Cystatin C-based equation for estimating glomerular filtration rate in Japanese children and adolescents

Background

Renal inulin clearance is the gold standard for evaluation of kidney function, but is compromised by problems of collecting urine samples in children, especially those <6 years or with a bladder dysfunction. Therefore, we should utilize the serum cystatin C (cysC)-based estimated glomerular filtration rate (eGFR) for measuring serum cysC. The purpose of the present study is to determine the applicability of the new serum cysC-based eGFR in Japanese children and adolescents, including infants with chronic kidney disease (CKD), for evaluation of renal function.

Methods

Inulin clearance and standardized serum cysC level determined by the colloidal gold immunoassay were measured in 135 pediatric CKD patients between the ages of 1 month and 18 years with no underlying disease that affects renal function except CKD, to determine serum cysC-based eGFR in Japanese children and adolescents.

Results

We showed the inulin clearance by expression of 1/serum cysC in pediatric CKD patients, which resulted in the equation: inulin GFR (mL/min/1.73 m²) = 104.1 × 1/serum cysC (mg/L) ? 7.80. We also validated the cysC-based eGFR formula for Japanese adults. eGFR values obtained with the adult formula significantly underestimated GFR by approximately 8 % in children with CKD.

Conclusion

We determined the new cysC-based eGFR formula is useful for clinical screening of renal function in Japanese children and adolescents, including infants.     

How to estimate kidney function in kidney transplant recipients with mild to moderate kidney impairment: comparison of estimated glomerular filtration (eGFR) values between creatinine-based GFR equations and cystatin C-based GFR equations for Japanese population

Background

With the recent increase in renal transplantations in Japan, accurate assessment of renal function is required.

Methods

This study included 73 patients who had undergone renal transplantation at Nagoya Daini Red Cross Hospital at least 6 months previously and had stable renal function for >3 months. Glomerular filtration rates (GFRs) were measured by inulin clearance (mGFR) and compared with estimated cystatin C-based GFRs (eGFRcys), estimated creatinine-based GFRs (eGFRcre) and their average values (eGFRave).

Results

mGFR was 43.3 ± 14.1 mL/min/1.73 m², eGFRcre was 39.6 ± 11.7, eGFRcys was 56.0 ± 17.1, and eGFRave was 47.8 ± 13.7 mL/min/1.73 m². Serum cystatin C was 1.39 ± 0.37 mg/L and serum creatinine was 1.58 ± 0.51 mg/dL. The correlation coefficients between mGFR and eGFRcre, eGFRcys, and eGFRave were 0.768, 0.831, and 0.841, respectively (P < 0.001, for all).The intraclass correlation coefficients were 0.754, 0.816, and 0.840, respectively (P < 0.001, for all).The mean differences between measured and estimated GFR values were 3.74 mL/min/1.73 m² with a root-mean square error (RMSE) of 9.06 for eGFRcre, +12.64 with RMSE of 9.48 for eGFRcys, and +4.45 with RMSE of 7.86 for eGFRave. Bland–Altman plots showed that eGFRcys overestimated GFR values compared with mGFR values in most cases and that eGFRave overestimated GFR values in 53 of 73 cases, whereas eGFRcre underestimated the values in 53 of 73 cases.

Conclusion

eGFRave may be the best marker to estimate kidney function in Japanese renal transplant recipients with mildly reduced or normal kidney function.     

Suitability of Estimated Glomerular Filtration Rate for Live Kidney Donor Selection

Introduction

The assessment of the glomerular filtration rate (GFR) in kidney donor candidates is required for determining donor candidate acceptability. This assessment can be done using an estimated GFR (eGFR) or a measured GFR (mGFR). The primary objective of the present study was to compare, in healthy adult kidney donor candidates, GFR measured by the clearance of iothalamate to GFR estimated using the Chronic Kidney Disease Epidemiology Collaboration equation and to determine if eGFR was a suitable stand-alone assessment. A secondary objective was to explore demographic factors that affect the relationship of the eGFR and the mGFR.

Estimation of glomerular filtration rate by the MDRD study equation modified for Japanese patients with chronic kidney disease

Background

Accurate estimation of the glomerular filtration rate (GFR) is crucial for the detection of chronic kidney disease (CKD). In clinical practice, GFR is estimated from serum creatinine using the Modification of Diet in Renal Disease (MDRD) study equation or the Cockcroft-Gault (CG) equation instead of the time-consuming method of measured clearance for exogenous markers such as inulin. In the present study, the equations originally developed for a Caucasian population were tested in Japanese CKD patients, and modified with the Japanese coefficient determined by the data.

Methods

The abbreviated MDRD study and CG equations were tested in 248 Japanese CKD patients and compared with measured inulin clearance (Cin) and estimated GFR (eGFR). The Japanese coefficient was determined by minimizing the sum of squared errors between eGFR and Cin. Serum creatinine values of the enzyme method in the present study were calibrated to values of the noncompensated Jaffé method by adding 0.207?mg/dl, because the original MDRD study equation was determined by the data for serum creatinine values measured by the noncompensated Jaffé method. The abbreviated MDRD study equation modified with the Japanese coefficient was validated in another set of 269 CKD patients.

Results

There was a significant discrepancy between measured Cin and eGFR by the 1.0 × MDRD or CG equations. The MDRD study equation modified with the Japanese coefficient (0.881 × MDRD) determined for Japanese CKD patients yielded lower mean difference and higher accuracy for GFR estimation. In particular, in Cin 30–59?ml/min per 1.73?m², the mean difference was significantly smaller with the 0.881 × MDRD equation than that with the 1.0 × MDRD study equation (1.9 vs 7.9?ml/min per 1.73?m²; P P 2, the accuracy was significantly higher, with 85% vs 69% of the points deviating within 50% (P P 2.

Conclusions

Although the Japanese coefficient improves the accuracy of GFR estimation of the original MDRD study equation, a new equation is needed for more accurate estimation of GFR in Japanese patients with CKD stages 3 and 4.     

Preoperative estimated glomerular filtration rate as a significant predictor of long-term outcomes after coronary artery bypass grafting in Japanese patients

Purposes

The aim of this retrospective study was to investigate the effect of chronic kidney disease (CKD) on outcomes after coronary artery bypass grafting (CABG), and to determine whether preoperative estimated glomerular filtration rate (eGFR) can be a predictor of long-term outcomes after CABG.

Methods

486 Japanese patients who underwent isolated CABG between December 2000 and August 2010 were evaluated. Preoperative eGFR was estimated by the Japanese equation according to guidelines from the Japanese Society of Nephrology. We defined CKD as a preoperative eGFR of less than 60 ml/min/1.73 m². 203 patients had CKD (CK group) and 283 patients did not (N group).

Results

During a mean observation time of 53 months, the overall survival rate was significantly lower in the CK group than in the N group (p = 0.0044). Similarly, the CK group had significantly more unfavorable results with regard to freedom from cardiac death, major adverse cardiovascular and cerebrovascular events (MACCE), and hemodialysis. Using multivariate analyses, preoperative eGFR was an independent predictor of all-cause mortality (HR 0.983; p = 0.026), cardiac mortality (HR 0.963; p = 0.006), and incidence of MACCE (HR 0.983; p = 0.002).

Conclusions

The CK group had significantly more unfavorable outcomes than the N group. Preoperative eGFR was an independent predictor of long-term outcomes after CABG in Japanese patients.     

Creatinine-based equation to estimate the glomerular filtration rate in Japanese children and adolescents with chronic kidney disease

Background

Renal inulin clearance is the gold standard for evaluation of kidney function, but cannot be measured easily in children. Therefore, we utilize the serum creatinine (Cr)-based estimated GFR (eGFR) measuring serum Cr by the enzymatic method, and we have reported simple serum Cr-based eGFR in Japanese children aged between 2 and 11 years old. Furthermore, we should use serum Cr-based eGFR in Japanese adolescents as well as children with chronic kidney disease for evaluation of renal function.

Methods

The inulin clearance and serum Cr level determined by an enzymatic method were measured in 131 pediatric chronic kidney disease (CKD) patients between the ages of 2 and 18 years old with no underlying disease affecting renal function except CKD to determine the serum Cr-based eGFR in Japanese children and adolescents.

Results

We offer the complex estimated GFR equation using polynomial formulae for reference serum creatinine levels with body length in Japanese children except infants, resulting in the following equation: $$ {\text{eGFR}} = 110.2 \times ({\text{reference serum Cr}}/{\text{patient's serum Cr}}) + 2.93 $$ Reference serum Cr levels (y) are shown by the following two equations of body length (x): $$ \begin{aligned} {\text{Males}}:\quad \, y = & -1.259x^{5} + 7.815x^{4} -18.57x^{3} + 21.39x^{2} -11.71x + 2.628 \\ {\text{Females}}:\quad \, y = & -4.536x^{5} + 27.16x^{4} -63.47x^{3} + 72.43x^{2} -40.06x + 8.778 \\ \end{aligned} $$

Conclusion

The new polynomial eGFR formula showing the relationship with body length and serum Cr level may be applicable for clinical screening of renal function in Japanese children and adolescents aged between 2 and 18 years.     

Glomerular filtration rate in prospective living kidney donors

Purpose

Measurements of glomerular filtration rate (GFR) are frequently interpreted assuming a linear variation with age. Nonlinear relationships may give a better representation of the changes associated with normal ageing.

Methods

This was a retrospective study of 904 subjects (468 women, 436 men; age range 18–84 years) undergoing assessment as prospective living kidney donors. GFR was evaluated from ⁵¹Cr-EDTA plasma clearance using blood samples taken at 2, 3 and 4 h. The slope–intercept GFR was corrected for body surface area (BSA) using the Haycock formula and for the fast exponential using the Brochner-Mortensen equation. The relationship between age, gender and GFR was examined using best-fit curve analysis. Nonlinear relationships with age were explored using fractional polynomials.

Results

There was no gender difference in BSA-corrected GFR over five decades of age (P = 0.40). However, female donors with a body mass index >30 kg/m² had a statistically significantly lower GFR than nonobese women (P < 0.01). The best-fit relationship between age and GFR was nonlinear and described using a fractional polynomial model of degree 1 (GFR = 103.9–0.0061 × Age² mL/min/1.73 m²) with a root mean standard error of 12.9 mL/min/1.73 m². The residual variance for this model was significantly smaller than for the best-fit linear model (P = 0.006).

Conclusions

GFR measurements in prospective living kidney donors are best corrected for age using a nonlinear relationship.     

Usefulness of Multi-Detector Computed Tomography Scanning as a Replacement for Diethylenetriamine Pentaacetic Acid

Background

Diethylenetriamine pentaacetic acid (DTPA) and multi-detector computed tomography (MDCT) can predict postoperative estimated glomerular filtration rate (eGFR) in a live kidney donor. Accordingly, we compared predicted eGFR measured by use of DTPA and MDCT.

A Higher Glomerular Filtration Rate Predicts Low Risk of Developing Chronic Kidney Disease in Living Kidney Donors

Background

The risk of developing chronic kidney disease (CKD) among living kidney donors (LKDs) is seldom included in evaluations of patients’ outcomes. Potential risk factors and new criteria for estimating the glomerular filtration rate (eGFR) indexed for body surface area (BSA) were investigated with a view to prevent the development of CKD in LKDs.

Methods

We conducted a retrospective study of LKDs from May 1983 to March 2011. The Mann–Whitney U test and χ² test were used to analyze the male versus female groups. Survival analysis was plotted as CKD-free survival and analyzed separately by different eGFR index classifications. The Cox regression model was used to identify potential risk factors for development of CKD.

Results

A total of 105 LKDs with a mean age of 46.3 ± 12.5 years had a mean eGFR indexed for BSA of 88.9 ± 21.5 ml/min per 1.73 m². After a mean duration of 5.4 ± 4.9 years’ follow-up, eGFR dropped to 61.4 ± 16.4 ml/min per 1.73 m² (p = 0.002). Median CKD-free survival was only 5.7 years. The difference between eGFR ≥ 80 ml/min per 1.73 m² and <80 ml/min per 1.73 m² was not statistically significant (p = 0.980). Multivariate Cox regression analysis showed that higher eGFR at donation (HR = 0.952, p = 0.0199) could be a protective factor. The receiver operating characteristic (ROC) curve for initial eGFR with best sensitivity of 52.78 % and specificity of 81.40 % was obtained with a cutoff value of 90.2 ml/min per 1.73 m² for preoperative eGFR. An eGFR of 90 ml/min per 1.73 m² yielded a significant survival curve (p = 0.0199) after 21 years of follow-up. Further classifications of eGFR >90 ml/min per 1.73 m² into 90–99 ml/min per 1.73 m², 100–109 ml/min per 1.73 m², and ≥110 ml/min per 1.73 m² were examined, but this survival curve was not statistically significant (p = 0.1247).

Conclusions

Living kidney donors will develop CKD after a long duration of follow-up if there is insufficiently high eGFR at donation. An eGFR above 90 ml/min per 1.73 m² before donation is the only factor that predicts prevention of CKD. Larger studies with longer duration of follow-up are necessary to clarify the clinical outcome of this postoperative CKD group, especially for patients with eGFR between 80 and 90 ml/min per 1.73 m².     

Performance of GFR equations in Japanese subjects

Background

Japanese GFR equations based on serum creatinine (Scr) (Eq_cr), serum cystatin C (Scys) (Eq_cys) and average value of Eq_cr and Eq_cys (Eq_average), and coefficient-modified CKD-EPI equations based on Scr (CKD-EPI_cr), Scys (CKD-EPI_cys) and Scys in combination with Scr (CKD-EPI_cr-cys) are now available for Japanese subjects. Performance of these equations has not been well evaluated in subjects stratified by GFR. Therefore, the bias, precision and accuracy of the GFR equations were compared in Japanese subjects stratified by measured GFR.

Methods

Three hundred fifty Japanese subjects were included for validation. These subjects were stratified by measured GFR (0–29, 30–59, 60–89, 90–119 ml/min/1.73 m² and total). Japanese equations (Eq_cr, Eq_cys and Eq_average) were compared with coefficient-modified CKD-EPI equations (0.813 × CKD-EPI_cr, CKD-EPI_cys and 0.908 × CKD-EPI_cr-cys), respectively. GFR was measured by inulin renal clearance. Standardized Scr was measured by enzymatic method. Standardized Scys was measured by colloidal gold immunoassay.

Results

Bias and accuracy were not significantly different between Japanese GFR equations and coefficient-modified CKD-EPI equations in all mGFR ranges. The precision of Eq_cr was significantly better in GFR 0–29 ml/min/1.73 m² and significantly worse in GFR 60–89 and GFR 90–119 ml/min/1.73 m² compared with 0.813 × CKD-EPI_cr. The precision of Eq_cys was significantly better in GFR 30–59 and GFR 60–89 ml/min/1.73 m² compared with CKD-EPI_cys. The precision of Eq_average was significantly better in GFR 30–59 ml/min/1.73 m² and significantly worse in GFR 90–119 ml/min/1.73 m² compared with 0.908 × CKD-EPI_cr-cys.

Conclusion

Japanese GFR equations performed well in subjects with GFR under 60 ml/min/1.73 m² compared with the coefficient-modified CKD-EPI equations.     

Creatinine-based equations to estimate glomerular filtration rate in Japanese children aged between 2 and 11 years old with chronic kidney disease

Background

Renal inulin clearance is the gold standard for glomerular filtration rate (GFR), but is compromised by problems of collecting urine samples in children, especially those <6 years of age or with a bladder dysfunction. Therefore, we should utilize the serum creatinine (Cr)-based estimated GFR (eGFR), measuring serum Cr by enzymatic method. The updated Schwartz formulae were reported by enzymatic Cr instead of by the Jaffe method in American children aged 1–16 years old. We believe it would be better to determine serum Cr-based eGFR by the enzymatic method in Japanese children for evaluation of renal function.

Methods

Serum Cr-based eGFR was determined by measuring inulin clearance and serum Cr level in 76 pediatric chronic kidney disease (CKD) patients (49 males and 27 females) aged 2–11 years with no underlying disease that would affect renal function.

Results

We showed the inulin clearance by expression of the body length/serum Cr ratio in pediatric CKD patients, which resulted in the equation: $ {\text{inulin}}\;{\text{GFR}} = 0. 3 4 2 \times {\text{body length}}\;({\text{cm}})/{\text{serum}}\;{\text{Cr}}\;({\text{mg}}/{\text{dL}}) \pm 2. 7 5 $ . Additionally, we suggest the following serum Cr-based eGFR formula passing through the origin: $ {\text{eGFR}}\; ( {\text{mL}}/{ \hbox{min} }/ 1. 7 3 \,{\text{m}}^{ 2} )= 0. 3 5 \times {\text{body}}\;{\text{length}}\; ( {\text{cm)/serum}}\;{\text{Cr}}\; ( {\text{mg}}/{\text{dL)}} $ , because it is simple and easy to remember, thus making it clinically useful.

Conclusion

The new eGFR formula derived from body length and serum Cr level is applicable for clinical screening of renal function in Asian as well as Japanese children aged between 2 and 11 years old.     

Assessment of kidney function in children by enzymatic determination of 2- or 24-h creatinine clearance: comparison with inulin clearance

Background

Although renal inulin clearance (Cin) is the gold standard for evaluation of kidney function, it cannot be measured easily. Therefore, creatinine clearance (Ccr) is often used clinically to evaluate kidney function. Enzymatically measured Ccr was recently found to be much higher than Cin because of the tubular secretion of creatinine (Cr). This study compared three measures of renal clearance, inulin, 2-h Ccr, and 24-h Ccr, in children.

Methods

Kidney function was evaluated in 76 children (51 males and 25 females) aged 1 month to 18 years with chronic kidney disease (CKD) by three renal clearance methods at almost the same time.

Results

Correlations between each pair of three renal clearance measurements were determined. Approximate glomerular filtration rate (GFR) was equal to 62 % of 2-h Ccr or 76 % of 24-h Ccr.

Conclusion

Cr secretion by renal tubules was approximately 50 % of the GFR. In this study, we indicate that the measurements of 2-h Ccr or 24-h Ccr do not show true GFR but we could infer approximate GFR from the values. The use of 2- or 24-h Ccr might contribute to the treatment of pediatric CKD patients.

     

Performance of the Japanese Glomerular Filtration Rate Equation Based on Standardized Serum Cystatin C in Potential Kidney Donors

Background

It was reported that the glomerula filtration rate (GFR) equation based on serum creatinine underestimated the GFR in potential kidney donors. Recently, the Japanese GFR equation based on standardized serum cystatin C was reported. Therefore, we assessed the performance of the equation in potential kidney donors.

Methods

Forty-five potential kidney donors from 2 hospitals were included. GFR was measured (mGFR) using inulin renal clearance. Serum creatinine was measured using the enzymatic method. Serum cystatin C was measured using a nephelometric immunoassay (Siemens) and calibrated to the standardized value traceable to ERM-DA471/IFCC using an equation reported previously. The estimated GFR (eGFR) was calculated using the Japanese GFR equation based on serum creatinine (eGFRcreat) and the Japanese GFR equation based on serum cystatin C (eGFRcys). Bias (mGFR - eGFR) and accuracy (P30) of the equations were evaluated.

Results

Inulin clearance, eGFRcreat, and eGFRcys were 91.0 ± 18.2, 78.5 ± 18.8, and 93.3 ± 16.3 mL/min/1.73 m², respectively. Bias of eGFRcreat was 12.4 ± 15.8 mL/min/1.73 m² and significantly different from zero, indicating underestimation of GFR. Bias of eGFRcys was −2.3 ± 16.3 mL/min/1.73 m² and was not significantly different from zero, suggesting better performance. But, the precision (standard deviation [SD] of bias) and accuracy (P30: Percentage of participants with eGFR within 30% of mGFR) of eGFRcys were not better compared with eGFRcreat. Accuracies (P30) of eGFRcreat and eGFRcys were 87% (95% confidence interval [CI], 74–94) and 82% (95% CI, 69–91), respectively.

Conclusion

Bias of eGFRcys was better compared with eGFRcreat. But, the precision (SD of bias) and accuracy of eGFRcys were not superior compared with eGFRcreat in potential kidney donors.     

Thyroid hormone replacement therapy for primary hypothyroidism leads to significant improvement of renal function in chronic kidney disease patients

Background

The interactions between kidney and thyroid functions have been known for many years; however, there are few studies on the extent of the improvements and long-term changes of renal function after thyroid hormone replacement therapy (THRT) in chronic kidney disease (CKD) patients. The purpose of this study was to determine how THRT affects the estimated glomerular filtration rate (eGFR) in CKD patients with primary hypothyroidism.

Methods

A retrospective investigation was performed on 51 Japanese patients (15 men and 36 women) with primary hypothyroidism. The changes in eGFR after THRT were examined according to the existence of CKD and severity of thyroid function.

Results

eGFR increased rapidly over the first 6 months after THRT in CKD patents, which was followed by a plateau. There was a correlation between eGFR and the severity of hypothyroidism, which was independent of age, and eGFR in severely hypothyroid patients significantly increased up to levels that were similar to mildly hypothyroid patients after THRT. eGFR improved more in the lower initial eGFR group and increased about 30 % in CKD patients (47.5 ± 7.7 vs. 62.1 ± 9.5 ml/min/1.73 m², P < 0.01). Moreover, eGFR in CKD patients with mild to moderate hypothyroidism was significantly increased compared to that in non-CKD patients.

Conclusion

Our data suggested that hypothyroidism contributed to the reduction in eGFR, especially in CKD patients; therefore, patients with CKD should positively be examined for thyroid function, and appropriate THRT should be started if needed.     

Extra-uterine renal growth in preterm infants: Oligonephropathy and prematurity

Background

Nephron number in humans is determined during fetal life. The objective of this study was to investigate the effects of preterm birth on nephron number using renal volume as a surrogate for nephron number.

Methods

This observational study was conducted over 12 months in a tertiary perinatal center. Preterm babies less than 32 weeks of gestation were recruited and followed until discharge. Term infants were recruited for comparison. The babies underwent renal sonography and renal function measurements at 32 and 38 weeks corrected age. The primary outcome measurement was total kidney volume at 38 weeks and the secondary outcome was estimated glomerular filtration rate (eGFR).

Results

Forty-four preterm infants and 24 term infants were recruited. At 38 weeks corrected age, premature infants had lower total kidney volume than term infants (21.6?±?5.7 vs. 25.2?±?5.7 ml; p?=?0.02) and a significantly lower eGFR (73.6 [IQR 68.1–77.6] vs. 79.3 [IQR 72.5–86.6] ml·min^?1·1.73 m^?2; p?=?0.03). There was a significant correlation between total kidney volume and eGFR in premature and term babies.

Conclusions

Premature infants have smaller kidney volume and likely decreased nephron number and lower estimated glomerulofiltration rate relative to infants born at term.     

Association between renal function and cardiovascular and all-cause mortality in the community-based elderly population: results from the Specific Health Check and Guidance Program in Japan

Background

Chronic kidney disease is a significant risk factor for end-stage kidney disease, cardiovascular events, and premature death. However, the prognostic value of low estimated glomerular filtration rate (eGFR) in the elderly is debatable.

Methods

We determined eGFR using the Japanese equation in 132,160 elderly subjects (65–75 years) who attended the special health checkup (Tokutei-Kenshin) in 2008 and investigated the association between baseline eGFR and 5-year all-cause and cardiovascular mortality.

Results

The median (SD) eGFR was 70.5 ± 15.3 mL/min/1.73 m². During follow-up, we noted 2045 all-cause deaths including 408 from cardiovascular events. A J-shaped curve was obtained when all-cause and cardiovascular mortality rates were compared with decreases in eGFR, with the highest mortality observed for eGFR <45 mL/min/1.73 m². These trends were statistically significant in the Kaplan–Meier analysis (P < 0.001). In the Cox proportional hazard analysis, after adjusting for possible confounders, those with eGFR <45 mL/min/1.73 m², but not eGFR 45–59 mL/min/1.73 m² showed a higher all-cause and cardiovascular mortality than those with eGFR >90 mL/min/1.73 m² [hazard ratio (HR) 1.43, 95% confidence interval (CI) 1.06–1.91 for all-cause mortality, HR 2.28, 95% CI 1.28–4.03 for cardiovascular mortality]. Sex-based subgroup analyses showed similar results for both men and women.

Conclusions

We conclude that eGFR <45 mL/min/1.73 m² is an independent risk factor for all-cause and cardiovascular mortality in the elderly population.

     

Effect of glomerular filtration rate and proteinuria on medical cost among screened subjects

Background

Chronic kidney disease is a predictor of end-stage renal disease (ESRD) and cardiovascular disease (CVD). Therefore, the medical expenses are higher with the decrease in glomerular filtration rate (GFR). However, few studies have examined the medical expenses according to the baseline GFR.

Methods

We investigated the relationship between GFR at health checks and medical expenses, combining the registries of both the health checks and report of medical expenses (receipts). The health checks were done from April 2008 to March 2009, and the eligible subjects were covered by the Okinawa Branch of the Japan Health Insurance Association. All reports of medical expenses were reviewed from April 2008 to March 2010 (24 months).

Results

A total of 74,354 subjects, 38.2 % females with the mean age of 48.1 years, were examined according to whether they had visited medical facilities during the study period. The total number of receipts was 773,276. The average receipt point, 1 point = 10 Yen, was 686,410 (eGFR < 15), 56,408 (eGFR 15–29), 47,263 (eGFR 30–44), 24,372 (45–59), 16,018 (eGFR 60–74), 13,893 (eGFR 75–89), 13,990 (eGFR 90–104), 14,717 (eGFR 105–119), and 19,139 (eGFR 120 and over), respectively. The relationship between eGFR and medical expense was U-shaped, and the expense was lowest at eGFR 75–89.

Conclusion

We demonstrate that the medical expenses increase as eGFR decreases. Subjects with higher eGFR, 120 and over, seemed to have higher medical expenses.     

Prevalence and predictors of abdominal aortic calcification in healthy living kidney donors

Background

Vascular calcification (VC) is common and is both a marker and a cause of increased cardiovascular morbidity and mortality, especially so in chronic kidney disease (CKD) patients. Renal transplantation is the cornerstone of the successful long-term management of CKD, and in order to satisfy transplantation needs, more use is made now of living kidney donors (LKD). Prior to selection for transplantation, much screening of potential LKD takes place, including for cardiovascular issues. It is not known; however, how much these potentially healthy LKD may be prone to clinically silent VC.

Methods

We identified 103 living kidney donors from 2011 renal transplant records. Abdominal aortic calcification (AAC) was assessed using existing abdominal CT imaging using multi-channel CT aortograms (used primarily to assess renal vascular anatomy). Using these CT scans, manual calcium scoring was undertaken to calculate total aortic calcium load (AAC severity score). The prevalence, severity and associations of AAC between calcified and non-calcified donors were then compared.

Results

A total of 103 donors were identified from records. Ninety three of these had detailed clinical records to complement their CT scans. Fifty of ninety-three donors were male, and the mean age was 45.9 ± 1.8 years. Mean MDRD eGFR was 88.73 ± 2.97 ml/min/1.73 m². 7.14 ± 3.07 % of the aorta in these donors was calcified with a mean AAC severity score of 0.98 ± 0.56. In kidney donors >50 years of age, there was significantly more AAC than in those <50: 2.47 ± 1.56 versus 0.31 ± 0.29, p < 0.001. There was no relationship between the presence or severity of aortic VC and donor GFR, systolic blood pressure, pulse pressure, calcium–phosphate product or smoking.

Conclusions

AAC prevalence, patterns and severity in this important donor population have not previously been described in the literature. There was relatively little VC in what would be regarded as a “healthy” donor population. VC was more common with age, but the other possible risk factors for the presence or severity of VC did not impact on overall AAC scores. VC did not influence vascular stiffness as represented by pulse pressure. Following the evolution of AAC over time in those who have donated a kidney, and lost some global renal function as a consequence, would be of considerable interest.     

Prevalence of renal disease within an urban HIV-infected cohort in northern Italy

Background

Renal disease is an increasingly recognized noninfectious comorbidity associated with human immunodeficiency virus (HIV) infection.

Methods

Our retrospective, cross-sectional study evaluated prevalence of nephropathy among HIV-infected patients followed up in our outpatient clinic during the year 2011. Renal dysfunction and chronic kidney disease (CKD) were defined as estimated glomerular filtration rate (eGFR) <90 ml/min per 1.73 m² and as renal damage or eGFR <60 ml/min per 1.73 m² over a 3-month or greater period, respectively.

Results

We enrolled 894 HIV-infected patients with a mean age of 44.2 years and a mean current CD4 lymphocyte count of 508 cells/mm³. The prevalence of renal dysfunction and CKD was 27.4 and 21.3 %, respectively. Older age, male gender, hypertension, diabetes, proteinuria, hypertriglyceridemia, lower nadir CD4 cell count, current use of tenofovir or tenofovir plus a ritonavir-boosted protease inhibitor were independently associated with renal dysfunction.

Conclusion

Renal dysfunction is a frequent comorbidity among HIV-infected persons and requires a careful clinical and laboratory monitoring of renal function.     

Predictive Factors of Renal Adaptation After Nephrectomy in Kidney Donors

Background

Despite compensatory hyperfiltration in remaining nephrons following donor nephrectomy, some donors show impaired renal adaptation and low estimated glomerular filtration rate (eGFR). We investigated the factors predicting early renal adaptation after nephrectomy and identified kidney donors at risk of inadequate renal adaptation.