2.3 Disease Prevention, Lifestyle Counselling, & Harm Reduction

Disease Prevention, Lifestyle Counselling, & Harm Reduction

Health promotion and disease prevention form the foundation of preventive medicine in Canadian healthcare. Physicians must master the four levels of prevention, evidence-based lifestyle counseling, and pragmatic harm reduction strategies for substance use disorders.

---

The Four Levels of Disease Prevention

Preventive care is classified into four distinct levels based on the stage of disease and the objective of the intervention.

Definitions & Clinical Examples

1. Primary Prevention: Actions aimed at preventing the initial occurrence of a disease or injury in a healthy population.
   • Examples: Routine pediatric immunizations, public health legislation (seatbelt/helmet laws), workplace safety regulations, counseling for smoking prevention, fluoridation of municipal drinking water.
2. Secondary Prevention: Early detection and prompt management of asymptomatic disease or precursor lesions before clinical symptoms manifest.
   • Examples: Mammography, Pap tests, FIT stool testing, routine screening blood pressure measurements, screening for asymptomatic Chlamydia/Gonorrhea.
3. Tertiary Prevention: Clinical interventions designed to slow disease progression, prevent complications, reduce disability, and rehabilitate patients with established symptomatic clinical disease.
   • Examples: Cardiac rehabilitation post-myocardial infarction, tight glycemic and blood pressure control in Type 2 Diabetes to prevent nephropathy and retinopathy, physical therapy following a cerebrovascular accident (stroke).
4. Quaternary Prevention: Actions taken to identify patients at risk of overmedicalization, protecting them from unnecessary diagnostic procedures, overdiagnosis, unproven therapies, and ethical/procedural medical harms.
   • Examples: Refusing routine lumbar spine X-rays for acute simple low back pain without red flags, deprescribing inappropriate polypharmacy in elderly patients, advising against routine PSA screening in average-risk asymptomatic men.

---

Tobacco Cessation & Pharmacotherapy

Tobacco use remains the leading cause of preventable morbidity and premature mortality in Canada. Primary care physicians should systematically apply the 5 As Framework for smoking cessation:

1. Ask: Identify and document tobacco use status for every patient at every visit.
2. Advise: Strongly urge all tobacco users to quit in a clear, non-judgmental, personalized manner.
3. Assess: Determine readiness to make a quit attempt (Transtheoretical Model / Stages of Change).
4. Assist: Aid the patient in quitting (counseling, setting a quit date, prescribing pharmacotherapy).
5. Arrange: Schedule follow-up contact within the first week after the quit date.

Pharmacotherapy Comparison

---

Alcohol Guidance & Substance Harm Reduction

Canada's Guidance on Alcohol and Health (2023 Update)

Published by the Canadian Centre on Substance Use and Addiction (CCSA), this framework defines a continuum of risk associated with weekly standard drink consumption (1 standard drink = 12 oz / 341 mL 5% beer, 5 oz / 142 mL 12% wine, or 1.5 oz / 43 mL 40% spirits):

• 0 Drinks per week: No risk; best health outcomes, especially during pregnancy or breastfeeding.
• 1 to 2 Standard Drinks per week: Low risk of alcohol-related harms.
• 3 to 6 Standard Drinks per week: Moderate risk; increased risk of developing several types of cancer (breast, colorectal).
• 7 or more Standard Drinks per week: Increasingly high risk; exponentially higher risk of cardiovascular disease, stroke, liver cirrhosis, and violent injury.

Harm Reduction Principles & Opioid Use Disorder

Harm reduction encompasses evidence-informed public health policies and pragmatic interventions designed to minimize the adverse health, social, and economic consequences of substance use without requiring complete abstinence.

• Take-Home Naloxone (THN) Kits: Widespread distribution of intranasal or intramuscular naloxone to individuals who use opioids, their families, and community members for rapid reversal of opioid toxicity.
• Supervised Consumption Services (SCS) & Overdose Prevention Sites (OPS): Medically supervised facilities providing sterile consumption equipment, emergency overdose intervention, wound care, STI screening, and direct referral pathways to addiction treatment.
• Needle & Syringe Programs (NSP): Provision of sterile injection and inhalation supplies to prevent transmission of blood-borne pathogens (HIV, Hepatitis B, Hepatitis C).
• Opioid Agonist Therapy (OAT):
  • Buprenorphine-Naloxone (Suboxone): First-line OAT in Canada. Partial mu-opioid agonist with high receptor affinity and a safety "ceiling effect" on respiratory depression. Combined with naloxone to deter intravenous misuse.
  • Methadone: Second-line OAT. Full mu-opioid agonist requiring daily witnessed pharmacy ingestion. Requires strict monitoring for QTc prolongation, drug interactions, and fatal overdose during dose titration.

---

Lifestyle Counseling: Nutrition, Movement & Sleep

• Canada's Food Guide: Emphasizes healthy eating habits rather than rigid food groups. Recommended plate model: 1/2 vegetables and fruits, 1/4 protein foods (emphasizing plant-based proteins such as beans, lentils, nuts), and 1/4 whole grain foods. Water should be the beverage of choice.
• Canadian 24-Hour Movement Guidelines (Adults 18–64 Years):
  • Physical Activity: Accumulate at least 150 minutes per week of moderate-to-vigorous aerobic physical activity.
  • Muscle Strengthening: Incorporate muscle-strengthening activities involving major muscle groups at least 2 days per week.
  • Sleep: Maintain 7 to 9 hours of good-quality sleep per night with consistent sleep-wake timing.
  • Sedentary Behavior: Limit sedentary time to 8 hours or less per day, including no more than 3 hours of recreational screen time.

Exam Trap: Bupropion is a common MCCQE Part I trap. If a patient seeking smoking cessation has a history of anorexia nervosa, bulimia nervosa, or seizures, Bupropion is strictly contraindicated. Select Varenicline or Nicotine Replacement Therapy instead.

Clinical Scenario: A 34-year-old man with severe Opioid Use Disorder presents seeking treatment. He has experienced two non-fatal respiratory overdoses in the past year. What is the most appropriate first-line pharmacotherapy to initiate in Canada?
Answer: Buprenorphine-naloxone (Suboxone). Suboxone is recommended as the first-line Opioid Agonist Therapy (OAT) in Canadian guidelines because its partial agonist mechanism provides a safety ceiling against respiratory depression, significantly reducing overdose mortality compared to Methadone.