The presence of one or more diseases or conditions other than those of primary interest. In a An investigation of a healthcare problem. There are different types of studies used to answer research questions, for example randomised controlled trials or observational studies. looking at Something done with the aim of improving health or relieving suffering. For example, medicines, surgery, psychological and physical therapies, diet and exercise changes. for one disease or condition (for example, heart disease), some of the individuals may have other diseases or conditions that could affect their Outcomes are measures of health (for example quality of life, pain, blood sugar levels) that can be used to assess the effectiveness and safety of a treatment or other intervention (for example a drug, surgery, or exercise). In research, the outcomes considered most important are ‘primary outcomes’ and those considered less important are ‘secondary outcomes’. (e.g. diabetes).