Assessment of preoperative anxiety: comparison of measures in patients awaiting surgery for breast cancer.

We have compared three measurements of anxiety to determine their equivalence in assessing anxiety before surgery. Forty-four patients awaiting breast cancer surgery completed the state scale of the state-trait anxiety inventory (STAI), the hospital anxiety and depression scale (HAD) and a 100-mm visual analogue scale (VAS). Analysis restricted to correlations between the scales gave the misleading impression that VAS scores were inconsistent with those of the HAD and STAI. However, when scores were considered in relation to normative cut-off values to categorize anxiety levels, the three scales showed good agreement. We conclude that the scales were equivalent in their assessment of anxiety before surgery, but that reference to normative data was important in establishing such equivalence and in determining the patient's state.