The PAIN OUT registry collected data from >30,000 patients on pain on the first postoperative day in hospitals worldwide. 
PAIN OUT registry
ASs were identified through the ICD9-Code and subgrouped into laparoscopic surgery and open surgery. 
ICD9-Code
After identifying patients in this subset with and without EA, propensity-score matching was performed on the basis of demographics and comorbidities. 
propensity-score matching