Standardization of patient outcomes reporting in percutaneous nephrolithotomy

There exist no global standards for defining patient outcomes in renal stone surgery. The objective of this study was to evaluate the quality of reporting of outcomes in studies investigating percutaneous nephrolithotomy (PCNL) and to propose standardized consensus definitions for common outcomes.

We performed a literature search in PubMed for randomized controlled studies that investigated PCNL between 2002 and 2012. All outcomes reported were analyzed for each study. Each article was examined to identify the definition of each reported patient outcome. Various aspects of patient outcomes were presented to a panel of 85 experts in a Delphi process consisting of three rounds. The experts were asked to select options that they believed would best describe each outcome. Finally, we composed recommendations for definition of the most common outcomes reported in PCNL studies.

Eighty-three RCTs were included in the review of patient outcomes. Stone-free rate (55, 63.9%), length of stay (47, 56.6%), complication rate (44, 53.0%), and changes in hemoglobin (40, 48.2%) were the most frequently reported outcomes in randomized controlled trials of PCNL. Only 24/53 (45.3%) studies had a formal definition of stone-free status. Only 31/40 (77.5%) studies, which reported change in hemoglobin, had a unit of measurement; however, 22/40 (55.0%) did not report the timing of postoperative hemoglobin measurement. A set of recommendations for defining patient outcomes in PCNL is presented for the 15 most commonly reported outcomes in PCNL.

Wide variations and underspecification exist in the definition and reporting of outcomes in PCNL. We propose recommendations for the definition of outcomes based on a review of the literature and expert opinion. Standardization of outcome definition and reporting will improve the quality of urologic research.