Japanese sleep disturbance and fatigue disability weights in evaluating the effects of increasing temperatures on health by a life cycle approach

Purpose: This study aimed to establish a set of disability weights (DWs) for sleep problems and fatigue which could be applied in composite health outcome measures in order to quantify the burden of symptoms and economically evaluate the effects of increasing temperatures on a life cycle approach. Methods: The conditions were evaluated by a two-step questionnaire study. In the first step, specialists determined the DW for each condition. The second step was identical to the first, except that the determinations were made by primary care physicians. Both groups of medical practitioners used an interpolation method consisting of a comprehensive set of 31 disease-specific DWs. Results and discussion: Mean DWs for sleep disturbance were 0.101 for environmental sleep disturbance, 0.069 for mild sleep disturbance, and 0.086 for moderate sleep disturbance. Mean DWs for chronic fatigue syndrome (CFS) were 0.099 for a diagnosis of CFS, 0.164 for mild handicap, 0.281 for moderate handicap, and 0.459 for severe handicap. Mean DWs assigned by primary care physicians for sleep disturbance were 0.114 for environmental sleep disturbance, 0.140 for mild sleep disturbance, and 0.126 for severe sleep disturbance. Those for CFS were 0.154 for a diagnosis, 0.099 for mild handicap, 0.147 for moderate handicap, and 0.226 for severe handicap. Conclusions: Using the present valuation protocol, it appeared feasible to establish the burden of symptoms as attributable to increasing temperatures. The results can be applied in composite health outcome measures for public health research, environmental research, and economic evaluations.