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C-reactive protein concentration and the vascular benefits of statin therapy: an analysis of 20 536 patients in the Heart Protection Study
It has been suggested that inflammation status, as assessed by C-reactive protein (CRP) concentration, modifies the vascular protective effects of statin therapy. In particular, there have been claims that statins might be more beneficial in people with raised CRP concentrations, and might even be ineffective in people with low concentrations of both CRP and LDL cholesterol. This study aimed to test this hypothesis.
In 69 UK hospitals, 20 536 men and women aged 40—80 years at high risk of vascular events were randomly assigned to simvastatin 40 mg daily versus matching placebo for a mean of 5·0 years. Patients were categorised into six baseline CRP groups (<1·25, 1·25—1·99, 2·00—2·99, 3·00—4·99, 5·00—7·99, and ≥8·00 mg/L). The primary endpoint for subgroup analyses was major vascular events, defined as the composite of coronary death, myocardial infarction, stroke, or revascularisation. Analysis was by intention to treat. This study is registered, number ISRCTN48489393.
Overall, allocation to simvastatin resulted in a significant 24% (95% CI 19—28) proportional reduction in the incidence of first major vascular event after randomisation (2033 [19·8%] allocated simvastatin vs 2585 [25·2%] allocated placebo). There was no evidence that the proportional reduction in this endpoint, or its components, varied with baseline CRP concentration (trend p=0·41). Even in participants with baseline CRP concentration less than 1·25 mg/L, major vascular events were significantly reduced by 29% (99% CI 12—43, p<0·0001; 239 [14·1%] vs 329 [19·4%]). No significant heterogeneity in the relative risk reduction was recorded between the four subgroups defined by the combination of low or high baseline concentrations of LDL cholesterol and CRP (p=0·72). In particular, there was clear evidence of benefit in those with both low LDL cholesterol and low CRP (27% reduction, 99% CI 11—40, p<0·0001; 295 [15·6%] vs 400 [20·9%]).
Evidence from this large-scale randomised trial does not lend support to the hypothesis that baseline CRP concentration modifies the vascular benefits of statin therapy materially.
Inflammation is thought to contribute to the pathogenesis of coronary heart disease.1 C-reactive protein (CRP), an acute phase reactant synthesised by the liver, is the most extensively studied systemic marker of inflammation. Results from a meta-analysis2 of individual participant data from 54 prospective observational studies showed that CRP concentration was associated with the risk of coronary heart disease, ischaemic stroke, and vascular and non-vascular mortality. However, associations with ischaemic vascular diseases were explained largely by conventional risk factors (eg, CRP is positively correlated with smoking, diabetes, physical inactivity, blood pressure, body-mass index, non-HDL cholesterol, and triglycerides2), and so they might not reflect causality (which is supported by genetic-epidemiological studies3). Nonetheless, the ability of CRP to predict vascular risk means that it might still be useful as a biomarker to identify individuals who would particularly benefit from therapies to reduce risk.4
Some,5, 6 but not all,7 subgroup analyses undertaken in previous randomised trials of statin therapy have suggested that the vascular benefits might be greater in the presence of inflammation than in its absence. It has even been suggested that people who have low concentrations of both LDL cholesterol and CRP might not benefit much from statin therapy.8 The JUPITER trial9randomly allocated 17 802 apparently healthy men and women with LDL cholesterol concentrations less than 130 mg/L (3·4 mmol/L) but CRP concentrations 2·0 mg/L or greater to receive either rosuvastatin 20 mg daily or matching placebo. Allocation to rosuvastatin reduced LDL cholesterol at 1 year by about 50% (ie, 1·2 mmol/L) and CRP by about 40% (1·3 mg/L) and, during median treatment duration of about 2 years, there was a significant 44% reduction in the primary composite endpoint of myocardial infarction, stroke, arterial revascularisation, admission to hospital for unstable angina, or death from cardiovascular causes.9 It has been suggested that this large relative risk reduction is greater than might have been expected given the achieved LDL cholesterol reduction,9, 10 raising the possibility that the benefits of statins might be proportionally greater in people with high CRP concentrations. Secondary analyses of the JUPITER trial did not record any evidence that the effect of rosuvastatin on vascular events differed according to baseline CRP concentration,11 but these analyses included only three baseline groups for CRP (because of the relatively small number of events) and were not able to assess the effect in people with CRP concentration less than 2·0 mg/L (because they were not eligible for the trial).
The Heart Protection Study (HPS) is, to date, the largest randomised trial of statin therapy and was undertaken in high-risk patients in whom large numbers of major vascular events occurred during the study treatment period. This study tested the hypothesis that the effects of statin therapy differ according to baseline concentrations of CRP and LDL cholesterol.