Every general-practice consultation is an opportunity to go beyond the presenting complaint and address prevention, early detection, and health promotion. This lecture, delivered by Prof William CW Wong (Department of Family Medicine & Primary Care, HKU), anchors the Family Medicine clerkship by teaching you how to think about prevention systematically — from the population level down to the individual sitting in front of you — and illustrates it with a deep-dive into Hepatitis B as a model for cross-society health promotion. ^[1]

1. Session 1 — Preventive activities in Family Medicine: Recap the criteria and range of screening and understand what screening means for an individual person.
2. Session 2 — Health promotion in primary care: Understand health promotion activities specific to primary care (using Hepatitis B as an example), recognise difficulties in delivering health promotion, and learn ways to overcome them.

• Family Medicine is one of the six whole-class sessions in the GCBC-FM curriculum. ^[2]
• Prevention questions are perennial in Fourth Summative SAQs and MCQs — they test your ability to classify levels of prevention, apply Wilson-Jungner screening criteria, and recognise which screenings are recommended vs. controversial vs. "recommend against." ^[3][4]
• The HBV case study models translational public-health thinking: from evidence (cost-effectiveness analysis) → policy → community engagement → primary care implementation — a framework applicable to any disease.

"~50% of all deaths in the US are attributable to modifiable behavioural causes." ^[1]

Why this matters: The top three killers are all lifestyle-related. This is the intellectual backbone of preventive medicine — if you can modify behaviour, you prevent half of all deaths. Primary care is the front line for this because it is where patients present repeatedly, often for unrelated complaints, giving you multiple "windows of opportunity."

The lecture defines four levels of prevention mapped to the disease continuum. ^[1]

Every general practice consultation has four domains beyond the presenting complaint. ^[1]

┌─────────────────────────────────────────┐
│         GP Consultation Potential        │
├───────────────────┬─────────────────────┤
│ Presenting        │ Continuing care      │
│ complaint         │ (chronic disease     │
│ (overt/covert)    │ management)          │
├───────────────────┼─────────────────────┤
│ Prevention,       │ Modification of      │
│ early detection,  │ abnormal help-       │
│ health promotion  │ seeking behaviour    │
├───────────────────┼─────────────────────┤
│ Coordination      │                     │
│ of care           │                     │
└───────────────────┴─────────────────────┘

Why this model matters: A patient comes in for a sore throat. You treat the sore throat (presenting complaint). But you also notice they smoke — so you give brief smoking cessation advice (prevention). You check if their BP has been measured recently (early detection). If they've been coming in frequently for trivial complaints, you explore why (modification of health-seeking behaviour). If they have diabetes being managed by a specialist, you ensure follow-up is coordinated (coordination of care). This "opportunistic" approach is the hallmark of comprehensive primary care.

The lecture lists eight domains of individual preventive activities: ^[1]

1. Immunisation
2. Birth control
3. Sexually transmitted diseases
4. Mental health
5. Smoking
6. Alcohol
7. Screening
8. Dental care

Each of these represents a conversation you can have during any consultation. The key is being systematic and opportunistic — you don't wait for the patient to ask; you proactively screen and counsel.

The lecture lists the following childhood vaccines:

In Hong Kong, the Childhood Immunization Programme (HKCIP) covers most of these through MCHC visits. The ICHDP covers > 90% of newborns. ^[5]

The lecture distils the 10 Wilson-Jungner criteria into 5 key points: ^[1]

Additional points from slide: RCT evidence is needed. There is huge pressure to screen. There are ethical/legal issues. ^[1]

Why each criterion matters from first principles:

• Long pre-clinical phase: If a disease goes from undetectable to lethal in days (e.g., pancreatic cancer), screening is futile — you can't catch it early enough. Cervical cancer takes 10-20 years to progress from dysplasia → carcinoma, making it ideal for screening.
• Treatment must improve outcome: If you can detect it early but there's no treatment that changes the natural history, you've just given the patient more years of anxiety (lead-time bias). This is the core argument against routine PSA screening.
• Sensitive test: A test that misses most cases (low sensitivity) will give false reassurance. You want high sensitivity for screening (you'll sort out false positives later with confirmatory tests).
• Acceptable to patient: A perfect test that nobody agrees to take is useless. This is why FIT (faecal immunochemical test) has replaced guaiac FOBT — it's easier, more acceptable, and more sensitive.
• Cost-effective: Healthcare resources are finite. Screening must be compared against alternative uses of the same money.

The full 10-point Wilson-Jungner criteria are also listed in senior notes and are frequently examined. ^[6][7]

Chronic illnesses in four domains:

1. Cardiovascular disease
2. Cancers
3. Degeneration
4. Disability of ageing

The lecture lists the following CV risk factors to screen for:

Connection to related material: The HK Consensus 2016 on primary CVD prevention recommends non-pharmacological measures (diet, moderate-intensity exercise ≥30 min × ≥5 days/week, weight loss, smoking cessation) alongside pharmacological optimisation (BP, glucose to HbA1c < 7%, LDL targets based on risk stratification). ^[8]

Prof Wong uses Hepatitis B as a paradigm for cross-society health promotion because:

1. HBV is highly prevalent in Hong Kong and China (endemic area, ~7-8% chronic carriage rate).
2. Despite neonatal vaccination since 1988, there is a huge undiagnosed pool of adults infected before universal vaccination.
3. Effective treatment exists (nucleos(t)ide analogues) — meaning that finding cases saves lives.
4. It illustrates the full spectrum: primary prevention (vaccination), secondary prevention (screening), tertiary prevention (treatment to prevent cirrhosis/HCC), and quaternary prevention (avoiding unnecessary invasive procedures in low-risk carriers).

In Hong Kong, only 22% of HBV-infected individuals are diagnosed, and only 17% are treated. ^[1]

"Newborn vaccination and maternity testing alone is insufficient to eliminate HBV (requires 90% reduction in new chronic infections and 65% reduction in mortality). We need to find the missing patients!" ^[1]

Why this matters: Vaccination prevents new infections but does nothing for the estimated 290 million people worldwide already chronically infected. You need active case-finding (screening) + linkage to care (treatment) to reduce mortality.

The lecture highlights WHO policy guidance for targeted HBV/HCV screening:

• Dialysis patients
• Intravenous drug users
• Concomitant HIV patients
• "HBV/HCV screening should be provided in conjunction with STD screening, at intervals informed by risk assessment" ^[1]

Key findings (Wong WC as co-first author):

1. Universal HBV screening in China is cost-effective
2. Data robust in different sensitivity analyses
3. Can save 3.46 million lives
4. Impact decreases if screening is delayed
5. Screening alone cannot reduce mortality by 65% — treatment uptake is also essential

Methodology ^[1]:

• Markov decision-analytic model simulating HBV natural history
• Examined 15 target groups stratified by age (18-30, 18-40, 18-50, 18-60, 18-70 years), born before HBV vaccine was integrated into the Chinese national immunisation programme (free since 2002)
• Four screening strategies compared:
  1. HBsAg alone
  2. HBsAg + HBsAb
  3. HBsAg + HBsAb + HBcAb
  4. HBsAg + HBsAb + HBeAg + HBeAb + HBcAb ("Five-test" panel)
• Three initiation years: 2021, 2026, 2031 (to show cost of delay)

Result: The five-test (HBsAg/HBsAb/HBeAg/HBeAb/HBcAb) screening in people aged 18-70 was the MOST cost-effective strategy in 2021-2031. ^[1]

Why five tests? Each serological marker tells you something different:

• HBsAg: Currently infected?
• HBsAb: Immune (from vaccine or resolved infection)?
• HBcAb: Ever been exposed (past or current)?
• HBeAg: Actively replicating (higher infectivity)?
• HBeAb: Seroconversion (lower replication)?

Using all five allows you to classify the patient's HBV status precisely, determine who needs treatment, who needs vaccination, and who is immune — maximising the public health impact per dollar spent.

The new WHO strategies recommend decentralising routine hepatitis testing and care to primary care. ^[1]

The lecture presents a second cost-effectiveness study comparing three scenarios:

"Improving HBV antiviral treatment uptake is the key to improving the shared-care models' effectiveness and cost-effectiveness." ^[1]

Why this is clinically important: In Hong Kong and China, most HBV patients are managed in hospital specialist clinics. This creates bottlenecks. The evidence shows that training primary care doctors to manage stable CHB (with clear referral criteria for complex cases) is not just clinically effective — it actually saves money.

The lecture outlines a multi-pronged approach:

1. Policy and Guideline — e.g., HBV guideline for primary care in Mainland China (11,552 online reads)
2. Evidence to do better — e.g., universal screening research
3. Engaging medical professionals and industries
4. Traditional and Digital Media — World Hepatitis Day promotion videos (FB views: 435,030), social media campaigns
5. Community Outreach — vulnerable HCV communities, media coverage (18 outlets)
6. Within and Beyond Hong Kong and China — BBC Future series, YouTube/social media channels

Why this matters for exams: Health promotion is not just about clinical knowledge — it's about communication, community engagement, policy advocacy, and using multiple channels to reach people. Family Medicine questions may ask about barriers to health promotion and how to overcome them.

• "Name the levels of prevention": List all four (Primary, Secondary, Tertiary, Quaternary) with one-line definitions.
• "State the Wilson-Jungner criteria": List all 5 condensed points (or full 10 if asked). The 5-point version from this lecture is sufficient for FM questions.
• "What is quaternary prevention?": "Action to identify patients at risk of over-medicalisation and protect them from unnecessary medical interventions" — must include the concept of harm from medicine itself.