title: Uses and misuses of statistics: the case of strontium ranelate and the number needed to treat.
abstract: In the last 15 years, several pharmacological agents for the prevention of fractures have been developed and commercialized. Most of them showed to be effective in reducing fracture risk. The enhanced availability of drugs to prevent fractures has generated a fierce competition among pharmaceutical companies to conquer a share of the potential market, often with claims of superiority of a drug over another without direct comparisons. The definitive way to compare different treatments would require randomized head to head trials. These trials are expensive, need large samples and are unlikely to be ever performed. Therefore, it has become a common practice to compare pharmacological agents through observational studies on administrative databases or by the indirect comparison of the results of individual randomised-controlled trials (RCT) and their meta-analyses. These studies may produce evidence of clinical value, complementary to that given by RCT. However, without a proper and complete analysis, they may result in a biased picture of effectiveness and be completely misleading. In this article, we critically disclose how such competition may produce biased and misleading picture of evidence, by reviewing the significance of the number needed to treat, absolute risk reduction and relative risk reduction in relation to vertebral fractures prevention with available drugs.
authors.affiliation: Department of Internal Medicine and Biomedical Sciences, Parma University, Via Gramsci 14, 43100 Parma, Italy. mario.pedrazzoni@unipr.it
authors.forename: M
authors.initials: M
authors.lastname: Pedrazzoni
authors.forename: A
authors.initials: A
authors.lastname: Giusti
authors.forename: G
authors.initials: G
authors.lastname: Pioli
mesh_terms: D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D004345:Drug Industry; D050723:Fractures, Bone / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D061366:Numbers Needed To Treat / Q000592:standards*; D009942:Organometallic Compounds / Q000627:therapeutic use*; D010024:Osteoporosis / Q000150:complications / Q000188:drug therapy*; D016032:Randomized Controlled Trials as Topic; D013876:Thiophenes / Q000627:therapeutic use*
chemical_list: D050071:Bone Density Conservation Agents; D009942:Organometallic Compounds; D013876:Thiophenes; C081587:strontium ranelate
references.citation: Adv Ther. 2008 Dec;25(12):1235-56
references.pmid: 19066755
references.citation: N Engl J Med. 2007 May 3;356(18):1809-22
references.pmid: 17476007
references.citation: J Bone Miner Res. 2004 Aug;19(8):1241-9
references.pmid: 15231010
references.citation: Rheumatol Int. 2010 May;30(7):863-9
references.pmid: 20035331
references.citation: JAMA. 1999 Oct 13;282(14):1344-52
references.pmid: 10527181
references.citation: Bone. 2006 Feb;38(2 Suppl 1):19-22
references.pmid: 16455319
references.citation: J Investig Med. 2010 Aug;58(6):764-9
references.pmid: 20479661
references.citation: Best Pract Res Clin Endocrinol Metab. 2008 Oct;22(5):671-85
references.pmid: 19028351
references.citation: Lancet. 1996 Dec 7;348(9041):1535-41
references.pmid: 8950879
references.citation: N Engl J Med. 2001 May 10;344(19):1434-41
references.pmid: 11346808
references.citation: JAMA. 1999 Aug 18;282(7):637-45
references.pmid: 10517716
references.citation: CMAJ. 2008 Sep 9;179(6):549-53
references.pmid: 18779528
references.citation: N Engl J Med. 2004 Jan 29;350(5):459-68
references.pmid: 14749454
references.citation: BMJ. 1995 Feb 18;310(6977):452-4
references.pmid: 7873954
references.citation: Osteoporos Int. 2010 Oct;21(10):1657-80
references.pmid: 20480148
references.citation: Cochrane Database Syst Rev. 2006 Jul 19;(3):CD005326
references.pmid: 16856092
references.citation: Curr Osteoporos Rep. 2009 Sep;7(3):96-102
references.pmid: 19723468