Couples’ catastrophizing and co-rumination: Dyadic diary study of patient fatigue after cancer.

Fatigue is a prevalent and long-lasting symptom among patients with cancer that is known to be worsened by patients' catastrophizing thoughts about their fatigue. Spouses are also burdened by patient fatigue, which may lead them to catastrophize as well. Based on the dyadic coping literature, this study hypothesized that patient and spouse catastrophizing translate into worse fatigue through co-rumination-couples' communications dwelling on the negative aspects of fatigue (H1). While maladaptive for fatigue, co-rumination also was expected to foster couple relationship satisfaction (H2).Posttreatment patients with cancer and their spouses (n = 101 dyads) completed daily diaries for 14 days. Patients reported on their momentary fatigue severity. Both couple members reported on their catastrophizing about the patients' fatigue, co-rumination, and their momentary relationship satisfaction. Multilevel structural equation modeling was applied to test within-person actor- and partner-effects between catastrophizing, co-rumination, and changes in fatigue (H1) and between co-rumination and changes in relationship satisfaction (H2).Whereas patient catastrophizing was directly related to their fatigue (b = 0.52, 95% credibility interval [CI] [0.09, 0.95]), as hypothesized, the effect of spouse catastrophizing on patient fatigue was mediated through co-rumination (indirect effect = 0.32, 95% CI [0.07, 0.60]). Unexpectedly, patient- and spouse-reported co-rumination were unrelated to both couple members' relationship satisfaction.Spouse catastrophizing contributes to patient fatigue severity through couples' ruminative communications. Co-rumination was not related to relationship satisfaction. Reducing patient and spouse catastrophizing and fostering adaptive dyadic communication in daily life could be targets for future interventions aiming to relieve fatigue in patients after completion of cancer treatment. (PsycINFO Database Record (c) 2019 APA, all rights reserved).