Predictive validity of Waterlow Scale for pressure ulcer development risk in hospitalized patients

J Wound Ostomy Continence Nurs. Nov-Dec 2009;36(6):640-6. doi: 10.1097/WON.0b013e3181bd86c9.


Aim: We sought to evaluate the predictive validity of the Waterlow Scale in hospitalized patients.

Subjects and setting: The study was conducted at a general private hospital with 220 beds and a mean time of hospitalization of 7.4 days and a mean occupation rate of approximately 80%. Adult patients with a Braden Scale score of 18 or less and a Waterlow Scale score of 16 or more were studied. The sample consisted of 98 patients with a mean age of 71.1 + or - 15.5 years.

Methods: Skin assessment and scoring by using the Waterlow and Braden scales were completed on alternate days. Patients were examined at least 3 times to be considered for analysis. The data were submitted to sensitivity and specificity analysis by using receiver operating characteristic (ROC) curves and positive (+LR) and negative (-LR) likelihood ratios.

Results: The cutoff scores were 17, 20, and 20 in the first, second, and third assessment, respectively. Sensitivity was 71.4%, 85.7%, and 85.7% and specificity was 67.0%, 40.7%, and 32.9%, respectively. Analysis of the area under the ROC curve revealed good accuracy (0.64, 95% confidence interval [CI]: 0.35-0.93) only for the cutoff score 17 in the first assessment. The results also showed probabilities of 14%, 10%, and 9% for the development of pressure ulcer when the test results were positive (+LR) and of 3% (-LR) when the test results were negative for the cutoff scores in the first, second, and third assessment, respectively.

Conclusion: The Waterlow Scale achieved good predictive validity in predicting pressure ulcer in hospitalized patients when a cutoff score of 17 was used in the first assessment.

Publication types

  • Validation Study

MeSH terms

  • Adult
  • Age Distribution
  • Aged
  • Aged, 80 and over
  • Confidence Intervals
  • Databases, Factual
  • Female
  • Follow-Up Studies
  • Hospitalization / statistics & numerical data*
  • Hospitals, General
  • Humans
  • Incidence
  • Length of Stay
  • Middle Aged
  • Nursing Assessment / methods*
  • Nursing Evaluation Research
  • Predictive Value of Tests
  • Pressure Ulcer / diagnosis*
  • Pressure Ulcer / epidemiology*
  • Pressure Ulcer / nursing
  • Probability
  • ROC Curve
  • Risk Assessment
  • Severity of Illness Index
  • Sex Distribution
  • Wound Healing / physiology