Biostatistics, Epidemiology and Evidence-Based Medicine
Core concepts
Understand study designs - randomized controlled trials, cohort, case-control, cross-sectional - and their strengths and weaknesses. Know measures of association (relative risk for cohort studies, odds ratio for case-control studies), measures of effect (absolute risk reduction, number needed to treat), and the interpretation of confidence intervals and p-values. Cover sensitivity, specificity, positive and negative predictive values, and likelihood ratios. Understand bias (selection, information, confounding), the levels of evidence, and the critical appraisal of systematic reviews and meta-analyses.
Traps
Examiners test the fact that predictive values depend on prevalence, while sensitivity and specificity do not. Watch for confusing relative risk with absolute risk - a 50% relative reduction from a tiny baseline may be clinically trivial. Remember that a p-value does not measure effect size, and that confidence intervals crossing 1 (for ratios) or 0 (for differences) indicate non-significance.
Worked rule of thumb
NNT = 1/ARR. If a drug reduces mortality from 2% to 1%, ARR = 1% and NNT = 100. Always ask: what is the baseline risk, and is the benefit clinically meaningful?
Key points
- RR for cohort studies; OR for case-control studies.
- PPV and NPV depend on prevalence.
- NNT = 1/absolute risk reduction.
- A p-value is not a measure of effect size.
- Confidence intervals convey precision and significance.
Behavioral Science
Core concepts
Understand the biopsychosocial model, the stages of change (precontemplation, contemplation, preparation, action, maintenance), and motivational interviewing. Know the psychiatric disorders most relevant to internal medicine: depression, anxiety, somatization, and substance use disorders. Cover the approach to the patient with medically unexplained symptoms, the assessment of suicide risk, and the principles of breaking bad news and communicating with families. Understand the psychological impact of chronic illness and the role of coping and social support.
Traps
Examiners test the difference between delirium (acute, fluctuating, impaired attention) and dementia (chronic, progressive) and depression (mood-related cognitive complaints). Watch for the trap of assuming a physical symptom is "all in the mind" - always exclude organic causes first. Remember that a patient in the precontemplation stage is not ready for action-oriented advice; meet them where they are.
Worked rule of thumb
For behavior change, match the intervention to the stage: in precontemplation, raise awareness and explore ambivalence; in preparation, set concrete goals. Direct advice to a precontemplator usually produces resistance.
Key points
- Delirium is acute and fluctuating; dementia is chronic and progressive.
- Match interventions to the stage of change.
- Exclude organic causes before attributing symptoms to psychology.
- Assess suicide risk directly and sensitively.
- Motivational interviewing reduces resistance.
Ethics and Professionalism
Core concepts
Know the four principles - autonomy, beneficence, non-maleficence, and justice - and how they interact in clinical decisions. Understand informed consent (capacity, disclosure, voluntariness, understanding), decision-making capacity assessment, advance directives, and surrogate decision-making. Cover confidentiality and its limits (public safety, reportable diseases), end-of-life care, futile treatment, and resource allocation. Understand professionalism: boundaries, conflicts of interest, honesty, and the duty to report impaired colleagues.
Traps
Examiners test the difference between capacity (clinical, decision-specific) and competence (legal). A patient with capacity may refuse treatment even if the decision seems unwise. Watch for the trap of assuming a family member can consent for an adult with capacity - they cannot. Remember that confidentiality can be breached when there is a serious risk to others or a legal obligation.
Worked rule of thumb
When a patient refuses treatment, assess capacity: does the patient understand the information, appreciate the consequences, reason about options, and communicate a choice? If capacity is intact, respect the refusal; if not, proceed through surrogate decision-making and best-interest standards.
Key points
- Capacity is clinical and decision-specific; competence is legal.
- Informed consent requires capacity, disclosure, and voluntariness.
- Patients with capacity may refuse treatment.
- Confidentiality yields to serious public safety risks.
- Report impaired colleagues through appropriate channels.