Abstract
BackgroundResearch waste is estimated to be very common, but assessments of its prevalence and scope are rare. As an example, we assessed research waste in clinical research on calcium intake (assessing study design and endpoint type) and vitamin D supplementation (assessing endpoint type).MethodsWe examined 404 randomised controlled trials (RCTs) and observational studies of calcium intake (diet or supplements) and bone mineral density (BMD) or fracture, and 547 RCTs of vitamin D supplements, and assessed the proportion of studies that used surrogate or clinical endpoints. For studies with BMD or fracture as an endpoint, we estimated when the ‘tipping’ point occurred indicating the need for RCTs with fracture as an endpoint (based on cumulative meta-analyses of BMD RCTs, and chronological review of observational studies), and whether each study published at least 5y after the tipping point was novel, added new clinical knowledge or was research waste.ResultsObservational studies of calcium intake and BMD or fracture outnumbered RCTs by 3.3–4.5 times. For both calcium intake and vitamin D supplements, studies using surrogate endpoints outnumbered studies using clinical endpoints by 1.6–3 times. Of 41 RCT publications of calcium intake and BMD or fracture published at least 5y after the tipping point in 1994, we considered that 19 (46%) lacked novelty, another 13 (32%) added no new clinical knowledge, and 30 (73%) were research waste. Of 204 observational study publications of calcium intake and BMD or fracture, 197 (96%) lacked novelty, another 5 (2%) added no new clinical knowledge, and 202 (99%) were research waste. Of 39 RCTs of vitamin D supplementation and BMD or fracture published at least 5y after the tipping point in 1999, 14 (36%) lacked novelty, another 13 (33%) added no new clinical knowledge, and 27 (69%) were research waste.ConclusionsA high proportion of studies of calcium intake since 2000 (95%) and trials of vitamin D supplements since 2005 (69%) on BMD or fracture represent research waste.
Highlights
Research waste is estimated to be very common, but assessments of its prevalence and scope are rare
We use existing databases compiled from our recent meta-analyses, which collated all studies of increased calcium intake and all randomised controlled trials (RCTs) of vitamin D supplements
We focus on study design in calcium intake studies and type of endpoint in vitamin D supplementation RCTs
Summary
Research waste is estimated to be very common, but assessments of its prevalence and scope are rare. Very few studies have systematically examined research topics for evidence of waste, or established the methodology for doing so In these companion reports [2], we assessed research waste in a single field - calcium and vitamin D research. The large body of published research in these fields allows an assessment of one important aspect of research waste, the quantity of research conducted that was unnecessary because existing knowledge was extensive. In this first report, we use existing databases compiled from our recent meta-analyses, which collated all studies of increased calcium intake and all randomised controlled trials (RCTs) of vitamin D supplements. We focus on study design (observational versus RCT) in calcium intake studies and type of endpoint (surrogate versus clinical) in vitamin D supplementation RCTs
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