Microcirculatory function deteriorates with advancing stages of chronic kidney disease independently of arterial stiffness and atherosclerosis

Cardiovascular disease is the main cause of mortality in chronic kidney disease (CKD). Endothelial dysfunction and capillary rarefaction are established cardiovascular risk factors. Nailfold video capillaroscopy provides a thorough assessment of capillary density and functional reserve. This study aimed to examine possible differences in structural and functional capillary density in CKD stages 2-4 with nailfold video capillaroscopy. Ninety-six CKD patients, divided into four equally sized groups according to CKD stage (2, 3a, 3b, 4), underwent nailfold video capillaroscopy, during which capillary density was measured at baseline, after 4-min arterial occlusion and after 2-min venous occlusion. Arterial stiffness and wave parameters were measured with applanation tonometry and common carotid intima-media thickness (ccIMT) with ultrasound. Baseline capillary density showed a progressive reduction with advancing CKD stages (stage 2: 32.6 +/- 2.8, stage 3a: 31.2 +/- 3.8, stage 3b: 32.5 +/- 3.3, stage 4: 28.5 +/- 3.1,p = 0.011). Similar reductions were observed during postocclusive hyperemia (39.4 +/- 3.0, 37.6 +/- 4.2, 38.4 +/- 3.8, and 33.8 +/- 3.3, respectively;p = 0.021) and after venous congestion (41.1 +/- 3.1, 39.0 +/- 4.4, 39.9 +/- 3.5, and 35.2 +/- 3.4;p = 0.032). Office PWV and ccIMT showed nonsignificant increasing trends with advancing CKD. In multivariate analysis, eGFR showed a positive association (per ml/min increase;beta: 0.053, 95% CI: 0.004-0.101), whereas diabetes (beta: -1.706, 95% CI: -3.176 to -0.236) and parathyroid hormone (PTH) (per pg/ml increase;beta: -0.022, 95% CI: -0.036 to -0.008) had negative associations with postocclusive capillary density. Both structural and functional capillary density progressively decrease with advancing CKD stages. Apart from reduced eGFR, diabetes and increased PTH levels are independently associated with this reduction. This capillary rarefaction may largely contribute to the increased cardiovascular risk of CKD patients.

Automated summary

As chronic kidney disease (CKD) progresses, both structural and functional capillary density decrease gradually. In addition to reduced eGFR, diabetes and increased parathyroid hormone levels are independently associated with this decrease in capillary density, which may significantly contribute to the increased cardiovascular risk in CKD patients.