Summary of "RASTREAMENTOS em Saúde: Conceito, Evidências e Ética"

This educational video provides a comprehensive overview of health screenings (rastreamentos), focusing on their concepts, scientific evidence, ethical considerations, and practical application in clinical practice. The lesson is divided into two parts, with this first part addressing the foundational principles and ethical dilemmas surrounding screening.

Main Ideas and Concepts

1. Definition and Concept of Screening

Screening is the active search for diseases or risk factors in asymptomatic individuals.
It differs from early diagnosis, which applies to symptomatic patients.
Screening aims to detect preclinical conditions before symptoms appear, enabling early intervention.
It should be personalized based on factors like age, sex, family history, and individual risk factors, rather than a “one size fits all” approach.

2. Checkup vs. Screening

Traditional checkups involve a complete medical exam (anamnesis + physical exam + complementary tests).
Checkups are comprehensive and include health promotion, vaccination status, lifestyle evaluation, and opportunistic screening.
Opportunistic screening occurs during visits for other reasons (e.g., fitness certificates).
Checkups are broader than screening but often include screening components.

3. Levels of Prevention and Screening’s Role

Prevention is divided into five levels:
- Primary Prevention: Prevent disease occurrence (e.g., vaccination, lifestyle changes).
- Secondary Prevention: Early detection via screening to halt progression.
- Tertiary Prevention: Minimize complications and rehabilitate patients with established disease.
- Quaternary Prevention: Prevent harm caused by medical interventions (avoid overdiagnosis, overtreatment).
- Quinary Prevention: Focus on healthcare professionals’ well-being to improve patient care.
Screening fits within Secondary Prevention.

4. Criteria for Valid Screening

Screening is justified only if it meets these criteria:

The disease is frequent and clinically significant.
There is a known preclinical phase detectable by tests.
The screening test is reliable (low false positives and false negatives).
Effective treatment exists that can alter the disease’s natural history.
The test is cost-effective and socially acceptable.
Early treatment does not cause more harm than the disease itself.

5. Risks and Harms of Screening

Screening can cause anxiety, false positives, false negatives, unnecessary invasive procedures, and overtreatment.
Overdiagnosis: detecting abnormalities that would never cause symptoms or affect quality of life.
Example: Thyroid nodules and thyroid cancer screening have increased diagnoses without reducing mortality, illustrating overdiagnosis.
False positives lead to unnecessary follow-up tests and treatments.
False negatives may give false reassurance, delaying diagnosis.
Screening should not be performed indiscriminately or without scientific backing.

6. Scientific Evidence and Biases in Screening Studies

Screening effectiveness must be proven by high-quality scientific studies (systematic reviews, meta-analyses).
Evidence-based guidelines from organizations like the American and Canadian Task Forces guide screening recommendations.
Common biases that affect screening studies:
- Lead-Time Bias (Time-Gain Bias): Early detection appears to increase survival time after diagnosis without extending overall life expectancy.
- Length-Time Bias (Variable Duration Bias): Screening preferentially detects slower-progressing, less aggressive diseases, giving a false impression of benefit.
- Adherence Bias (Selection Bias): Healthier, more compliant individuals are more likely to participate in screening, skewing results.
Randomized controlled trials are essential to minimize these biases and assess true benefits.

7. Clinical Decision-Making in Screening

Screening decisions must be individualized, considering:
- Pre-test probability (disease prevalence and patient risk factors).
- Test availability, cost, and patient acceptance.
Screening tests are typically sensitive but not diagnostic; positive results require confirmatory testing.
Screening is a shared decision-making process between doctor and patient, weighing risks and benefits.
Avoid “checklist” ordering of multiple tests without indication.

8. Ethical Considerations

The ethical principle “primum non nocere” (first, do no harm) is central.
Screening healthy individuals demands careful evaluation to avoid harm.
Overuse of tests for financial gain or patient demand without evidence is unethical.
Physicians should educate patients to change the cultural mindset that “more tests equal better health.”
Screening should be rational, evidence-based, and patient-centered.

Summary of Methodology / Instructions for Screening Practice

Understand the difference between screening and early diagnosis.
Perform a comprehensive checkup that includes lifestyle and vaccination assessment, not just tests.
Apply screening only when:
- The disease is common and serious.
- There is a detectable preclinical phase.
- The test is reliable and cost-effective.
- Effective treatment exists that improves outcomes.