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Table 4 Examples of claims based on potentially biased evidence

From: Accuracy of drug advertisements in medical journals under new law regulating the marketing of pharmaceutical products in Switzerland

Type Drug Claim Reference Reasons for potential bias
Abstract Pantozol® (Pantoprazol) Similar healing of reflux disease as omeprazol 20 mg Bardnan KD et al. Gastroenterology 116(Suppl.4II): A 118, 1999 Abstract, open study, no blinded outcome assessment
Selection Bias Neurodol® (Lidocaine) Neurodol tissugel reduces pain and allodynia in postherpetic neuralgia Meier T et al., Pain 106: 151–158, 2003 Selection bias (only patients who had already successfully been treated with lidocaine for more than 1 month were included in study), very few patients
Publication bias Lamictal® (Lamotrigine) Well tolerated Bowden CL et al. Drug Safety 2004; 57: 173–184 Narrative review, possible publication and selective reporting of evidence bias
At least 3 quality criteria missing Zoloft® (Sertraline) Increases cognitive capacity Newhouse PA et al. J Clin Psych 2000;61:559–68 High drop out rate(>30%), no descriptions of losses to follow-up, selective reporting of positive outcomes
Post hoc analysis Jarsin® (St. John's word) Similar efficacy as synthetic antidepressants Brenner R et al. Clinical Therapeutics 22: 411–419, 2000 Post-hoc analysis, only 15 patients in each group, no sample size calculation