Validity and Reliability of the Turkish Version of National Comprehensive Cancer Network/Functional Assessment of Cancer Therapy Ovarian Symptom Index-18 (NFOSI-18) and Neurotoxicity-4 (NTX-4) for Patients with Advanced Ovarian Cancer

Objectives. The aim of this study was to investigate the validity and reliability of the Turkish version of the National Comprehensive Cancer Network/Functional Assessment of Cancer Therapy Ovarian Symptom Index-18 (NFOSI-18) and Functional Assessment of Cancer Therapy/Gynecologic Oncology Group Neurotoxicity 4-item (NTX-4) in patients with advanced ovarian cancer (OC). Methods. Ninety-four women with OC were included. Pearson correlation coefficients were used to examine the convergent validity between the European Quality of Life Survey-5 Dimension-3 Level (EQ-5D-3L) and the Turkish NFOSI-18 and NTX-4. The internal consistencies of the Turkish NFOSI-18 and NTX-4 were calculated using Cronbach’s alpha. Turkish NFOSI-18 and Turkish NTX-4 were readministered to 62 (67.4%) patients with OC after 14–21 days to evaluate test-retest reliability.Results. Turkish NFOSI-18 and Turkish NTX-4 showed excellent internal consistency (Cronbach’s alpha: 0.919 and 0.917, respectively). The test-retest reliability of Turkish NFOSI-18 and Turkish NTX-4 was detected as good to excellent for total score (ICC [95%] = 0.93 [0.88-0.95] and ICC [95%] = 0.90 [0.85-0.94], respectively). Significant correlations were detected between the EQ-5D-3L total score, NFOSI-18 (r = 0.648, $p$ < 0.01), and NTX-4 (r = 0.694, $p$ < 0.01) indicating sufficient convergent validity. Conclusion. The Turkish NFOSI-18 and Turkish NTX-4 are reliable and valid tools to assess disease-related symptoms in patients with advanced OC.