Contemporary Natural History of Observed Staghorn Calculi
Britney Atwater, MD, Vernon M. Pais, Jr., MD.
Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.
Contemporary Natural History of Observed Staghorn Calculi Introduction and Objective The AUA Guidelines recommend removal of staghorn calculi in patients who are able to withstand surgical intervention. Older data report that non-operative, conservative management of staghorn calculi is associated with worse patient outcomes. The 10-year mortality for patients with staghorn stones who chose observation was 4 times higher than those that elect surgery (28% vs. 7.2%). Up to 30-70% of patients who refuse surgical intervention may develop life-threatening renal failure or sepsis from a urinary source within 6 years.However, given the frequent asymptomatic nature of staghorn calculi, some patients decline surgical intervention and, instead, choose observation. Given that the data on natural history of observed staghorn stones was reported over 40 years ago and may not represent present-day outcomes, we sought to update the existing evidence base by conducting a retrospective cohort study of patients who opted observation of their staghorn calculi.Methods A retrospective review of patients diagnosed with a staghorn calculus at our institution between 2007 and 2020 with a minimum of 1 year follow up. Patients were identified using the ICD-9 code 592 and confirming a diagnosis of a staghorn stone on CT scan. A staghorn stone was defined as a branching renal stone occupying the renal pelvis and 1 or more calyces. Data was collected regarding stone-related complications and the interval timeframe from diagnosis to complication.Results A total of 192 patients were diagnosed with a staghorn stone between 2007 and 2020. Fifty-seven (29.7%) patients fully met inclusion criteria with an average follow up of 3.8 ± 2.7 years. At the time of staghorn diagnosis, 12 (21%) patients declined intervention and elected for observation with a mean follow up of 4.4 ± 4.0 years. Of those who opted observation, 25% developed sepsis at a mean of 18 ± 10.4 months, 16.7% required urgent stent placement at a mean of 24 ± 0 months, and 8.3% progressed to renal failure at a mean of 6.0 ± 0 months. None of these patients required urgent nephrostomy tube placement. The overall mortality rate was 25% for this cohort at a mean of 4.7 ± 1.2 years (range 3.6-6 years), with no deaths due to sepsis but rather competing causes including malignancy.ConclusionsHistoric data suggests that the incidence of complications from untreated staghorn stones is relatively high; however, these studies are outdated. Our data indicates that patients who elect observation of staghorn stones have a lower risk of stone-related complications than previously reported. In our series, no mortality was directly attributable to staghorn calculi but rather competing causes. This data provides a contemporary update on anticipated natural history of staghorn in selected patients who decline surgical intervention and may allow more informed counseling.
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