🛡️ Disease prevention and screening are core aspects of public health and general practice.
They aim to reduce morbidity, mortality, and healthcare costs by intervening before illness develops or by detecting disease at an early, treatable stage.
🌍 Levels of Prevention
- Primary Prevention: Prevents disease before it occurs.
Examples: immunisation 💉, smoking cessation 🚭, healthy diet and exercise advice 🍎🏃.
- Secondary Prevention: Detects disease early to allow prompt treatment.
Examples: cancer screening programmes, BP checks for hypertension, cervical smear tests.
- Tertiary Prevention: Reduces impact of established disease by preventing complications.
Examples: cardiac rehab after MI ❤️🩹, diabetic foot care 👣.
🧪 Principles of Screening (Wilson & Jungner, WHO)
- Disease should be an important health problem with a detectable early stage.
- A suitable test should exist – safe, acceptable, accurate (high sensitivity/specificity).
- Facilities for diagnosis and treatment must be available.
- Early treatment should improve outcomes.
- Programme must be cost-effective and acceptable to population.
📋 NHS National Screening Programmes (UK)
| Condition |
Who is Screened |
Method |
| 🧬 Newborn screening |
All babies |
Heel-prick blood spot test (9 rare but serious conditions, e.g., PKU, sickle cell, CF) |
| 🍼 Newborn hearing |
All babies |
Automated otoacoustic emission test |
| 🧑🦱 Cervical cancer |
Women 25–64 yrs |
HPV primary testing (cervical smear every 3–5 yrs) |
| 🎗️ Breast cancer |
Women 50–70 yrs |
Mammography every 3 yrs |
| 🦠 Bowel cancer |
Men & women 60–74 yrs (England) |
FIT (faecal immunochemical test) every 2 yrs ± colonoscopy if positive |
| 🫀 Abdominal aortic aneurysm (AAA) |
Men 65 yrs |
Abdominal ultrasound |
| 🦠 Infectious diseases |
Pregnant women |
Screening for HIV, syphilis, hepatitis B |
🔍 Opportunistic Case Finding
- Not formal population screening, but identifying disease during unrelated healthcare contact.
- Examples: BP checks in GP clinic → hypertension, spirometry in smokers → COPD, HbA1c → diabetes.
⚖️ Benefits vs Harms of Screening
- Benefits: Early treatment → better outcomes, reduced mortality, reassurance.
- Harms: False positives (anxiety, unnecessary tests), false negatives (false reassurance), overdiagnosis, overtreatment.
🩺 Role of the Clinician
- Educate patients about prevention and screening.
- Encourage lifestyle modification (smoking, alcohol, weight, exercise).
- Offer and explain relevant NHS screening tests.
- Be aware of eligibility, recall systems, and follow-up pathways.
📊 Example: Cervical Cancer Screening
✅ Prevents invasive cervical cancer by detecting and treating pre-cancerous lesions.
⚠️ Harms include discomfort, false positives, and anxiety.
👩 Patients with persistent high-risk HPV → referred for colposcopy.
📚 Summary
- Disease prevention = stopping illness before it starts.
- Screening = detecting illness early to improve prognosis.
- NHS provides structured national screening programmes for high-burden diseases.
- Doctors must balance benefits vs harms and communicate clearly with patients.
