Metabolic Characteristics and Risks Associated with Stone Recurrence in Korean Young Adult Stone Patients

Ae index is an independent predictor of kidney stone recurrence in overweight and obese patients

BACKGROUND

Finding some convenient and economical indicators to initially screen overweight and obese patients at high risk of kidney stone recurrence can help them prevent stone recurrence with lower medical cost. The purpose of this article is to determine the clinical value of Ae index (Apo B × 1000/eGFR) as an independent predictor for kidney stone recurrence in overweight and obese populations.

METHODS

We queried the electronic medical records of patients with kidney stone operated at our hospital from March 2016 to March 2022, and selected BMI ≥ 25 kg/m2 as the study population and divided the patients into stone recurrence group and non-recurrence group. Relevant parameters of routine blood and biochemical test, glycated serum protein (GSP), and history of hypertension and hyperglycemia were collected. Then the Chi-square test, independent samples t-test or Wilcoxon rank-sum test were used to calculate the differences between the two groups of data. Next, we performed univariate and multivariate logistic regression analysis to screen out the most significant variables Apo B and eGFR, and then we calculated the Ae index using the formula Apo B × 1000/eGFR, and analyzed the relationship between Ae index and kidney stone recurrence.

RESULTS

Univariate analysis found that Apo B (OR:8.376,95%CI:3.093-22.680), Creatinine (OR:1.012,95%CI:1.003-1.021), Cystatin C(OR:2.747,95%CI:1.369-5.508), LDL-C (OR:1.588,95%CI:1.182-2.134), TC (OR:1.543,95%CI:1.198-1.988) were positively associated, eGFR (OR:0.980,95%CI:0.970-0.991) was negatively associated with kidney stone recurrence. And multivariate logistic regression analysis suggested that Apo B (OR:11.028, 95%CI:3.917-31.047) and eGFR (OR:0.976, 95%CI:0.965-0.988) were the most significant factors. Then we calculated Ae index and analyzed it, the sensitivity was 74.26% and the specificity was 60.00%, higher than either individual variable. Its smoothed curve revealed a non-linear relationship between them with the inflection point of 9.16. And the OR on the left side of the inflection point was 1.574 (95% CI: 1.228-2.018), whereas the OR on the right side of the inflection point was 1.088 (95% CI: 1.007-1.177).

CONCLUSIONS

Ae index is an easily calculated and obtained index that has some predictive value for kidney stone recurrence in overweight and obese patients, which is of interest.

Metabolic stone workup abnormalities are not as important as stone culture in patients with recurrent stones undergoing percutaneous nephrolithotomy

To investigate the association between metabolic urinary abnormalities and urinary tract infection (UTI) and the stone recurrence status in patients undergoing percutaneous nephrolithotomy (PCNL). A prospective evaluation was performed for patients who underwent PCNL between November 2019 and November 2021 and met the inclusion criteria. Patients with previous stone interventions were classified as recurrent stone formers. Before PCNL, a 24 h metabolic stone workup and midstream urine culture (MSU-C) were done. Renal pelvis (RP-C) and stones (S-C) cultures were collected during the procedure. The association between the metabolic workup and UTI results with stone recurrence was evaluated using univariate and multivariate analyses. The study included 210 patients. UTI factors that showed significant association with stone recurrence included positive S-C [51 (60.7%) vs 23 (18.2%), p < 0.001], positive MSU-C [37 (44.1%) vs 30 (23.8%), p = 0.002], and positive RP-C [17 (20.2%) vs 12 (9.5%), p = 0.03]. Other factors were mean ± SD GFR (ml/min) (65 ± 13.1 vs 59.5 ± 13.1, p = 0.003), calcium-containing stones [47 (55.9%) vs 48 (38.1%), p = 0.01], median (IQR) urinary citrate levels (mg/day) [333 (123-512.5) vs 221.5 (120.3-412), p = 0.04], and mean ± SD urinary pH (6.1 ± 1 vs 5.6 ± 0.7, p < 0.001). On multivariate analysis, only positive S-C was the significant predictor of stone recurrence (odds ratio: 9.9, 95% confidence interval [CI] (3.8-28.6), p < 0.001). Positive S-C, and not metabolic abnormalities, was the only independent factor associated with stone recurrence. A focus on preventing UTI might prevent further stone recurrence.

Risk factors for kidney stone disease recurrence: a comprehensive meta-analysis

Background

Kidney stone disease (KSD) is a common illness that causes an economic burden globally. It is easy for patients to relapse once they have suffered from this disease. The reported recurrence rate of KSD ranged from 6.1% to 66.9%. We performed this meta-analysis to identify various potential risk factors for the recurrence of KSD.

Methods

The PubMed, Embase and Web of Science databases were searched using suitable keywords from inception to Mar 2022. A total of 2,663 records were collected initially. After screening the literature according to the inclusion and exclusion criteria, 53 articles (40 retrospective studies; 13 prospective studies) including 488,130 patients were enrolled. The study protocol was registered with PROSPERO (No. CRD42020171771).

Results

The pooled results indicated that 12 risk factors including younger age (n = 18), higher BMI (n = 16), family history of kidney stones (n = 12), personal history of kidney stones (n = 11), hypertension (n = 5), uric acid stone (n = 4), race of Caucasian (n = 3), suspected kidney stone episode before the first confirmed stone episode (n = 3), surgery (n = 3), any concurrent asymptomatic (nonobstructing) stone (n = 2), pelvic or lower pole kidney stone (n = 2), and 24 h urine test completion (n = 2) were identified to be associated with KSD recurrence. In the subgroup analysis, patients with higher BMI (OR = 1.062), personal history of nephrolithiasis (OR = 1.402), or surgery (OR = 3.178) had a higher risk of radiographic KSD recurrence.

Conclusions

We identified 12 risk factors related to the recurrence of KSD. The results of this analysis could serve to construct recurrence prediction models. It could also supply a basis for preventing the recurrence of KSD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-022-01017-4.

Predictors of Repeat Surgery and Stone-related Events After Flexible Ureteroscopy for Renal Stones

OBJECTIVES

To evaluate the risk of repeat surgery and stone-related events after flexible ureteroscopy (fURS) for renal stones, and to identify their predictive factors.

PATIENTS AND METHODS

This was a single-center, retrospective cohort study of patients (n = 664) who underwent fURS for renal stones with or without concomitant ureteral stones between January 2012 and December 2019. The primary outcomes were time to ipsilateral stone-related surgical intervention and any stone-related event (including ipsilateral renal colic, symptomatic ureteral calculi, obstructive urinary tract infection, and surgical intervention).

RESULTS

During median follow-up of 31.1 months, 103 (15.5%) and 135 (20.3%) patients experienced surgical intervention and any stone-related event, respectively. The estimated 2-year intervention-free survival and stone-event-free survival was 86.9% and 81.6%, respectively. On Cox multivariate analysis, younger age (hazard ratio [HR] 0.96), history of stone surgery (HR 2.17), larger preoperative stone burden (HR 1.03), and larger residual fragment (HR 1.09) showed an association with future intervention. Use of the four identified risk factors (age ≤60, history of stone surgery, stone burden ≥20 mm, and residual fragment ≥4 mm) allowed stratification of patients based on the risk of future intervention (low [score: 0-1], intermediate [2], and high [3-4] risk). The estimated 2-year intervention-free survival rates in low-, intermediate-, and high-risk groups were 96.2%, 86.4%, and 71.3%, respectively.

CONCLUSION

Patients undergoing fURS are at risk of future ipsilateral surgical intervention and stone-related events. Our simple predictive tool can facilitate treatment decision-making by identifying patients who are at high risk of recurrence.

Clinical and demographic predictors of repeat stone surgery

OBJECTIVE

To identify the clinical and demographic predictors of repeat stone surgery.

MATERIALS AND METHODS

We retrospectively analysed 1496 consecutive patients, aged > 18 years, who underwent stone surgery at our institution in the period from January 2009 to May 2017 and who had at least 12 months of postoperative follow-up. We defined surgical recurrence as repeat surgery on the same renal unit or on the opposite renal unit if the original imaging did not demonstrate significant stones on that side. Characteristics associated with the risk of surgical recurrence in univariate Cox regression analysis were entered into a multivariate model.

RESULTS

Most patients underwent ureteroscopy and laser lithotripsy (83.0%). Approximately 60% of the patients had a personal history of stone disease and 50% were obese. Over a mean (median; interquartile range) follow-up of 4.1  (3.9; 2.4-5.9) years, 24.5% of patients had surgical recurrence, with 82% of repeat surgeries performed for symptomatic nephrolithiasis. The factors associated with increased risk of surgical recurrence in the multivariate model were: age <60 years, female gender, malabsorptive gastrointestinal disease, diabetes, recurrent urinary tract infections, personal history of nephrolithiasis, renal stones and bilateral nephrolithiasis. The hazard ratios for these variables ranged within an interval of <0.5 (from 1.30 to 1.71).

CONCLUSION

We identified eight demographic and clinical factors associated with increased risk of repeat renal stone surgery. These factors could be combined as a numerical count that allows stratification of patients into low-, intermediate- and high-risk subgroups.

Sodium chloride pica causing recurrent nephrolithiasis in a patient with iron deficiency anemia: a case report

Background

Iron deficiency anemia is a common finding in women of child-bearing age. Pica, or the ingestion of non-food or non-nutritive items, is a well-known manifestation of iron deficiency. A high sodium diet increases risk for nephrolithiasis. We describe the case of a 31-year-old woman with recurrent calcium nephrolithiasis and anemia who ate ice chips as well as spoons of salt daily. Treatment of pica may prove effective in preventing recurrent nephrolithiasis.

Case presentation

A 31-year-old white woman with a past medical history of menorrhagia, anemia, and recurrent calcium nephrolithiasis presented for preoperative evaluation prior to ureterolithotomy. She described a daily pattern of eating continually from a cup of ice chips accompanied by multiple spoons of salt directly out of a salt shaker. These cravings had been present for many years, were bothersome to her, and interfered with her daily life. Laboratory findings revealed hemoglobin of 10.9 g/dL with ferritin of 3 ng/mL. History, physical, and laboratory data were consistent with pica secondary to iron deficiency anemia. She was prescribed orally administered ferrous sulfate 325 mg three times a day with meals. She continues to struggle with the symptoms of pica and orally administered supplementation.

Conclusions

It is important that clinicians consider the possible diagnosis of sodium chloride pica in patients with iron deficiency anemia and recurrent nephrolithiasis. Treatment of anemia and resolution of pica may prove effective in preventing future nephrolithiasis. Specific questioning about pica symptoms in patients with iron deficiency anemia and recurrent nephrolithiasis may be helpful diagnostically and therapeutically.