WACP Primary flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Incidence vs prevalence

Incidence is the number of new cases per population at risk per unit time; prevalence is all existing cases divided by total population. Prevalence approximates incidence multiplied by average disease duration.

Herd immunity threshold

The proportion of a population that must be immune to interrupt transmission, calculated as 1 minus 1/R0. Measles with R0 of 12–18 needs roughly 92–95% two-dose coverage.

Lead-time bias

Apparent survival improvement in screened populations because diagnosis occurs earlier, not because death is delayed. It inflates survival time without changing mortality and must be excluded by mortality-based trials.

Case-control odds ratio

Odds of exposure among cases divided by odds of exposure among controls. It approximates relative risk when the disease is rare, generally under 10% in the population.

Levels of prevention

Primary prevents exposure or disease onset; secondary detects disease early through screening; tertiary limits disability and supports rehabilitation. Screening requires a detectable latent phase and effective treatment.

WHO analgesic ladder

Step 1 uses non-opioids such as paracetamol or NSAIDs; step 2 adds weak opioids such as codeine or tramadol; step 3 uses strong opioids such as morphine. Adjuvants may be added at any step.

Reduced-osmolarity ORS

Oral rehydration solution with osmolarity 245 mOsm/L and sodium 75 mmol/L. Give 50–100 mL/kg over 3–4 hours for some dehydration, replacing ongoing losses with additional solution.

IMCI danger signs

Inability to drink or breastfeed, persistent vomiting, convulsions, lethargy or unconsciousness, stridor at rest, and severe malnutrition. Any sign mandates urgent referral or admission.

Zinc in childhood diarrhoea

Zinc 20 mg daily (10 mg if under 6 months) for 10–14 days shortens diarrhoea duration and reduces recurrence. It is given alongside oral rehydration solution and continued feeding.

Asthma reversibility criterion

Post-bronchodilator FEV1 improvement of at least 12% and at least 200 mL from baseline. A pre-bronchodilator FEV1/FVC ratio below 0.70 confirms airflow obstruction.

Emergency contraception window

Levonorgestrel 1.5 mg is effective up to 72 hours after unprotected intercourse, with reduced efficacy over time. Copper IUD insertion within 5 days is the most effective option.

Anion gap formula

Sodium minus the sum of chloride and bicarbonate, normally 8–12 mmol/L. Correct for hyperglycaemia by adding 0.3 times the glucose excess above 5.5 mmol/L to measured sodium.

Winter's formula

Expected PaCO2 equals 1.5 times bicarbonate plus 8, plus or minus 2. It assesses respiratory compensation in metabolic acidosis; deviation indicates a mixed acid–base disorder.

KDIGO acute kidney injury

Creatinine rise of at least 26.5 micromol/L within 48 hours, or at least 1.5 times baseline within 7 days, or urine output below 0.5 mL/kg/hour for 6 hours.

Hyponatraemia correction limit

Correct serum sodium by no more than 8–10 mmol/L in 24 hours. Faster correction risks osmotic demyelination, presenting with dysarthria, dysphagia, and quadriparesis.

CURB-65 severity score

Confusion, urea above 7 mmol/L, respiratory rate 30 or more, blood pressure below 90/60, and age 65 or older. Each scores one; a total of 2 or more suggests hospital admission.

Sepsis-3 definition

Suspected infection with an acute rise in SOFA score of at least 2 points. Septic shock is vasopressor-requiring hypotension with lactate above 2 mmol/L despite adequate fluid resuscitation.

Heart failure with reduced EF

Left ventricular ejection fraction of 40% or less with symptoms. Guideline therapy includes an ACE inhibitor, ARB, or ARNI, a beta-blocker, an MRA, and an SGLT2 inhibitor, plus loop diuretics for congestion.

Positive likelihood ratio

Sensitivity divided by one minus specificity. It indicates how much a positive test raises the probability of disease; values above 10 produce large, often conclusive changes.

Reference interval definition

The range containing the central 95% of values from a healthy reference population, from the 2.5th to 97.5th percentile. About 5% of healthy people fall outside it by definition.

Ferritin in iron deficiency

Serum ferritin below 30 micrograms/L is the most specific marker of iron deficiency. Because ferritin is an acute-phase reactant, it may appear normal during inflammation or infection.

AST to ALT ratio

A ratio above 2 suggests alcoholic liver disease. In most other liver diseases ALT exceeds AST, and a ratio above 1 in chronic hepatitis may indicate progression to cirrhosis.

Mixing study interpretation

Plasma mixed with normal plasma corrects a prolonged clotting time when a factor is deficient. Failure to correct indicates an inhibitor such as a lupus anticoagulant or specific factor antibody.

Pre-analytical laboratory error

Mistakes occurring before analysis, including wrong tube type, haemolysis, delayed processing, and prolonged tourniquet time. They account for most laboratory errors and can invalidate results.

APGAR score components

Appearance, Pulse, Grimace, Activity, and Respiration, each scored 0–2 at 1 and 5 minutes. It documents condition at birth but does not guide resuscitation decisions.

Paediatric maintenance fluids

Holliday–Segar rule: 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg, and 20 mL/kg/day for each kilogram thereafter. It estimates daily maintenance needs.

Neonatal resuscitation compression ratio

Provide positive-pressure ventilation if apnoeic or heart rate is below 100. If heart rate remains below 60 despite effective ventilation, give chest compressions at a 3:1 ratio with breaths.

Pathological neonatal jaundice

Jaundice appearing within 24 hours of birth, bilirubin rising above 85 micromol/L per day, conjugated fraction above 20%, or persistence beyond 14 days. These features require investigation.

Child weight estimation formula

For ages 1–6 years, weight in kg equals 2 times (age plus 4). For ages 7–12 years, weight equals (7 times age minus 5) divided by 2.

Serotonin syndrome features

Clonus, hyperreflexia, agitation, and hyperthermia after serotonergic drugs. Management is stopping the offending agents, supportive care, and cyproheptadine in severe cases.

Neuroleptic malignant syndrome

Rigidity, hyperthermia, autonomic instability, and raised creatine kinase after antipsychotic use. Stop the drug and give dantrolene or bromocriptine with supportive care.

Schneiderian first-rank symptoms

Auditory hallucinations such as third-person voices or running commentary, thought insertion, withdrawal or broadcast, and passivity phenomena. They are classically associated with schizophrenia.

Alcohol withdrawal timeline

Tremor and anxiety begin at 6–24 hours, seizures at 6–48 hours, and delirium tremens at 48–96 hours. Benzodiazepines are first-line, with thiamine given before glucose.