¹University of Lübeck, Department of Rheumatology and Clinical Immunology, Lübeck
²University of Lübeck, Department of Medical Clinic III, Lübeck

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Introduction: Fatigue affects approximately 70% of patients with primary Sjögren syndrome (pSS) and significantly impacts their quality of life [1]. Notably, improvements in VO2max, a marker of cardiorespiratory fitness, appear to be associated with reductions in fatigue [2]. Photoplethysmography (PPG) sensor technology has been shown to accurately measure resting heart rate (RHR) – a validated population-level biomarker of cardiorespiratory fitness [3]. While a single RHR measurement provides limited information, PPG-based wearables allow continuous monitoring, with longitudinal data serving as a valuable prognostic marker [4]. The study aimed to investigate the correlation between fatigue scores and RHR in pSS patients.

Methods: Eight pSS patients and seven healthy controls were recruited over six months. Heart rate was measured using the wireless VitalPatch^® PPG-sensor, and fatigue was assessed using the FACIT-F questionnaire [5]. Participants wore the sensor for seven consecutive days as part of their daily lives. After the technology use period, the sensor and completed questionnaire were returned to our clinic. An in-house R script was developed to automate both the visualization and computation of resting heart rate data.

Results: Patients with pSS demonstrated a higher mean RHR compared to healthy controls (62.6 ± 1.84 bpm vs. 56.1 ± 3.03 bpm). The minimum RHR in the pSS group was 57 bpm, whereas the healthy controls reached as low as 46 bpm, suggesting that pSS patients may maintain a higher heart rate even at rest. The FACIT-F scores indicated a mean of 33.4 ± 7.82 for pSS patients, compared to a higher mean score of 48.7 ± 3.59 in controls (lower FACIT-F scores indicate higher fatigue). No significant correlation between fatigue scores and RHR was found (p=0.098).

Conclusion: pSS patients demonstrated a significantly higher RHR compared to healthy controls. Continuous, high-quality heart rate data collected via a PPG-based wearable device highlight the potential use of RHR as a non-invasive clinical marker of cardiovascular health in pSS patients. Further recruitment is required to better understand the relationship between fatigue levels and RHR in this population.

Abbreviations: pSS: primary Sjoegren Syndrome RHR: Resting heart rate FACIT-F: Functional Assessment of Chronic Illness Therapy – Fatigue VO2max: maximal oxygen intake PPG: photoplethysmography

Literatur

[1] Mæland E, Miyamoto ST, Hammenfors D, Valim V, Jonsson MV. Understanding Fatigue in Sjögren's Syndrome: Outcome Measures, Biomarkers and Possible Interventions. Front Immunol. 2021 Jun 25;12:703079. DOI: 10.3389/fimmu.2021.703079
[2] Miyamoto ST, Lendrem DW, Ng WF, Hackett KL, Valim V. Managing fatigue in patients with primary Sjögren's syndrome: challenges and solutions. Open Access Rheumatol. 2019 Apr 24;11:77-88. DOI: 10.2147/OARRR.S167990
[3] Gonzales TI, Jeon JY, Lindsay T, Westgate K, Perez-Pozuelo I, Hollidge S, Wijndaele K, Rennie K, Forouhi N, Griffin S, Wareham N, Brage S. Resting heart rate is a population-level biomarker of cardiorespiratory fitness: The Fenland Study. PLoS One. 2023 May 11;18(5):e0285272. DOI: 10.1371/journal.pone.0285272
[4] Quer G, Gouda P, Galarnyk M, Topol EJ, Steinhubl SR. Inter- and intraindividual variability in daily resting heart rate and its associations with age, sex, sleep, BMI, and time of year: Retrospective, longitudinal cohort study of 92,457 adults. PLoS One. 2020 Feb 5;15(2):e0227709. DOI: 10.1371/journal.pone.0227709
[5] Cella D, Lai JS, Stone A. Self-reported fatigue: one dimension or more? Lessons from the Functional Assessment of Chronic Illness Therapy--Fatigue (FACIT-F) questionnaire. Support Care Cancer. 2011 Sep;19(9):1441-50. DOI: 10.1007/s00520-010-0971-1