Fig. 1

Heatmap of response rates and inter-item, corrected item-total and item-QoL correlations. The items are shown on the right and the bottom sidebar. Inter-item correlations are shown in the main body of the heatmap, with values between -1 (blue) and 1 (red). Response rates, corrected item-total and item-QoL correlations are shown on the right, with values between -1 (blue) and 1 (red) for correlations and values between 0 (white) and 1 (red) for response rates. The left side bar shows if the item was selected to be deleted (black), to be modified (gray), or to be unchanged (white)