Validation of an abbreviated quality of life scale for schizophrenia

The field of therapeutics in schizophrenia is redefining optimal outcome, moving beyond clinical remission to a more comprehensive model that also includes functional recovery. The Quality of Life Scale (QLS) has been adopted by many large clinical trials, including CATIE and CUtLASS, as a measure of functioning. The QLS is a 21-item semi-structured interview that takes approximately 45min to administer. Although the QLS is considered comprehensive, its length limits its applicability across studies. To circumvent this issue, short scales of the QLS have been created that estimate total scores with high accuracy. However, these abbreviated measures have not been adequately cross-validated in a large enough sample to allow for subsample estimations nor has its predictive ability been compared to the full scale. Here, we used data from the CATIE trial (n=1460) to demonstrate the validity and utility of an abbreviated 7-item QLS. The shortened QLS was robust in estimating total scores (r=0.953, p<0.001) across subsamples and demonstrated predictive ability similar to the full QLS in multiple regression models. The abridged QLS is recommended as a surrogate measure of psychosocial functioning, especially in cases where functioning is not the primary outcome.