Chemical Burns in Northern China: Co-Occurrence of Low TBSA and Recorded Full-Thickness Involvement in a 7-Year Retrospective Cohort.

Background: Total body surface area (TBSA) quantifies burn extent, whereas burn depth reflects tissue involvement. In chemical burns, small surface-area injuries may still include deeper tissue damage, but this patient-level co-occurrence remains incompletely described; we therefore examined it in hospitalized patients in northern China. Methods: We retrospectively analyzed a merged 2016-2022 burn database. Records coded as chemical burns were included when the recorded length of stay exceeded one day. Results: Of 5929 screened records, 214 were coded as chemical burns. Exclusion of two short-stay records left 212 unique patients. Most were male (74.5%) and aged 18-60 years (84.9%). Workplace exposure was recorded for 47.2%. Among 105 patients with ≤2% TBSA and a known depth, 87 (82.9%; 95% confidence interval [CI]: 74.5-88.9%) had a recorded maximum-depth category involving a full-thickness component. Among all 109 patients with ≤2% TBSA, 81 (74.3%; 95% CI: 65.4-81.6%) had a positive recorded III/IV-degree area. Acids and alkalis accounted for 30.2% and 29.7% of recorded exposures, respectively, and 37.3% underwent at least one operation. Conclusions: Working-age adults predominated, and workplace exposure was the most common recorded setting. Low TBSA frequently co-occurred with recorded full-thickness involvement in this selected inpatient cohort. The findings support reporting recorded burn depth alongside TBSA in hospitalized chemical injuries and improving standardized prospective documentation.