Objective To develop a patient-reported outcome measure for lung cancer patients undergoing immunotherapy and to test its reliability and validity, to provide an effective self-assessment tool for patient-reported outcomes.

Methods From February to August 2025, an item pool was constructed through literature analysis, case review, semi-structured interviews, and group discussions. The preliminary version of the measure was established via expert consultation. From October 2025 to February 2026, a convenience sample of lung cancer patients receiving immunotherapy was recruited from a tertiary hospital in Guangdong Province to refine the measure items and assess its reliability and validity.

Results The final patient-reported outcome measure for lung cancer patients undergoing immunotherapy consisted of 4 domains, 17 dimensions, and 57 items. Exploratory factor analysis extracted 9, 2, 3, and 3 common factors in the four domains, with cumulative variance contributions of 73.984%, 79.044%, 78.637%, and 79.735%, respectively. The overall split-half reliability coefficient was 0.765, the overall Cronbach’s α was 0.914, and the test-retest reliability was 0.908, indicating good internal consistency. The scale-level content validity index was 0.906.

Conclusion The patient-reported outcome measure developed for lung cancer patients receiving immune checkpoint inhibitor therapy demonstrates good reliability and validity and can be used to assess patient-reported outcomes in this population.