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

High phosphate and calcium induce osteoblastic phenotype switching and calcification of corneal epithelial cells in a Runx2-dependent and synergistic manner; a possible mechanism of chronic kidney disease-associated corneal calcification

Patients with advanced chronic kidney disease (CKD) have elevated circulating calcium × phosphate product levels and exhibit soft tissue calcification. Besides the cardiovascular system, calcification is commonly observed in the cornea in CKD patients on hemodialysis. Cardiovascular calcification is a cell-mediated, highly regulated process, and we hypothesized that a similar regulatory mechanism is implicated in corneal calcification with the involvement of corneal epithelial cells (CECs). We established a mouse model of CKD-associated corneal calcification by inducing CKD in DBA/2J mice with an adenine and high phosphate diet. CKD was associated with aorta and corneal calcification as detected by OsteoSense staining and corneal Ca measurement (1.67-fold elevation, p < 0.001). In vitro, excess phosphate and Ca induced human CEC calcification in a dose-dependent and synergistic manner, without any influence on cell viability. High phosphate and Ca-containing osteogenic medium (OM; 2.5 mmol/L excess phosphate and 0.6 mmol/L excess Ca over control) increased the protein expression of Runx2 and induced its nuclear translocation. OM increased the expression of the bone-specific Ca-binding protein osteocalcin (130-fold increase, p < 0.001). Silencing of Runx2 attenuated OM-induced CEC calcification. Immunohistology revealed upregulation of Runx2 and overlapping between the Runx2 and the Alizarin red positive areas of calcification in the cornea of CKD mice. This work sheds light on the mechanism of CKD-induced corneal calcification and provides tools to test calcification inhibitors for the prevention of this detrimental process.

Corneal and Coronary Calcification in Maintenance Hemodialysis: The Face Is No Index to the Heart

Although the eyes are the main site of metastatic calcification in patients with chronic kidney disease (CKD), corneal and conjunctival calcification (CCC) is poorly evaluated in this population. Whether CCC correlates with coronary artery calcification remains unknown since studies so far have relied on methods with low sensitivity. Our objective was to test the relationship between CCC and coronary calcification based on tomography. This was a cross-sectional study that included patients on maintenance dialysis. Clinical, demographic, and biochemical data (calcium, phosphorus, parathormone, alkaline phosphatase, and 25(OH)-vitamin D) were recorded. Hyperparathyroidism was defined as parathyroid hormone (PTH) > 300 pg/mL. CCC was evaluated by anterior segment optical coherence tomography (AS-OCT), and coronary calcium scores (Agatston method) were assessed by computed tomography. We compared no/mild with moderate/severe CCC. Twenty-nine patients were included (49.6 ± 15.0 years, 62.1% female, on hemodialysis for 5.7 [2.7-9.4] years, 17.2% with diabetes mellitus, 75.9% with hyperparathyroidism). CCC was found in 82.7% of patients, with median scores of 9 (3, 14.5), ranging from 0 to 16. CCC was classified as absent/mild, moderate, and severe in 27.6%, 20.7%, and 51.7%, respectively. Coronary calcification was found in 44.8% of patients, with median scores of 11 (0, 464), varying from 0 and 6456. We found no significant correlation between coronary calcium scores and CCC (r = 0.203, p = 0.282). Hyperphosphatemia was more frequent in patients with moderate/severe CCC than in those with absent/mild CCC. We concluded that CCC was frequent in patients with CKD on dialysis and did not correlate with coronary calcium scores. Hyperphosphatemia appears to contribute to CCC. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Detection of signs of disease in external photographs of the eyes via deep learning

Retinal fundus photographs can be used to detect a range of retinal conditions. Here we show that deep-learning models trained instead on external photographs of the eyes can be used to detect diabetic retinopathy (DR), diabetic macular oedema and poor blood glucose control. We developed the models using eye photographs from 145,832 patients with diabetes from 301 DR screening sites and evaluated the models on four tasks and four validation datasets with a total of 48,644 patients from 198 additional screening sites. For all four tasks, the predictive performance of the deep-learning models was significantly higher than the performance of logistic regression models using self-reported demographic and medical history data, and the predictions generalized to patients with dilated pupils, to patients from a different DR screening programme and to a general eye care programme that included diabetics and non-diabetics. We also explored the use of the deep-learning models for the detection of elevated lipid levels. The utility of external eye photographs for the diagnosis and management of diseases should be further validated with images from different cameras and patient populations.

The Relationship Between Dry Eye in Adults with Indications for Kidney Transplantation and Influence Factors

Purpose

Patients with end-stage renal failure are susceptible to dry eye disease. This study explores the relationship between dry eye disease and influence factors.

Patients and Methods

The control group consisted of 57 healthy subjects who were kidney donors. They were of the same age and sex as the kidney transplant recipients. The outcome variable was the dry eye condition of the participants. The Schirmer test confirmed dry eye disease, TBUT (breakup time test), and the Eye Surface Disease Index (OSDI) questionnaire, using linear regression to evaluate the association.

Results

The total number of subjects was 146 (89 kidney recipients and 57 kidney donors). When univariate analysis found the level of visual acuity, the age group involved was statistically significant, while the other factors were not statistically significant. In multivariable logistic regression analysis, age (odds ratio: 2.8, p<0.05), smoking history (odd ratio: 0.1, p<0.05), corneal conjunctival calcification (odd ratio: 0.2, p<0.05); central corneal thickness (odd ratio: 1.02, p<0.05) is considered to be an influence factor for disease progression.

Conclusion

Age group, smoking history, corneal central thickness, and conjunctival calcification are factors for dry eye disease in patients preparing to receive a kidney. These results reinforce the evidence for multifactorial dry eye disease in patients with renal impairment.

Corneal and Conjunctival Calcification in a Dialysis Patient Reversed by Parathyroidectomy

Mineral and bone metabolism disorders are relatively common among patients with end-stage renal disease on maintenance hemodialysis. Corneal and conjunctival calcification is the main extravascular site for calcification. Recently, this form of calcification has been linked to vascular calcification. Secondary hyperparathyroidism can lead to high levels of calcium and phosphorus and increase the risk of calcification. Here, we report a case of a 38-year-old female with severe hyperparathyroidism who underwent eye examination before and after parathyroidectomy. Anterior segment optical coherence tomography showed an improvement in the number and size of ocular calcifications 6 months after surgery. This case calls attention to the importance of eye examination in patients on dialysis and brings the possibility of recovery of calcification in a short-term follow-up.

Evaluation of Dry Eye Using Anterior Segment Optical Coherence Tomography in Patients With End-Stage Renal Disease Undergoing Hemodialysis

The aim of the present study was to evaluate dry eye parameters with conventional tests and tear meniscus with Anterior Segment Optical Coherence Tomography (AS-OCT) in patients with end-stage renal disease (ESRD). Thirty-eight ESRD patients undergoing hemodialysis, and 40 healthy individuals were enrolled. An ocular surface disease index questionnaire (OSDI) was administered. Before conventional dry eye tests, tear meniscus were evaluated using AS-OCT. After a complete ocular examination, Schirmer and break-up time (BUT) tests were performed and probable corneal staining was investigated. Schirmer test and BUT values were significantly lower in ESRD patients (P < 0.05). OSDI scores and corneal staining scores were significantly higher in ESRD patients (P < 0.05). Tear meniscus height, tear meniscus depth, and tear meniscus area, which were obtained by AS-OCT were significantly lower in patients with ESRD (P < 0.05). Tear meniscus evaluation using AS-OCT is an effective and non-invasive method to assess tear meniscus in patients with ESRD. Patients with ESRD undergoing hemodialysis should obtain regular ophthalmic examination, especially for dry eye.

Association Between Conjunctival and Corneal Calcification and Atherosclerotic Changes in the Carotid Artery in Maintenance Hemodialysis Patients

PURPOSE

We aimed to investigate the association between atherosclerotic changes in the common carotid artery (CA) and conjunctival and corneal calcification (CCC) in maintenance hemodialysis (MHD) patients.

METHODS

Fifty eyes of MHD patients with the highest CCC scores were enrolled. CCCs were scored according to the method described by Tokuyama et al. The eyes with the highest CCC scores were selected for further analysis. According to their CCC scores, the patients were classified into 3 groups: mild (0-2 score), moderate (3-5), and severe (6-10 score). Atherosclerosis of the common CA was evaluated by determination of intima-media thickness (IMT), peak systolic (PSV) and end diastolic (EDV) flow velocities, pulsatility index, and resistive index values by using Doppler ultrasonography.

RESULTS

The mean IMT of the CA was 0.61 ± 0.09 mm in the mild group, 0.82 ± 0.16 mm in the moderate group, and 1.21 ± 0.32 mm in the severe group (P < 0.001). The PSV and EDV were significantly higher in the severe group than in the mild and moderate groups (all, P < 0.001). The CCC score was positively correlated with the duration of hemodialysis, ocular surface disease index score, IMT, PSV, EDV, lymphocyte, calcium, and sedimentation rate. In multiple stepwise linear regression analysis, IMT was the best predictive factor for the CCC score (R = 0.812, β = 9.526 ± 1.05, and P < 0.001).

CONCLUSIONS

Our results suggest that chronic ocular ischemia due to atherosclerotic changes may have a role in the formation or progression of CCC in MHD patients.

Tear function in patients with chronic renal failure undergoing hemodialysis

OBJECTIVES

To evaluate dry eye symptoms and clinical tear film alterations in patients with chronic renal failure (CRF).

MATERIALS AND METHODS

Thirty-five non-diabetic CRF patients undergoing hemodialysis, and 31 healthy individuals were enrolled. An ocular surface disease index questionnaire (OSDI) was administered, and after a complete ocular examination, Schirmer and tear break-up time (TBUT) tests were performed.

RESULTS

OSDI scores were significantly higher (p<0.01) and TBUT tests were significantly lower (p=0.01) in CRF patients than in the control group. Schirmer test results were also lower in the CRF patients group, but lacked statistical significance (p=0.20).

CONCLUSION

Patients with CRF should be advised to obtain an ophthalmic examination, especially for dry eye.

Impact of living environment on 2-year mortality in elderly maintenance hemodialysis patients

Background

Studies on risk factors of mortality in elderly patients with hemodialysis usually focus on comorbidities, nutrition, and inflammation. Discussion on the correlation between living environment and mortality of these patients is limited.

Methods

A total of 256 elderly hemodialysis patients participated in this 2-year prospective observational study. The subjects were divided into 2 subgroups based on whether they were living in Taipei Basin (n = 63) or not (n = 193). Demographic, hematological, nutritional, inflammatory, biochemical, and dialysis-related data were obtained for cross-sectional analysis. Causes of death and mortality rates were also analyzed for each subgroup.

Results

Patients in the basin group had a higher incidence of combined protein-energy wasting and inflammation than those in the around basin group. At the end of the 2-year follow-up, 68 patients had died. Univariate binary logistic regression analysis revealed that a very advanced age, basin group, serum albumin levels, serum creatinine levels, non-anuria, and the complications of stroke and CAD were associated with 2-year mortality. Meanwhile, log high-sensitivity C-reactive protein (hs-CRP) levels were not associated with 2-year mortality. Multivariate Cox regression analysis revealed that basin group, serum albumin levels, and the complications of stroke and CAD were significant risk factors for 2-year mortality in these patients.

Conclusion

The results of this study indicate that factors such as living in the Taipei Basin with higher air pollutant levels in elderly hemodialysis patients is associated with protein-energy wasting and inflammation, as well as 2-year mortality. These findings suggest that among this population, living environment is as important as comorbidities and nutrition. Furthermore, air pollution should be getting more attention especially in the overcrowding Basin topography.

Is there an association between elevated or low serum levels of phosphorus, parathyroid hormone, and calcium and mortality in patients with end stage renal disease? A meta-analysis

BACKGROUND

Biochemical markers of altered mineral metabolism have been associated with increased mortality in end stage renal disease patients. Several studies have demonstrated non-linear (U-shaped or J-shaped) associations between these minerals and mortality, though many researchers have assumed linear relationships in their statistical modeling. This analysis synthesizes the non-linear relationships across studies.

METHODS

We updated a prior systematic review through 2010. Studies included adults receiving dialysis and reported categorical data for calcium, phosphorus, and/or parathyroid hormone (PTH) together with all-cause mortality. We performed 2 separate meta-analyses to compare higher-than-referent levels vs referent and lower-than-referent levels vs referent levels.

RESULTS

A literature review showed that when a linear relationship between the minerals and mortality was assumed, the estimated associations were more likely to be smaller or non-significant compared to non-linear models. In the meta-analyses, higher-than-referent levels of phosphorus (4 studies, RR = 1.20, 95% CI = 1.15-1.25), calcium (3 studies, RR = 1.10, 95% CI = 1.05-1.14), and PTH (5 studies, RR = 1.11, 95% CI = 1.07-1.16) were significantly associated with increased mortality. Although no significant associations between relatively low phosphorus or PTH and mortality were observed, a protective effect was observed for lower-than-referent calcium (RR = 0.86, 95% CI = 0.83-0.89).

CONCLUSIONS

Higher-than-referent levels of PTH, calcium, and phosphorus in dialysis patients were associated with increased mortality risk in a selection of observational studies suitable for meta-analysis of non-linear relationships. Findings were less consistent for lower-than-referent values. Future analyses should incorporate the non-linear relationships between the minerals and mortality to obtain accurate effect estimates.