Validity of the Parsley Symptom Index—an Electronic Patient-Reported Outcomes Measure Designed for Telehealth: Prospective Cohort Study

BACKGROUND: Electronic patient-reported outcomes measures (e-PROMs) are a valuable tool for the monitoring and management of chronic conditions over time. However, there are few validated tools available that capture symptoms across body systems in telehealth settings. The Parsley Symptom Index (PSI) is a recently developed symptom assessment for adults with chronic disease in telehealth settings. A previous study demonstrated the feasibility and acceptability of the PSI in a clinical telehealth setting. OBJECTIVE: The purpose of this study was to assess convergent validity between the PSI and the self-rated health (SRH) item. METHODS: This prospective cohort study took place from January 15, 2021, to December 15, 2021, among a sample of 10,519 adult patients at Parsley Health, a subscription-based holistic medical practice. The PSI and the SRH were completed by patients via an online portal. The association between the PSI and SRH was assessed via polyserial and polychoric correlations, while weighted κ scores provided information related to agreement between the PSI and SRH. RESULTS: From 22,748 responses, there were moderate levels of association (polyserial r=0.51; polychoric r=0.52) and agreement (weighted κ=0.46) between the PSI and SRH. In total, 74.13% (n=16,865) of responses between the PSI and SRH were relatively congruent while 36.17% (n=8229) were literally congruent. CONCLUSIONS: The PSI demonstrates convergent validity with the SRH for adults with chronic disease in a telehealth setting. This finding further supports the validation of the PSI in a real-world clinical setting. Although it is conceptually similar to the 1-question SRH, the PSI is a 45-item PROM designed to capture quality of life and specific symptoms by body system. Future studies will compare the PSI to multi-item PROMs.