{'fraction_non_alphanumeric': 0.05647309536494406, 'fraction_numerical': 0.06499733617474694, 'mean_word_length': 4.7784615384615385, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Smoking and risk of surgical bleeding: nationwide analysis of 5,452,411 surgical cases.

BACKGROUND
Although smoking is associated with several postoperative complications, a possible association with surgical bleeding remains unclear. We examined if smoking is associated with a higher risk of surgical bleeding.


STUDY DESIGN AND METHODS
We included patients from the American College of Surgeons National Surgical Quality Improvement Program 2007-2016 from 680 hospitals across the United States. Patients with information on age, sex, surgical specialty, and smoking status were included. Surgical bleeding was defined as 1 or more red blood cell (RBC) units transfused intraoperatively to 72 hours postoperatively. The association between smoking and surgical bleeding was examined using logistic regressions adjusted for age, sex, body mass index, ethnicity, comorbidities, laboratory values, American Society of Anesthesiologists score, type of anesthesia, duration of surgery, work relative value unit (surrogate for operative complexity), surgical specialty, and procedure year.


RESULTS
A total of 5,452,411 cases were recorded, of whom 19% smoked and 6% received transfusion. Odds ratios for transfusion were 1.06 (95% confidence interval [CI], 1.05-1.07) for smokers versus nonsmokers and 1.06 (95% CI, 1.04-1.09) for current smokers versus never-smokers. Odds ratios for cumulative smoking were 0.97 (95% CI, 0.95-1.00) for greater than 0 to 20 versus 0 pack-years, 1.04 (95% CI, 1.01-1.07) for greater than 20 to 40, and 1.12 (95% CI, 1.09-1.15) for greater than 40 (p for trend < 0.001). Hazard ratios for reoperations due to any cause and to bleeding were 1.28 (95% CI, 1.27-1.31) and 0.99 (95% CI, 0.93-1.04).


CONCLUSION
Smoking was associated with a higher risk of RBC transfusion as a proxy for surgical bleeding across all surgical specialties combined.