HSC 404: Quiz 11

Lead time bias

Difference in the time between the data of diagnosis with screening and the date of diagnosis without screening which if counted in the survival time of patients will give a misleading picture of the benefits of treatment

b

Screening fir disease involves which type of prevention? A. Primary B. Secondary C. Tertiary

Overdiagnosis bias

Screening identifies an illness that wouldn't have shown clinical signs before death from other causes

A

Selective screening involves applying the screening test to which of the following? A. High risk groups B. Low risks groups C. Selection criteria do not involve the risk level of the individual

Length bias

Slow progressing cases of disease with a better prognosis are more likely to be identified than faster progressing cases of disease with a poorer prognosis. Thus cases diagnosed through screening tend to have a better prognosis than the average of all cases

Selection bias

The screening test looks better than it actually is, because younger, healthier people are more likely to get the test

B

Which of the following best defines specificity? A. Proportion of people with the disease who have a positive test B. Proportion of people without the disease who have a negative test C. Proportion of people with a positive test who have the disease D. Proportion of people with a negative test who do not have the disease

B

Which of the following is not true? A. A screening measure may be reliable and invalid B. A screening measure may be unrealistic but valid C. A screening measure may be unreliable but invalid D. A screening measure may be reliable and valud

C

Which of the following measures is conditioned in having a positive test? A. Sensitivity B. Specificity C. Predictive value positive D. Predictive value negative

predictive

ability of a measure to predict some attribute/characteristic in the future

reliability

ability of measuring instrument to give consistent results on repeated trials

validity

ability of measuring instruments to give a true measurement

epidemiologic surveillance

aims at the protection of community health through case detection and intervention

selective screening

applied to subsets of the population at high risk for disease or certain conditions as the result of family history, age, or previous exposures. more economical and likely to yield more true cases

case-control studies

case - fatal cases of the disease; control - nonfatal cases; exposure - screening programs

ecologic time trends

compare geographic regions with screening programs ot those without

measurement bias

constant errors that are introduced by the faculty measuring device (miscalibrated blood pressure manometer)

repeated measurement

degree of consistence among repeated measurements of the same individual on more than one occasion

construct

degree to which the measurement agrees with the theoretical concept being investigated

halo effect

influence upon an observation of the observer's perception of the characteristics f the individual observed (health care provider;s tendency to rate a patient's sexual behavior used in a particular manner)

concurrent

estimate the validity of a measure by correlating it with an alternative measure of the same phenomenon taken at the same point in time

internal consistency reliability

evaluates the degree of agreement or homogeneity within a questionnaire measure of an attitude, personal characteristics, or psychological attribute

content

extent to which the measurement incorporates the domain of the phenomenon under study

recalibrate screening instrument

for those test utilize technology it may be possible to reduce the amount of imprecision through refinement of the methodology

survey

gain knowledge regarding the distribution and determinants of diseases in selected populations. not considered screening. no benefit to population.

social

health problem should be important for the individual and community. diagnostic follow-up and intervention should be available to all who require them. should be favorable cost-benefit ratio. public acceptance must be high

nomenclature

highly specific set of terms for describing and recording clinical or pathologic diagnoses to classify ill persons into groups

social desirability effect

introduced when a respondent of findings on a previous occasion manner that corresponds to the prevailing socially acceptable norms instead of giving the true answer (boys exaggerating sexual partners)

retrained screeners

if the test requires human assessment, then improving the precision of measurement through additional training sessions will reduce the amount of misclassification

utilize a different test

in some situations there may be more than one way to measure the outcome of interest. if one assay performs poorly, it may be possible to replace it with a better assay

selection bias

individuals who are more motivated enough to participate in screening programs may have a different probability of disease than individuals who refuse participation

scientific

natural history of the condition should be adequately understood. identification should occur during prepathogenesis with sufficient lead time. sound case definition in addition to a policy regarding whom to treat as patients. knowledge base exists for efficacy of prevention and occurrence of side effects. prevalence of the disease or condition is high

issues in classification

nomenclature and classification of disease are central to the reliability measurement of the outcome variable in epidemiologic research

mass health examinations

purpose is to gain new knowledge regarding the distribution and determinants of diseases in carefully selected populations.

lead time bias

perception that the screen-detected case has a longer survival simply because the disease was identified earlier in the natural history of the disease

screening

presumptive identification of unrecognized disease or detects by the application of tests, examinations, or other procedures that can be applied rapidly. Diagnostic confirmation is required, benefit with more thorough clinical examination and additional tests

ethical

provider initiates the service and should have evidence that the program can alter the natural history of the condition in a significant proportion of those screened. suitable, acceptable tests for screening and diagnosis of the condition as well as acceptable, effective methods of prevention are available

interjudge reliability

reliability assessments derived from agreement among trained experts

mass screening

screening of total population groups on a large scale, regardless of any prior information as to whether the individuals are members of a high risk subset of the population

classification

statistical compilation of groups of cases of disease by arranging disease entities into categories that share similar features

bias

systematic deviation of results/inferences from truth

improve specificity

the cut point should be moved farther in the range typically associated with the disease (high end of normal)

improve sensitivity

the cut point used to classify individuals as diseased should be move farther in the range of nondiseased (normal).

length bias

tumors that are detected by a screening program tend to be slower growing and have an inherently better prognosis than tumors that are more rapidly growing and are detected as a result of clinical manifestation

multiphasic screening

use of two or more screening tests together among large groups of people (information on risk factor status). pre-employment physical = passing the examination may be necessary condition for employment in the organization

case finding

utilization of screening tests for detection of condition unrelated to the patient's chief complaint

criterion referenced

validity that is found by correlating a measure with an external criterion of the entity being assessed

prevalence of disease

when prevalence decreases the predictive value positive falls and predictive value negative rises