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Effect of Core Preventative Screening on Kidney Stone Surgical Patterns - Beyond the Abstract

Stone disease, or urinary system calculi, is a broad disease and usually presents with acute kidney colic and intractable pain, leading to patients presenting to the emergency department (ED) for acute management. In the acute setting, stone disease can be surgically managed in multiple ways depending on disease severity and the presence of hydronephrosis.

Ureteroscopy (URS) is usually the standard of care for surgical removal of stones (≤20mm in non-lower poles and ≤10mm in lower poles) and comprises passing a scope via the urethra to endoscopically remove the stone.1 Shock wave lithotripsy (SWL) uses high-energy pulses to physically break down stones into smaller particles which are then passed by the patient. SWL has similar indications to that of URS but given that it is less invasive, it has a lower morbidity and complication rate.1 Percutaneous nephrolithotomy (PNL), on the other hand, is more invasive kidney stone surgery and is used for more severe cases or when refractory to SWL and URS therapies. PNL involves surgically accessing the kidneys and removing the stone via a new tract from the kidney to the patient’s skin.1 While multiple patient-level factors such as socioeconomic factors, disease severity, and stone locations have been implicated in initial surgical intervention, literature to date has underexplored the role of community-wide preventative screening in kidney stone disease. In this study, we found that core preventative screening and overall surgical frequency (i.e. the number of stone surgeries) directly correlated with the type of initial surgical intervention (URS vs. SWL vs. PNL). Communities with a higher prevalence of preventive screenings were associated with more SWL (prevalence: 23.5% in the low screening group vs. 34.2% in the high screening group) and with fewer PNL (prevalence: 4.7% in the low screening group vs. 3.0% in the high screening group) over a period of five years

Studies have shown that SWL has the lowest postoperative stone-free rates (SFR). Three-month postoperative SFR is 90.8% for PNL, 75.3% for URS, and 64.7% for SWL.2 This phenomenon may explain the observed lower frequency of PNL which may be due to their superior stone-free rates. However, intent to treat with PNL indicates higher stone complexity and possibly increased stone burden, indicating other factors at play that mediate the observed effect between surgery type and surgical frequency. Formal analysis of such pathways using mediation analysis showed that the effect of core preventative screening on surgical frequency can be indicated largely through rates of SWL and PNL. This explains that the initial surgical intervention, mostly influenced by intent to treat, explains the observed association between core preventative screening and surgical frequency. We hypothesize that this association may be due to increased access to healthcare in patients receiving preventative screening. Core preventative screening can be a reasonable proxy for primary care visits and utilization as primary care is involved in managing uncomplicated nephrolithiasis, both in prevention and early referral to urological care which may explain increased surgical frequency albeit with less invasive surgeries given early detection of less complicated stone cases.

Since uncomplicated nephrolithiasis management is within the scope of practice of primary care physicians,3 differences in primary care utilization across certain demographics may provide an explanation for the findings on how PNL rates differ. One explanation is that reduced primary care utilization could affect the timing of specialized urological care, and patients with reduced access may present with more complicated disease warranty PNL as their initial surgery. Whereas, patients with adequate primary care access could either be triaged appropriately for less invasive surgery or treated conservatively with measures prescribed by stone clinics with diet and hydration.4 This further implications for marginalized communities with historically less access to primary care such as communities with higher rates of African American and Hispanic populations.5,6,7 This was also observed in this study in that the Hispanic race, counter-intuitively was associated with lower surgical frequency, however, the Hispanic race along with the African American race was associated with increased PNL prevalence.

Future studies that stratify patients by their primary care utilization and proactively observe the patient for the development of complicated vs. uncomplicated nephrolithiasis and surgery required to address the disease may further clarify this association.

Written by:

  • Chibuzor Nwachukwu, Fellow, WACP (Family Medicine), Federal Medical Centre, Umuahia, Abia, Nigeria
  • Sudarshan Srirangapatanam, University of Central Florida, College of Medicine, Orlando, FL
  • Linda Guan, University of Central Florida, College of Medicine, Orlando, FL
  • Caroline Baughn, University of Central Florida, College of Medicine, Orlando, FL
  • Hubert S. Swana, University of Central Florida, College of Medicine, Orlando, FL, Department of Urology, Orlando Health, Orlando, FL
  • David B. Bayne, University of California, San Francisco, San Francisco, CA
References:

  1. Assimos D, Krambeck A, Miller NL, et al. Surgical Management of Stones: American Urological Association/Endourological Society Guideline, PART II. Journal of Urology. 2016;196(4):1161-1169.
  2. Yuri P, Hariwibowo R, Soeroharjo I et al (2018) Meta-analysis of Optimal Management of Lower Pole Stone of 10–20 mm: flexible ureteroscopy (FURS) versus extracorporeal shock wave lithotripsy (SWL) versus Percutaneous Nephrolithotomy (PNL). Acta Med Indones 50(1):18–25
  3. Fontenelle, Leonardo Ferreira, and Thiago Dias Sarti. “Kidney Stones: Treatment and Prevention.” American family physician vol. 99,8 (2019): 490-496.
  4. Carvalho M, Ferrari AC, Renner LO, Vieira MA, Riella MC (2004) Quantificação do stone clinic effect em pacientes com nefrolitíase Quantification of the stone clinic effect in patients with nephrolithiasis. Rev Assoc Med Bras 50(1):79–82.
  5. Williams, D R, and T D Rucker. “Understanding and addressing racial disparities in health care.” Health care financing review vol. 21,4 (2000): 75-90.
  6. Bayne DB, Usawachintachit M, Armas-Phan M et al (2019) Influence of socioeconomic factors on stone burden at presentation to tertiary referral center: data from the registry for stones of the kidney and ureter. Urology 131:57–63.
  7. Scales CD Jr, Smith AC, Hanley JM, Saigal CS (2012) Urologic diseases in America project prevalence of kidney stones in the United States. Eur Urol 62(1):160–165.
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