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

Background: Measuring eudaimonic well-being is important to gain a complete picture of the wellbeing of individuals with mild intellectual disabilities or borderline intellectual functioning (MIDBIF), 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 wellbeing 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.