A new look at the WHOQOL as health-related quality of life instrument among visually impaired people using Rasch analysis

To examine the psychometric characteristics of the World Health Organization Quality of Life instrument—modified Indian version
(modified WHOQOL) and its subscales in adults with visual impairment (VI) using Rasch analysis.

Cross-sectional data were of people aged ≥40 years with VI (n = 1,333) who responded to the modified WHOQOL in the Andhra Pradesh Eye Disease Study, India. Rasch analysis was used to
explore the instrument and its subscales for key indices such as measurement precision by person separation reliability, PSR
(i.e., discrimination between strata of participants’ health-related QOL [HRQOL], recommended minimum value 0.8), unidimensionality
(i.e., measurement of a single construct), and targeting (i.e., matching of item difficulty to participants’ HRQOL).

Rasch-guided iterative approach including category re-organization to enable threshold ordering and item deletion to overcome
multidimensionality resulted in a unidimensional 9-item WHOQOL and a 6-item level of independence (LOI) subscale with adequate
PSR (0.81 and 0.82, respectively). Targeting was sub-optimal for both (−1.58 logits for WHOQOL and −2.55 logits for the subscale).
Remaining subscales were dysfunctional.

The WHOQOL and LOI subscale can be improved and shortened, and the Rasch-revised versions are likely to assess the HROQL of
VI patients best because of their brevity, reliability, and unidimensionality.