Monday, May 31, 2010

Side effects of statin treatment in England and Wales

British Medical Journal published an analysis of the effects (benefits / risks) or unintentional side of statin therapy, registered in health centers in England and Wales. Includes the calculation of the NNT (number needed to treat to benefit) and the NNH (number needed to risk of adverse effects).

Cardiovascular disease is the leading cause of premature death in developed countries. Numerous published scientific papers recommending the use of statins to reduce cardiovascular risk among high-risk patients. Thus, statins have become one of the most prescribed drugs in primary care, and is likely to go to continue to increase their prescription. Side effects of these treatments, particularly those that appear over time are an underdeveloped area of research so far. However, having this information enables more informed decisions with a risk/ benefit balance shared with our patients.

The results presented in this research are from a prospective cohort study (six years) on a electronic medical records of patients whose information is dumped into a research database as many British health centers. We identified those patients treated with statins, at least one year, aged between 30 and 84 years.

Clinically relevant outcomes sought were: acute renal failure, venous thromboembolism, Parkinson's disease, dementia, rheumatoid arthritis, cataracts, osteoporotic fractures, common cancers (stomach, colon, esophagus, lung, kidney, breast, prostate, melanoma) impaired liver function moderate / severe in patients without prior liver involvement, myopathy moderate / severe or rhabdomyolysis.

The study could not confirm the potential protective effect of statins in reducing the risk of developing Parkinson's disease, pulmonary embolism, rheumatoid arthritis, osteoporotic fractures, and dementia. The authors acknowledge that the study has potential uncontrolled confounding biases. In connection with the development of cancers, it is confirmed that there is no clear link between taking statins and common cancers, except for esophageal cancer in which there is a risk reduction, and in the colon that appears pravastatin ruvastatina protective effect and increases the risk.

Confirm an adverse effect of class in relation to the occurrence of myopathy, liver dysfunction, acute renal failure and cataract.

These risks persist throughout the treatment time and were mostly in the first year of treatment. After stopping treatment, the risk of cataract, esophagus cancer, kidney failure and liver dysfunction at initial returns to age within one to three years.

As main contribution, the study provides the national estimate of the number of expected additional adverse effects associated with statin therapy per 10,000 populations, if all patients with high cardiovascular risk (15% and 20% risk of QRISK2) received statin therapy. We summarize the highlights in the following table.

QRISK2 score >20%: risk at 5 years without treatment

NNH o NNT [IC 95%] (*)

No cases prevented / at risk per 10,000 patients [95%]

Potential damage in women

Acute renal failure







307 (260-355)

Liver disfunction


136 (109-175)

74 (57-91)




39 (27-54)

Potential damage in men

Acute renal failure


346 (245-539)

29 (19-41)



52 (44-63)

191 (158-225)

Liver disfunction


142 (115-180)

71 (56-87)



91 (74-112)

110 (90-134)

Benefits in women

Cardiovascular disease


-37 (-64­_-27)

-271 (-374_-157)

Esophageal cancer


-1266 (-3460_-850)

-8 (-12_-3)

Benefits in men

Cardiovascular disease


-33 (-57_-24)

-301 (-417_-174)

Esophageal cancer


-1082 (-2807_-711)

-9 (-14_-4)

(*) No negative indicate number needed to treat or cases prevented. No. positive indicate number needed to harm or cases are extra

Julia Hippisley-Cox and Carol Coupland.Unintended effects of statins in men and women in England and Wales: population based cohort study using the QResearch database
BMJ 2010;340:c2197, doi: 10.1136/bmj.c2197 (Published 20 May 2010)

See also:
High doses of simvastatin and risk of muscular and renal impairment

Posted by Pilar Astier
English version by Jesús Moreno

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