Acetazolamide versus metolazone as adjunctive therapy to loop diuretics in hospitalized patients with volume overload: A retrospective cohort study
Phuoc (Tyler) Bui, Lizbeth RamosAbstract
Purpose
Sequential nephron blockade is commonly used to augment diuresis in patients with volume overload receiving loop diuretics. While metolazone is frequently used, acetazolamide has emerged as an alternative adjunctive agent. Real-world data comparing these strategies remain limited. This study evaluated the effectiveness and safety of acetazolamide vs metolazone as adjunctive therapy.
Methods
This single-center, retrospective cohort study included adult patients receiving adjunctive acetazolamide or metolazone with loop diuretics for volume overload. The primary outcome was cumulative urine output within 48 hours. Secondary outcomes included high diuretic response (urine output above the cohort median), hypotension, acute kidney injury, hypokalemia, and metabolic acidosis. Multivariable regression and propensity score–matched analyses were performed.
Results
A total of 120 patients were included (metolazone, n = 70; acetazolamide, n = 50). Patients receiving metolazone were older and had higher baseline serum creatinine levels. Mean (SD) cumulative urine output was greater with acetazolamide (10,637 [13,847] vs 5,752 [10,231] mL; P = 0.028). After adjustment, acetazolamide remained associated with greater urine output (β = 4,735 mL; 95% confidence interval [CI], 39-9,430 mL; P = 0.048). High diuretic response occurred more frequently with acetazolamide (64% vs 40%), with higher adjusted odds (odds ratio, 3.18; 95% CI, 1.40-7.47; P = 0.0065). Findings were consistent in propensity score–matched analyses. Adverse event rates were similar between the groups.
Conclusion
Adjunctive acetazolamide was associated with greater urine output and a higher likelihood of achieving a robust diuretic response compared with metolazone. Given the retrospective study design, these findings are hypothesis generating and warrant confirmation in prospective comparative studies.