The pharmacology dictionary, in two languages.

The arithmetic difference between the event rate in the control group and the event rate in the treated group, expressing the absolute benefit of a treatment over a defined period.

An observational study that starts from people with a given outcome (cases) and comparable people without it (controls) and compares their past exposure to a suspected cause, such as a drug.

An observational study that follows groups of people defined by their exposure (e.g., to a drug) over time and compares the incidence of outcomes between exposed and unexposed groups.

A range of values, calculated from sample data, that is expected to contain the true population value of an estimate with a stated level of confidence, conventionally 95%.

A study design in which neither the participants nor the investigators treating or assessing them know which treatment each participant receives, to minimize performance and assessment bias.

The ratio of the hazard (instantaneous event rate) in one group to that in another, usually estimated from time-to-event data with a Cox proportional hazards model.

An analysis strategy in which all randomized participants are analyzed in the groups to which they were originally assigned, regardless of the treatment actually received, adherence or withdrawal.

A statistical method that combines the quantitative results of several independent studies addressing the same question to produce a pooled estimate of effect with greater precision.

A trial designed to show that a new treatment is not unacceptably worse than an active comparator, i.e., that any loss of efficacy does not exceed a prespecified non-inferiority margin (Δ).

The average number of patients who need to be treated with an intervention for a specified period for one additional patient to experience a particular harm compared with the control treatment.

The average number of patients who need to be treated with an intervention for a specified period to prevent one additional adverse outcome compared with the control treatment.

The ratio of the odds of an outcome (or exposure) in one group to the odds in another group, where the odds is the probability that an event occurs divided by the probability that it does not.

The probability, assuming the null hypothesis is true, of obtaining a result at least as extreme as the one observed; small values indicate that the data are unlikely under the null hypothesis.

The main outcome measure prespecified in a trial protocol to answer the principal research question, on which the sample size calculation and the main conclusion of the trial are based.

A prospective experimental study in which participants are allocated by chance to an intervention or a control (placebo, usual care or an active comparator) and followed up to compare outcomes.

The ratio of the risk (cumulative incidence) of an outcome in an exposed or treated group to the risk in an unexposed or control group over the same period.

The proportional reduction in the risk of an outcome in a treated group compared with a control group, calculated as the absolute risk reduction divided by the control event rate.

A laboratory measurement or physical sign used as a substitute for a clinically meaningful outcome (how a patient feels, functions or survives) and expected to predict the effect of therapy on that outcome.

A review that uses explicit, prespecified and reproducible methods to identify, select, critically appraise and synthesize all relevant studies addressing a clearly formulated question.