We report on the development of a brief (nine-item) Impact of Illness Scale
(IIS), which measures the degree that an illness is perceived to restrict
psychosocial functioning. The measure is shown to have high Internal consis
tency in a variety of samples. Its construct validity is indicated by corre
lations with other scales measuring general functioning in samples affected
by illness. There is little variation in correlations between the IIS and
other measures across a number of groups from different language and cultur
al backgrounds. This, together with the finding that items retain their psy
chometric properties when used to make general ratings of mental disorders,
suggests that the content of the IIS Is valid. The results suggest the IIS
is a reliable and valid measure of psychosocial impact of illness that may
be applicable in a wide range of sociocultural settings. Copyright (C) 200
1 by W.B. Saunders Company.