The landscape of clinical trials in nephrology: a systematic review of Clinicaltrials.gov

Abstract

Background: Well-designed trials are of paramount importance in improving the delivery of care to patients with kidney disease. However, it remains unknown whether contemporary clinical trials within nephrology are of sufficient quality and quantity to meet this need.

Study design: Systematic review.

Setting & population: Studies registered with ClinicalTrials.gov.

Selection criteria for studies: Interventional (ie, nonobservational) studies (both randomized and nonrandomized) registered between October 2007 and September 2010 were included for analysis. Studies were reviewed independently by physicians and classified by clinical specialty.

Predictor: Nephrology versus cardiology versus other trials.

Outcomes: Select clinical trial characteristics.

Results: Of 40,970 trials overall, 1,054 (2.6%) were classified as nephrology. Most nephrology trials were for treatment (75.4%) or prevention (15.7%), with very few diagnostic, screening, or health services research studies. Most nephrology trials were randomized (72.3%). Study designs included 24.9% with a single study group, 64.0% that included parallel groups, and 9.4% that were crossover trials. Nephrology trials, compared with 2,264 cardiology trials (5.5% overall), were more likely to be smaller (64.5% vs 48.0% enrolling≤100 patients), phases 1-2 (29.0% vs 19.7%), and unblinded (66.2% vs 53.3%; P<0.05 for all). Nephrology trials also were more likely than cardiology trials to include a drug intervention (72.4% vs 41.9%) and less likely to report having a data monitoring committee (40.3% vs 48.5%; P<0.05 for all). Finally, there were few trials funded by the National Institutes of Health (NIH; 3.3%, nephrology; 4.2%, cardiology).

Limitations: Does not include all trials performed worldwide, and frequent categorization of funding source as university may underestimate NIH support.

Conclusions: Critical differences remain between clinical trials in nephrology and other specialties. Improving care for patients with kidney disease will require a concerted effort to increase the scope, quality, and quantity of clinical trials within nephrology.

Keywords: Chronic kidney disease; end-stage renal disease; kidney transplantation; randomized controlled trial; systematic review.

Figure 1

Flow Diagram of nephrology-classified trials registered between October 1, 2007 and September 27, 2010. Abbreviation: MeSH, medical subject heading;

Figure 2

Primary purpose of clinical trials in nephrology based on studies registered in ClinicalTrials.gov between October 1, 2007, and September 27, 2010.

Figure 3

Primary patient population of nephrology trials registered in ClinicalTrials.gov between October 1, 2007, and September 27, 2010. The “other” category consists of drug studies, pharmacokinetic studies, or other interventions among non-nephrology patients but with renal endpoints.