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Gemfibrozil, one of the standard therapies used to control triglyceride levels, has only modest effects in patients with HAART-associated triglyceride elevations, according to a small randomised study reported this month in the journal AIDS.

The study, conducted by St Vincent’s Hospital in Sydney, randomised 37 men with a median fasting triglyceride level of 5.6mmol/L to receive either gemfibrozil 600mg twice daily or placebo after a four week diet phase.

Triglyceride levels fell by 1.22mmol/L in the gemfibrozil group (-18%) and rose by 0.35mmol/L in the placebo group over 12 weeks, a non-significant difference (p=0.08). The study was powered to detect a difference of at least 2mmol/L between the groups. Only one individual experienced a reduction in triglyceride levels to the normal range.

Glossary

triglycerides

A blood fat (lipid). High levels are associated with atherosclerosis and are a risk factor for heart disease.

 

placebo

A pill or liquid which looks and tastes exactly like a real drug, but contains no active substance.

powered

A study has adequate statistical power if it can reliably detect a clinically important difference (i.e. between two treatments) if a difference actually exists. If a study is under-powered, there are not enough people taking part and the study may not tell us whether one treatment is better than the other.

statin

Drug used to lower cholesterol (blood fats).

p-value

The result of a statistical test which tells us whether the results of a study are likely to be due to chance and would not be confirmed if the study was repeated. All p-values are between 0 and 1; the most reliable studies have p-values very close to 0. A p-value of 0.001 means that there is a 1 in 1000 probability that the results are due to chance and do not reflect a real difference. A p-value of 0.05 means there is a 1 in 20 probability that the results are due to chance. When a p-value is 0.05 or below, the result is considered to be ‘statistically significant’. Confidence intervals give similar information to p-values but are easier to interpret. 

The authors note that whilst gemfibrozil treatment has resulted in triglyceride reductions of up to 55% in HIV-negative patients, the reduction seen in this study was much smaller (18%), and the authors suggest that further studies should look at higher doses (gemfibrozil was well tolerated in this study) and combination therapy with a statin. However, they also admit that gemfibrozil may not be addressing the root cause of hypertriglyceridemia – ongoing insulin resistance or another metabolic disturbance generated by HAART.

References

Miller J et al. A randomised, double blind study of gemfibrozil for the treatment of protease inhibitor-associated hypertriglyceridemia. AIDS 16: 2195-2200, 2002.