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Research Christmas 2011: Professional Matters

Relevance of the expression “obs stable” in nursing observations: retrospective study

BMJ 2011; 343 doi: (Published 20 December 2011) Cite this as: BMJ 2011;343:d7504
  1. Gregory Scott, academic clinical fellow in neuroscience1,
  2. Roshan Vijayan, trauma senior house officer2,
  3. Pandora Male, final year medical student3
  1. 1Imperial College Healthcare NHS Trust, Hammersmith Hospital, London W12 0HS, UK
  2. 2Imperial College Healthcare NHS Trust, St Mary’s Hospital, London
  3. 3School of Medicine, Imperial College London, London
  1. Correspondence to: G Scott gregory.scott99{at}
  • Accepted 7 October 2011


Objective To ascertain whether use of the term “obs stable” with respect to the nursing observations is so liberal as to render it meaningless.

Design Retrospective study.

Setting Three teaching hospitals in London, United Kingdom.

Methods We searched progress notes for the current admission of 46 inpatients for entries containing the phrases “obs stable” and “observations stable,” and reviewed the nursing observations recorded during the 24 hour period preceding each entry containing at least one phrase. We calculated the frequency of abnormalities and of persistent abnormalities (defined as occurring in every observation) observed during these 24 hour periods, and the range of observation values over a 24 hour period if at least two observations had been recorded.

Results We found at least one entry in 36 (78%) progress notes (95% confidence interval 66% to 90%). Observations in the 24 hours preceding an entry included at least one abnormality for 113 (71%) of 159 cases and at least one persistent abnormality for 31 (19%). The most frequently occurring abnormalities were tachypnoea (respiratory rate ≥20 breaths/min) and hypotension (systolic blood pressure <100 mm Hg). An abnormality occurred in the observations immediately preceding an entry in 42% of cases. Mean ranges of observations over 24 hours were within the limits of normal diurnal variation, although we found that some instances of greater than normal variability were described as “stable.”

Conclusions The expression “obs stable” does not reliably indicate normal observations or variations in observations within physiological limits. Doctors should avoid using the expression altogether or clarify it with further information.


  • We thank Frank Cross, Jeremy Wyatt and Bryony Dean for their comments on an early draft of the paper.

  • Contributors: GS and RV jointly designed the study, wrote the article, and are coguarantors of the study. GS, RV, and PM undertook the data collection. GS undertook the data analysis. PM reviewed literature on diurnal variation.

  • Funding: None.

  • Competing interests: All authors have completed the Unified Competing Interest form at (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethics approval: Ethics approval was not required according to the Clinical Research Governance Office.

  • Data sharing: No additional data available.

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