Abnormal photoplethysmography waveforms are associated with chemotherapy induced neuropathy

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-dependent adverse event of many chemotherapy agents that affects autonomic, motor, and sensory nerve fibers. The purpose of this study is to describe abnormal photoplethysmography waveforms (PPGs) in the setting of CIPN in cancer patients screened for peripheral arterial disease (PAD), which to our knowledge has not been previously described. Patients and methods: 147 patients who underwent vascular physiologic testing in evaluation for PAD with an ankle brachial index (ABI) or toe brachial index (TBI), segmental pressures, pulse volume recordings, and toe PPGs, in a tertiary cancer center's vascular lab between January 1, 2019 and January 31, 2021 were included in the study. Results: Odds ratio analysis demonstrates 3 times increased odds of abnormal PPGs in patients with PAD (OR 3.2256 95% CI 1.523-6.832, p=0.002), 7 times increased odds of abnormal PPGs in patients with CIPN (OR 7.802 95% CI 3.606-16.880, p<0.001), 9 times increased odds of abnormal PPGs in patients with both CIPN and PAD (9.895 95% CI 2.643-37.043, p=0.001), and 7 times increased odds of abnormal PPGs in patients with chemotherapy agent known to cause CIPN (7.821 95% CI 3.619-16.902, p<0.001). Logistic regression demonstrated that PAD (coefficient 1.171 std. error 0.383 wald 9.354 p=0.002), CIPN (coefficient 2.054 std. error 0.394 wald 27.227 p<0.001), and chemo agent known to cause CIPN (coefficient 2.057 std. error 0.393 wald 27.370 p<0.001) were all predictors of abnormal PPGs. Conclusions: CIPN had greater odds for abnormal PPGs than PAD. Additional larger studies are needed to assess if PPG analysis could be utilized to assess for early diagnosis of CIPN.