Evaluating quality of life and response shift from a couple-based perspective: a study among patients with colorectal cancer and their partners.

objectivesTo examine (1) measurement invariance of quality of life (QoL) domains over time for patients with colorectal cancer and partners (i.e., response shift--recalibration, reprioritization, and reconceptualization), (2) between dyad-member measurement invariance and (3) QoL trajectories.

methodsParticipants completed the WHOQOL-Bref preoperative (Time-0) and 3 (Time-1) and 6 months (Time-2) postoperative. A stepwise procedure, using nested factor models, examined the viability of restricting specific model parameters to be equal across measurements and between dyad members.

findingsNo reconceptualization and reprioritization was detected, but indications for recalibration were present. Therefore, comparisons were restricted to group-level statistics at factor level. For patients, a decrease in the Physical Health domain occurred at Time-1 (p < 0.001), with partial recovery to baseline at Time-2 (p = 0.055). For partners, factor means in this domain remained constant (p's > 0.05) and were at each time point higher than patients' factor means (p's < 0.05). Patients' and partners' Psychological Health decreased at Time-1 (p's < 0.05), with stabilization at Time-2 (p's > 0.05). Patients and partners' factor means were comparable (p's > 0.05). Patients and partners' Social Relationship factor means decreased at Time-1 (p's < 0.05), which decreased further for patients (p = 0.011) but stabilized for partners (p = 0.214). Partners' factor means were only lower than patients' factor means at Time-1. A similar decrease in the Environmental domain factor means occurred for both patients and partners at Time-1 (p's < 0.05), with stabilization at Time-2 (p's > 0.05).

conclusionSince both patients and partners are affected by the patients' disease and treatment, we recommend that attention is paid to the couple instead of solely the patient.