Association of severity of conjunctival and corneal calcification with all-cause 1-year mortality in maintenance haemodialysis patients

Background. Conjunctival and corneal calcification (CCC) is the most common form of metastatic calcification in patients with chronic renal failure. The aim of this study is to investigate if severity of CCC correlates with vascular calcification and mortality inmaintenance haemodialysis (MHD) patients. Methods. One hundred and nine MHD patients were recruited. CCC was evaluated by external eye photographs, and was graded and scored according to modified Porter and Crombie classification system described by Tokuyama et al. Chest X-ray examination was used to evaluate aortic arch calcification. Geographic, haematological, biochemical and dialysis-related data were obtained. The patients were analysed for traditional and non-traditional risk factors for cardiovascular disease stratified by severity of CCC. All patients were followed up for 1 year to investigate the risks for mortality. Results. Forty-three, 35 and 31 patients had mild (scores <= 4), moderate and severe (scores >= 9) CCC at baseline, respectively. With trend estimation, patients with severe CCC had a significantly higher percentage of severe aortic arch calcification. Multiple linear regression analysis showed that hypertension, haemodialysis duration and corrected calcium level were associated with scores of CCC in MHD patients. Moreover, age, corrected calcium-phosphate level, and moderate and severe CCC were associated with grades of aortic arch calcification. At 1-year follow-up, 11 of 109 (10.1%) patients had died. Multivariate Cox proportional hazards model showed that age, corrected calcium and severe CCC were significant risk factors for all-cause 1-year mortality in MHD patients. Each increment of one score of CCC is associated with a 26.4% increased risk for all-cause mortality. Conclusions. Severity of CCC, which is easily obtained at bedside, acts as an independent predictor for all-cause 1-year mortality in MHD patients.