VASCalc

Introduction and Aims: Vascular calcification is associated with higher cardiovascular morbidity and mortality in hemodialysis patients. A single X-ray film or a CT scan easily helps us to know each patient's current vascular status. However, we do not know how many years are required until the plain X-ray reveals vascular changes, such as new-onset or worsening calcification.

Methods: VasCalc Score is a sum of vascular calcification scores of the peripheral (proper and common palmar digital, radial, ulnar, splenic, and internal and external iliac arteries) and the central (i.e., aorta) arteries. The dialysis Unit has a policy to have bone X-ray films taken basically once a year in each patient. Patients on maintenance hemodialysis 3 times a week with bone films taken 4 or more times over the period of at least 4 years were eligible for the analysis. A set of 5 plain bone films covers the bilateral hands and fingers, the cervical and lumbar spines, the skull and the pelvis. The films were analyzed by staff physicians blinded to the previous results. On each film, the degree of vascular calcification was ranked as none, mild or severe. Automatic summing up of the total film score yields the VasCalc Score, which is 0 (none), 0.5 (focal or patchy), 1 (diffuse but mild) and 2 (diffuse and severe both in peripheral and central). Nutritional status was assessed by malnutrition-inflammation score (MIS), which was performed semi-annually and was averaged during the period.

Results: A total of 83 patients (68.7±11.5 years old, m±SD; M:F = 56:27), which comprised more than 90% of the patients who received hemodialysis in the Unit for 4 or more years, were included, with a follow-up period of 5.8±0.9 years. A baseline VasCalc Score, an average of the initial 3 years, ranged widely; 0.5 or less in 34 patients, more than 0.5 up to 1.0 in 33, more than 1.0 up to 1.5 in 8 and more than 1.5 in 8, with a median of 0.83. During the study period, those with a lower baseline VasCalc Score (1.0 or less; n=67) had more increase in the Score (0.34±0.29 vs 0.12±0.37, P=0.012) than those with a higher Score. The increase in the Score over the period was minimal in most of the patients, with a median of 0.25; the increase by more than 0.5 was seen in only 14 (16.9%). MIS was positively correlated with the VasCalc Score (R2=0.089, P=0.004), but not with a velocity of changes in the VasCalc Score (P=0.50).

Conclusions: Vascular calcification can be visualized on plain X-ray film slowly but definitely, with the change taking 4 years or more in the hemodialyzed patients. Malnourished patients had a higher degree of baseline vascular calcification but had the speed of worsening thereafter similar to the well-nourished patients.