What Is the Parsley Symptom Index?
An Overview of this e-PROM for Telehealth
The Parsley Symptom Index (PSI) is a 45-item electronic patient-reported outcome measure (e-PROM) designed specifically for use in telehealth settings to function as a review of systems (ROS). It was developed in 2021 by Parsley Health, a subscription-based holistic medicine practice in New York, with the purpose of facilitating PROM collection in the telehealth setting in response to the lack of a single, short-form assessment that could be easily integrated into the clinician workflow or electronic medical record (EMR) or that can capture symptoms across body systems.
Scoring System and Health Classifications of PSI
The form is administered online through Parsley Health’s official website (parsleyhealth.com). Items in the PSI are grouped into 9 body systems, with each containing 4 to 7 items per group that are ranked on a scale from 0 (asymptomatic) to 10 (extremely symptomatic). The numeric score for each item is tallied up to calculate a total score with the following 4 cutoff ranges and health classifications: 0-24 (i.e. “well”), 25-43 (i.e. “symptomatic”), 44-71 (i.e. “very symptomatic”), and greater than 71 (i.e. “sick”). The website then offers a tailored health and wellness plan based on the individual’s overall score.
Strengths and benefits of using the PSI
The PSI was created following the framework outlined by the Federal Drug Agency (FDA) guide for PROM development. It holds the advantage of serving as an electronic ROS that captures symptoms across all body systems and is most useful in the telehealth setting where patients can immediately view their PSI score as well as receive their results in a graphical, body system-stratified format upon completion of the survey. The electronic nature of the form makes it easy to integrate into the EMR and thus into clinician workflow.
Validity and Reliability of the PSI
PSI also demonstrates good construct, face, convergent, and criterion validity with other established measures of patient-perceived health. The original 2021 validation study exhibited appropriate comparative fit index (0.943), Tucker–Lewis index (0.938), and root mean square error of approximation (0.028) values when compared to a variety of chronic health symptoms and PROMs. A follow-up study in 2022 established moderate levels of association, agreement, and congruency with the Self-rated Health (SRH) item. In 2024, when compared to the Patient-Reported Outcome Measurement Information System 10-item form (PROMIS-10), the PSI had significant relationships via univariate analyses with the PROMIS-10 physical and mental health scores.
Limitations and Considerations of the PSI
The main consideration for the PSI is that it is still a recently developed e-PROM that, despite initial validation studies, requires further comparisons to established PROMs in order to support its clinical utility. PSI is also limited in its generalizability given the fact that it was administered to only Parsley Health members, a cohort of mainly white and female patients living in the states of New York and California. Additionally, while the PSI can aid in the efficiency and workflow in the telehealth setting, it is still a 45-item questionnaire that can be lengthier than other established measures such as the SRH.
Costs, Licensing and Accessibility of the PSI
PSI is currently administered by Parsley Health online using their official website. A given patient can access the survey and obtain their calculated score free of cost, but they would need to create an account and consent to receiving emails to obtain the score. Moreover, a patient would have to become a member of Parsley Health to receive a personalized care plan after completing PSI. The PSI is the intellectual property of Parsley Health Providers, rendering discussion with Parsley Health for its official administration and integration in unincorporated medical practice settings.
Conclusion: Is PSI a Valuable Telehealth PROM?
PSI is a new e-PROM that demonstrates significant promise in simplifying the collection of patient-perceived health across body systems in the telehealth setting while displaying early acceptable validity. Future studies should be performed to solidify its clinical relevance in holistic medicine.
Sources | Parsley Health (Root-Cause Resolution Medicine | Functional Medicine | Parsley Health) | Validity of the Parsley Symptom Index—an Electronic Patient-Reported Outcomes Measure Designed for Telehealth: Prospective Cohort Study (JMIR Formative Research – Validity of the Parsley Symptom Index—an Electronic Patient-Reported Outcomes Measure Designed for Telehealth: Prospective Cohort Study) | The Development of a Digital Patient-Reported Outcome Measurement for Adults With Chronic Disease (The Parsley Symptom Index): Prospective Cohort Study (JMIR Formative Research – The Development of a Digital Patient-Reported Outcome Measurement for Adults With Chronic Disease (The Parsley Symptom Index): Prospective Cohort Study) | Predictive Criterion Validity of the Parsley Symptom Index Against the Patient-Reported Outcomes Measurement Information System-10 in a Chronic Disease Cohort: Retrospective Cohort Study (JMIR Formative Research – Predictive Criterion Validity of the Parsley Symptom Index Against the Patient-Reported Outcomes Measurement Information System-10 in a Chronic Disease Cohort: Retrospective Cohort Study)