Nephrolithiasis as a Risk Factor for CKD: The Atherosclerosis Risk in Communities Study

Risk Factors of Asymptomatic Kidney Stone Passage in Adults with Recurrent Kidney Stones

Key Points

Background

Kidney stones are a common health problem and are characterized by a high risk of recurrence. A certain number of kidney stones pass asymptomatically. Data regarding the frequency of asymptomatic spontaneous stone passages are limited.

Methods

To assess the frequency of asymptomatic spontaneous stone passage and its covariates, we conducted a post hoc analysis of the prospective randomized NOSTONE trial. All asymptomatic spontaneous stone passages were identified by comparing the total number of kidney stones on low-dose noncontrast computed tomography (CT) imaging at the beginning and end of the study, considering symptomatic stone passages and surgical stone removal. The statistical analysis focused on the association of independent variables and the number of asymptomatic spontaneous stone passages using linear regression analyses.

Results

Of the 416 randomized patients, 383 with both baseline and end-of-study CT were included in this analysis. The median follow-up period was 35 months, the median patient age was 49 years (interquartile range [IQR], 40–55), and 20% of the patients were female. A total of 442 stone events occurred in 209 of 383 (55%) patients: 217 of 442 (49%) were symptomatic spontaneous stone passages, 67 of 442 (15%) were surgically removed stones, and 158 of 442 (36%) were asymptomatic spontaneous stone passages. The median size of asymptomatic stones (2.4 mm; IQR, 1.95–3.4) and the size of symptomatic stones (2.15 mm; IQR, 1.68–2.79) that passed spontaneously were not significantly different (P = 0.37). The number of asymptomatic spontaneous stone passages was significantly associated with a higher number of stones on CT at randomization (P = 0.001). Limitations include the lack of data on stone size at the time of passage and overrepresentation of White men.

Conclusions

Asymptomatic stone passage was common in patients with recurrent calcium-containing kidney stones. The higher the number of stones at presentation, the more likely it was that a kidney stone would spontaneously pass over time without causing any symptoms.

Clinical Trial registry name and registration number:

NOSTONE trial and: NCT03057431.

Association between kidney stones and poor sleep factors in U.S. adults

The purpose of our study is to examine the correlation between sleep factors and the prevalence of kidney stones in US adults. A total of 34,679 participants from the National Health and Nutrition Examination Survey 2007 to 2018 were included in the analyses. Sleep data collection included: presleep factors (difficulty falling asleep, sleep onset latency), intra-sleep factors (risk index of obstructive sleep apnea, restless leg syndrome, difficulty maintaining sleep), post-sleep factors (daytime sleepiness, non-restorative sleep), sleep schedule and duration, and sleep quality. Logistic regression models were used to analyze the correlation between sleep factors and the prevalence of kidney stones. Among the 34,679 participants, the overall incidence of kidney stones was 9.3%. The presence of presleep factors (difficulty falling asleep [odds ratios [OR], 1.680; 95% CI, 1.310-2.150], prolonged sleep onset latency [OR, 1.320; 95% CI, 1.020-1.700]), intra-sleep factors (higher risk index of obstructive sleep apnea [OR, 1.750; 95% CI, 1.500-2.050], restless leg syndrome [OR, 1.520; 95% CI, 1.150-1.990], difficulty maintaining sleep [OR, 1.430; 95% CI, 1.130-1.810]), post-sleep factors (daytime sleepiness [OR, 1.430; 95% CI, 1.220-1.680], non-restorative sleep [OR, 1.400; 95% CI, 1.110-1.760]), short sleep duration (OR, 1.190; 95% CI, 1.080-1.310), mediate sleep quality (OR, 1.140; 95% CI, 1.020-1.290), and poor sleep quality (OR, 1.500; 95% CI, 1.310-1.720) are linked to the occurrence of kidney stones. However, short sleep onset latency, bedtime and wake-up time were not significantly associated with the prevalence of kidney stones. These findings showed positive associations between higher kidney stone prevalence and poor sleep factors.

Risk of incident chronic kidney disease among patients with urolithiasis: a nationwide longitudinal cohort study

Background

Urolithiasis has been infrequently implicated to have a causal association with chronic kidney disease (CKD). Recently, several studies have demonstrated the relationship between urolithiasis and CKD. However, the generalizability of their results is limited. This study aimed to investigate the association between urolithiasis and the risk of incident CKD.

Methods

This longitudinal cohort study used the National Health Insurance Service data, including 219 570 Korean adults with incident urolithiasis requiring procedural interventions and without prior kidney disease and 219 570 age- and sex-matched controls without urolithiasis between 1 January 2002 and 31 December 2020. Primary outcome was the development of CKD, defined by an estimated glomerular filtration rate <60 ml/min/1.73 m2 for at least two consecutive measurements at least 90 days apart. The risk for incident CKD was further examined using the outcome defined by newly occurring diagnostic codes indicating CKD.

Results

Over a mean follow-up of 6 years, 12 338 (2.8%) primary outcome events of CKD were observed (incidence rate 4.6/1000 person-years). Per multivariable Cox analysis, urolithiasis was associated with a higher risk of incident CKD [adjusted hazard ratio 1.41 (95% confidence interval 1.36-1.46)]. This association remained consistent across all clinically relevant subgroups and when the CKD outcome was defined based on the diagnostic codes in the sensitivity analysis.

Conclusions

In this large national cohort study, patients with urolithiasis were associated with a higher risk of incident CKD than those without urolithiasis. Further studies are warranted to establish the benefits of preventing urolithiasis in reducing CKD development.

Vitamin D and Calcium Supplementation and Urolithiasis: A Controversial and Multifaceted Relationship

Patients with urolithiasis, and particularly those with hypercalciuria, frequently have a marked reduction of bone mineral content up to the levels of osteoporosis, with a significant increase in bone fracture risk. For these reasons, the indication to prescribe vitamin D and/or calcium supplementations is very frequent in such patients. On the other hand, both calcium supplementation, and even more vitamin D therapy, can worsen the risk of developing urolithiasis by increasing calcium, phosphate, and oxalate urinary excretion. Despite the clinical and practical relevance of this issue, the evidence on this topic is scarce and contradictory. Therefore, some concerns exist about how and whether to prescribe such supplements to a patient with a history of kidney stones. In this narrative review, we resume some pivotal pathophysiological concepts strictly related to the dealt topic, and we draw some considerations and personal opinions on the pros and cons of such prescriptions. Finally, we share with the reader our pragmatic algorithm for handling the urolithiasis risk in patients who have strong indications to be prescribed vitamin D and calcium supplementations.

Prevalence of chronic kidney diseases and its determinants among Iranian adults: results of the first phase of Shahedieh cohort study

Background

Chronic kidney disease (CKD) is one of the major global causes of mortality, described as the most neglected chronic disease. This study aimed to determine the prevalence and determinants of CKD in the setting of the Shahedieh cohort study in Yazd, Iran.

Methods

This cross-sectional study was conducted on adults in the baseline phase of the Shahedieh cohort study in Yazd, Iran. In this study, 9781 participants aged 30–73-year-old were investigated. The data used in this study included demographic and clinical variables and blood samples. Adjusted odds ratios were employed using multivariate logistic regression; meanwhile, population attributable risks for CKD were calculated and reported.

Results

CKD prevalence was 27.5% (95%CI: 26.57–28.34) in all participants, 24% in male, and 30.3% in female. The results of multivariate logistic regression analysis identified age (OR = 1.89, 95%CI:1.082–1.96), women (OR = 1.62, 95%CI: 1.45–1.79), BMI ≥ 30 (OR = 1.40,95%CI: 1.20–1.62), diabetes (OR = 1.38, 95%CI: 1.22–1.57), hypertriglyceridemia(OR = 1.20, 95%CI: 1.01–1.43), history of cardiovascular disease (OR = 1.20, 95%CI: 1.01–1.43), hypertension (OR = 1.18, 95%CI: 1.04–1.33), smoking (OR = 1.17, 95% CI: 1.02–1.33), LDL ≥ 130 (OR = 1.15, 95%CI: 1.01–1.31), history of kidney stone (OR = 1.14, 95%CI: 1.01–1.32) and hypercholesterolemia (OR = 1.14, 95%CI: 1.01–1.32) as risk factors for CKD. Among individual factors, obesity (11.25%), Hypertriglyceridemia (9.21%), LDL ≥ 130 (7.12%) had the greatest Population-Attributable Fraction, followed by Hypercholesterolemia (5.2%), diabetes (5.05%), smoking (3.73%) and high blood pressure (2.82%).

Conclusion

The results showed that the main determinants of CKD are potentially modifiable risk factors. Therefore, implementing early detection and screening programs in people at risk as well as preventive measures such as lifestyle modification programs and risk factors controlling can prevent the disease.

Upper urolithiasis in cats with chronic kidney disease: prevalence and investigation of serum and urinary calcium concentrations

OBJECTIVES

This study aimed to define the prevalence of upper urolithiasis in cats with chronic kidney disease (CKD) in a referral population, and to compare urinary calcium:creatinine ratio (UCa:Cr), and total and ionised calcium between cats with CKD with and without upper urolithiasis.

METHODS

The medical records of cats diagnosed with CKD were reviewed for signalment, body weight, diet and prevalence of upper urolithiasis. Cats with preserved urine samples were further classified into two groups: urolithiasis group (upper urolithiasis identified by abdominal ultrasonography) and control group (CKD of unknown origin). Serum biochemical analysis, CKD stage, blood gas analysis, urine specific gravity and UCa:Cr were compared between groups using a two-sample t-test or Mann-Whitney U-test for continuous variable and a χ2 test or Fisher's exact test for categorical variables. Multivariable binary logistic regression analysis was used to identify risk factors.

RESULTS

Among the 140 cats with CKD, the prevalence of upper urolithiasis was 73%. Fifty cats (5, 29 and 16 cats with CKD stages 1, 2 and 3, respectively) with urine samples met the inclusion criteria and were included in the analysis. Among cats with CKD, being purebred (odds ratio [OR] = 81.56; P = 0.03) and being fed dry food only (OR = 25.06; P = 0.001) were identified as independent upper urolithiasis risk factors; those with upper urolithiasis were more likely to be exclusively fed with urine-acidifying food (P <0.001) and have increased serum ionised calcium (iCa) (P = 0.044), fractional excretion of calcium (P = 0.45) and UCa:Cr (P = 0.005) than cats with CKD without upper urolithiasis.

CONCLUSIONS AND RELEVANCE

Cats with CKD that were purebred, fed dry food and fed urine-acidifying food only often had upper urolithiasis. A higher UCa:Cr may be a result of increased serum iCa and may cause upper urolithiasis.

Incidence and risk factors of chronic kidney disease: results of a nationwide study in Iceland

Background

Information on the incidence of chronic kidney disease (CKD) in the general population is scarce. This study examined the incidence and risk factors of CKD stages 1–5 in Iceland, based on multiple markers of kidney damage.

Methods

All SCr values, urine protein measurements and diagnosis codes for kidney diseases and comorbid conditions for people aged ≥ 18 years were obtained from electronic medical records of all healthcare institutions in Iceland in 2008–2016. CKD was defined according to the KDIGO criteria as evidence for kidney damage and/or eGFR &lt; 60 mL/min/1.73 m2 for &gt; 3 months. Alternatively, CKD was defined using age-adapted eGFR thresholds. Mean annual age-standardized incidence of CKD was calculated for persons without CKD at study entry. Risk factor assessment was based on ICD diagnosis codes. Incidence was reported per 100 000 population.

Results

We retrieved 1 820 990 SCr values for 206 727 persons. Median age was 45 years (range, 18–106) and 47% were men. Mean annual age-standardized incidence of CKD per 100 000 was 649 in men and 694 in women, and 480 in men and 522 in women using age-adapted eGFR thresholds. The incidence reached over 3000 in men and women aged &gt; 75 years. Traditional CKD risk factors, such as acute kidney injury, diabetes, hypertension and cardiovascular disease, as well as less well characterized risk factors, including chronic lung disease, malignancy and major psychiatric illness were associated with increased risk of CKD, and the same was true for obesity and sleep apnea in women.

Conclusion

The annual incidence of CKD, with strict adherence to the KDIGO criteria, was &lt; 0.7% but markedly lower using age-adapted eGFR thresholds. Apart from acute kidney injury, the observed risk factors comprised chronic and potentially modifiable disorders.

Clinical and Kidney Structural Characteristics of Living Kidney Donors With Nephrolithiasis and Their Long-term Outcomes

Nephrolithiasis in living kidney donors is concerning due to the potential impact on long-term postdonation kidney function.

Calcium and Vitamin D Supplementation and Their Association with Kidney Stone Disease: A Narrative Review

Kidney stone disease is a multifactorial condition influenced by both genetic predisposition and environmental factors such as lifestyle and dietary habits. Although different monogenic polymorphisms have been proposed as playing a causal role for calcium nephrolithiasis, the prevalence of these mutations in the general population and their complete pathogenetic pathway is yet to be determined. General dietary advice for kidney stone formers includes elevated fluid intake, dietary restriction of sodium and animal proteins, avoidance of a low calcium diet, maintenance of a normal body mass index, and elevated intake of vegetables and fibers. Thus, balanced calcium consumption protects against the risk for kidney stones by reducing intestinal oxalate availability and its urinary excretion. However, calcium supplementation given between meals might increase urinary calcium excretion without the beneficial effect on oxalate. In kidney stone formers, circulating active vitamin D has been found to be increased, whereas higher plasma 25-hydroxycholecalciferol seems to be present only in hypercalciuric patients. The association between nutritional vitamin D supplements and the risk for stone formation is currently not completely understood. However, taken together, available evidence might suggest that vitamin D administration worsens the risk for stone formation in patients predisposed to hypercalciuria. In this review, we analyzed and discussed available literature on the effect of calcium and vitamin D supplementation on the risk for kidney stone formation.

Outcomes of kidney donors with pre- and post-donation kidney stones

Roughly 25% of US transplant centers exclude donor candidates with kidney stones fearing future obstructive consequences and the possible association between stones and CKD. We compared the development of hypertension, proteinuria, and reduced eGFR in 227 kidney donors with kidney stones to 908 propensity score-matched donor controls without kidney stones using data from The Renal and Lung Donor Evaluation (RELIVE) Study which studied intermediate and long-term outcomes of 8922 donors who donated between 1963 and 2007. 200 donors had kidney stones prior to donation, 21 had post-donation stones, and 6 had pre- and post-donation stones. Donors with stones were older, more likely to be Caucasian, less likely to be related to the recipient and had a higher fasting glucose. After 16.5 ± 10.9 years (range 0-44 years) from donation to study close, no ESKD occurred in donors with stones. The multivariable risks of hypertension, proteinuria, and reduced GFR were similar in donors with and without kidney stones. We could not demonstrate an association between stones and adverse renal outcomes in kidney donors, and the occurrence of post-donation stones was distinctly rare. These data may provide a rationale for possibly a wider acceptance of donor candidates with low kidney stones burden.

Advantages of Herbal Over Allopathic Medicine in the Management of Kidney and Urinary Stones Disease

Kidney and urinary stone disease (Nephrolithiasis and urolithiasis) are the condition where urinary stones or calculi are formed in the urinary tract. The problem of urinary stones is very ancient; these stones are found in all parts of the urinary tract, kidney, ureters, and the urinary bladder and may vary considerably in size. It is a common disease estimated to occur in approximately 12% of the population, with a recurrence rate of 70-81% in males and 47-60% in females. The treatment of kidney and urinary stone diseases such as a western (allopathy) medicine and surgery is now in trends. However, most people preferred plant-based (herbal) therapy because of the overuse of allopathic drugs, which results in a higher incidence rate of adverse or severe side effects. Therefore, people every year turn to herbal therapy because they believe plant-based medicine is free from undesirable side effects, although herbal medicines are generally considered to be safe and effective. In the present article, an attempt has been made to emphasize an herbal therapy is better than allopathic therapy for the management of the kidney and urinary stone disease.

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian-Vegan Diets

Nephrolithiasis is a common medical condition influenced by multiple environmental factors, including diet. Since nutritional habits play a relevant role in the genesis and recurrence of kidney stones disease, dietary manipulation has become a fundamental tool for the medical management of nephrolithiasis. Dietary advice aims to reduce the majority of lithogenic risk factors, reducing the supersaturation of urine, mainly for calcium oxalate, calcium phosphate, and uric acid. For this purpose, current guidelines recommend increasing fluid intake, maintaining a balanced calcium intake, reducing dietary intake of sodium and animal proteins, and increasing intake of fruits and fibers. In this review, we analyzed the effects of each dietary factor on nephrolithiasis incidence and recurrence rate. Available scientific evidence agrees on the harmful effects of high meat/animal protein intake and low calcium diets, whereas high content of fruits and vegetables associated with a balanced intake of low-fat dairy products carries the lowest risk for incident kidney stones. Furthermore, a balanced vegetarian diet with dairy products seems to be the most protective diet for kidney stone patients. Since no study prospectively examined the effects of vegan diets on nephrolithiasis risk factors, more scientific work should be made to define the best diet for different kidney stone phenotypes.

The risk of nephrolithiasis is causally related to inactive matrix Gla protein, a marker of vitamin K status: a Mendelian randomization study in a Flemish population

Background

Vitamin K (VK)-dependent γ-glutamate carboxylation and serine phosphorylation activate matrix Gla protein (MGP) to a potent locally acting inhibitor of calcification. Nephrolithiasis represents a process of unwanted calcification associated with substantial mortality and high recurrence rates. We hypothesized that the risk of nephrolithiasis increases with VK shortage, as exemplified by higher plasma levels of desphospho-uncarboxylated MGP (dp-ucMGP).

Methods

In 1748 randomly recruited Flemish individuals (51.1% women; mean age 46.8 years), we determined dp-ucMGP and the prevalence of nephrolithiasis at baseline (April 1996-February 2015) and its incidence during follow-up until March 2016. We estimated the multivariable-adjusted relative risk associated with the doubling of dp-ucMGP, using logistic or Cox regression. We did a Mendelian randomization analysis using four MGP genotypes as instrumental variables.

Results

With adjustments applied for sex, age and 24-h urinary volume and calcium excretion, the odds of having prevalent nephrolithiasis [n = 144 (8.2%)] associated with dp-ucMGP was 1.31 [95% confidence interval (CI) 1.04-1.64; P = 0.022]. dp-ucMGP levels were associated (P ≤ 0.001) with MGP variants rs2098435, rs4236 and rs2430692. In the Mendelian analysis, the causal odds ratio was 3.82 (95% CI 1.15-12.7; P = 0.029). The incidence of nephrolithiasis over 12.0 years (median) was 37 cases (0.2%). With similar adjustments as before, the hazard ratio in relation to dp-ucMGP was 2.48 (95% CI 1.71-3.61; P < 0.001). Additional adjustment for a nephrolithiasis propensity score produced consistent results.

Conclusion

Higher levels of inactive dp-ucMGP may be causally associated with the risk of nephrolithiasis. Whether or not VK deficiency plays a role in these observations remains to be firmly established.

Epidemiology and economics of nephrolithiasis

Nephrolithiasis is a disease common in both the Western and non-Western world. Several population based studies have demonstrated a rising prevalence and incidence of the disease over the last several decades. Recurrence occurs frequently after an initial stone event. The influence of diet on the risk of nephrolithiasis is important, particularly dietary calcium and fluid intake. An increasing intake of dietary calcium and fluid are consistently associated with a reduced risk of incident nephrolithiasis in both men and women. Increasing evidence suggests that nephrolithiasis is associated with systemic diseases like obesity, diabetes, and cardiovascular disease. Nephrolithiasis places a significant burden on the health care system, which is likely to increase with time.

KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors

The 2017 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors is intended to assist medical professionals who evaluate living kidney donor candidates and provide care before, during and after donation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach and guideline recommendations are based on systematic reviews of relevant studies that included critical appraisal of the quality of the evidence and the strength of recommendations. However, many recommendations, for which there was no evidence or no systematic search for evidence was undertaken by the Evidence Review Team, were issued as ungraded expert opinion recommendations. The guideline work group concluded that a comprehensive approach to risk assessment should replace decisions based on assessments of single risk factors in isolation. Original data analyses were undertaken to produce a "proof-in-concept" risk-prediction model for kidney failure to support a framework for quantitative risk assessment in the donor candidate evaluation and defensible shared decision making. This framework is grounded in the simultaneous consideration of each candidate's profile of demographic and health characteristics. The processes and framework for the donor candidate evaluation are presented, along with recommendations for optimal care before, during, and after donation. Limitations of the evidence are discussed, especially regarding the lack of definitive prospective studies and clinical outcome trials. Suggestions for future research, including the need for continued refinement of long-term risk prediction and novel approaches to estimating donation-attributable risks, are also provided.In citing this document, the following format should be used: Kidney Disease: Improving Global Outcomes (KDIGO) Living Kidney Donor Work Group. KDIGO Clinical Practice Guideline on the Evaluation and Care of Living Kidney Donors. Transplantation. 2017;101(Suppl 8S):S1-S109.

Urinary Stone Disease and Cardiovascular Disease Risk in a Rural Chinese Population

Introduction

Urinary stone disease (USD) is associated with cardiovascular disease (CVD) in Western populations. However, the prevalence and relationship between USD and CVD risk have not been fully examined in the Chinese population.

Methods

We performed a cross-sectional study of 10,281 participants in rural China. All subjects underwent renal ultrasound to detect USD, brachial−ankle pulsewave velocity (baPWV) measurement to estimate arterial stiffness, and ankle−brachial index (ABI) examination to detect peripheral arterial disease (PAD) (defined as ABI <0.9 on at least 1 side of the body).

Results

Mean age of the study population was 55.4 ± 10.0 years; 47.1% were men. Among all participants, 5.7% (n = 582) had USD, mean baPWV was 15.6 ± 3.2 m/s, and 4.0% had PAD. The prevalence of USD increased in parallel with mean arterial pressure, albuminuria, Framingham risk score, and baPWV. In multivariate analyses after adjustment for demographic characteristics, USD was significantly associated with an increased risk of hypertension (odds ratio [OR]: 1.32; 95% confidence interval [CI]: 1.08−1.62), albuminuria (OR: 2.17; 95% CI: 1.74−2.69), chronic kidney disease (OR: 2.11; 95% CI: 1.70−2.62), increased arterial stiffness (OR: 1.24; 95% CI: 1.01−1.52), and PAD (OR: 1.50; 95% CI: 1.04−2.16).

Discussion

In rural China, USD was associated with a high prevalence of traditional CVD risk factors, increased arterial stiffness, and PAD. The presence of USD should increase physician awareness of the concomitant presence of CVD risk factors.

The Risk of Chronic Kidney Disease Associated with Urolithiasis and its Urological Treatments: A Review

PURPOSE

Urolithiasis can impair kidney function. This literature review focuses on the risk of kidney impairment in stone formers, the specific conditions associated with this risk and the impact of urological surgery.

MATERIALS AND METHODS

The PubMed® and Embase® databases were searched for publications on urolithiasis, its treatment, and the risk of chronic kidney disease, end stage renal disease and nephrectomy in stone formers.

RESULTS

In general, renal stone formers have twice the risk of chronic kidney disease or end stage renal disease, and for female and overweight stone formers the risk is even higher. Patients with frequent urinary tract infections, struvite stones, urinary malformations and diversions, malabsorptive bowel conditions and some monogenic disorders are at high risk for chronic kidney disease/end stage renal disease. Shock wave lithotripsy or minimally invasive urological interventions for stones do not adversely affect renal function. Declines in renal function generally occur in patients with preexisting chronic kidney disease or a large stone burden requiring repeated and/or complex surgery.

CONCLUSIONS

Although the effect size is modest, urolithiasis may cause chronic kidney disease and, thus, it is mandatory to assess patients with renal stones for the risk of chronic kidney disease/end stage renal disease. We suggest that all guidelines dealing with renal stone disease should include assessment of this risk.

History of kidney stones and risk of chronic kidney disease: a meta-analysis

BACKGROUND

Although the relationship between a history of kidney stones and chronic kidney disease (CKD) has been explored in many studies, it is still far from being well understood. Thus, we conducted a meta-analysis of studies comparing rates of CKD in patients with a history of kidney stones.

METHODS

PubMed, EMBASE, and the reference lists of relevant articles were searched to identify observational studies related to the topic. A random-effects model was used to combine the study-specific risk estimates. We explored the potential heterogeneity by subgroup analyses and meta-regression analyses.

RESULTS

Seven studies were included in this meta-analysis. Pooled results suggested that a history of kidney stones was associated with an increased adjusted risk estimate for CKD [risk ratio (RR), 1.47 95% confidence interval (CI) [1.23-1.76])], with significant heterogeneity among these studies (I² = 93.6%, P < 0.001). The observed positive association was observed in most of the subgroup analyses, whereas the association was not significant among studies from Asian countries, the mean age ≥50 years and male patients.

CONCLUSION

A history of kidney stones is associated with increased risk of CKD. Future investigations are encouraged to reveal the underlying mechanisms in the connection between kidney stones and CKD, which may point the way to more effective preventive and therapeutic measures.

DASH (Dietary Approaches to Stop Hypertension) Diet and Risk of Subsequent Kidney Disease

BACKGROUND

There are established guidelines for recommended dietary intake for hypertension treatment and cardiovascular disease prevention. Evidence is lacking for effective dietary patterns for kidney disease prevention.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Atherosclerosis Risk in Communities (ARIC) Study participants with baseline estimated glomerular filtration rate (eGFR) ≥ 60mL/min/1.73m2 (N=14,882).

PREDICTOR

The Dietary Approaches to Stop Hypertension (DASH) diet score was calculated based on self-reported dietary intake of red and processed meat, sweetened beverages, sodium, fruits, vegetables, whole grains, nuts and legumes, and low-fat dairy products, averaged over 2 visits.

OUTCOMES

Cases were ascertained based on the development of eGFRs<60mL/min/1.73m2 accompanied by ≥25% eGFR decline from baseline, an International Classification of Diseases, Ninth/Tenth Revision code for a kidney disease-related hospitalization or death, or end-stage renal disease from baseline through 2012.

RESULTS

3,720 participants developed kidney disease during a median follow-up of 23 years. Participants with a DASH diet score in the lowest tertile were 16% more likely to develop kidney disease than those with the highest score tertile (HR, 1.16; 95% CI, 1.07-1.26; P for trend < 0.001), after adjusting for sociodemographics, smoking status, physical activity, total caloric intake, baseline eGFR, overweight/obese status, diabetes status, hypertension status, systolic blood pressure, and antihypertensive medication use. Of the individual components of the DASH diet score, high red and processed meat intake was adversely associated with kidney disease and high nuts, legumes, and low-fat dairy products intake was associated with reduced risk for kidney disease.

LIMITATIONS

Potential measurement error due to self-reported dietary intake and lack of data for albuminuria.

CONCLUSIONS

Consuming a DASH-style diet was associated with lower risk for kidney disease independent of demographic characteristics, established kidney risk factors, and baseline kidney function. Healthful dietary patterns such as the DASH diet may be beneficial for kidney disease prevention.

Kidney Function After the First Kidney Stone Event

OBJECTIVE

To determine whether there is a persistent decline in kidney function after the first kidney stone event.

PATIENT AND METHODS

Incident symptomatic stone formers and age- and sex-matched controls underwent 2 study visits 90 days apart to assess kidney function, complete a survey, and have their medical records reviewed. Kidney function was compared between stone formers and controls adjusting for clinical, blood, and urine risk factors.

RESULTS

There were 384 stone formers and 457 controls. At visit 1, a median of 104 days after the stone event, stone formers compared with controls had similar serum creatinine (0.86 vs 0.84 mg/dL; P=.23), higher serum cystatin C (0.83 vs 0.72 mg/L; P<.001), higher urine protein (34.2 vs 19.7 mg/24 h; P<.001) levels, and were more likely to have albuminuria (24 h urine albumin >30 mg: 5.4% vs 2.2%; P=.02). Findings were similar after adjustment for risk factors and at visit 2, a median of 92 days after visit 1. In the 173 stone formers with serum creatinine levels from care before study participation, the mean serum creatinine level was 0.84 mg/dL before the stone event, increased to 0.97 mg/dL (P<.001) at the stone event, but returned to 0.85 mg/dL (P=.38) after the stone event (visit 1).

CONCLUSIONS

Incident symptomatic stone formers have a rise in serum creatinine levels that resolves. However, stone formers have sustained higher cystatin C levels and proteinuria that may affect long-term risk of chronic kidney disease.

Comparative risk of chronic kidney diseases in patients with urolithiasis and urological interventions: a longitudinal population-based study

Large cohort studies on whether any association existed between urological interventions for urolithiasis and the development of CKD are lacking. From claims data of the National Health Insurance (NHI) program of Taiwan, we identified 54,433 patients newly diagnosed with urolithiasis during 1998-2010. For each case, four individuals without urolithiasis were randomly selected and frequency matched by age, sex, and diagnosis year. Both groups were followed up until the end of 2010. Incident CKD events were identified by the International Classification of Diseases, Ninth Revision (ICD-9) code in the NHI registration database. The overall incidence of periodontal diseases was 1.85-fold greater in the urolithiasis group than in the comparison group (33.9 vs 18.3 per 10,000 person-years; 95 % confidence interval [CI] 1.81-1.90). Compared with the adjusted hazard ratios (aHRs) of nonurolithiasis patients, those of patients with urolithiasis increased with the number of medical visits (from 0.91 [95 % CI 0.83-1.00] to 10.6 [95 % CI 9.48-11.8]) and urological interventions (from 1.22 [95 % CI 1.10-1.35] to 86.4 [95 % CI 67.6-110.6]). The aHR was similar in different urological intervention methods, extracorporeal shock wave lithotripsy, ureteroscopy, percutaneous nephrostolithotomy, and open stone surgery. The urological intervention for urolithiasis is associated with an increased risk of CKD. We should be aware of the risk for CKD, especially in patients who have received multiple urological interventions and those elderly.