Measurement invariance of the PROMIS emotional distress and subjective well-being domains among autistic and General Population adolescents

PurposeQuality of life (QoL) is identified as a clinical and research priority by the autistic community. Researchers have the responsibility to ensure that instruments used to measure QoL do so reliably and accurately among autistic participants.MethodsOur study evaluated measurement invariance of Emotional Distress (Depression, Anxiety, Anger, Psychological Stress) and Subjective Well-Being (Life Satisfaction, Positive Affect, and Meaning & Purpose) scales of the Patient-Reported Outcomes Measurement Information System (PROMIS) among groups of autistic (N=140, n per scale=132-140) and general population (N=1,224, n per scale=406-411) teenagers (14-17 years). These scales were included in the PROMIS Autism Battery-Lifespan, which uses PROMIS scales to measure QoL domains most relevant for autistic people.ResultsMulti-group confirmatory factor analyses using permutation tests demonstrated that Depression and Positive Affect scales exhibited scalar invariance between groups, indicating that scores can be meaningfully compared across autistic and general population teens. Anger and Psychological Stress scales demonstrated metric invariance between groups, indicating that these scales measure the same latent trait in both groups, but group comparisons are not supported.ConclusionWe provide guidance as to how these scales can be used in psychometrically supported ways to capture constructs relevant for understanding QoL among autistic teens. Quality of life is an important outcome for autistic people and their families. However, many quality of life scales have not been tested to make sure they accurately measure quality of life among autistic people. It is important to make sure that quality of life measures works similarly among the autistic population. The goal of our study is to test whether scales on a common quality of life measure - the Patient-Reported Outcomes Measurement Information System (PROMIS) - measures quality of life in the same way between autistic and general population adolescents. We found that some of the PROMIS scales worked the same way for autistic and general population adolescents and others did not. These results help researchers confidently use the PROMIS scales to measure different aspects of quality of life among autistic youth.