When making decisions in health care all relevant outcomes should be considered. Clinically relevant outcomes are patient orientated, and measure directly how a patient feels, functions or survives. Examples of clinically relevant outcomes in anaesthesia could be mortality, postoperative morbidity, postoperative nausea and vomiting (PONV) and postoperative pain. Other relevant outcomes relate to length of stay in hospital, intensive care admittance, quality of life measures, and costs.

Different types of trials measure different types of outcomes, and trial quality is an equally important factor in estimating treatment effectivity. Surrogate outcomes are sometimes used instead of the real outcome in question, because they save time, money and number of patients. Surrogate outcomes are, however, not very reliable and extreme care should be taken if a surrogate outcome measure is used as the base of clinical decisions.

Introduction

When we consider the implementation of an intervention in health care practice, we want to know how this affects our patients. The randomised controlled trial measures the effects of the intervention in question on the outcomes decided by the investigators. The optimal clinical trial explores the effects of a well-described, well-defined, clinically relevant intervention on all relevant outcomes, including benefits and harms, costs and ease of practice.