Family Practice Vol. 19, No. 5, 567
© Oxford University Press 2002
Lipid-lowering drugs and erectile dysfunction
Department of General Practice Erasmus University Rotterdam The Netherlands
Lipid-lowering drugs and erectile dysfunction
We have serious concerns about the review on lipid-lowering drugs and erectile dysfunction (ED) reported by Rizvi et al.1 Although the authors mention that the technique of systematic reviews has been little used in the area of adverse drug reactions, this may not lead to an incomplete reporting of such procedures. In their review, some basic methodological issues have been overlooked.
The term systematic reviews suggests a systematic search strategy, study selection (based on eligibility criteria concerning ED patients, lipid-lowering drugs and design), quality assessment and data extraction. The authors only present information on the search strategy, but do not ‘select’ studies, perform quality assessment or provide insight in the data extraction.
They make no comment on the methodological quality of included reports. Potential sources of bias are not discussed. Especially, confounding-by-indication may be an issue in this topic as it has been clearly described that high cholesterol levels may cause ED.2 Most of the ‘evidence’ suggested by the authors was provided by case reports. The authors suggested, furthermore, that several reviews support the suggestion that fibrates may induce ED. These reviews, however, refer to the same case reports as the current review, or describe empirical ‘evidence’.
Finally, we have concerns about the accuracy of the references: one of ‘case reports’ did not include any ED case, but the author discussed the possible effect of clofibrate on erectile function (which ‘was not to be expected’), and pointed at the possible effects of the underlying pathology.3
Using Sackett’s rules of evidence, the authors should have concluded that there is level 4–5 evidence concerning the effect of lipid-lowering drugs on erectile function, meaning that the basis for evidence is on case series (and poor quality cohort and case–control studies) and expert opinion.4 The effect can, therefore, never be classed as causal.
References
1 Rizvi K, Hampson JP, Harvey JN. Do lipid-lowering drugs cause erectile dysfunction? A systematic review. Fam Pract 2002; 19: 95–98.
2 Wei M, Macera CA, Davis DR, Hornung CA, Nankin HR, Blair SN. Total cholesterol and high density lipoprotecin cholesterol as important predictors of erectile dysfunsion. Am J Epidemiol 1994; 140: 930–937.
3 Vogt HJ. [Letter: Impotence caused by clofibrate therapy] Impotenz durch Behandlung mit Clofibrat [German]. Med Klin 1976; 71: 257.[Medline]
4 Sackett DL, Straus SE, Richardson WS, Rosenberg W, Haynes RB. Evidence-based Medicine: How to Practice and Teach EBM, 2nd edn. Edinburgh: Churchill Livingstone, 2000.
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