Clinical significance of isolated periappendiceal red patch in ulcerative colitis: A systematic review, meta-analysis, and meta-regression

OBJECTIVES: Ulcerative colitis (UC) is characterized by continuous mucosal inflammation beginning in the rectum with variable proximal extension. However, up to 17% of patients demonstrate patchy cecal inflammation known as a periappendiceal red patch (PARP). Although PARP has historically been linked to severe disease and worse outcomes, its long-term clinical significance remains unclear. We conducted a systematic review and meta-analysis to evaluate outcomes in UC patients with isolated PARP. METHODS: A comprehensive literature search of MEDLINE, Embase, Scopus, and Cochrane CENTRAL was performed to identify studies comparing UC patients with and without endoscopic or histologic evidence of PARP. Meta-analysis was conducted using R (version 4.4.3). Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated, and between-study heterogeneity was assessed using Higgins' I2 statistic. RESULTS: Thirteen nonrandomized studies, including 2289 UC patients (PARP+: 725; PARP-: 1564), were analyzed. PARP was significantly associated with higher odds of proctitis (OR, 1.54; 95% CI, 1.09-2.18; P = .02). No significant associations were observed between PARP and left-sided colitis (OR, 0.88; 95% CI, 0.57-1.35; P = .51) or extensive colitis (OR, 0.84; 95% CI, 0.50-1.41; P = .45). PARP was not associated with disease progression, pharmacotherapeutic escalation, or colectomy. However, moderate-to-high heterogeneity was observed across most of the outcomes. CONCLUSION: PARP is more frequently observed in patients with ulcerative proctitis but does not appear to influence long-term disease progression or major clinical outcomes, supporting its classification as a benign endoscopic finding in UC.