[02.11a] Global Health & Screening Part 1 V2.1.pdf

Sputum smear microscopy

What was specified as the screening test for tuberculosis in the National Tuberculosis Program Manual of Procedures (NTP MOP 1980)?

Violet acid-fast bacilli

What is a positive result for sputum smear microscopy in tuberculosis screening?

75% sensitive, 94% specific

What are the sensitivity and specificity percentages for sputum smear microscopy for tuberculosis?

Culture

What is the gold standard for laboratory confirmation of tuberculosis?

GeneXpert MTB/RIF

What PCR technology is used to diagnose Mycobacterium tuberculosis and test for rifampicin resistance?

84% sensitive, 100% specific

What are the sensitivity and specificity percentages for GeneXpert MTB/RIF for tuberculosis?

Screening

What is defined as a systematic process of identifying individuals or objects within a population who have specific characteristics, conditions, or risk factors?

To detect potential issues or conditions at an early stage, often before symptoms appear, to facilitate timely intervention and treatment

What is the primary purpose of screening?

Medical tests, questionnaires, observations, assessments

What are various methods used in screening?

Further evaluation, intervention, or follow-up actions

What do the results of screening serve as, guiding decisions based on identified risks or conditions?

Intervention for the community, city, or region

In public health, what do screening results lead to?

Definitive diagnostic testing and ultimately patient treatment

For clinicians, what do screening results lead to?

Mammography screening

What public health screening method is recommended for women of a certain age to detect breast cancer at an early, treatable stage?

Pap smear

What public health screening method is recommended for women to detect precancerous changes in the cervix?

Cholesterol screening

What public health screening method involves measuring cholesterol levels in adults to assess the risk of heart disease?

Newborn screening

What public health screening method tests newborns for a variety of genetic and metabolic disorders shortly after birth?

HIV screening

What public health screening method encourages individuals to get tested for HIV to detect the virus early and access appropriate care and treatment?

Biopsy

What is the confirmatory test after mammography screening or Pap smear?

Actual laboratory test

What is the confirmatory test after cholesterol screening?

Screening

Which aims to identify individuals with a potential condition/risk factor at an early stage and determine if further diagnostic evaluation is needed?

Diagnostics

Which aims to confirm/rule out a specific condition/disease in suspects or those at risk, providing a definitive diagnosis to guide treatment decisions?

Broader or specific target populations

What population is typically targeted by screening?

Suspected/symptomatic individuals or those identified with higher risk through screening

What population is typically targeted by diagnostics?

Quick, cost-effective, less invasive, and identify potential cases (less accurate)

What are the characteristics of tests used in screening?

More thorough, expensive, more accurate, and aimed at definitively confirming/excluding a particular condition

What are the characteristics of tests used in diagnostics?

Gold standard

What term refers to a diagnostic test with the highest accuracy?

Further diagnostic evaluation

What does a positive screening result typically lead to?

Final step in confirming a diagnosis and guides treatment decisions

What is the action after a diagnostic test?

Mammography for breast cancer screening, blood pressure checks, developmental assessments in early childhood

Provide examples of screening tests.

Biopsy to confirm cancer, blood tests (HIV or diabetes), imaging scans (fractures or internal injuries)

Provide examples of diagnostic tests.

Mass Screening

What type of screening involves systematic screening of a large segment of a population for a specific condition, regardless of risk, exposure, or symptoms?

To identify potential cases or individuals with risk factors early on, often before symptoms appear, to initiate timely interventions, treatment, or preventive measures at a population level

What is the aim of mass screening?

Targeted (Selective) Screening

What type of screening focuses on specific individuals or groups (e.g., based on age, sex, occupation) who are at higher risk for a particular condition?

More efficient and cost-effective in identifying cases or risks while minimizing unnecessary screening in low-risk populations

Why is targeted screening considered beneficial?

Breast cancer screening targeting females aged 40 and above

Provide an example of targeted screening.

Opportunistic Screening

What type of screening occurs when healthcare providers offer screening tests to individuals during routine healthcare visits, often regardless of risk profile or reason for visit?

Takes advantage of healthcare encounters to offer screenings opportunistically

What is the benefit of opportunistic screening?

Age and gender

What considerations lead to tailoring screening approaches, such as mammography for women 40 y/o and above or prostate cancer screening for men?

More frequent or specialized screening

What might populations with known genetic predispositions or high-risk factors undergo?

Family history of disease, HIV, or residing in countries with higher risk for diabetes (e.g., Pacific Island nations)

Provide examples of high-risk populations due to genetic predispositions or risk factors.

Lung function tests and screening for construction workers exposed to asbestos or industrial fumes

What type of screening might be conducted for individuals with occupational exposures?

Behavioral assessment and counseling

What is important for conditions linked to lifestyle choices, such as obesity or substance abuse?

Geographic location and environmental factors

What factors might require screening due to exposure to pollutants, infectious diseases, or contaminated waste, such as communities near mining operations?

Limited access to healthcare facilities (rural areas or geographically isolated and disadvantaged areas - GIDA)

What affects the design and implementation of screening programs and may require more effort to reach individuals?

Cultural beliefs, language barriers, and healthcare access

What can impact screening effectiveness, requiring culturally sensitive approaches?

HIV screening among commercial sex workers in predominantly Roman Catholic populations

Provide an example of an ethnic and cultural consideration in screening, highlighting the need for protection and education despite potential societal views.

Sickle-cell anemia or certain types of cancer in communities in Africa

What diseases may disproportionately affect specific ethnic/racial groups, requiring targeted screening?

Socioeconomic factors

What affects access to healthcare and screening services, potentially requiring outreach and support for individuals lacking physical or financial access?

Universal Health Care

What initiative ensures the government provides needed services to all Filipinos, aiming to promote equity?

Disease prevalence

What factor dictates that regions with higher disease prevalence require more extensive screening to control or reduce spread and impact?

Extensive screening in areas where COVID-19 is more widespread

Provide an example of screening based on disease prevalence.

Targeted screening (rather than mass screening)

What type of screening may be less cost-effective in areas where a disease is rare?

Definitive and expensive screening for rare conditions

What is more recommended for rare diseases instead of broad screening?

Overall public health goals and available resources

What are public health goals and resources based on when prioritizing certain populations or conditions for screening?

Disease severity and potential consequences

What influences the screening approach and prioritization, with more fatal diseases like cancer given more priority over self-limiting conditions like the flu?

Technological advancements

What influences changes in screening methods, availability, and choice of screening tests?

GeneXpert

What technology is now utilized for screening tuberculosis, detecting positive infection and antimicrobial resistance?

Stronger drugs will immediately be given for treatment

What is the benefit of GeneXpert detecting antimicrobial resistance of first-line TB drugs?

Crisis or emergency situations (e.g., pandemics)

What requires screening programs to be adaptable for rapid screening to control the spread of infectious diseases?

Adjusted screening tests, such as at least two antigen results showing a positive result being sufficient to confirm a COVID-19 case

What adjustments were made to COVID-19 screening when the number of cases became too high, moving away from sole reliance on RT-PCR?

False positives

What are individuals who do not actually have the condition but are detected positive by a screening test?

Unnecessary anxiety, further tests, and costs

What can false positives cause, especially in diseases like cancer?

False negatives

What are individuals with the condition who are not detected by a screening test?

Delayed diagnosis and treatment

What can false negatives lead to if the disease is not detected early on?

Ethical and psychological concerns

What challenges include ethical dilemmas like the disclosure of sensitive information leading to stigmatization, or psychological distress from false-positive results?

Stigmatization of diseases (e.g., tuberculosis, HIV)

What can the disclosure of sensitive information from screening lead to?

Resource constraints

What limitation makes screening for rare diseases inadvisable and suggests focusing on communities with a higher yield of cases for diseases to be cost-efficient?

Careful planning and prioritization

What do resource-intensive screening activities require?

Gold standard

What is the definitive, confirmatory test against which the performance of a screening test is assessed?

The best single test (or combination of tests) that is the currently preferred method of diagnosing a particular disease (X)

How is the gold standard defined?

TB culture in tuberculosis, biopsy in breast cancer

Provide examples of gold standards.

Sensitivity (SN)

What indicator of diagnostic performance measures the ability to detect true cases?

SN = True Positives / All confirmed cases x 100%

What is the formula for sensitivity?

True Positives + False Negatives

What equals the total confirmed cases in the sensitivity formula?

Specificity (SP)

What indicator of diagnostic performance measures the ability to screen out non-cases?

SP = True Negatives / All confirmed non-cases x 100%

What is the formula for specificity?

True Negatives + False Positives

What equals the total non-confirmed cases in the specificity formula?

Positive Predictive Value (PPV)

What indicator of diagnostic performance is the probability (%) that an individual actually has the condition if tested positive?

PPV = True Positives / All who tested positive x 100%

What is the formula for Positive Predictive Value?

False Positives + True Positives

What equals the total positive tests in the PPV formula?

Negative Predictive Value (NPV)

What indicator of diagnostic performance is the probability (%) that an individual actually doesn't have the condition if tested negative?

NPV = True Negatives / All who tested negative x 100%

What is the formula for Negative Predictive Value?

False Negatives + True Negatives

What equals the total negative tests in the NPV formula?

True Positives (TP)

What term describes cases confirmed positive by the gold standard and screened positive by the screening test?

False Negatives (FN)

What term describes cases confirmed positive by the gold standard but screened negative by the screening test?

False Positives (FP)

What term describes cases confirmed negative by the gold standard but screened positive by the screening test?

True Negatives (TN)

What term describes cases confirmed negative by the gold standard and screened negative by the screening test?

Incidence (%)

What measure of disease frequency signifies new cases detected, calculated as Cases/Total population x 100%?

Improves with low false negatives

What does good sensitivity indicate?

Improves with low false positives

What does good specificity indicate?

Improves with low false positives

What does good PPV indicate?

Improves with low false negatives

What does good NPV indicate?

Prevalence

What measure of disease frequency determines the percentage of existing cases of a disease, usually for chronic and non-communicable diseases with longer development?

Incidence

What measure of disease frequency is used for diseases with fast development/incubation periods, acute diseases, or new cases like injuries?

Less than 5% incidence rate

What defines a rare disease in terms of incidence rate, suggesting screening tests may not be cost-effective?

Sensitivity

What diagnostic performance indicator is particularly important when missing a true positive case can have serious consequences, such as in cancer screening?

Lower specificity

What may increasing sensitivity lead to?

Specificity

What diagnostic performance indicator is particularly important when the consequences of a false positive result are significant, such as unnecessarily subjecting individuals to invasive follow-up tests or psychological distress?

Lower sensitivity

What may increasing specificity lead to?

Receiver Operating Curve (ROC)

What analysis is used to appreciate the balance between sensitivity and specificity and evaluate diagnostic tests?