Development and psychometric assessment of a psychological well-being instrument for adults with mild intellectual disability or borderline intellectual functioning research in developmental disabilities

Background: Measuring eudaimonic well-being is important to gain a complete picture of the well-being of individuals with mild intellectual disabilities or borderline intellectual functioning (MID-BIF), but there is no measurement instrument available for this population coding for multiple dimensions of eudaimonic well-being. Aims: The current study developed and piloted a new instrument coding for eudaimonic well-being in individuals with MID-BIF. Methods and procedures: The instrument (SPWB-ID) was adapted from Ryff’s scales of psychological well-being, including subscales addressing purpose in life, environmental mastery, positive relationships, self-acceptance, personal growth, and autonomy. Adaptations were based on the literature and interviews with people with MID-BIF and experts in the field. The SPWB-ID was piloted among 103 adults with MID-BIF. Outcomes and results: The trimmed version of the SPWB-ID showed sufficient to good internal consistency and test-retest reliability. Hypothesis testing for construct validity suggested the subscales of the SPWB-ID measured well-being, showing moderate to high correlations with quality of life, and differences in eudaimonic well-being between participants with and without clinically relevant depression scores. Conclusions and implications: The SPWB-ID reliably measures eudaimonic well-being in individuals with MID-BIF. This enables support providers to collect information on eudaimonic well-being, providing input for person-centred care and support for individuals with MID-BIF