Arab Board Internal Medicine Part 1 key terms

The number of patients who must receive an intervention for one additional patient to benefit, calculated as the reciprocal of the absolute risk reduction. Lower values indicate greater clinical efficiency of the treatment.

The arithmetic difference in event rates between a control group and a treated group, expressed as a proportion or percentage. It reflects the true clinical impact of therapy and is the basis for calculating number needed to treat.

A range of values, calculated from sample data, that is expected to contain the true population parameter with a stated probability, usually 95%. Width reflects precision, and intervals crossing no effect suggest statistical uncertainty.

The probability of observing a result at least as extreme as that found, assuming the null hypothesis is true. It is not the probability that the null hypothesis is correct, nor a measure of effect size.

Incorrectly rejecting a true null hypothesis, that is, declaring a difference when none exists. Its probability is the significance level alpha, conventionally set at 0.05.

Failing to reject a false null hypothesis, thereby missing a real difference. Its probability is beta, and statistical power equals one minus beta, conventionally targeted at 0.80 or higher.

The proportion of people who truly have a disease and are correctly identified by a test as positive. A highly sensitive test is useful for ruling out disease when negative.

The proportion of people without the disease who are correctly identified by a test as negative. A highly specific test is useful for confirming disease when positive.

The probability that a person with a positive test result actually has the disease. Unlike sensitivity, it depends strongly on disease prevalence in the population tested.

The probability that a person with a negative test result truly does not have the disease. It rises as disease prevalence falls and is useful when excluding a diagnosis.

The ratio of the probability of a given test result in people with disease to that in people without disease. Values far from 1 meaningfully shift post-test probability and are less prevalence-dependent than predictive values.

Analysis in which participants are evaluated according to the group to which they were originally randomized, regardless of adherence or crossover. It preserves randomization and gives a conservative estimate of efficacy.

Allocation of study participants to intervention groups by chance, so that known and unknown confounders are distributed similarly between groups. It is the defining strength of the randomized controlled trial.

A distortion of the association between exposure and outcome caused by a third variable related to both. Randomization prevents it in trials; observational studies must adjust for it statistically.

Systematic error arising when the groups compared differ in ways related to the outcome, often because of how participants were recruited, enrolled, or retained. It threatens validity and cannot be fixed by larger sample size.

A patient's voluntary agreement to a test or treatment after receiving adequate information about its nature, benefits, risks, and alternatives, given while the patient has decision-making capacity. It is both ethical and legal requirement.

A patient's clinical ability to understand relevant information, appreciate the consequences of choices, reason about options, and communicate a consistent decision. Capacity is task-specific and assessed by clinicians, unlike legal competence.

A written statement prepared while a patient has capacity, specifying future treatment preferences or naming a surrogate decision-maker in case the patient later loses capacity.

The clinical judgment that an intervention cannot achieve its intended physiological goal or meaningful benefit for a patient. It informs, but does not alone authorize, decisions to withhold or withdraw treatment.

The professional duty to protect patient health information from unauthorized disclosure, subject to defined exceptions such as serious risk to others, mandatory reporting, or legal order.

The concurrent use of multiple medications, commonly five or more, which increases risk of drug interactions, adverse effects, and non-adherence, particularly in older adults. Regular medication review is the main mitigation.

A published list of potentially inappropriate medications for older adults, organized by drug class, drug-disease interaction, and drugs to use with caution. It is a screening aid, not an absolute prohibition.

The cumulative effect of taking several drugs with anticholinergic activity, linked in older adults to confusion, falls, constipation, urinary retention, and cognitive decline. Reducing the load is a common deprescribing target.

The systematic, supervised process of withdrawing or reducing medications that are no longer beneficial, are causing harm, or no longer align with a patient's goals of care.

The time required for the plasma concentration of a drug to fall by half. It determines dosing interval and time to steady state, which is generally reached after four to five half-lives.

A theoretical volume relating the amount of drug in the body to its plasma concentration. Large values indicate extensive tissue distribution; small values indicate confinement to plasma.

The volume of plasma from which a drug is completely removed per unit time. It determines the maintenance dose needed to sustain a target steady-state concentration.

Metabolism of an orally administered drug in the gut wall or liver before it reaches systemic circulation, reducing oral bioavailability. Drugs with high first-pass effect require larger oral than intravenous doses.

The fraction of an administered drug dose that reaches systemic circulation unchanged. Intravenous administration is defined as 100 percent, and oral bioavailability is often lower because of incomplete absorption or first-pass metabolism.

Increased expression of cytochrome P450 enzymes after repeated exposure to certain drugs, which accelerates metabolism of co-administered substrates and can lower their efficacy. Effects develop over days to weeks.

Reduced activity of cytochrome P450 enzymes by a competing or binding drug, slowing metabolism of co-administered substrates and raising their concentrations and toxicity risk. Effects typically occur rapidly.

The ratio between a drug's toxic dose and its effective dose. A narrow index means small dose changes or interactions can cause toxicity, so monitoring drug levels is often needed.

The difference between measured serum sodium and the sum of chloride and bicarbonate, normally about 8 to 12 mmol/L. An elevated gap indicates accumulation of unmeasured anions such as ketones, lactate, or toxins.

The difference between measured and calculated serum osmolality. An elevated gap suggests the presence of unmeasured osmoles such as methanol, ethylene glycol, or isopropanol.

The percentage of filtered sodium excreted in urine, calculated from paired serum and urine sodium and creatinine. Values below 1 percent suggest prerenal physiology; higher values suggest intrinsic renal injury.

A brief episode of focal neurological dysfunction caused by cerebral ischemia without infarction on imaging. It is a warning sign of high short-term stroke risk requiring urgent evaluation.

A standardized 15-item clinical score quantifying stroke severity, from 0 (no deficit) to 42 (severe). It guides treatment decisions such as thrombolysis and predicts outcome.

Sepsis with persisting hypotension requiring vasopressors to maintain mean arterial pressure of at least 65 mmHg and a lactate above 2 mmol/L despite adequate fluid resuscitation. Mortality is high without prompt source control.

Life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized as an increase in the Sequential Organ Failure Assessment score of at least 2 points.

A bedside screen for sepsis using respiratory rate of 22 or more, altered mentation, and systolic blood pressure of 100 mmHg or less. Two or more criteria identify patients at higher risk of poor outcome.