No changes of inflammatory indices of atherosclerosis despite improvement of insulin sensitivity by CPAP therapy in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is seen as one feature of the metabolic syndrome leading to increased cardiovascular mortality. Continuous positive airway pressure (CPAP) is an effective therapy of OSAS and improves insulin sensitivity as a key finding in metabolic syndrome. We investigated, whether subclinical inflammation as a risk marker for atherosclerotic disease is also improved by CPAP.

We measured C-reactive protein, interleukin-6, intracellular and vascular adhesion molecule-1 and the chemokines RANTES and GRO-a as markers for subclinical inflammation in 30 patients with OSAS before and after 3 months therapy. We also measured soluble P-selectin as a marker of platelet activation and levels of prolactin and leptin, which may stimulate platelet activation. We found no significant changes of the inflammation markers despite a significant improvement of insulin sensitivity index (5.94±4.25 to 7.73±4.89µmol/kgxmin, p<0.001). There was a significant decrease of leptin levels (14.1±12.2 to 12.4±10.4 ng/ml p=0.024) without significant change of body mass index or percentage fat mass under therapy. The soluble P-selectin showed a tendency to lower values after therapy (229.7±67.8 to 204±79.1 ng/ml p=0.053).

Risk markers of atherosclerosis did not change after 3 months of effective CPAP therapy in patients with OSAS despite significant improvement of insulin sensitivity. Either this subclinical inflammation is already fixed in chronic disease or other conditions drive it in our patient group.