Beyond the Ratios: Evidence for Optimal Minimum Nurse-Patient-Ratios in Medical-Surgical Settings.
Farinaz Havaei, Claire Song, Danjie Zou and 3 others
PMID 40488662WHAT IT FOUND
Nurse-reported quality and safety outcomes deteriorated when assigned more than four patients per shift.
This supports a 1:4 nurse-to-patient ratio in medical-surgical settings, though the data is from 2015 and relies on self-reports rather than patient records.
Key findings
01Residual scores for quality of care and safety grades shifted from positive to negative when nurse-to-patient ratios increased from 1:4 to 1:5.
02Nurses reported more undone tasks and higher emotional exhaustion when ratios exceeded 1:4.
03The study cautions against causal conclusions due to the cross-sectional nature of the data and low response rate.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The data is from 2015 and may not reflect current healthcare conditions, particularly after the pandemic. The study relies entirely on nurses' self-reports, which are subject to recall and social desirability bias. The response rate for the original survey was low, raising concerns about non-response bias. The cross-sectional design prevents causal conclusions; it shows association, not that the ratio caused the outcome. There were insufficient data points at extreme ratios (1:1, 1:2, and 1:9), making those specific comparisons unstable.
Declared interests
The original survey was conducted in partnership with the provincial nurses' union, though the secondary analysis was performed by academic researchers to mitigate bias. The study was approved by the University of British Columbia Behavioural Research Ethics Board.
The easy way to misread this
Do not interpret this as evidence that a 1:4 ratio prevents patient mortality or adverse events. The study measured nurses' perceptions of quality and safety, not actual patient outcomes like falls or infections, and the data is from 2015.