Illness uncertainty and quality of life in patients with advanced cancer and their family caregivers: An actor‐partner interdependence model analysis

The relationship between illness uncertainty and quality of life (QOL) has been examined for either the patient or caregiver, but not among the patient-caregiver dyads. This study examined relationships between illness uncertainty and QOL among patients with advanced cancer and family caregivers.We conducted a secondary analysis of data from a randomized clinical trial that examined the effects of a dyadic-based intervention on psychological outcomes for patients with advanced cancer and family caregivers (N = 484 dyads). Illness uncertainty and QOL were measured using the shorten version of the Mishel Uncertainty in Illness Scale for Adult and the Functional Assessment of Cancer Therapy, respectively. The actor-partner interdependence model was used to examine whether an individual's uncertainty (either a patient's or caregiver's) was associated with their own QOL (i.e., an actor effect) and/or their partner's QOL (i.e., a partner effect).Significant actor effects included a negative association between patients' uncertainty and their own QOL (b = -0.422; p < 0.001) and a negative association between caregivers' uncertainty and their own QOL (b = -0.408; p < 0.001). In terms of partner effects, patients' uncertainty was negatively associated with caregivers' QOL (b = -0.095; p < 0.01). No partner effect was found for caregivers, suggesting that caregivers' uncertainty was not related to patients' QOL.Study findings support targeted interventions offered to both patients and their family caregivers to manage their illness uncertainty and improve their QOL.