The development and validation of the Pre-operative Intrusive Thoughts Inventory (PITI).

Pre-operative anxiety is common and influences postoperative pain, hospital stay and patient satisfaction. We set out to explore anxiety content and develop a tool to evaluate patient anxiety at the pre-operative assessment clinic. We recruited 128 day surgery patients. Pre-operative anxiety content was explored and six factors (themes) were identified: 'preoccupation', 'outcome concerns', 'being unconscious', 'loss of control', 'dependence on others' and 'pain/discomfort'. The Pre-operative Intrusive Thoughts Inventory (PITI) was constructed and evaluated using exploratory and confirmatory factor analysis. The PITI demonstrated internal consistency for the full scale (Cronbach's alpha = 0.91) and for the subscales (Cronbach's alpha 0.74-0.85) as well as sensitivity (0.88) and specificity (0.60) to clinically significant anxiety assessed using the Hospital Anxiety and Depression Scale. The properties of the PITI suggest that it has potential as an additional tool for the evaluation of pre-operative anxiety.