Assessment instruments for patients with fibromyalgia: properties, applications and interpretation.

A comprehensive assessment of the multiple symptom domains associated with fibromyalgia (FM) and the impact of FM on multidimensional aspects of function should form a routine part of the care of FM patients. Clinical trials and long-term clinical registries have used various outcome measures, but the key domains include pain, fatigue, disturbed sleep, physical functioning, emotional functioning, patient global ratings of satisfaction, and their health-related quality of life (HRQL). A number of measures have been ''borrowed'' from the fields of rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis and adapted to FM, and others are being developed specifically for FM. However, despite the burgeoning theoretical literature and the proliferation of instruments for measuring various health status domains, no unified approach has been developed and there is little agreement concerning the meaning of the results. There is, therefore, still a need for further consensus and the development of a core set of measures and response criteria, more refined measuring instruments, standardised assessor training, cross-cultural adaptations of health status questionnaires, electronic data capture, and the introduction of standardised quantitative measurements into routine clinical care. This article discusses the advantages and limitations of a selection of both newly developed and well-established and validated distress screening instruments that underlines the continuing challenge of assessing FM.