Beneficial effects of hydroxychloroquine on blood lipids and glycated haemoglobin: A randomised interventional study in patients with rheumatoid arthritis and systemic lupus erythematosus.

Introduction: Hydroxychloroquine (HCQ) exerts a large reduction of cardiovascular risk in patients with inflammatory diseases, but the mechanisms are not fully known. The aim of this study was to study potential mechanisms for this.

Methods: This interventional study (EudraCT 2014-005418-45) in 30 patients (23 with rheumatoid arthritis, 7 with systemic lupus erythematosus) investigates the effects of HCQ on cardiovascular risk factors and arterial stiffness in patients with inflammatory disease. Blood lipids, blood pressure, blood glucose, glycated haemoglobin (HbA1c) and arterial stiffness was assessed at initiation, after four weeks of treatment and after eight weeks of treatment with 200 mg HCQ daily.

Results: After four weeks of treatment with HCQ, total cholesterol had decreased from 5.4 mmol/L to 5.1 mmol/L (p<0.001), low-density lipoproteins from 3,0 mmol/L to 2.7 mmol/L (p<0.001) and apolipoprotein B from 0.96 g/L to 0.90 g/L (p<0.01). Those levels remained unchanged after eight weeks of treatment with HCQ. Levels of triglycerides, high-density lipoproteins and apolipoprotein A1 remained unchanged during the study. HbA1c decreased in most patients, especially in patients with high levels at start of HCQ, but increased HbA1c was seen in patients with low levels at start of treatment with HCQ. No significant effect was seen on blood pressure or any measure of arterial stiffness.

Conclusion: This study does not identify the mechanisms of cardiovascular risk reduction from HCQ. Arterial stiffness is not affected by HCQ. The impact of HCQ on HbA1c and blood lipids is rapid, but of modest magnitude, and these effects do not fully explain the reduced risk of cardiovascular disease seen in observational studies. The mechanisms of cardiovascular risk reduction from HCQ are yet not completely known.