CPH Exam Review Guide Questions With Advanced Answers#1

Incidence - correct answer A measure of the number of new cases of a disease. Cumulative Incidence - correct answer The number of new cases of disease in a population over a specific time period. EX: the risk of developing influenza among seniors vaccinated against the disease Incidence Rate - correct answer The number of new cases of the disease during person-time of observation. Prevalence - correct answer The number of existing cases of a disease during a given time period. This includes cases that already existed as well as new cases that developed during the time. Point prevalence - correct answer The proportion of the population that is diseases at a single point in time. Ex: a calendar date, a point in life such as college graduation Period prevalence - correct answer The proportion of of the population that is diseased during a specified duration of time Ex: a year endemic - correct answer A situation in a community in which there is a consistent elevated rate of a certain disease. Epidemic - correct answer An increase in the number of cases in a community, above what is expected. Pandemic - correct answer A worldwide epidemic Case studies/case reports - correct answer Studies used to alert people of a new illness or new association with illness. They usually are reports of only people with the condition of interest. cross-sectional studies - correct answer Studies that include people who are representative of a given population. Not selected on the basis of illness or exposure and can be used to determine initial associations and to identify the prevalence of either exposure or illness in a group. ecological studies - correct answer Studies that are used to describe populations. Data is not analyzed on the individual level, but rather on the aggregate level. ecological fallacy - correct answer occurs when group-level data are used to report on individuals case-control studies - correct answer Studies that select people with or without disease and then proceed to look back over time to see if people had different rates of exposure. Latency periods - correct answer refers to diseases that take a long time to develop ex: many cancers have a long latency period cohort studies - correct answer Studies that select people on the basis of exposure and determine if people develop disease at different rates. - good for rare exposures and may follow individuals into the future (prospective) or look back in time (retrospective). Randomized controlled trials (RCT) - correct answer RCTs test an intervention that is given by the researchers to two or more groups. _ people are randomly assigned into groups (randomization),a nd some are given the active item which the other group are given the usual treatment nothing (placebo). Systematic reviews and meta-analysis - correct answer Studies that pool the results of multiple independent studies with established criteria to identify the evidence for associations. Relative Risk (RR) - correct answer a measure of the magnitude of an association between an exposure and a disease that is used in cohort studies RR = risk (incidence) of outcome in the exposed/ risk (incidence) of outcome in the nonexposed = A/(A + B) / C/(C+D) Odds Ration (OR) - correct answer Is calculated in case-control studies or cross-sectional studies, as we do not have incidence data to calculate the RR of those studies OR = Odds of Outcome in the Exposed/ Odds of Outcome in the Nonexposed = A/B / C/D = AD/BC RR or OR = 1 - correct answer Means there is no association between the exposure and outcome - The risk or odds in the exposed equals the risk or odds in the nonexposed. RR or OR 1 - correct answer Means the exposure increases the risk of the outcome. - The risk or odds in the exposed is greater than the risk or odds in the nonexposed. RR or OR 1 - correct answer Means the exposure decreases the risk of the outcome. - The risk or odds in the exposed is less than the risk or odds in the nonexposed. Bias - correct answer a systemic error as compared to an error attributable to chance along - the bias can cause us to believe there is an association when there is none, or bias away from the null - the bias can hide association that actually exists, or bias toward the null selection bias - correct answer results from procedures used to select participants into a study. This bias would result in a different outcome from what would have been obtained from the entire population targeted for the study. - most likely to occur in case-control or retrospective studies because the exposure and outcome have occurred at the time of study selection observation bias - correct answer systematic error that arises from inaccurate measurements or misclassification of subjects according to exposure and outcome status; also called information bias recall bias - correct answer inaccurately reporting of past events interviewer bias - correct answer may include the effects of the interviewer's body language, voice, or demeanor on the response Misclassification error - correct answer happens when participants are incorrectly classified into the wrong population, distorting the link between exposure and outcome - differential (bias different between groups) - nondifferential (bias is equal across groups) Confounding - correct answer occurs when a researcher is evaluating the relationship between an exposure and an outcome, but a third variable, which is association with both the exposure and the outcome, distorts the finding Effect modification - correct answer occurs when the magnitude of the association between an exposure and outcome varies by the presence or level of a third variable