Measuring vital sign observation timeliness in hospital wards

Ironside-Smith, Rupert 2025. Measuring vital sign observation timeliness in hospital wards. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Clinical staff in hospital wards regularly monitor patients’ health by measuring basic health indicators, such as blood pressure, heart rate, temperature, and respiratory rate. The act of completing a pre-defined catalogue of these measurements is known as a vital sign observation, which facilitates scoring each parameter against banded limits then aggregating into a convenient single digit called the National Early Warning Score (NEWS). A patient’s subsequent vital sign observation is scheduled in proportion to their current NEWS, where higher-acuity patients are observed more frequently. Whilst individually scheduled, observations are commonly managed collectively as part of ward round practices (typically 2-4 times daily), which is effective for most stable patients since their observation frequencies typically align with ward round timing. Handheld devices are replacing paper charts for documenting and scheduling these observations, and in doing so, also capture rich metadata (who took the observation, when, and what was the patient’s condition) ideal for data-driven timeliness audits- whether observations occur as scheduled and, if not, by how much they are delayed. Using this data, existing studies have documented systemic vital sign observation delays; however, there is disagreement about when exactly an observation should be considered “delayed”, and whether some level of delay is acceptable. We therefore begin this thesis by establishing consistent terminology and thresholds for timeliness research. The methodological core of the thesis is a statistical framework that, rather than labelling observations on-time or late against a fixed threshold, estimates the probable time to a patient’s next observation- without requiring any additional data-collection infrastructure. It also shows how standardised schedules (1-, 2-, 4-, 6-, 8-, and 12-hours, set according to observed patient acuity) interact in non-standard ways with the daily rhythm of ward rounds. Measuring timeliness, however, is not the same as measuring patient safety. If we assume a patient’s risk of deterioration is correlated with their current condition (for example, a high-acuity patient now is likely to remain high-acuity in the short term), the framework can estimate the probability that a patient crosses a high-acuity NEWS threshold before their next observation. Expressing timeliness as patient risk proxy also lets institutions target that risk rather than raw timeliness, preventing the headline measure from becoming a self-defeating target. Simulating stricter timeliness adherence shows that better timeliness may indeed improve patient outcomes, particularly for high-acuity patients; for the majority, apparent “delays” instead reflect clinical prioritisation, allowing flexible timing for stable patients. Our methods, results, and recommendations aim to support discussions on whether achieving patient equity (i.e., strict timeliness policy adherence for all) can be achieved with current resources, or whether institutions must accept prioritising high-risk patients under resource constraints.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Computer Science & Informatics Schools > Social Sciences (Includes Criminology and Education)
Subjects:	Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Date of First Compliant Deposit:	28 August 2026
Date of Acceptance:	3 July 2026
Last Modified:	28 Aug 2026 14:29
URI:	https://orca.cardiff.ac.uk/id/eprint/189231

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