Reliability of patient-reported toxicities during adjuvant chemotherapy

Background: Patient-reported outcomes (PROs) are validated tools to assess the impact of efficacy and toxicities of cancer treatments on patients' health status. Because of the demonstrated little reliability of humans in reporting memories of painful experiences, this work explores the reliability of cancer patients in reporting chemotherapy-related toxicities.

Aim: This study aims to evaluate the concordance between toxicities experienced by the patients during chemotherapy and toxicities reported to the doctor at the end of the cycles.

Methods: Questionnaires concerning chemotherapy-related toxicities were administered on days 2, 5, 8, 11, 14, and 17 of each chemo cycle and at the end of the same cycle to patients undergoing adjuvant chemotherapy. The co-primary end-points were Lins's concordance correlation coefficient (CCC) and mean difference between real-time and retrospective toxicity assessments.

Results: In total, 7182 toxicity assessments were collected from 1096 questionnaires. Concordance was observed between the retrospective evaluations and the toxicity assessments at early (day 2), peak (maximum toxicity), late (day 14 or 17), and mean real-time evaluations for each chemotherapy cycle (CCC for mean ranging from 0.52 to 0.77). No systematic discrepancy was found between real-time and retrospective evaluations, except for peak, which was systematically underestimated retrospectively.

Conclusions: Toxicities reported by the patients to the doctor at the end of each chemotherapy cycle reflect what they actually experienced without any substantial distortion. This result is very relevant both for the clinical implications in daily patients' management and in the light of the current growing impact on digital monitoring of PROs.