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


METHODS
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).


RESULTS
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.


CONCLUSIONS
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.
Meera and L B Deshpande Centre for Sight Enhancement, Vision Rehabilitation Centres, L. V. Prasad Eye Institute, Dr. Kallam Anji Reddy Campus, L. V. Prasad Marg, Banjara Hills, Hyderabad, 500034, Andhra Pradesh, India. vijayagothwal@gmail.com
Vijaya K
VK
Gothwal
Marmamula
M
Srinivas
Gullapalli N
GN
Rao
D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D015203:Reproducibility of Results; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires / Q000592:standards*; D015354:Vision, Low / Q000523:psychology*; D014792:Visual Acuity; D019987:Persons with Visual Disabilities / Q000523:psychology* / Q000534:rehabilitation; D014944:World Health Organization