Arm circumference as a predictor of cancer outcomes: validity of proposed cutoff points and BMI adjustment factors

Objectives To evaluate the prognostic value of proposed midupper arm circumference (MUAC) cut-offs and body mass index (BMI) adjustment factors in hospitalized patients with cancer. Methods Retrospective pooled analysis of prospective cohorts including hospitalized patients diagnosed with cancer. Data was collected within 48 h of admission. MUAC and BMI were assessed using standardized methods. Low MUAC was defined as <28 cm in males and <25 cm in females, with BMI-adjusted values (MUAC adj ) also analyzed. The primary outcome was 3-mo mortality; secondary outcomes included in-hospital mortality and length of stay. Kaplan–Meier curves and regression models were applied. Results A total of 618 patients were included (52.9% male; 69.4% older adults), with a median BMI of 25.2 kg/m². Gastrointestinal tumors and advanced disease predominated. In-hospital and 3-mo mortality were 8.6% and 18.1%, respectively. Low MUAC was present in 29.3% of patients, rising to 43.2% after BMI adjustment. Both low MUAC and MUAC adj were associated with higher 3-mo mortality (hazard ratio [HR] 2.95, 95% CI 2.02; 4.31; and HR 2.48, 95% CI 1.67; 3.68). Among patients with excess weight, associations were stronger for MUAC (HR 6.45, 95% CI 2.77; 14.98) than MUAC adj (HR 2.49, 95% CI 1.26; 4.95). Both measures were also associated with in-hospital mortality and longer length of stay. In patients with excess weight, only MUAC adj remained independently associated with hospital outcomes. Conclusions MUAC and BMI-adjusted MUAC are useful predictors of mortality and adverse hospital outcomes in patients with cancer, supporting their role as practical markers of muscle mass in clinical practice.