Highlights
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We present a time-driven activity-based costing analysis of neuroimaging pathways.
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Outpatient pathway offered a 20% cost reduction compared with the ED.
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Outpatient pathway reduced imaging visit time from ∼6 to 2 hours.
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Lower personnel and facility utilization drove outpatient pathway cost savings.
Objective
To compare the costs and efficiency of an outpatient STAT neuroimaging pathway against traditional emergency department (ED)-based neuroimaging for patients with optic disc edema.
Design
Retrospective cost analysis using time-driven activity-based costing (TDABC) methodology.
Subjects
One-hundred twenty-nine patients with optic disc edema, seen at the Wilmer Eye Institute, underwent expedited neuroimaging between November 2018 and February 2024.
Methods
We identified patients who received neuroimaging for optic disc edema either through the ED or a dedicated outpatient STAT neuroimaging pathway implemented in November 2020. Process maps were developed for each pathway. TDABC methodology was used to calculate the cost of personnel, equipment, facilities, and consumables based on resource-specific capacity cost rates and time utilization data extracted from the electronic medical record and staff interviews.
Main Outcome Measures
The primary outcome was the total cost of neuroimaging via the STAT outpatient versus ED pathway. Secondary outcomes included total visit duration and the distribution of costs across different resource categories.
Results
The outpatient STAT pathway was significantly less costly than the ED pathway. The median total cost per patient was $285 for the STAT pathway compared with $355 for the combined ED pathway ( P <.001), representing a 20% cost reduction. This savings was primarily driven by lower personnel ($154 vs $220; P <.001) and facilities costs ($1.30 vs $6.70; P <.001). The median imaging visit duration was 70% shorter in the STAT pathway (1.93 hours) compared with the ED (6.47 hours; P <.001). This time difference was largely attributable to the pre-MRI phase, which was over 20 times shorter in the outpatient setting (0.22 vs 4.80 hours; P <.001).
Conclusions
An outpatient STAT neuroimaging pathway is a cost- and time-saving alternative to the ED for expedited neuroimaging in select patients presenting with optic disc edema. The novel use of TDABC methodology in this setting allowed for an unbiased assessment of healthcare costs, independent of local reimbursement structures or payor variability. Additionally, a detailed process map of the imaging workflow facilitated identification of inefficiencies. Together, these methods provide a reliable framework to optimize care pathways, substantially reduce healthcare costs, and alleviate burden on EDs.
Introduction
O ptic disc edema can indicate a range of vision- or life-threatening conditions, including elevated intracranial pressure, infiltrative or inflammatory disorders, ischemic optic neuropathy, infectious diseases, toxic or metabolic disorders, and compressive lesions. About 62% to 76% of patients with optic disc edema exhibit neuroimaging abnormalities, , underscoring the need for prompt neuroimaging. However, growing demand for imaging over the last two decades has strained access to urgent studies, ,,,,, leaving the emergency department (ED) as the primary option for expedited neuroimaging in many areas. This growing reliance on ED-based neuroimaging presents several challenges. EDs frequently face high patient volumes, which not only delay services but also heighten costs, compromise care quality, and accentuate systemic inefficiencies. , Moreover, emergency care can exacerbate health disparities, as patients from minoritized racial, ethnic, and language groups frequently experience longer wait times, lower triage acuity, inadequate pain management, and fewer diagnostic tests, leading to worse clinical outcomes and increased risk of missed or delayed diagnoses. ,,, These disparities can be further exacerbated during periods of high imaging demand. Additionally, many ED providers may lack familiarity with ophthalmic care, and the majority of eye-related visits do not constitute true ocular emergencies. , These factors underscore the importance of developing alternative pathways for patients who require urgent, but not emergent, care. Alternative pathways, such as diverting patients to same-day ophthalmology clinics, have shown promising results by offering faster and more cost-effective care. ,
To address these challenges, our institution developed an outpatient STAT neuroimaging pathway for patients presenting with optic disc edema and other neuro-ophthalmic conditions. This initiative was designed to alleviate ED congestion and ensure patients receive expedited neuroimaging in a setting better aligned with their clinical needs. In this study, we employ a time-driven activity-based costing (TDABC) methodology to provide a granular, real-world cost analysis of this pathway compared with traditional ED-based neuroimaging. By delineating both the economic and operational impacts of these two approaches, we aim to inform practice improvements that optimize resource utilization and enhance care of patients with neuro-ophthalmologic conditions.
METHODS
This study was a retrospective economic analysis comparing an outpatient STAT neuroimaging pathway vs conventional ED-based neuroimaging for patients with optic disc edema at a quaternary care center. The study was approved by the Institutional Review Board of the Johns Hopkins University School of Medicine and complied with the Declaration of Helsinki.
Patients were retrospectively identified through an electronic medical record (EMR) query for those presenting with papilledema (codes H47.1 and H47.11 of the International Classification of Diseases, Tenth Revision) who underwent at least one neuroimaging scan (MRI skull base, MRI brain with contrast, MRI brain without contrast, or MRI orbits with contrast) between November 1, 2018 and February 6, 2024. This timeframe was chosen to include patients both before and after the implementation of the STAT neuroimaging pathway, which began on November 1, 2020. Patients were assigned to their respective neuroimaging pathways at the discretion of their treating neuro-ophthalmologist as part of their routine clinical care. Charts were manually reviewed to confirm eligibility, including neuroimaging ordered for “STAT” outpatient completion or ED referral for emergent neuroimaging, before performing manual data extraction.
The TDABC methodology, developed by Kaplan and Anderson, was applied to determine the overall cost of each pathway, using the following steps:
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Process mapping. Clinical flow diagrams were developed through close collaboration with our neuroradiology division and ED to delineate each step in the STAT pathway and ED care cycle ( Figure ).
FIGURE Process map for neuroimaging via (A) the STAT neuroimaging outpatient pathway and (B) the emergency department (ED), depicting resources used in every activity of these care cycles. The ED pathway was artificially cut-off after MRI completion to exclude any nonimaging related activities.
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Capacity cost rates. Cost estimates were computed for each resource category including personnel, equipment, facilities, and consumables. The total cost of each resource was gathered using recent regional salary data and interviews with vendors and internal administrative personnel regarding square footage, purchasing, maintenance, construction, and unit costs. These total costs were then divided by their respective practical capacity (ie, the total available working minutes), to yield a monetary value per hour for each resource (Supplemental Table 1).
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Time data . To estimate the duration of each activity, timestamps were collected from the EMR, including the time of patient arrival, triage start and end, IV order and placement, MRI scan start and end, and final MRI interpretation. For tasks without documented times, such as the duration of emergency physician consultation, transport to and from MRI, pre-MRI preparation (form completion and donning gowns), MRI interpretation, and discharge from the facility, average durations were derived from consultations with departmental supervisors and frontline staff. For ED visits, an artificial 30-minute cut-off was applied after MRI completion to exclude any nonimaging related activities that may have followed the MRI (eg, lumbar puncture, admission for interventional or surgical treatments, etc.).
The main outcome of interest was the difference in total costs associated with the STAT pathway vs ED-based neuroimaging. Secondary outcomes included imaging visit length, pre- and post-pathway differences in ED costs, and distribution of time and costs within each care cycle. Descriptive statistics were used to summarize demographic and clinical variables. Sex was defined by that recorded in the electronic medical record of each patient. Group comparisons were performed using the Wilcoxon rank-sum test for continuous variables and the Chi-square test or Fisher’s exact test (if n < 5) for categorical variables, assuming a P -value of less than.05 for statistical significance. Statistical comparisons focused on STAT vs ED Combined (combining all ED patients seen pre- and postimplementation of neuroimaging pathway) and STAT vs ED Postimplementation groups. All analyses were conducted in MATLAB (MathWorks, Natick, MA).
RESULTS
A total of 129 patients with optic disc edema who underwent expedited neuroimaging were included. Of these, 37 (29%) were evaluated through the outpatient STAT pathway and 92 (71%) through the ED pathway. Within the ED group, 33 (36%) were seen before the STAT pathway was implemented (ED Prepathway) and 59 (64%) after (ED Postpathway).
These groups differed in several baseline characteristics ( Table 1 ), likely reflecting the clinical triage criteria used by treating neuro-ophthalmologists to select the most appropriate imaging pathway. Patients in the STAT outpatient pathway were older than those in the ED Postpathway subgroup (median age 38.8 vs 28.9 years, P =.035). The outpatient cohort had a significantly higher body mass index (BMI) compared with the combined ED group (mean 38.5 vs 32.2 kg/m 2, P =.003). There were no significant differences in the distribution of sex, race, or ethnicity between the pathways.
TABLE 1
Presenting Characteristics of Patients Imaged Through the Outpatient STAT Pathway vs the Emergency Department.
| Outpatient STAT Pathway | Emergency Department | Total | P -value (STAT vs ED Post) | P -Value (STAT vs ED) | |||
|---|---|---|---|---|---|---|---|
| Prepathway | Postpathway | Combined | |||||
| n | 37 | 33 | 59 | 92 | 129 | ||
| Age (years), median [IQR] | 38.8 [24.6, 52.7] | 30.4 [20.8, 52.9] | 28.9 [22.3, 38.6] | 29.9 [22.1, 44.4] | 31.1 [22.5, 50.1] | .035 | .051 |
| Sex, n (%) | |||||||
| Female | 32 (86.5%) | 21 (63.6%) | 45 (76.3%) | 66 (71.7%) | 98 (76.0%) | .221 | .076 |
| Race, n (%) | .957 | .690 | |||||
| White | 15 (40.5%) | 20 (60.6%) | 26 (44.1%) | 46 (50.0%) | 61 (47.3%) | – | – |
| Black or African American | 19 (51.4%) | 11 (33.3%) | 28 (47.5%) | 39 (42.4%) | 58 (45.0%) | – | – |
| Asian | 1 (2.7%) | 0 | 1 (1.7%) | 1 (1.1%) | 2 (1.6%) | – | – |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 1 (1.7%) | 1 (1.1%) | 1 (0.8%) | – | – |
| Other/Unknown | 2 (5.4%) | 2 (6.1%) | 3 (5.1%) | 5 (5.4%) | 7 (5.4%) | – | – |
| Ethnicity, n (%) | |||||||
| Hispanic or Latino | 2 (5.6%) | 2 (6.1%) | 3 (5.1%) | 5 (5.4%) | 7 (5.5%) | 1.000 | 1.000 |
| BMI (kg/m²), mean ± SD | 38.5 ± 11.7 | 31.1 ± 6.4 | 32.8 ± 8.7 | 32.2 ± 8.0 | 33.9 ± 9.5 | .013 | .003 |
| Visual acuity (logMAR), median [IQR] | |||||||
| Right eye | 0.1 [0, 0.2] | 0 [0, 0.2] | 0.1 [0, 0.5] | 0.1 [0, 0.3] | 0.1 [0, 0.2] | .248 | .615 |
| Left eye | 0.1 [0, 0.2] | 0.1 [0, 0.2] | 0 [0, 0.5] | 0 [0, 0.4] | 0 [0, 0.3] | .491 | .580 |
| Mean deviation (dB), median [IQR] | |||||||
| Right eye | −1.9 [−3.8, −0.5] | −1.7 [−3.7, −0.4] | −5.6 [−19.1, −2.4] | −3.5 [−10.0, −1.1] | −2.9 [−6.7, −0.9] | .002 | .081 |
| Left eye | −2.1 [−4.3, −1.3] | −3.5 [−8.5, −1.8] | −6.5 [−12.4, −2.3] | −3.9 [−11.0, −2.0] | −3.4 [−8.4, −1.8] | .003 | .008 |
| RNFL thickness (μm), median [IQR] | |||||||
| Right eye | 158 [126, 185] | 149 [101, 253] | 179 [122, 271] | 160 [119, 264] | 158 [119, 234] | .162 | .361 |
| Left eye | 148 [120, 176] | 145 [96, 225] | 148 [101, 247] | 145 [100, 243] | 145 [105, 223] | .901 | .768 |
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