Development of needs-based quality of life instruments.

The methods employed in the development of needs-based quality of life (QoL) instruments have evolved with time as advances have been made in the field of psychometrics and as experience has grown. This paper illustrates the current instrument development methodology with reference to three needs-based QoL measures recently developed for use in dermatology: the Quality of Life Index for Atopic Dermatitis (QoLIAD); the Psoriasis Index of Quality of Life (PSORIQoL); and the Parents' Index of Quality of Life-Atopic Dermatitis (PIQoL-AD).