Low-dose tolvaptan to control disease progression in Chinese patients with autosomal dominant polycystic kidney disease: a retrospective cohort study

Background: Tolvaptan has been shown to be effective in the treatment of autosomal dominant polycystic kidney disease (ADPKD). However, there is limited evidence regarding optimal dosing and its application within the Chinese population. In this study, we aimed to determine whether a lower tolvaptan dose could effectively control ADPKD in Chinese patients. Methods: This retrospective, single-center cohort study was conducted in a real-world setting and included all patients newly diagnosed with rapidly progressive ADPKD who initiated tolvaptan treatment and maintained it for at least 12 months. Data were collected at baseline and at 1, 2, 4, 8, and 12 months after treatment initiation. Patients began with morning/evening tolvaptan doses of 7.5 mg/7.5 mg, and the dose was subsequently adjusted based on effectiveness and tolerability. The patients were categorized by baseline estimated glomerular filtration rate (eGFR) and final daily tolvaptan dose. Changes in eGFR and other key physiological indicators after treatment were compared within each group. Results: The study included 43 patients with ADPKD, of whom 20 were female, with a median age of 34.3 years (range, 16-85 years). At 12 months, eGFR improved by 5.48 mL/min/1.73 m(2) [95% confidence interval (CI): 2.68-8.29] (P<0.001) compared to baseline. Significant improvements were observed in patients with baseline eGFR levels of 30-59, 60-89, and >= 90 mL/min/1.73 m(2) (P=0.007, 0.045, and 0.02, respectively), as well as in medium and high dose groups (P=0.002 and 0.02, respectively). At 12 months, the annual height-adjusted total kidney volume (HtTKV) growth slope decreased by -0.17 %/year (95% CI: -0.33 to -0.01) (P=0.04). Significant decreases were observed in patients with an eGFR of 30-59 mL/min/1.73 m(2) (P=0.008) and in the medium dose group (P=0.03). Thirst was reported in 22 (51.2%) patients, all of whom experienced mild symptoms. No liver-associated adverse events were noted. Conclusions: Tolvaptan is well tolerated at low initial doses in Chinese patients with ADPKD. Significant improvements in eGFR and reduced HtTKV growth were observed in the overall population and across various baseline eGFR and final dose groups.