Key message: The effect of atorvastatin on lowering total cholesterol, LDL-cholesterol and triglyceride was proportional to the dose given. HDL-cholesterol was not significantly affected.
Atorvastatin is one of the most commonly prescribed drugs for preventing coronary heart disease. However, it is licensed in a large range of doses and there is uncertainty about the comparative The ability of an intervention (for example a drug, surgery, or exercise) to produce a desired effect, such as reduce symptoms. of these different doses. Also, there is often discord between clinicians and patients when discussing preventative medicines which give patients no day to day symptomatic benefit. Patients can have valid concerns about increased doses of Atorvastatin as there is a greater likelihood of side-effects and many patients prefer a “less rather than more” approach for their medications.
This new review included 33,504 participants in 254 Clinical trials are research studies involving people who use healthcare services. They often compare a new or different treatment with the best treatment currently available. This is to test whether the new or different treatment is safe, effective and any better than what is currently used. No matter how promising a new treatment may appear during tests in a laboratory, it must go through clinical trials before its benefits and risks can really be known. assessing different doses of atorvastatin over a period of 3 to 12 weeks. The doses assessed ranged from 2.5mg to 80mg per day.
What did they find?
- Total cholesterol was reduced 19.5% for 2.5mg, peak reduction was 38.7% for 80mg
- LDL-cholesterol was reduced by 26.2% for 2.5mg and 53.5% for 80mg
- HDL-cholesterol was not significantly affected
- Triglycerides were reduced by 11.6% for 2.5mg and 32.1% for 80mg
- The effect in each case was proportional to the dose
How good was the evidence?
- There was a high A way of expressing the chance of an event taking place, expressed as the number of events divided by the total number of observations or people. It can be stated as ‘the chance of falling were one in four’ (1/4 = 25%). This measure is good no matter the incidence of events i.e. common or infrequent. of Any factor, recognised or not, that distorts the findings of a study. For example, reporting bias is a type of bias that occurs when researchers, or others (e.g. drug companies) choose not report or publish the results of a study, or do not provide full information about a study. in many of the papers included, as many were not Blinding is the process of preventing those involved in a trial from knowing to which comparison group a particular participant belongs., had limited sequence generation and allocation concealment
- There was poor reporting of adverse events; therefore it was not possible to ascertain the The number of new occurrences of something in a population over a particular period of time, e.g. the number of cases of a disease in a country over one year. of adverse events with confidence
- Approximately half of the trials were industry funded; half were funded by Pfizer (the manufacturer of atorvastatin) and half by other manufacturers
- Publication bias was assessed as not significant
This review helps clarify the relationship between the dose of Atorvastatin and the effect it has on cholesterol levels, which will allow for a more factual and open discussion between clinicians and patients about the expected effects of their medication.
Adams SP, Tsang M,Wright JM. Lipid lowering efficacy of atorvastatin. Cochrane Database of In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. 2012, Issue 12. Art. No.: CD008226. DOI: 10.1002/14651858.CD008226.pub2.
Editorial by Julian Higgins: Convincing evidence from controlled and uncontrolled studies on the lipid-loweringeffect of a statin. The Cochrane Library. 12 December 2012. http://www.thecochranelibrary.com/details/editorial/3992221/Convincing-evidence-from-controlled-and-uncontrolled-studies-on-the-lipid-loweri.html
Harry was with the UK Cochrane Centre from October 2012 – May 2013, where he undertook a fellowship in systematic reviews. He is currently part way through his Cardiology specialist training within the Oxford Deanery and before this undertook his medical training in London. He is interested evidence based medicine within cardiology, particular in relation to cardiovascular risk in women, imaging and devices.
You can follow Harry on Twitter @harry9bo