Measures of dyspnea in patients with amyotrophic lateral sclerosis.

Respiratory symptoms are not well characterized in amyotrophic lateral sclerosis (ALS). The baseline dyspnea index (BDI) and transition dyspnea index (TDI) are indices designed to measure change in dyspnea over time. They are easy to administer and do not inquire about specific physical tasks. The latter makes these scales particularly well suited for use in ALS. This study evaluated the ability of the BDI and TDI to measure dyspnea in 46 subjects with ALS. The BDI/TDI had excellent reproducibility. The TDI detected worsening dyspnea by 4 weeks and declined significantly more over the subsequent 8 weeks. The TDI was significantly associated with changes in forced vital capacity and appeared more sensitive to changes in dyspnea than the ALS functional rating scale-respiratory subscale (ALS-FRS R) and a visual analog scale of breathlessness. The BDI and TDI thus appear to be useful measures in ALS and may have both clinical and research applications.