Finding the vulnerable postoperative population: A two-step cluster analysis of the PAIN-OUT registry.

Improvement of postoperative pain requires assessment methods that go beyond pain intensity scores. We perform a cluster analysis among PAIN-OUT patients that revealed a cluster of vulnerable postoperative patients, using a novel composite measure of postoperative outcomes: the factor scores of the International Pain Outcomes Questionnaire. By changing the focus from pain intensity to multidimensional pain outcomes, male gender and number of comorbidities appeared as new risk factors for worse postoperative outcomes. The study also identified procedures that require urgent quality improvements.