Forest plot

checks for existence of publication bias and heterogeneity

Funnel diagram

selection of a subset from a population to estimate characteristics of/represent the whole population

sampling

involves random selection, allowing strong statistical inferences about the entire population

probability sampling

involves non random selections based on convenience of other criteria, allowing easier collection of data

non-probability sampling

process by which participants in clinical trials are assigned by chance to separate groups that are given different treatments or other interventions

randomization

every member of a population has an equal chance of being selected (ex. using random number generator)

simple random sampling

population is divided into subgroups, then randomly or systemically sample individuals from each subgroup; can allow more precise conclusions by ensuring every subgroup properly represented

stratified random sampling

population is divided into subgroups (similar to overall population), then randomly select entire subgroup

cluster sampling

each member of a population is listed with a number; individuals are chosen at regular intervals

systematic

matched sampling pairs an individual in the group with an individual in the experimental group where the individuals share all characteristics EXCEPT THE ONE UNDER INVESTIGATION

matching

characteristics that prospective participants must have in order to be included in a study

inclusion criteria

factors that would disqualify a person from participating in a specific study

exclusion criteria

based on a single sequence of random assignments; more difficult to establish that the outcome was caused by treatment and not other variables; the researches ability to draw conclusions about study outcomes are greatly weakened due to threats to validity (ex. placebo effect)

simple randomization

blinds how trial participants are sorted into groups until moment of assignment; prevents selection bias affecting which patients are given treatment (which is what randomization is trying to avoid)

concealed allocation

the sum of all values divided by the total number of values, most affected by outliers (extreme values) = sum of all values/ total number of values

mean

middle number in an ordered dataset

median

most frequent value; least affected by outliers

mode

how much variability exists in a set of values, around the mean of these values

standard deviation variance= (SD)^2 o=SD; n= sample size

estimate of how much variability exists in a theoretical set of a sample means around the true population mean; decreases as a sample size increases

standard error SE+ o/ sqrt(n)

measure of dispersion of a sample (how closely the observations cluster around the mean); measure of the spread of a dataset

variability

difference between the highest and lowest values

range

range of the middle half of a distribution

interquartile range

average distance from the mean

standard deviation

average of squared distance from the mean

variance

concept of how the data evens out, if a variable is extreme the first time you measure it, it will be closer to the average of the next time you measure it; describes how a random variable outside the norm eventually leads to return to the norm ex) winning streak usually happens because of a sampling error

regression to the mean

probability distribution that is symmetric about the mean, shows that data near the mean occur more frequently than data far from the mean, also called Gaussian distribution or bell shaped for normal distribution, mean is the best measure of central tendency for skewed data, median is better measure

normal distribution

suggest 2 different populations; has 2 peaks or modes around which values tend to cluster within a single distribution

bimodal distribution

mean > median > mode

positive skew

mean < median < mode

negative skew

conjecture based on knowledge obtained while formulating a question

hypothesis

testing that the question or conjecture that the hypothesis is false, there is no statistically significant difference between the 2 groups ex) there is no difference in students that have at least 6 hours of sleep the night prior to taking an exam vs students that study all/most of the night

null hypothesis

that a drug or therapy performs better than chance ex) students that have at least 6 hours of sleep prior to an exam will perform better on exams than students that study all night prior to exam

alternative hypothesis

medical and biomedical research leads to discoveries and technologies of medicine that have direct application in clinical settings

parallelism between basic research and clinical practice

formalizes the use of the scientific method in clinical decision making, use of the most current and best evidence from clinical trials to form diagnoses in individual patient cases; requires physicians to assess and understand what the best available evidence is, use his or her clinical judgment, and do so in the context of the patient's values and preferences

evidence-based medicine

to avoid personal biases within a RCT, the treating physician should not have any personal biases that one treatment is better than the other, there should be genuine uncertainty in the expert medical community whether a treatment will be beneficial derives from assertion that no hypothesis can be rejected or accepted until an experiment is performed

equipoise in RCTs

solves problems by forming possible explanations, or hypotheses, based on previous knowledge; search for order among facts by directing the process of fact selection and interpretation of observation the more conclusive the evidence is the more probable the most reasonable hypothesis is

scientific method

idiopathic

Description: To examine whether a sedation strategy with dexmedetomidine can improve clinical outcomes in patients with sepsis undergoing ventilation. Patients received either sedation with dexmedetomidine (n = 100) or sedation without dexmedetomidine (control group; n = 101). This study represents an example of a:

randomized control trial

Secondary HLH due to Streptococcus pneumoniae infection in a splenectomised patient for spherocytosis, a 37-year-old patient who was splenectomised in childhood for spherocytosis, without immuneprophylaxis induced by antipneumococcal vaccine. This study represents an example of a:

case study

Sepsis has recently been defined as "life-threatening organ dysfunction caused by a dysregulated host response to infection". A great amount of effort has been made to develop early treatments for sepsis through the Surviving Sepsis Campaign. Efforts have been made to define sepsis, septic shock and infection in the burn population but there is constant need for revisions. In this manuscript, we will discuss the differences in burn sepsis versus sepsis of the general population. This study represents an example of a:

systematic review

We performed an observational study focusing on 129 very low birth weight infants. Thermal gradient alteration was defined as a difference of > 2°C maintained during 4 hours. We then determined its association with the late-onset sepsis variable through logistic regression. This study represents an example of a:

cohort study

which study results would most likely lead to a large multicenter trial and may influence patient treatment?

randomized control trial

induction of developmental defects in fetus by drugs or toxins, generally non inheritable type determination: Tx pregnant female animals during early pregnancy ex) thalidomide, alcohol, valproic acid

teratogenesis

induction of genetic mutation in animals of any age leading to induction of inheritable abnormalities determination: Ames test or "dominant lethal test" ex) cancer chemotherapeutic agents

mutagenesis

induction of malignant characteristics in cells determination: Ames test exhibits moderate correlation with carcinogenicity in animal studies ex) polycyclic aromatic hydrocarbons, coat tar, nitrosamines

carcinogenesis

a detailed summary of results of all preclinical studies performed on a drug prepared by the developer, reviewed byFDA

investigational new drug application (IND)

combined phases 1 and 2 of clinical trials

antineoplastic drugs

financial and operational incentives for development of drugs to treat rare diseases

orphan disease

most persuasive phases in clinical trials

phases 1-3

least persuasive phase in clinical trials

phase 4- post marketing surveillance

"generic" name of drug, only on per drug, US applied name committee

the non-proprietary name

assigned by drug company, protected by law, paten lasts 20 years, "trade" name, registration lasts 50 years

the proprietary name

requires written prescription, no refills without exam by MD, providers must keep in secured area

schedule II prescription requirement for controlled substances

prescription can be written or phoned by MD, DO, etc prescription must be renewed every 6 months and can be refilled up to 6 times

schedules III and IV prescription requirement for controlled substances

prescription for many V's (OTC), pt must be 18 years or older, and may need to sign pharmacist's dispensing log ex) cough syrup

schedule V prescription requirement for controlled substances

nonrandom sampling or treatment allocation of subjects such that the study population is not representative of the target population; most commonly a sampling bias ex) the way a study ad is worded might discourage or encourage certain groups of people to participate

selection bias

case and or controls selected from hospitals are less healthy and have different exposures

Berkson bias

participants lost to follow up have different prognosis (or characteristics) than those who complete the study ways to reduce: randomization, ensure choice of most appropriate comparison/reference group

attrition bias

systematic error when participants do not remember previous events or experiences accurately and/or omit details ex) food journal awareness of a disorder alters subjects' recall, common in retrospective studies ex) patients with a disease recall exposures after learning of similar cases

recall bias

ways to reduce ___ bias- reduce time from exposure, use medical records to confirm self report, use other resources (diaries, calendars, texts, etc) to strengthen accuracy

recall bias

information collected for use as a study variable is inaccurate, information gathered in systemically distorted manner ex) using faulty sphygmomanometer Hawthorne effect- participants change behaviors when they are aware they are being observed ways to reduce: use objective, standardized, previously tested methods of data collection, use placebo

measurement bias

subjects in different groups are not treated the same; unfair amount of pressure applied to subjects, forcing them to complete responses quickly ex) patients in treatment group spend more time in highly specialized hospital

procedure bias

ways to reduce ___ bias: blinding and using a placebo reduce influence of participants and researches on procedures and interpretation of outcomes

procedure bias

a factor related to both the exposure and the outcome distorts the effect on exposure on the outcome ex) an uncontrolled study shows association btw drinking coffee and lung cancer. However, people who drink coffee may smoke more, which might explain this association

confounding bias

ways to reduce ___ bias: multiple/repeated studies, crossover studies where subjects act as their own control, matching patients w/ similar characteristics in both treatment and control groups effect modification: association shown differently in individual subgroups due to stratification by given factor even when there's association btw exposure and outcome

confounding bias

early detection interpreted as increased survival, but the disease course has not changed; early diagnosis of disease falsely makes it look like people are surviving longer ex) breast cancer diagnosed early by mammography may seem to have exaggerated survival time because patients are known to have cancer for longer

lead time bias

ways to reduce ____ bias: measure "back end" survival, adjust survival according to the severity of disease at the time of diagnosis

lead to time bias

screening test detects diseases with long latency periods, while those with shorter latency periods become symptomatic earlier; overestimation of survival duration due to relative excess of cases detected that are slowly progressing ex) slowly progressive cancer is more likely to detect by screening test than a rapidly progressive cancer

length time bias

ways to reduce ___ bias: a randomized controlled trial assigning subjects to screening program or no screening

length time bias

hypothesis of no difference or no relationship ex) there is no association btw the disease and the risk factor in the population

null hypothesis (H0)

hypothesis of some difference or relationship ex) there is some association between the disease and the risk factor in the population

alternative hypothesis (H1)

statistical tests performed to see if ____ hypothesis is true. If it is not, reject ____ and the ___ hypothesis is accepted and observed difference is statistically significant

null hypothesis (H0) null hypothesis (H0) alternative hypothesis (H1)

probability of obtaining test reults at least as extreme as those observed during the test, assuming that H0 is correct commonly accepted as 0.05 functions as evidence against H0 a small value (0.005) means there is a 5% chance the observed results happened merely by chance

P value

Stating there is an effect or difference when one exists

H0 rejected in favor of H1/ Type I Error (a)

stating there is no effect or difference when none exists

H0 not rejected/ Type II Error (b)

also called false positive error, alpha is the probability of making a ___ error, increases significantly with multiple comparisons, if alpha increases= increase in statistical significance level

type I error (alpha)

also called false negative error, Beta is the probability of making a ___ error. when type __ error increases, type __ error decreases Beta is the statistical power (1-B) which is the probability of rejecting H0 when it is false increase sample size, increase power, decrease B

Type II error (beta)

range of values likely to induce the true mean of population is expected to fall, with a specified probability

confidence interval

comparison planned before data collection based on prior knowledge, deductions, and theory

a priori analysis

researchers choose additional comparisons to study after viewing the data based on results of planned comparisons and viewing of the data caveat: danger of fitting a theory around the data

post hoc analysis

breaking down the sample into groups based on characteristics for comparison and to check consistency across population can lead to spurious findings (false positives) and have too little power due to small sample sizes (false negatives)

subgroup analysis

an investigator suspects that diphenhydramine use during the first trimester of pregnancy can cause neural tube defects. She estimates the risk of neural tube defect in the general population is 1:1000. What kind of study is this?

cohort study

which parameter is most likely to be the least biased estimator of central tendency for this distribution of test scores?

mode

500 women aged 40-54 are asked about meat consumption at routine check ups. 20% of the women are vegetarian. Over the next 5 years, 5 vegetarians and 43 non-vegetarians develop colorectal cancer. what kind of study is this ?

cohort study

a group of patients with oropharyngeal cancer is matched to a group of patients without oropharyngeal cancer. their tobacco habits over the course of their lives are compared, and the researcher then compute the odds of tobacco use among the 2 groups. This is an example of

case control study

a group of patients diagnosed with COVID 19 are contacted after diagnosis and at 6 and 12 months to identify prevalence of and risk factors for post acute sequelae of COVID 19. what kind of study is this

longitudinal study

most useful technique in over-reporting from a placebo group

blinding