BACKGROUND CONTEXT: Psoriasis is a chronic, autoimmune disease of the skin that affects approximately 3% of the US adult population. Patients with psoriasis may be predisposed to spine surgical site infections (SSI) related to the condition and/or related medications following surgeries such as lumbar laminotomy/discectomy. PURPOSE: To assess the potential correlation of psoriasis and its related treatment medications on the risk of infection-related complications after lumbar laminotomy/discectomy. STUDY DESIGN: Retrospective case control, national administrative database study. PATIENT SAMPLE: Adult patients who underwent isolated single-level lumbar discectomy between 2010 and Q1 of 2021 were identified in the PearlDiver Mariner Ortho151 national administra-tive database (excluding those with concurrent diagnoses of fractures, neoplasms, or infections). OUTCOME MEASURES: Ninety-day postoperative rates of surgical site infection and sepsis. METHODS: Lumbar laminotomy/discectomy patients with versus without psoriasis were matched 1:4 based on age, sex, and Elixhauser Comorbidity Index. The risk of SSI and sepsis in the 90-day postoperative window between the cohorts were compared with multivariable analyses. Five-year reoperation rates were also compared with log rank test. The matched psoriasis cohort was further sub-divided by psoriasis treatment regimens - no medication treatment (NT), topical therapies only (TT), topical therapies with oral systemic treatments (TT/OS), and topical therapies with biologics (TT/B). Multivariable logistic regression was used to assess the risk of SSI and sepsis within 90 days after lumbar laminotomy/discectomy for each treatment subgroup compared to patients without psoriasis. RESULTS: In total, 2,262 patients with psoriasis who underwent single-level lumbar laminotomy/dis-cectomy were identified and matched by age, sex, and Elixhauser Comorbidity Index to 9,044 patients without psoriasis. Multivariable logistic regression showed that, compared to the patients without pso-riasis, patients with psoriasis had a 1.795 times higher chance of developing SSI (odds ratio [OR]) (p<.001) and sepsis (OR: 1.743, p=.027) within 90 days of surgery. Having psoriasis did not signifi-cantly correlate with 5-year reoperation rates. Of those with psoriasis, NT subcohort had 1,038 patients, TT subcohort 571 patients, TT/OS subcohort 226 patients, and TT/B subcohort 140 patients. Based on multivariable analysis and compared to nonpsoriasis patients, those in the NT, TT, TT/OS were not at greater odds of postoperative SSI or sepsis. Conversely, those in the TT/B subcohort were at significantly greater odds of SSI (OR: 3.102, p=.019) and sepsis (OR: 6.367, p=.027). CONCLUSIONS: Of single-level lumbar laminotomy/discectomy patients with psoriasis, only those on topical therapies and biologics were at greater risk of postoperative SSI and sepsis. This subcohort warrants specific attention when undergoing lumbar laminotomy/discectomy and possibly holding such medications for a period prior to surgery may be warranted if possible. (c) 2023 Elsevier Inc. All rights reserved.