Jump to comment:

• Infant to staff ratios and risk of mortality in very low birth weight infants
  Richard P Bowker
  Published on: 9 January 2022
• Re: Infant to staff ratios and risk of mortality in very low birthweight infants
  Jon S Dorling
  Published on: 9 January 2022

• Published on: 9 January 2022

  Infant to staff ratios and risk of mortality in very low birth weight infants

  • Richard P Bowker, Clinical Research Fellow

  Dear Editor

  I was very interested to read the article by Callaghan and colleagues,[1] in which they conclude that increased staffing numbers may be detrimental to the survival of preterm infants on their neonatal intensive care unit. I was puzzled to determine how these results could differ from the logical assumption that with more nurses to care for critically ill infants there should be an improved outcome....

  Show More

  Dear Editor

  I was very interested to read the article by Callaghan and colleagues,[1] in which they conclude that increased staffing numbers may be detrimental to the survival of preterm infants on their neonatal intensive care unit. I was puzzled to determine how these results could differ from the logical assumption that with more nurses to care for critically ill infants there should be an improved outcome.

  One explanation may be the way the results have been statistically handled. Neither CRIB scores nor infant to staff ratios are normally distributed. Yet Callaghan and colleagues have used parametric tests on their data. Thus, there may very well have been true differences between the CRIB scores of the infants in the three groups (as shown in table 4) which may not have been picked up by assuming normal distribution in these populations. If this were the case then the conclusions drawn about outcomes and staffing ratios would be inaccurate, and the survival differences may then be better explained by the patient characteristics.

  In view of previous publications [2,3] and guidance by the British Association of Perinatal Medicine [4] I would be concerned if neonatal intensive care units across the United Kingdom adjusted their staffing levels on the basis of these results alone.

  References

  1. Callaghan LA, Cartwright DW, O’Rourke P, et al. Infant to staff ratios and risk of mortality in very low birthweight infants. Arch Dis Child Fetal Neonatal Ed 2003;88:F94–7.

  2. Hamilton K, Gould C, Tarnow-Mordi W, et al. Hospital mortality in relation to staffing levels in the first three days of neonatal care. Proceedings of the 4th Annual Congress of the Perinatal Society of Australia and New Zealand 2000. Brisbane, Sydney, Australia: PSANZ, 2000:109.

  3. BAPM. Standards for hospitals providing neonatal intensive and high dependency care, 2nd edn. London: British Association of Perinatal Medicine, 2001.

  4. The UK Neonatal Staffing Study Group. Patient volume, staffing, and workload in relation to risk-adjusted outcomes in a random stratified sample of UK neonatal intensive care units: a prospective evaluation. Lancet 2002;359:99–107.

  Show Less

  Conflict of Interest:
  None declared.

  • Back to top
• Published on: 9 January 2022

  Re: Infant to staff ratios and risk of mortality in very low birthweight infants

  • Jon S Dorling, Specialist Registrar in Neonatal Medicine
  • Other Contributors:
    • Jag S. Ahluwalia

  Dear Editor

  We were very interested to read the article by Callaghan et al.[1] They report a decline in mortality with less nurses caring for high-risk infants over the first three days of life. This is a suprising finding, which is counter-intuitive to established neonatal wisdom. Indeed the authors quote a smaller study by Hamilton et al,[2] which found an increase in mortality with a reduced...

  Show More

  Dear Editor

  We were very interested to read the article by Callaghan et al.[1] They report a decline in mortality with less nurses caring for high-risk infants over the first three days of life. This is a suprising finding, which is counter-intuitive to established neonatal wisdom. Indeed the authors quote a smaller study by Hamilton et al,[2] which found an increase in mortality with a reduced ratio of nurses to infants. Callaghan et al.'s findings may be true, with the most likely explanation of the deaths being excessive handling. Clearly, if this finding is replicated then establishing the optimum number of nurses could lead to improved outcomes for high risk infants. It certainly warrants further study within the NHS and the United Kingdom.

  It is widely assumed that increased numbers of nurses in the UK will improve the outcome of neonatal intensive care. Currently, in the National Health Service there is difficulty in maintaining adequate numbers of neonatal nurses, with many units having nurse staffing levels substantially below those recommended by the British Association of Perinatal Medicine.[3] Unfortunately, this recommendation for more staff is not based on a great deal of evidence, and the authors are to be praised for studying this topic.

  Their results should, however be interpreted with caution. The health systems of the UK and Australia are different, most particularly in the proportion of centralised care and the ratio of nurses to infants. Callaghan et al make the point that the UK has a ratio of 2 VLBW infants to one nurse, whereas in Australia the ratio is approximately 1 to 1. The UK Neonatal Staffing Study has recently looked at 13,500 infants from 54 randomly selected units throughout the UK.[4] This study did not show a clear relationship between staff establishment and outcome, although it did show a linear relationship between mortality and occupancy rates and a trend to increased risk of mortality with a lower nurse - infant ratio.

  Callaghan et al discuss some of the weaknesses of their own study. There are also 2 factors that we wish to highlight. The first is that the authors have not looked in detail at the quality and abilities of the nursing staff. There is a wide variation in the abilities of staff, particularly when nursing agencies are used to provide nurses. As these staff may not work full - time or have much experience of the individual unit, they may be less efficient or able when compared to those full-time staff based on the unit.

  The second factor is the method of determining nurse workload. Measuring the ratio of babies to staff is not an accurate assessment of nurse activity; a large number of well babies often need less care than a small number of sicker babies. It is not clear from the paper how the authors dealt with the term infants, and whether these are included in calculating the ratio. Did the authors use the number of nurses per VLBW infant or per all babies in the unit? In addition, large babies can also generate a substantial workload if they are very unwell (e.g. for example babies with persistent pulmonary hypertension of the newborn or congenital diaphragmatic hernia). Further studies measuring the true overall workload may give a better indication of the relationship with outcomes.

  References

  (1) Callaghan LA, Cartwright DW, O'Rourke P, Davies MW. Infant to staff ratios and risk of mortality in very low birthweight infants. Arch Dis Child Neonatal Ed 2003:88:F94-F97.

  (2) Hamilton K, Gould C, Tarnow-Mordi W, et al. Hospital mortality in relation to staffing levels in the first three days of neonatal care. Proceedings of the 4th Annual Congress of the Perinatal Society of Australia and New Zealand 2000. Brisbane, Australia. Sydney: PSANZ,2000:109.

  (3) BAPM. Standards for Hospitals Providing Neonatal Intensive and High Dependency Care. Second edition, 2001. British Association of Perinatal Medicine, London.

  (4) The UK Neonatal Staffing Study Group. Patient volume, staffing, and workload in relation to risk-adjusted outcomes in a random stratified sample of UK neonatal intensive care units: a prospective evaluation. Lancet 2002; 359: 99-107.

  Show Less

  Conflict of Interest:
  None declared.

  • Back to top