Interpreting patient-reported outcomes from clinical trials in COPD: a discussion

One of the challenges faced by the practising physician is the interpretation of patient-reported outcomes (PROs) in clinical trials and the relevance of such data to their patients. This is especially true when caring for patients with progressive diseases such as COPD. In an attempt to incorporate the patient perspective, many clinical trials now include assessments of PROs. These are formalized methods of capturing patient-centered information. Given the importance of PROs in evaluating the potential utility of an intervention for a patient with COPD, it is important that physicians are able to critically interpret (and critique) the results derived from them. Therefore, in this paper, a series of questions is posed for the practising physician to consider when reviewing the treatment effectiveness as assessed by PROs. The focus is on the St George's Respiratory Questionnaire for worked examples, but the principles apply equally to other symptom-based questionnaires. A number of different ways of presenting PRO data are discussed, including the concept of the minimum clinically important difference, whether there is a ceiling effect to PRO results, and the strengths and weaknesses of responder analyses. Using a worked example, the value of including a placebo arm in a study is illustrated, and the influence of the study on PRO results is considered, in terms of the design, patient withdrawal, and the selection of the study population. For the practising clinician, the most important consideration is the importance of individualization of treatment (and of treatment goals). To inform such treatment, clinicians need to critically review PRO data. The hope is that the questions posed here will help to build a framework for this critical review.