MCPS Family Medicine key terms

The number of patients who must receive a treatment for one additional patient to gain the intended outcome, calculated as the reciprocal of the absolute risk reduction. A smaller value means a larger clinical benefit.

The arithmetic difference in event rates between a control group and a treated group, expressed as a percentage or proportion. Unlike relative measures, it reflects the actual size of benefit in the population studied.

The ratio of the risk of an outcome in an exposed or treated group to the risk in an unexposed or control group. It exaggerates perceived benefit when baseline risk is low, so it should be read alongside absolute measures.

The ratio of the odds of exposure among cases to the odds of exposure among controls, or of outcome odds between groups. It approximates relative risk only when the outcome is rare and is standard in case-control studies.

An observational design that starts with people who already have an outcome and compares their past exposures with those of matched people without the outcome. It is efficient for rare diseases but vulnerable to recall and selection bias.

Distortion of an exposure-outcome association by a third variable that is linked to both the exposure and the outcome but lies outside the causal pathway. Randomization, restriction, matching, or statistical adjustment can reduce it.

An analysis that assigns every participant to the group they were randomized to, regardless of adherence or crossover. It preserves the benefits of randomization and gives a conservative estimate of real-world effectiveness.

Sensitivity is the proportion of people with disease who test positive; specificity is the proportion without disease who test negative. They describe test performance and are independent of how common the disease is in the population tested.

The probability that a person with a positive test result truly has the disease. It rises as disease prevalence rises, so a good test can still yield many false positives when screening a low-risk population.

How much a test result multiplies the pre-test odds of disease. A positive likelihood ratio above 10 or a negative ratio below 0.1 usually shifts clinical decision-making meaningfully; values near 1 change little.

Apparent lengthening of survival that occurs only because screening detects disease earlier, not because death is postponed. It makes screening programs look effective even when the time of death is unchanged.

Overestimation of screening benefit caused by preferential detection of slowly progressive disease, which has a longer detectable preclinical phase. Aggressive tumors are missed between screening rounds, flattering survival statistics.

The relationship between a drug's toxic dose and its effective dose, often expressed as the ratio of lethal or toxic dose to effective dose. A narrow index means small dosing errors or interactions can cause serious harm.

The plasma drug level reached when the amount absorbed per dosing interval equals the amount eliminated. It is generally attained after about four to five half-lives of regular dosing.

A theoretical volume relating the total amount of drug in the body to its plasma concentration. Large values indicate extensive tissue uptake; the concept guides loading-dose calculations and interpretation of dialysis removal.

Changes in drug metabolism when one agent inhibits or induces hepatic P450 enzymes, raising or lowering levels of co-administered drugs. Inhibitors act quickly and can cause toxicity; inducers act slowly and can cause treatment failure.

A patient's voluntary agreement to a test or treatment after receiving and understanding information about its nature, risks, benefits, and alternatives, plus the consequences of declining. It requires decision-making capacity and can be withdrawn at any time.

A patient's clinical ability to understand relevant information, appreciate how it applies to them, reason through options, and communicate a choice. It is task-specific and judged by clinicians, unlike legal competence decided by courts.

A written statement made while a patient has capacity that records future treatment preferences or names a substitute decision-maker. A living will states wishes; a durable power of attorney for health care appoints a proxy.

A collaborative process in which clinician and patient exchange evidence and values to reach a mutually agreed plan. It is most useful when options carry closely balanced benefits and harms, such as screening or chronic disease treatment choices.

A directive, patient-centered counseling style that explores and strengthens a person's own reasons for change while avoiding argument. Open questions, affirmations, reflective listening, and summarizing are core techniques, especially for substance use.

A public health approach that uses validated questionnaires to identify unhealthy substance use, delivers short structured advice or counseling, and refers those needing specialized care. It targets risky use before dependence develops.

The combined interpretation of test accuracy and disease prevalence when deciding whether a screening program is worthwhile. High sensitivity suits rule-out tests; high specificity suits confirmation, and low prevalence undermines positive predictive value.

Indirect protection of unvaccinated people that arises when a sufficiently large share of the population is immune, interrupting chains of transmission. The threshold varies by pathogen and is higher for measles than for influenza.

Conditions in which a vaccine should not be given because risk clearly outweighs benefit, such as severe allergy to a component or, for live vaccines, significant immunosuppression and pregnancy. Mild illness and antibiotic use are not contraindications.

The legal duty of clinicians and laboratories to report specified diagnoses to public health authorities so that outbreaks can be detected and controlled. Requirements vary by jurisdiction and often include tuberculosis, measles, and sexually transmitted infections.

Systemic inflammatory response signs such as fever or hypothermia, tachycardia, tachypnea, and abnormal white count. Sepsis is life-threatening organ dysfunction from infection, now scored with SOFA; SIRS alone is nonspecific.

Classification of sudden kidney function loss by serum creatinine rise or urine output fall, as in the KDIGO stages. Prerenal, intrinsic, and postrenal causes are distinguished using history, urinalysis, and bladder assessment.

A low-bicarbonate acidosis with elevated unmeasured anions, calculated as sodium minus chloride and bicarbonate. Common causes include ketoacidosis, lactic acidosis, renal failure, and toxins such as salicylates or methanol.

A pregnancy complication with hemolysis, elevated liver enzymes, and low platelets, often overlapping with severe preeclampsia. It typically presents in the third trimester with right upper quadrant pain, nausea, and hypertension, and requires urgent delivery.

Pregnancy hypertension with proteinuria or organ dysfunction, including severe-range blood pressures, thrombocytopenia, renal or liver impairment, pulmonary edema, or visual and cerebral symptoms. Management is magnesium sulfate plus timely delivery.

Testing for glucose intolerance first recognized during pregnancy, usually a one-hour glucose challenge followed by a diagnostic three-hour test. Treatment of hyperglycemia reduces macrosomia and shoulder dystocia.

Failure to deliver the fetal shoulders after the head emerges, an obstetric emergency linked to macrosomia and diabetes. Maneuvers such as McRoberts positioning and suprapubic pressure are used, with attention to brachial plexus injury risk.

Age-linked skills in gross motor, fine motor, language, and social domains used to monitor a child's progress. Red flags such as no babbling by nine months or no walking by eighteen months prompt further evaluation.

Use of validated tools at defined well-child visits to detect deficits in social communication and restricted or repetitive behaviors. Positive screens require diagnostic evaluation and early intervention referral, which improves outcomes.

Inadequate weight gain or growth in a child, often defined by crossing downward on growth curves or weight below expected percentiles. Causes include inadequate intake, malabsorption, and psychosocial factors; evaluation addresses all three.

A decision tool indicating ankle imaging is needed only if there is pain near the malleoli plus inability to bear weight or bone tenderness at specified sites. It safely reduces unnecessary radiographs.

Elevated pressure within a closed fascial compartment that compromises perfusion, causing pain out of proportion, especially with passive stretch. It is a surgical emergency requiring fasciotomy; pulses may remain normal.

Median nerve compression at the wrist producing nocturnal numbness and tingling in the thumb, index, and middle fingers. Diagnosis is clinical, supported by nerve conduction studies; splinting and activity modification are first-line.

A four-question screen for lifetime problematic alcohol use, asking about cutting down, annoyance at criticism, guilt, and morning eye-openers. It performs poorly for detecting risky drinking below dependence thresholds.

A potentially fatal toxidrome from serotonergic drugs causing agitation, autonomic instability, hyperreflexia, and clonus, especially at the ankles. It is distinguished from neuroleptic malignant syndrome by rapid onset and prominent clonus.