Reactive leukocytosis in older patients with acute colonic diverticulitis: A retrospective study utilizing logistic regression analysis

AIM: Although various neutrophilic immunosenescence mechanisms have been shown, there are few clinical studies on age‐related differences in leukocytosis against acute bacterial infections, including acute colonic diverticulitis. METHODS: We performed a retrospective study of 26 patients ≥65 years old and 211 patients 16–64 years old who were hospitalized for acute colonic diverticulitis at Toho University Medical Center Omori Hospital between 2010 and 2016. We compared patients' characteristics, including sex, immunocompromised status, diverticulitis site, complications, severity, previous diverticulitis, vital signs, leukocyte counts, neutrophil‐to‐lymphocyte ratio and serum C‐reactive protein on admission. To adjust for confounding factors, we performed a logistic regression analysis. RESULTS: Univariate comparisons showed that leukocyte count (older: 10 850 [interquartile range, 9400–12 000]/mm(3) vs. younger: 12 600 [interquartile range, 10 500–15 000]/mm(3), P = 0.004) and prevalence of leukocytosis (leukocytes >11 000/mm(3)) were lower in older compared with younger patients. There were significantly more female, left‐sided diverticulitis and immunocompromised patients in the older compared with the younger group. Logistic regression showed that leukocyte count, prevalence of female patients, and left‐sided diverticulitis were independent predictors for the older patients: Their odds ratios were 0.866 (95% confidence interval [95% CI] 0.753–0.996), 2.631 (95% CI, 1.032–6.707) and 5.810 (95% CI, 2.328–14.497), respectively. CONCLUSION: Caution should be taken when managing older patients with colonic diverticulitis because reactive leukocytosis might be poor, possibly reflecting immunosenescence. Geriatr Gerontol Int 2020; 20: 951–955.