Establishing the validity of pressure ulcer risk assessment scales: a novel approach using illustrated patient scenarios.

Preventing pressure ulcers is an important nursing goal and over the years a number of risk assessment scales (RASs) have been developed to expedite clinical judgement. The aim of this study was to examine the validity of the three most commonly used RASs compared to nurses' own clinical judgement. Patient simulations were presented to 236 clinical nurses. Nine hundred and forty one assessments were completed and compared to the ratings from a panel of tissue viability experts. Clinical judgement exactly matched expert opinion (69.1%) more often than assessment with any of the RASs. The Waterlow Score matched exactly in 20% of cases, the Braden Scale in 8.5% of cases and the Norton Score in 4.6% of cases. Thus none of these RASs can be considered valid, assuming that the expert panel genuinely reflected the 'gold standard' in terms of the external criterion. The implications for clinical practice are far-reaching considering the extent to which RASs are currently used to reach important clinical decisions relating to the deployment of expensive pressure-relieving aids and nursing time.