A copula approach to modelling dependency patterns in routine vital sign observation timeliness

Ironside-Smith, Rupert, Allen, Stuart ORCID: https://orcid.org/0000-0003-1776-7489, Noe, Beryl and Turner, Liam ORCID: https://orcid.org/0000-0003-4877-5289 2025. A copula approach to modelling dependency patterns in routine vital sign observation timeliness. Presented at: IEEE International Conference on Healthcare Informatics (ICHI) 2025, Cosenza, Italy, 18-25 June 2025.

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Abstract

Healthcare staff in a hospital ward setting typically monitor patients by taking vital sign observations at regular intervals, usually every 6 - 12 hours for routine observations, but more frequently for critical patients. Patients on similar schedules have been shown to be regularly batched in a practice called `ward rounds', but to what extent healthcare staff manage observations on `non-routine' intervals independently to those scheduled for the subsequent ward round has yet to be established. This study examines the Time-To-Next-Observation (TTNO) for vital sign observations with planned schedules (e.g., 1 hour) as random variables defined by their hazard distribution functions. Joint distribution functions sampled from any pair of TTNO distributions could be used to calculate the probability that any two observations on set schedules will happen collectively. However, it is clear that this model fails to capture underlying dependency structures seen in empirical results. We propose a copula approach to extract and quantify pairwise non-linear relationships for all standard observation intervals across 20 study wards. This study showed that most wards operate with significant levels of dependency between observation schedules, largely reflecting broad ward characteristics referenced in other works, yet present a deeper level of insight into individual ward operations. Understanding current levels of dependency between regular observation scheduling and routine operations has the potential to become essential knowledge for ward stakeholders when designing staff resource strategies.

Item Type:	Conference or Workshop Item (Paper)
Status:	In Press
Schools:	Schools > Computer Science & Informatics
Subjects:	H Social Sciences > HA Statistics R Medicine > RT Nursing
Uncontrolled Keywords:	Hospital Ward, Vital Signs Observations, Secondary Data Analysis, Hazard Function, Copula Method
Date of First Compliant Deposit:	26 June 2025
Date of Acceptance:	13 March 2025
Last Modified:	26 Jun 2025 16:15
URI:	https://orca.cardiff.ac.uk/id/eprint/178212

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