Distinct Clinical Phenotypes of Long COVID: Autonomic vs Inflammatory Presentations in Younger and Older Adults.

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E OGBEBOR1,2; S H X CHEONG3; S J LINNANE1

1. Department of Respiratory Medicine, Beacon Hospital, Dublin, Ireland; 2. Department of Postgraduate Medicine, Royal College Of Surgeons in Ireland, Dublin, Ireland ; 3. Department of Undergraduate Studies, UCD University, Dublin, Ireland.

Abstract

Introduction
While Post-Acute Sequelae of SARS-CoV-2 (PASC) is a recognised global priority, clinical definitions derive largely from working-age cohorts. Older adults face high acute severity risk, yet long-term survivorship remains under-characterised. We aimed to characterise and compare clinical PASC phenotypes in older (≥65 years) versus younger (<65 years) adults, distinguishing autonomic, inflammatory and psychosocial manifestations.

Method
We conducted a retrospective single-centre cohort study of 336 patients attending a dedicated Long COVID clinic at The Beacon Hospital, Ireland. Data were stratified by age. We performed comparative statistics using Fisher’s Exact Tests (to account for sample size disparities) and constructed age-stratified bipartite patient-symptom network graphs (using Neo4j force-directed layouts) to visualise emergent phenotypic clustering and node centrality.

Results
The cohort comprised 317 younger adults (94.3%) and 19 older adults (5.7%). Distinct symptom clusters emerged. Younger adults exhibited a predominant autonomic phenotype; palpitations were exclusively observed in this group (6.3% vs 0%), though statistical significance was limited by sample size (p=0.606). Conversely, older adults displayed a robust, statistically significant inflammatory phenotype, with markedly elevated rates of recurrent fevers (57.9% vs 16.1%, p<0.001), dry cough (73.7% vs 15.5%, p<0.001), and fatigue (p=0.002). Psychosocial analysis revealed a disproportionate burden of anxiety and sleep disturbance in older adults (36.8% vs 14.5%, p=0.016), reflecting the sequelae of national "cocooning" mandates.

Conclusion
Long COVID manifests as divergent clinical phenotypes based on age. Older adults experience persistent inflammatory sequelae and heightened psychosocial burden, distinct from the autonomic presentation of the young. These findings underscore the need for age-stratified rehabilitative frameworks.

Comments

Good work. This study…

Good work. This study provides valuable insight into age-specific Long COVID phenotypes, highlighting a predominantly inflammatory and psychosocial burden in older adults versus an autonomic pattern in younger patients. It reinforces the need for tailored, age-stratified approaches to post-COVID rehabilitation and care.

Thank You

Thank you for your thoughtful and encouraging feedback. Really appreciate the engagement with the study and your recognition of the importance of age-stratified approaches to Long COVID management and rehabilitation.

Great poster, really well…

Great poster, really well presented. Very interesting topic, feels as though this has been overlooked in literature/ clinical practice so a good topic choice.

Thank you for your feedback

Many thanks for your kind and thoughtful feedback. Grateful you found the poster well presented and the topic relevant. It is indeed an overlooked area in current literature, and we hope this work helps raise awareness and shed further light on it.

Which specialty?

Which specialty tends to take the lead in long-covid services? It seems as though the symptoms are multisystem and therefore likely to need broad input

Thank You for your observation and feedback

Thank you for this important observation and for your feedback! Long COVID is inherently multisystem, so the literature supports a multidisciplinary rather than single-specialty model. Primary care is likely to encounter these patients first and is central to early recognition, exclusion of alternative diagnosis and appropriate onward referral.

While respiratory medicine will frequently provide a key specialist framework for post-COVID services, management should ultimately be symptom and phenotype-led. In the older adult, Geriatricians can add particular value where frailty, multi-morbidity, functional decline, cognitive symptoms and rehabilitation needs are potentially more prominent.

Improved recognition of these differing phenotypes across specialties will support more targeted, age-stratified rehabilitation and follow-up care.

Interesting insights

This work does a great job of highlighting the differing presentations of Long COVID.

Thank you

Thank you for your kind feedback and comment. Very pleased the poster was well received and highlights the important differences of Long COVID presentation across age groups.