Ocena wszystkich istotnych i wiarygodnych danych.

Key points

  • A single study rarely provides enough evidence to guide treatment choices in healthcare
  • Assessments of the relative merits of alternative treatments should be based on systematic reviews of all the relevant, reliable evidence
  • As in individual studies testing treatments, steps must be taken to reduce the misleading influences of biases and the play of chance
  • Failure to take account of the findings of systematic reviews has resulted in avoidable harm to patients, and wasted resources in healthcare and research.

Introduction:  Is one study ever enough?

The simple answer is ‘hardly ever’. Very seldom will one fair treatment comparison yield sufficiently reliable evidence on which to base a decision about treatment choices.

This section shows why this is a problem and what can be done to address it.