Background: Measurement of functional interference (FI) of pain is crucial for postoperative pain management. This study examined the external validity of three FI items (respiration, mobilization and sleep) within the framework of the German quality improvement in postoperative pain management (QUIPS) project.
Material and methods: A total of 380 patients undergoing trauma/orthopedic or abdominal surgery were asked to complete the QUIPS outcome questionnaire. Criteria to determine external validity of FI assessment were tolerance to a continuous passive motion (CPM) machine for FI with mobilization, the pre-postoperative difference of peak flow for FI with respiration and sleep quality measured with actigraphy for FI with sleep.
Results: The QUIPS outcome questionnaire achieved satisfactory reliability (r(tt) =0 .783-0.954, internal consistency 0.597-0.941). The three FI items under examination achieved a significant correlation (r =0 .407-0.469) with the external criteria.