Risk Factors for Severe Hypotension with 5-ALA Photodynamic Diagnosis in TURBT Patients

Background: Oral 5-aminolevulinic acid (5-ALA) is widely used for photodynamic diagnosis (PDD) during transurethral resection of bladder tumor (TURBT) to improve lesion detection. However, hypotension after 5-ALA has been reported, and severe hypotension can lead to procedure cancellation and urgent medical interventions. We aimed to quantify the incidence of severe hypotension after oral 5-ALA for PDD-TURBT and to identify preoperative patient profiles associated with severe hypotension to inform perioperative risk counseling and planning. METHODS: We retrospectively analyzed consecutive PDD-TURBT procedures performed between 2018 and 2023 (n = 418). Severe hypotension was defined as hypotension requiring continuous vasopressor infusion, cardiology intervention, or procedure cancellation. We used a simple model with three preoperative variables (body mass index (BMI) ≥ 30 kg/m², estimated glomerular filtration (eGFR) rate < 60 mL/min/1.73 m², and age ≥ 80 years). We performed logistic regression with cluster‑robust standard errors clustered by patient. We also explored a 0–3 point triage index (one point per factor) and internally evaluated its discrimination using bootstrap resampling. RESULTS: Severe hypotension occurred in 15 of 418 procedures (3.6%, 95% CI 2.2–5.8%). In the prespecified multivariable analysis, BMI ≥ 30 (OR 15.6, 95% CI 2.1–116.0) and age ≥ 80 years (OR 4.7, 95% CI 1.1–19.9) were associated with severe hypotension; eGFR < 60 showed an elevated but imprecise association (OR 3.3, 95% CI 0.7–15.5). Observed risk increased with the triage score: 0 points 0.0% (0/201), 1 point 5.0% (7/139), 2 points 9.1% (7/77), and 3 points 1/1 (single procedure); classifying ≥ 2 points as high risk identified a subgroup with 10.3% risk (95% CI 5.3–19.0%). Mean cluster bootstrap AUC of the index was 0.80. CONCLUSIONS: Severe hypotension after oral 5‑ALA in PDD‑TURBT is uncommon overall but is enriched in patients with obesity, older age, and reduced renal function. An exploratory preoperative triage approach may help support perioperative risk counseling and planning, pending external validation.