Introduction There is currently no accepted disorder-specific measure of quality of life in bipolar disorder (BD). This paper reports on a 4-year mixed-method, patient-centred program of research to develop such a measure.
Methods The project was informed by standard protocols for the development of disorder-specific QoL measures. Item generation involved a qualitative investigation of individuals with BD, carers and relevant experts (Study 1, N = 52), as well as a literature review. Item reduction analyses involved an impact method analysis with affected individuals (Study 2, N = 28), a large field sample (Study 3, N = 225, including a repeated measures subset [n = 93]) and a final intensive item reduction study, again involving individuals with the disorder and experts in the area (Study 4, N = 31).
Results A 56-item, 14 domain measure (the QoL.BD) was developed and tested for psychometric properties. Internal reliability of subscales was found to be excellent, test-retest reliability appropriate, and correlations with external measures consistent with theory. Exploratory factor analyses suggested adequate correspondence between the instrument’s latent and surface structure. Analysis of sensitivity to clinical change suggested that the QoL.BD explains additional variance over and above commonly used generic measures of QoL.
Discussion Complete Phase I field testing suggests that the QoL.BD meets the urgent need for a disorder-specific measure of quality of life in BD. The latent structure of the instrument awaits confirmation in an independent sample, and further research will investigate its sensitivity to clinical change.