RATIONALE & OBJECTIVE: Data from clinical practice are needed to characterize the effectiveness of pharmacotherapy outside the controlled setting of clinical trials but lack an untreated placebo group for comparison. To assess the effectiveness of tolvaptan for autosomal dominant polycystic kidney disease (ADPKD) in nephrology practice, we performed a chart review of US patients and compared it with a historical matched control cohort.
STUDY DESIGN: Patient data from charts were provided by US nephrologists who participated in an online survey. Historical control data for patients with ADPKD not treated with tolvaptan were extracted from a database of ADPKD clinical studies (Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease, HALT Progression of Polycystic Kidney Disease [HALT-PKD], and OVERTURE).
SETTING & PARTICIPANTS: Nephrologist respondents (n=57) provided baseline data and up to 4 years of follow-up on estimated glomerular filtration rate (eGFR) for tolvaptan-treated adults (n=149). Historical ADPKD-affected controls were adults in Mayo imaging risk classes 1C–1E (ie, at increased risk of rapid progression, consistent with the tolvaptan indication).
EXPOSURE: Cases had to receive tolvaptan continuously for≥2 years. Historical controls received nontolvaptan standard of care, including various antihypertensive regimens.
OUTCOME: Annual rate of eGFR change.
ANALYTICAL APPROACH: Cases and controls were matched on baseline clinical characteristics (matched set A: age, sex, and chronic kidney disease stage [110 matched pairs]; matched set B: age, sex, and eGFR [98 matched pairs]) and compared using a mixed model.
RESULTS: The annual rate of eGFR decline was slower in tolvaptan-treated patients versus historical controls, by 1.40mL/min/1.73m2 (95% CI, 0.05-2.74; P=0.04) in set A. Set B demonstrated a similar trend: 1.18mL/min/1.73m2 per year (95% CI, −0.22 to 2.58; P=0.10).
LIMITATIONS: Risk of bias from convenience sampling and potential residual confounding after case/historical control matching.
CONCLUSIONS: Tolvaptan was associated with slower eGFR decline in routine clinical practice, consistent with the results of controlled trials.
