Development and Validation of a Brief Self-Report Scale to Measure Perceived Immune Vulnerability (PIV) in Cancer Population

Objective: Understanding immunity from the patient’s perspective is essential for optimizing cancer treatment and improving patient-reported outcomes. Currently, there are no established self-reported scales designed to assess immune vulnerability in cancer populations. We aimed to fill this gap by developing a brief scale fit for this purpose. Methods: We developed a five-item brief perceived immune vulnerability (PIV) scale and conducted a two-phase study on cancer survivors in China. In Phase 1, we assessed the reliability and factor structure of the PIV scale, while in Phase 2, we evaluated its construct validity by comparing it with measures of overall well-being and various patient characteristics. Results: Between October and December 2022, 100 patients completed Phase 1, while 1275 patients were enrolled in Phase 2. The mean age of the participants was 68.7 years (SD 10.3); 892 (64.9%) patients were female, and 537 (40.3%) patients had at least high-school education. In Phase 1, Cronbach’s α = 0.913, indicating good internal consistency. We identified one component with an eigenvalue of 3.72, explaining 70.17% of the variance. In Phase 2, patients reporting poor well-being had worse immune function (Pearson r = 0.202, p < 0.001). Additionally, patients undergoing active cancer treatment had worse immune function than those receiving survivorship care (p = 0.024). Meanwhile, patients with stage III/IV disease had worse immune function than those with stage I/II disease (p = 0.041). Conclusions: The PIV scale is a reliable and valid tool for assessing immune vulnerability in patients with cancer and preliminarily offers a convenient approach to monitoring and evaluating their self-reported immunity. Further research is needed to explore the broader utility of this instrument.