Conventional and retrospective change in health-related quality of life of trauma patients: an explorative observational follow-up study

BACKGROUND: Within trauma care measurement of changes in health-related quality of life (HRQL) is used in understanding patterns of recovery over time. However, conventionally-measured change in HRQL may not always reflect the change in HRQL as perceived by the patient. Recall bias and response shift may contribute to disagreement between conventional and retrospective change in HRQL. This study aimed to measure conventional and retrospective change of HRQL and assess to which extent recall bias and response shift contribute to disagreement between these two in a heterogeneous sample of adult trauma patients. METHODS: A sample of trauma patients (≥18 years) who attended the Emergency Department and were admitted to an Intensive Care unit or ward of one of ten Dutch hospitals received postal questionnaires 1 week (T1) and 3 months (T2) post-injury. At T1 and T2 participants completed the EQ-5D-3 L and EQ-VAS for their current health status. At T2 participants also filled out a recall and then-test regarding their health status at T1. The responses were used to assess conventional and retrospective change, recall bias and response shift. Wilcoxon signed rank tests were used to examine conventional and retrospective change on a group level. The intraclass correlation coefficient (ICC) was used to examine individual agreement between conventional and retrospective change. Uni- and multivariate linear regression analysis were used to investigate the association between background factors and recall bias and response shift. RESULTS: The EQ-5D-3 L, recall and then-test were completed by 550 patients. Mean EQ-5D-3 L summary score improved from 0.48 at T1 to 0.74 at T2. Mean EQ-VAS score improved from 56 at T1 to 73 at T2. Retrospective change was significantly higher than conventional change (EQ-5D-3 L: Z = -5.2, p < 0.05; EQ-VAS Z = -2.1, p < 0.05). Pairwise comparisons showed that agreement between conventional and retrospective change was fair (EQ-5D-3 L: ICC = 0.49; EQ-VAS: ICC = 0.48). For EQ-5-3 L response shift was significantly higher than recall bias (Z = − 4.5, p < 0.05). Patients with traumatic brain injury (TBI), severe injury and/or posttraumatic stress symptoms were more susceptible to recall bias and response shift. CONCLUSIONS: We conclude that, compared to recall bias, response shift contributed more to the disagreement between conventional and retrospective change in EQ-5D-3 L summary score and EQ-VAS. Predictable subgroups of trauma patients were more susceptible to recall bias and response shift.