Cannabis Use Does Not Increase Risk of Perioperative Complications Following Primary Total Hip Arthroplasty: A Cohort-Matched Comparison

Introduction: Cannabis use among arthroplasty patients has dramatically increased throughout the United States. Despite this trend, knowledge remains particularly limited regarding the effects of cannabis use on perioperative outcomes in total hip arthroplasty (THA). Therefore, the goal of this research was to investigate how cannabis use affects risk of perioperative outcomes, cost and length of stay (LOS) after THA.Materials and Methods: The National Inpatient Sample was used to identify 331,825 patients who underwent primary THA between 2010 and 2014 using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9) procedure code 81.51. Patients with an ICD-9 diagnosis code correlating to history of thromboembolic events, cardiac events, or active substance use other than cannabis were eliminated. The ICD-9 diagnosis codes for cannabis use (304.3-304.32, 305.2-305.22) were used to identify 538 patients with active use. Cannabis users were matched 1:1 to nonusers on age, sex, tobacco use, and comorbidities. The chi-square test was used to determine risk of major and minor complications, whereas the Kruskal-Wallis H test was used to compare hospital charges and LOS.Results: A total of 534 (99.3%) patients with cannabis use were successfully matched with 534 patients without cannabis use. Risk of major complications among cannabis users (25, 4.68%) was similar to that of nonusers (20, 3.74%, p=0.446). Minor complications also occurred at similar rates between cannabis users (77, 14.4%) and nonusers (87, 16.3%, p=0.396). LOS for cannabis users (3.07 +/- 2.40) did not differ from nonusers (3.10 +/- 1.45, p=0.488). Mean hospital charges were higher for cannabis users ($17,847 +/- 10,024) compared with nonusers ($16,284 +/- 7025, p<0.001).Conclusion: Utilizing statistically matched cohorts within a nationally representative database demonstrated that cannabis use is not associated with increased risk of complications or prolonged LOS after primary THA. However, cannabis use is associated with higher hospital charges.