Minimal clinically important difference of the EORTC QLQ-CIPN20 for worsening peripheral neuropathy in patients receiving neurotoxic chemotherapy

Context/objectives This is the first study to determine the minimal clinically important difference (MCID) of the European Organisation of Research and Treatment of Cancer Quality of Life Questionnaire-CIPN twenty-item scale (EORTC QLQ-CIPN20), a validated instrument designed to elicit cancer patients' experience of symptoms and functional limitations related to chemotherapy-induced peripheral neuropathy. Methods Cancer patients receiving neurotoxic chemotherapy completed EORTC QLQ-CIPN20 and the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity [FACT/GOG-NTX] at baseline, second cycle of chemotherapy (T2, n = 287), and 12 months after chemotherapy (T3, n = 191). Anchor-based approach used the validated FACT/GOG-NTX neurotoxicity (Ntx) subscale to identify optimal MCID cutoff for deterioration. Distribution-based approach used one-third standard deviation (SD), half SD, and one standard error of measurement of the total EORTC QLQ-CIPN20 score. Results There was a moderate correlation between the change scores of the Ntx subscale and sensory and motor subscales of QLQ-CIPN20 (T2: r = - 0.722, p < 0.001 and r = - 0.518, p < 0.001, respectively; T3: r = - 0.699; p < 0.001 and r = - 0.523, p < 0.001, respectively). The correlation between the change scores of the Ntx subscale and the QLQ-CIPN20 autonomic subscale was poor (T2: r = - 0.354, p < 0.001; T3: r = 0.286, p < 0.001). Based on the MCID derived using distribution-based method, the MCID for the QLQ-CIPN20 sensory subscale was 2.5-5.9 (6.9% to 16.4% of the subdomain score) and for motor subscale was 2.6-5.0 (8.1%-15.6% of the subdomain score). Conclusion The MCID for the EORTC QLQ-CIPN20 established using distribution-based approaches was 2.5-5.9 for the sensory subscale and 2.6-5.0 for the motor subscale. When noted in assessments even with small change in scores, clinicians can be alerted for appropriate intervention.