Image: CC/James Heilman. Stone in kidney (arrow), CT scan.
Primer: Kidney stones are a commonly encountered clinical problem, and while there is limited evidence linking stones to the development of chronic kidney disease, this relationship remains unclear. Determining the long-term implications of kidney stones may alter how we manage patients with them.
This [retrospective] study: Just published in BMJ, authors sought to explore the excess risk of several adverse renal outcomes (i.e., end-stage renal disease, stage 3b-5 chronic kidney disease, sustained doubling of serum creatinine from baseline) associated with nephrolithiasis. Data were obtained from the Alberta Kidney Disease Network database. All adults (≥18 years) residing in Alberta, Canada between April 1997 and March 2009 were eligible for inclusion, while patients with end-stage renal disease (ESRD) and pyelonephritis were excluded. The primary outcome measured was ESRD, and two other clinically relevant outcomes were new onset stage 3b-5 chronic kidney disease (<45 mL/min/1.73 m2) and doubling of the serum creatinine.
There were 3,089,194 eligible patients. The risk of ESRD (hazard ratio 2.16; 95% CI 1.79-2.62), new stage 3b-5 chronic kidney disease (hazard ratio 1.74; 95% CI 1.61-1.88), and sustained doubling of serum creatinine (hazard ratio 1.94; 95% CI 1.56-2.43) were all significantly higher in patients with one or more kidney stones during the follow-up period. It was also found that the risk of ESRD was greater for women than men, while the risk of new stage 3b-5 chronic kidney disease and doubling of serum creatinine were higher in patients <50 years of age.
In sum: Independent of potential confounders, kidney stones were found to be associated with all three adverse renal outcomes. Given these findings, kidney stones are an important risk factor for developing any of the three adverse renal outcomes, and this risk appears to be amplified with multiple episodes of nephrolithiasis. Limitations of the study include only assessing symptomatic kidney stones and the potential for misclassification regarding the number of presentations. Absolute values, while notable, were small.
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