Evaluation of studies of prognosis
- Center for Nursing Research and Evidence-Based Practice, University of Rochester School of Nursing, Rochester, New York, USA
When patients first receive a diagnosis of a disease or condition, their initial questions often focus on “what can be done?”—that is, questions of treatment. Patients also want to know what will happen to them in the short and long term, in terms of disease progression, survival, and quality of life. These are questions of prognosis. For example, the family of a patient who has had a first ischaemic stroke will want to know if the patient will die, if current disabilities such as paralysis or aphasia will continue and for how long, what kind of life the patient can expect to have after discharge from hospital, and whether the patient is likely to have a recurrent stroke. The answers to some of these questions will likely influence decision making about treatment. If a patient is likely to die in the short term, families may be unwilling to initiate invasive treatments or those associated with pain or other adverse effects. Similarly, some conditions, such as the common cold, are self limiting and will resolve in time without treatment. In such cases, patients will often forgo treatment, especially if it is costly or has unpleasant side effects.
Nurses, in various contexts, may be faced with questions of prognosis. It is therefore important for nurses to understand how to assess and interpret evidence related to disease prognosis. This users’ guide will focus on the critical appraisal of studies of prognosis. The specific questions that will guide this appraisal, initially outlined by Laupacis et al,1 are summarised below.
Questions to help critically appraise studies of prognosis
Are the results valid?
Was there a representative and well defined sample of patients at a similar point in the course of the disease?
Was follow up sufficiently long and complete?
Were objective and unbiased …