**3.3 The Brief Fatigue Inventory (BFI)**

The BFI was used to assess the severity of fatigue and the amount of interference with function caused by fatigue in this study. The BFI has 9 items that were designed to provide a measure of fatigue. Three items in the BFI ask patients to rate their fatigue during the past 24 hours at its "worst," "usual" or "average," and "now," with "0" being "no fatigue," and "10" being "fatigue as bad as you can imagine." Additional items assess how much fatigue has interfered with different aspects of the patient's life during the past 24 hours. The interference items included in the present study were mood, daily activity, walking ability, eating, relations with other people and enjoyment of life. Each interference item is scored on an eleven point rating scale from "0" (does not interfere) to "10" (completely interferes). A mean BFI score is calculated as the mean of the intensity and interference items (Çnar & Olgun, 2010).
