Introduction: Over 8% of adults in the United States are estimated to have moderate (stages 3 and 4) chronic kidney disease (CKD), which is increasingly recognized as one of the independent predictors for cardiovascular (CV) disease and related mortality. Secondary hyperparathyroidism with elevated serum intact parathyroid hormone (iPTH) is associated with increased CV mortality in end-stage renal disease and this relationship is unclear in moderate CKD.
Methods: Medical records of 196 patients at Harry S. Truman Memorial Veterans Hospital with stages 3 and 4 CKD (glomerular filtration rate, GFR 16-59 ml/min/1.73 m(2)) who had iPTH levels determined from 4/2006 to 9/2007 were reviewed. CV event was defined as occurrence of any of the following during follow-up: myocardial infarction, stroke, coronary/carotid/peripheral artery revascularization, and death due to CV reasons.
Results: During median follow-up of 27.2 months, 48 patients had CV events, while 148 patients did not. iPTH was elevated (156.43 ± 107.49) for patients who had CV events compared with those without (109.12 ± 86.54, P = 0.003). Among the covariates studied in the multivariate analysis including history of vascular disease, 25-OH Vit D, corrected calcium, phosphorus levels, calcium-phosphorus product, and GFR, iPTH level was found to have a positive association with CV events during follow-up period (odds ratio = 1.3 for 50 pg/ml change in iPTH, 95% CI: 1.03-1.55, P = 0.02)). Cardiovascular disease history was the only other significant variable with estimated odds ratio of 5.9 (P = 0.002).
Conclusion: iPTH level in patients with stages 3 and 4 CKD is associated with increased incidence of cardiovascular events independent of calcium-phosphorous level.