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The business of risk: how building design can contribute to increased patient safety

Colum Menzies Lowe
Head of Design and Human Factors
UK National Patient Safety Agency

Safety and risk reduction are cornerstones of the current hospital design process. However, as with all other industries, the concept of zero risk is a little misleading. Even the safest industries know they have to accept a certain level of risk, which is why terms such as “as low as reasonably practicable” and “reasonably foreseeable” have been developed. The issue here is what is foreseeable, and to whom it is reasonable. While the vast majority of healthcare is provided safely and successfully, problems do occur, and if you have just suffered a patient safety incident – for example, you have undergone treatment and picked up a secondary infection that requires you to stay in hospital for an extra 10 days and consume a variety of drugs – “reasonable” takes on a whole new meaning.(1)

Hospitals, as with every other aspect of life, will never be 100% safe – every time we get in a car, board a plane or cross the road we are exposing ourselves to the risk of accident and injury. Absolute safety is impossible to achieve, and we, as citizens and consumers, would not tolerate the level of disruption and intrusion into our lives that it would entail even if it were. The issue that needs to be addressed is, where to draw the line, what is an acceptable level of risk?

Measuring levels of risk
Other safety critical industries, such as offshore oil extraction, nuclear power and transport, all have their own ways of measuring and defining acceptable levels of risk and harm. Railtrack (the UK’s former rail infrastructure operator) used ALARP (as low as reasonably practicable) measures, which is a range of risk acceptability with a “passenger tolerability of risk of fatality per annum” of one in 100,000 being at the upper limit of risk tolerability, while one in 10,000,000 and below is considered broadly acceptable.(2) To provide more safety than this is deemed to be “grossly disproportionate” – in other words, the disproportion between costs and benefits would be gross.(3)
Healthcare needs its own limits to decide what is tolerable and broadly acceptable, and to design facilities, equipment and processes accordingly. Preliminary research carried out by Vincent et al found that 10% of acute inpatients suffer a safety incident, with as many as 8% of these incidents resulting in the patient’s death – 48% of which were considered avoidable.(4) This results in a risk of fatality per admission figure of approximately one in 233. This calculation is not directly comparable with Railtrack’s ALARP, nor is it appropriate to extrapolate the findings from 1,014 case records across a whole hospital, never mind the entire NHS. However, it is an indicator that further work, in terms of driving down the risk of harm to patients in healthcare, could produce significant safety benefits.

The National Patient Safety Agency’s (NPSA) reporting system, the National Reporting and Learning System, reported 420 deaths as a result of patient safety incidents between November 2003 and March 2005, during which time acute NHS trusts would have treated roughly 12 million patients.(5) This provides a risk of fatality per admission rate of one to 28,572, obviously much better than the Vincent figures would suggest, but still behind other safety critical industries such as aviation and passenger rail.

Improving healthcare facility design
To accept any figure, low or high, in terms of a situation that is “as low as reasonably practicable”, any safety improvement would have to be deemed grossly disproportionate in terms of a cost–benefit analysis. Ulrich and Zimring’s report, “The role of the physical environment in the hospital of the 21st century: a once-in-a-lifetime opportunity“, sets out to provide an evidence base for improvements in the design of healthcare facilities based on the best available scientific data. It provides the evidence base for better, safer design based on the findings of over 600 scientific studies.

The second section of the report, “Improve patient safety“, details how the design of hospitals can positively or negatively impact on hospital-acquired infections (HAIs), medication errors and patient falls. These three patient safety risks account for well over half of all incidents reported to the NPSA.(5) The Ulrich and Zimring report concludes with recommending seven actions that could be taken immediately:

  • Provide single-bed rooms in almost all situations.
  • Systematically reduce noise levels through environmental interventions.
  • Reduce patient stress through the provision of views of nature and other positive distractions.
  • Develop effective wayfinding systems above and beyond conventional signage.
  • Improve ventilation.
  • Improve lighting, especially access to natural lighting and full-spectrum lighting.
  • Design ward layouts and nurses stations to reduce staff walking and fatigue.(6)

Single-bed rooms
Item one, the provision of single-patient rooms in almost all situations, is common in the private healthcare sector, but it is not currently adopted in the NHS. According to the research, the patient safety benefits of single-patient rooms are clear: lower HAIs, a reduction in patient transfers and their associated medical errors, improved staff/patient communication, and greatly reduced noise levels and the subsequent patient stress and sleep deprivation this causes.(6) The argument for this approach would seem to be clear, but there are arguments against. In the February 2006 edition of Hospital Doctor, under the headline “Doubts cast over single room plan”, senior members of the UK’s Royal College of Surgeons and the Royal College of Anaesthetists rightly aired their concerns regarding the increase in staffing levels that may be required and reductions in staff to patient observation that may be caused with single-patient room adoption.(7) It is difficult to find robust evidence to support these concerns, and certainly none is quoted, while research does exist to the contrary. Hendrich, Fay and Sorrells found that the opposite was in fact true; single-patient, acuity-adaptable rooms actually “decrease the time and distance nurses must travel to help patients” and “significantly increased available nursing time”.(8)

Invariably the main resistance to the adoption of 100% single-patient rooms comes down to one of cost, the common belief being that to build hospitals with 100% single-patient rooms would incur grossly disproportionate costs to the benefits provided. Provisional investigations into the costs would suggest, as with most things in life, that it is not quite that straightforward. The NPSA is working with an NHS trust in southeast England on the design of their new hospital that incorporates some of the recommendations from the Ulrich and Zimring study. Early projections would suggest the following: a hospital with 575 beds, 50% single-patient rooms and 50% multibed wards would produce occupancy rates of on average 82%, or 472 beds. A hospital with 100% single-patient rooms with a degree of acuity, adaptability and ensuite facilities, while staying roughly within the same space and cost restraints, would reduce the total bed numbers to roughly 537. However, average occupancy rates could increase to as much as 90% (although 95% is believed to be achievable in many areas), or 483 beds. Also, due to the anticipated reduction of patient safety incidents (each one of which results on average in an increased length of stay of eight and a half days) and improved patient recovery times produced by a switch to 100% single-patient rooms, it is estimated that patient length of stay could reduce by up to half a day, allowing the hospital to perform 4,750 more episodes annually. In the era of payment by results and waiting list targets, this is a big benefit.

While these figures are predominantly projections and estimates, they do indicate that safer healthcare provision is not only good value, but can also be affordable. The UK’s Patient Safety Research Portfolio has recently commissioned the University of York to research the cost/benefit of designing and building safer healthcare premises in more detail.

The current UK hospital rebuilding programme represents a once in a lifetime opportunity to increase the safety of a significant proportion of the UK hospital stock by reducing the likelihood of reasonably foreseeable harm to patients. UK healthcare can benefit from lessons learned from other safety critical industries by focusing on reducing risks at the design stage, based on the best available evidence, until they are as low as reasonably practicable.


  1. Available from:…
  2. IEE Guidance Document on ENC and Functional Safety, Annex F, page 6. Available from:
  3. Health and Safety Executive, HMRI ALARP Guidance and General Principles, page 5.Available from:
  4. Vincent C, et al. Adverse events in British hospitals: preliminary retrospective record review. BMJ 2001;322:3517-19.
  5. Available from:
  6. Available from:
  7. Hitchen L. Doubts cast over single room plan. Hospital Doctor  2006 Feb 09. P. 2
  8. Hendrich AL, Fay J, Sorrells AK. Effects of Acuity adaptable rooms on flow of patients and delivery of care. Am J Crit Care 2004;13:35-45.