A cross-cultural adaptation and validation of a scale to assess illness identity in adults living with a chronic illness in South Africa: a case of HIV

The chronic illness trajectory and its outcomes are well explained by the concept of illness identity; the extent to which ill individuals have integrated their diagnosed chronic illness into their identity or sense of self. The capacity to measure illness identity in people living with HIV (PLHIV) is still relatively unexplored. However, this is potentially useful to help us understand how outcomes for PLHIV could be improved and sustained. This paper aims to explore the cross-cultural adaptation of a Belgian developed Illness Identity Questionnaire (IIQ) and validate the instrument using a sample of South African adults living with HIV. We followed a phased scale adaptation and validation process which included an investigation of conceptual, item, semantic and operational equivalence and also examined the psychometric properties of the IIQ. The concept of illness identity with its four factors; engulfment, rejection, acceptance and enrichment in PLHIV, was found to be relevant within this context. Five items from the original IIQ were excluded from the adapted IIQ due to either semantic insufficiency and/or inadequate measurement equivalence. The mode of administration of the IIQ was changed to accommodate current study participants. The original four factor 25-item model did not fit current data, however, a better contextualized, four-factor, 20-item model was identified and found valid in the current setting. The results showed adequate statistical fit; χ(2)/d.f. = 1.516, RMSEA = 0.076, SRMR = 0.0893, and CFI = 0.909. Convergent and discriminant validity were also tenable. The cross-cultural adaptation and validation of the IIQ was successful, resulting in the availability of an instrument capable of measuring illness identity in PLHIV in a high HIV prevalence and resource-constrained setting. This therefore addresses the paucity of information and expands on knowledge about illness identity.