Predictors and Cost Comparison of Subsequent Urinary Stone Care at Index versus Non-Index Hospitals. - Beyond the Abstract

Care fragmentation can be collectively defined as either the engagement of separate health care systems or repeated presentations to the same health system owing to poor care coordination along a patient’s continuum of care for a specific disease process. Care fragmentation is common post-operatively, with 22-33% of patients being re-admitted to non-index hospitals—defined as hospitals where patients did not have their primary surgery—and can negatively affect patient outcomes, including mortality, longer length of stay, and increased risk of re-admission.1-3 Nephrolithiasis is an increasingly prevalent and costly disease worldwide and, given its relapsing/remitting nature, is prone to fragmented acute care presentations that can sometimes span months.Our objective for this study was to examine the effects of care fragmentation on patients with urinary stone disease.

All-payer data from the 2016 Healthcare Cost and Utilization Project (HCUP) State Databases from Florida (FL) and New York (NY) were used to identify a cohort of adult patients who initially presented to an emergency department with a diagnosis of urolithiasis and subsequently re-presented to an index or non-index hospital for renal colic and/or urological intervention. A hospital was determined to be an index facility if it represented the same hospital where the patient experienced their initial ED encounter, whereas a hospital was determined to be a non-index facility if it differed from the initial ED encounter hospital. Patient demographics, regional/facility level data, and procedural information were collected, and 30-day episode-based costs were calculated. Multivariable logistic and gamma generalized linear regression were utilized to identify predictors of receiving subsequent care at an index hospital and associated costs, respectively.

Of the 33,863 patients who experienced a subsequent encounter related to nephrolithiasis, 9,593 (28.3%) received care at a non-index hospital. Receiving subsequent care at the index hospital was associated with fewer acute care encounters prior to surgery (2.5 vs. 2.7; p <0.001) and fewer days to surgery (29 vs. 42; p < 0.001). In multivariable analysis, predictors of receiving subsequent care at an index hospital included increasing Elixhauser Comorbidity Score, the presence of renal insufficiency, and unspecified non-white racial status. Conversely, factors associated with not receiving subsequent care at an index hospital included undergoing subsequent surgical intervention, having Medicare vs. private insurance, living in a rural area, and having an initial encounter at a minority serving hospital.

Total episode-based costs were higher in the non-index setting, with a mean difference of $783 (Non-index: $13,672, 95% CI $13,292 - $14,053; Index: $12,889, 95% CI $12,677 - $13,102; p < 0.001). This difference in episode-based costs persisted even after accounting for the initial episode of stone-related care, which was on average $899 higher among individuals who received subsequent care from an index vs. non-index hospital (Non-index: $4,762, 95% CI $4,554 - $4,969; Index: $5,661, 95% CI $5,536 - $5,785; p < 0.001).

FIGURE 1. Total episode-based costs for an initial emergency department visit for nephrolithiasis and subsequent encounters in the index and non-index setting.

Our findings demonstrate that care fragmentation for patients with urinary stone disease is a common and costly occurrence with nearly 1/3 of patients experiencing a subsequent health care encounter in a non-index hospital setting. Our cohort is unique in that it reflects patients who are largely in the pre-operative setting for a likely outpatient surgery, or who may not need surgical intervention at all. In fact, greater than 90% of patients who present to the emergency department with renal colic are discharged without intervention, and only a small portion, around 17%, end up requiring definitive surgery by 60 days.5 With these low rates of admission and intervention in mind, our findings demonstrate that there is a potential opportunity for improved outpatient care coordination which could target and prevent avoidable use of emergency services and duplicated workups at different hospitals.

One of the more notable predictors was insurance status, with the privately insured experiencing lower rates of care fragmentation. Our data, along with others in the literature, raises concern for system-level inequities and supports the idea that underserved populations receive fragmented, and subsequently lower value, care. Current evidence suggests market consolidation raises prices for medical care and is implicated as a driving factor for price discrimination, which is a hospital system’s attempt to care for and retain more privately funded patients as they often result in higher reimbursement rates.6 While our data is not granular enough to dive into specific hospital or patient driven motives, our data did show a predilection for patients with private insurance to present to index settings, which could represent hospitals selectively targeting these higher reimbursing patients.

Lastly, we observed that patients who presented to non-index hospitals accrued significantly higher total episode-based costs than patients who remained with their index hospital even though initial stone-related encounters were more costly for patients in the index cohort. Patients with renal colic are some of the most frequent presenters to the emergency department and rates of CT scan are greater than 90% despite the previously mentioned low rates of admission and intervention.7 This excessive use of resources in combination with the delays in intervention and increased acute care encounters shown in our study demonstrates that renal colic patients who experience fragmented care are at risk for costly duplicated workup, which often provides little benefit and rarely alters the course of clinical care.

In conclusion, fragmented care following an initial diagnosis of renal colic is associated with a greater number of health encounters, longer time to definitive surgery, and increased costs. Owing to the increasing incidence and cost burden of urinary stone disease within the US, care fragmentation experienced by patients with renal colic warrants the attention of ongoing value-based care initiatives. These interventions are likely to both improve patient experience and episode-based spending, especially among vulnerable populations.

Written by: William W. French MD & David F. Friedlander, MD, MPHDepartment of Urology, University of North Carolina Medical Center, Chapel Hill, NC, USA


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