Leukopenia is an independent risk factor for early postoperative complications following incision and drainage of anorectal abscess

Aim: Few data are available regarding the management of anorectal abscess in patients with leukopenia. The aim of this study was to investigate the impact of leukopenia among patients undergoing incision and drainage for anorectal abscess. Method: A retrospective review of the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database identified patients from 2015 to 2020. Perianal fistulas and supralevator abscesses were excluded. Patients were grouped based on white blood cell (WBC) count: WBC < 4.5 cells/μl, WBC = 4.5–11.0 cells/μl and WBC > 11.0 cells/μl. The 30-day overall complications and outcomes were compared using regression models, accounting for demographics and comorbidities. Results: Ten thousand two hundred and forty (70.3% male) patients were identified. Univariate analysis showed that, compared with patients with leukocytosis (WBC > 11.0 cells/μl) and normal WBC count (WBC = 4.5–11.0 cells/μl), patients with leukopenia (WBC <4.5 cells/μl) had higher rates of overall (p < 0.001), pulmonary (p < 0.001) and haematological complications (p < 0.001). They also had higher rates of readmission (p < 0.001), reoperation (p = 0.005), discharge to a care facility (p = 0.003), increased length of hospital stay (p = 0.004) and death (p < 0.001). Multivariable analysis identified leukopenia as an independent risk factor for overall complications [odds ratio (OR) 2.31, 95% CI 1.65–3.24; p < 0.001], pulmonary complications (OR 5.65, 95% CI 1.88–16.97; p = 0.002), haematological complications (OR 4.30, 95% CI 2.94–6.28; p < 0.001), unplanned readmission (OR 2.20, 95% CI 1.43–3.40; p < 0.001), reoperation (OR 1.80, 95% CI 1.10–2.93; p = 0.019) and death (OR 2.77, 95% CI 1.02–7.52; p = 0.046). Discharge to a care facility and length of stay were not significant on multivariable analysis. Conclusion: Leukopenia is associated with increased risk for pulmonary and haematological complications, readmissions, reoperations, discharge to a care facility and death after incision and drainage for anorectal abscess.