Case complexity in patients with chronic nonspecific musculoskeletal pain: a Delphi and feasibility study.

Assessment of case complexity in patients with chronic nonspecific musculoskeletal pain (CMP) is currently clinician based, not transparent, and with low reliability. The objective of this study was to explore case complexity and to initiate the development of a case complexity index (CCI). A three-round Delphi study among clinicians involved in multidisciplinary Pain Rehabilitation Programs was performed to identify important factors that are assumed to influence functioning in patients with CMP. The 10 most important factors were used to initiate the development of a CCI, with mean ratings of importance per factor as weights. The feasibility of the CCI was tested in a pilot study on 16 patients with CMP. In the first round, 166 factors were identified; in the second round, the 10 most important factors were selected; in the third round, relative weights of each factor were calculated, ranging from 1.75 (features of complaints) to 3.56 (psychiatric disorders) on a scale from 0 (no weight) to 4 (very heavy weight). The assessments for the factors were mainly based on clinical examination and reasoning. Clinicians could rate all patients using the CCI, which confirmed feasibility of the CCI. Ten, mainly psychosocial, factors were identified, which were assumed to be most important for the assessment of case complexity in a patient with CMP. With these factors, a CCI was created, for which feasibility was established. This CCI is transparent, easy to use, and might provide a basis for further development of a structured assessment of case complexity, which may have scientific and clinical relevance.