Estimating cost implications of potentially avoidable hospitalizations among Oncology Care Model patients with prostate cancer

Abstract

Purpose/Objectives:

We sought to estimate the expected cost savings generated if a set of potentially avoidable hospitalizations (PAHs) among oncology care model (OCM) patients with prostate cancer were shifted to an acute care model in the outpatient setting.

Methods:

We previously identified a set of 28 PAHs among OCM prostate cancer patients. Outpatient management costs for a characteristically similar cohort of cancer patients were obtained from our institution’s ambulatory acute-care Oncology Care Unit (OCU). We excluded OCU visits resulting in hospitalization, involving non-cancer diagnoses, and those missing clinical/financial information. Exact-matching based on the strata of age, categorically-defined presenting complaint, and systemic disease was used to match PAHs to OCU acute care visits. PAH costs obtained from OCM data were compared to costs from matched OCU visits.

Results:

We identified 130 acute care OCU visits, of which 47 met inclusion criteria. Twenty-four PAHs (89%) matched to 26 of these OCU visits. PAHs accounted for 5.8% of OCM expenditures during our study period. The mean inpatient cost among matched PAHs was $15,885 compared to $6,227 for matched OCU visits. Boot strapping within each match stratum produced a mean estimated cost savings of $12,151 (95% CI $10,488 to $13,814) per PAH. We estimate this per event savings to yield a 4.4% (95% CI 3.8% to 5.0%) an overall spending decrement for OCM prostate cancer episodes.

Conclusions:

PAHs contribute meaningfully to costs of care in oncology. Investment in specialized ambulatory acute care services for oncology patients could lead to substantial cost savings.

Introduction

Consistent with national trends in healthcare, expenditures in oncology continue to rise at unprecedented rates. Population-level economic studies have projected that from 2010 to 2020, total spending on cancer care in the United States will increase anywhere from 27–39%, with the most growth seen in the increasingly long-term care of patients with prostate cancer and breast cancer [1]. In response to this phenomenon, the Center for Medicare and Medicaid Innovation (CMMI) introduced the Oncology Care Model (OCM) pilot program in 2016. Tasked with driving value-based cancer care, OCM financially incentivizes participating institutions to provide higher quality care at lower costs [2]. By providing extensive Medicare claims data, OCM helps participants identify opportunities to enhance care coordination, efficiency, and outcomes in order to achieve this ultimate goal [3].

To be successful in these efforts, OCM and its participants must consider and address key cost drivers in oncology. While the proportion of total cancer care expenditures resulting from hospitalization has decreased in recent decades, hospital-based care remains a major contributor to oncology expense and thus represents an important cost-saving opportunity [4–6]. This is further supported by recent research which suggests that as many as 31% of hospitalizations involving cancer patients are potentially avoidable [7–9]. Recently, our group developed a rigorous and comprehensive two-stage consensus-driven review process to identify potentially avoidable hospitalizations (PAHs) in oncology. Our analysis ultimately found that 28% of hospitalizations in a cohort of Medicare patients with prostate cancer were potentially avoidable [10]. Though multiple studies have now shown that a substantial proportion of oncology admissions are potentially avoidable, the cost implications of these PAHs remain unknown. Addressing this important knowledge gap will be critical to catalyze the development and implementation of programs aimed at minimizing avoidable hospital care.

Our health system recently implemented one such program, the Oncology Care Unit (OCU), which is an oncology-specific urgent care center open during off-hours and weekends. This unit facilitates acute evaluation and management services that are generally beyond the capacity of most outpatient oncology centers. The development of this unit is in line with a broader national movement among academic cancer centers to provide enhanced ambulatory care services in an effort to reduce emergency room and hospital utilization [11–15]. The hope is that development of this program will reduce the rate of PAHs and thereby the cost of cancer care, while simultaneously improving patient outcomes and experience.

In this study, we compared OCM cost data from our previously identified PAHs with cost estimates from matched OCU acute care visits in order to model the potential cost savings that could result from shifting this care to the non-hospital setting.

Methods

Potentially Avoidable Hospitalizations (PAHs)

We previously characterized a group of 28 PAHs among Medicare patients with prostate cancer, which occurred in our health system between January 2012 and June 2015. Our methodology has been previously described in detail [10]. In brief, PAHs were identified using a two-stage, consensus-driven review process wherein two clinicians first independently evaluated each hospitalization using a standardized case review form. This form was modified from an assessment tool used in prior, similar studies and was designed to efficiently and reliably identify PAHs based on previously validated clinical criteria [7, 16]. In the second stage of review, all cases where the initial reviewers disagreed or where either reviewer felt further discussion was warranted were reviewed in a larger committee setting to generate a consensus determination regarding avoidability. Patient and clinical characteristics for each PAH were recorded at the time of chart review.

Cost data were obtained for each PAH via our participation in OCM. As these admissions each occurred up to seven years prior, all costs were trended to 2019 dollar amounts. Those PAHs with incomplete financial data were excluded from this analysis.

Comparison Cohort: Oncology Care Unit (OCU) Visits

OCU acute care visits were compiled from May 2017 to October 2018 as a comparison cohort for estimating the expected costs of non-hospital treatment for each PAH. OCU encounters were prospectively classified as ‘sick’ (acute care) or ‘non-sick’ by the triaging nurse based on the reason for presentation. Each OCU visit was thereafter reviewed by a committee of three physicians (a radiation oncology resident [W.H.S], a hematology/oncology fellow [A.B.P], and an attending radiation oncologist [K.D.]). Visits involving non-malignant diagnoses (e.g. benign hematologic conditions), those resulting in subsequent hospitalization, those with missing clinical documentation, and those unanimously deemed to have been erroneously classified as ‘sick’ visits based on clinical documentation were excluded from the comparison cohort. Cases wherein a patient was seen in the OCU multiple times for the reasonable and ongoing management of a single presenting complaint were considered as a single episode.

Clinical and demographic data for each OCU acute care visit were abstracted from electronic medical record review. The reason for each OCU visit was further classified based on committee review of clinic and treatment notes into one of four categories: (1) need for infusion/transfusion or observation, (2) asymptomatic laboratory abnormalities, (3) cancer symptom (e.g. pain) control, or (4) diagnostic work-up (e.g. infectious work-up). In cases where multiple reasons for OCU visit were identified, the single predominant reason as determined by the judgment of the review committee was selected. Each PAH was similarly classified into one of these four categories using reason for admission.

Cost estimates for each OCU visit were obtained from billing data available from our financial department. All bills were repriced to 2019 Medicare rates. In recognition that oftentimes management would include both care delivered in the OCU and in subsequent follow-up visits, an OCU event cost was estimated for each visit including all costs associated with the 8-day interval beginning on the date of the OCU visit. This interval length was chosen to match the average length of admission among our PAHs cohort (7.8 days). While OCU visits resulting in immediate (i.e. same day) hospitalization were excluded, any inpatient admissions, and their associated costs, were included in our estimates if they otherwise occurred within 8 day interval defining our follow-up period. Cases where complete financial data were not available were excluded from consideration.

Statistical Analysis

Descriptive analysis was performed to compare the demographic and clinical characteristics of PAHs and OCU visits before and after matching. For continuous variables, the mean (standard deviation) was reported; for categorical variables, the frequencies and percentages were presented.

Median costs for potentially avoidable and unavoidable hospitalizations were compared by the Wilcoxon rank sum test. Exact matching was used to match previously identified PAHs to OCU acute care visits based on strata of categorical form including: (1) age (≤ 70 years vs. > 70 years), (2) reason for visit (as described above), and (3) the presence of systemic disease (defined as metastatic disease or hematologic malignancy). Inpatient costs for matched PAHs and unmatched PAHs were compared using the Wilcoxon rank sum test; costs from matched OCU events were likewise compared with costs from unmatched OCU visits. Mean potential cost savings and 95% confidence intervals (CI) from transitioning inpatient PAH care to the ambulatory OCU setting were estimated by bootstrapping 20 times within each matched stratum and weighted by counts in each stratum.

Results

As previously reported, we initially identified a group of 160 hospital admissions involving 210 Medicare patients with prostate cancer. Of these, 28 of an evaluable 99 were found to be potentially avoidable by our two stage consensus driven review process [10]. As one PAH had incomplete financial data and was excluded, a cohort of 27 PAHs were eligible for matching. The mean cost per PAH was $15,885 (95% CI $11,871 – $19,899) as compared to $20,370 (95% CI $17,080 – $23,659) for unavoidable hospitalizations (p = 0.015). The average total cost per episode during this same period was $33,002 with PAHs accounting for 5.8% of total OCM expenditures during our study period.

For our comparison cohort, we identified 3,435 OCU visits occurring between May 1, 2017 and October 31, 2018. Of these 130 were prospectively labeled as sick (acute care) visits at the time of encounter. Three of these represented return visits relating to another OCU acute care visit and were included in the follow-up period for the original OCU encounter, as described above. Excluding those OCU visits resulting in hospitalizations (n=46), involving non-cancer patients (n=27), with missing financial data (n=3) or clinical documentation (n=1), and unanimously felt on committee review to have been erroneously classified as sick visits (n=3) produced a comparison cohort with 47 OCU visits. This is illustrated in Figure 1. Patient characteristics for both our PAH and OCU cohorts are detailed in Table 1.

Figure 1. CONSORT Diagram:

Details of patients ultimately included in the PAH and OCU cohorts. Abbreviations: CONSORT = Consolidated Standards of Reporting Trials.

Table 1:

Patient characteristics for PAHs and OCU acute care visit cohorts.

Characteristic	Total		Matched
	PAHs (n=27)	OCU (n=47)	PAH (n=24)	OCU (n=26)
Age in years, mean	74.1 yrs	61.5 yrs	73.0 yrs	65.6 yrs
> 70 yrs	20 (74%)	12 (26%)	17 (71%)	11 (42%)
≤ 70 yrs	7 (26%)	35 (74%)	7 (29%)	15 (58%)
Sex
Male	27 (100%)	27 (57%)	24 (100%)	12 (46%)
Female	0 (0%)	20 (43%)	0 (0%)	14 (54%)
Diagnosis
Prostate Cancer	27 (100%)	1 (2%)	24 (100%)	1 (4%)
Non-Prostate Solid Malignancy	0 (100%)	20 (43%)	0 (100%)	8 (31%)
Hematologic Malignancy	0 (0%)	26 (55%)	0 (0%)	17 (65%)
Disease Status
Localized Disease	3 (11%)	10 (21%)	0 (0%)	0 (0%)
Systemic Disease*	25 (89%)	37 (79%)	24 (100%)	26 (100%)
Reason for Presentation**
Transfusion/Infusion or Observation	5 (19%)	14 (30%)	5 (21%)	12 (46%)
Lab Abnormalities	2 (7%)	14 (30%)	2 (8%)	3 (12%)
Symptom Management	15 (56%)	13 (28%)	13 (54%)	10 (38%)
Diagnostic Work-Up	5 (19%)	6 (13%)	4 (17%)	1 (4%)

Abbreviations: PAH = potentially avoidable hospitalization; OCU = oncology care unit; yrs = years.

^*Systemic disease defined as metastatic solid malignancy or hematologic malignancy

^**In cases where there were multiple reasons for presentation, the single most predominant reason was chosen.

Our exact matching algorithm successfully matched 24 (89%) of our PAHs to 26 OCU acute care visits within 6 matching strata. Example clinical vignettes from matched PAHs and OCU visits are shown in Table 2. The mean cost per matched PAH was $16,375; there was no difference in the cost between matched and unmatched PAHs (p = 0.743). Comparatively, mean total cost per matched OCU event was $6,227; likewise there was no difference between the cost of matched versus unmatched OCU visits (p = 0.246). Figure 2 shows a cost histogram for all PAHs and OCU acute care visits (Figure 2a) and for matched PAHs and OCU visits alone (Figure 2b). Boot strapping within each matched stratum produced a mean estimated cost savings of $12,151 (95% CI $10,488 to $13,814) per PAH. Translating our previously determined 28% PAH rate across all 160 hospitalizations, we predict this difference would result in a 4.4% (95% CI 3.8%−5.0%) spending decrement per OCM episode.

Table 2:

Selected clinical vignettes and costs from matched PAHs and OCU visits

PAH Cost	PAH Vignette	OCU Vignette	OCU Cost
$12,067	A 79 year old man with a history of metastatic prostate cancer receiving carboplatin. The patient was directly admitted to the inpatient unit for chemotherapy infusion under observation.	A 79 year old man with a history of metastatic prostate cancer with known anemia of chronic disease. He was seen in the OCU for scheduled RBC transfusion and erythropoietin injection.	$1,843
$10,339	A 65 year old man with metastatic prostate cancer who presented with fatigue in the context of hyponatremia and anemia. Both were responsive to minimal hydration and simple transfusion upon admission.	A 58 year old woman with appendiceal mucinous tumor with pseudomyxoma peritonei who presented to the OCU with fatigue and hypotension after CBC demonstrated a hemoglobin of 7.0. She received 2 units of packed RBCs.	$1,329
$9,404	A 62 year old man a history of metastatic prostate cancer who presented with worsening musculoskeletal pain due to metastatic disease in the context of intolerance of his opioid pain regimen. He was admitted for pain control.	A 54 year old woman with breast cancer who presented with back pain and nausea/vomiting in the context of hypercalcemia. She was seen in the OCU for pain control with IV morphine and hydration.	$620
$12,056	A 75 year old man with metastatic prostate cancer and known AVMs who presented with lightheadedness in the context of self-resolving hematochezia. He was admitted for work-up and underwent EGD (showing known AVMs) and colonoscopy.	A 73 year old man with multiple myeloma who presented with fever and diarrhea shortly after receiving daratumumab infusion. He was seen for infectious work-up and IV hydration.	$912

Abbreviations: PAH = potentially avoidable hospitalization; OCU = oncology care unit; RBC = red blood cell; CBC = complete blood count; IV = intravenous; AVMs = arteriovenous malformation; EGD = esophagogastroduodenoscopy

Figure 2. Cost Histogram:

Frequency of costs for both matched and unmatched PAHs and OCU acute care visits (2A) and for matched PAHs and OCU acute care visits alone (2B).

Discussion

Hospital care remains an important driver of healthcare expenditures among oncology patients and PAHs account for a sizable portion of inpatient admissions in this population [7–10]. However, the cost implications of PAHs among such patients and the potential savings that could result from alternative care models remain poorly understood. To our knowledge, this study represents the first effort to account for the cost implications of PAHs in oncology and to estimate the potential cost savings that would result from avoiding these PAHs through enhanced outpatient care.

Based on our matching algorithm, we estimate that shifting inpatient care from these PAHs to the outpatient setting would have generated over $12,000 in cost savings per hospital admission. It is notable that these savings are reflective of all ambulatory costs over the 8-day period following an OCU acute care visit. This approach was undertaken in recognition that management of acute conditions frequently took place over several days and across multiple settings (e.g. OCU, oncology clinic, radiology department). Rather than attempt to retrospectively categorize each element of subsequent care as attributable or not attributable to the initial OCU visit, we felt it more comprehensive and unbiased to simply include all costs in our estimate. As a result, our cost savings estimate is likely conservative, with the actual financial savings potentially higher than we report.

Beyond the economic implications of avoiding unnecessary hospitalizations, investment in specialized ambulatory acute care services offers a more patient-centric approach that may improve clinical outcomes and patient satisfaction. Inpatient hospitalization is well documented to be associated with adverse outcomes in cancer patients, including increased psychologic distress, delirium, physical pain, iatrogenic complications, and post-hospital functional disability [17–19]. Preventing PAHs through the development of expanded outpatient services may therefore help avoid these adverse outcomes as well as any associated secondary costs. At the hospital level, reducing PAHs may additionally free up much needed resources for care during unavoidable hospitalizations.

While we found the cost per PAH to be significantly lower than that of unavoidable hospitalizations, PAHs nonetheless contributed meaningfully to the total costs of care over our study period. Indeed, between January 2012 and June 2015, PAHs accounted for an estimated 5.8% of total OCM prostate cancer expenditures in our cohort. The observed cost differential between PAHs and unavoidable hospitalizations is not surprising and is likely representative of inherent dissimilarities between these groups including differences in acute care needs, likelihood of admission to a monitored unit, and need for invasive procedure, among other characteristics. This observation is moreover consistent with data from non-cancer patients as well [20].

While we were careful to match PAHs to OCU acute care visits based on those characteristics felt to be most clinically significant, there remained considerable differences between these cohorts even after matching. Most notably, while our PAH cohort included only patients with prostate cancer (given our initial study population), there was significant heterogeneity in the primary disease sites of our comparison OCU cohort. Despite this, the presenting complaints of PAH and OCU patients alike were largely those common to cancer patients across disease sites including pain, dehydration, failure to thrive, and infection. As these cancer-related conditions (rather than the specific cancer) were central to directing acute care during PAHs and OCU visits, we believe matching on this basis nonetheless proved to be appropriate and valuable. Additionally, our modeled cost savings presupposes that all PAHs among prostate cancer patients could be prevented through the provision of enhanced ambulatory acute care services. However, it remains to be seen whether this will indeed be the case. Should these services bear no impact on the rate of PAHs, we may see an inadvertent rise in OCM costs as patients receive both enhanced outpatient and continued inpatient care. The real effect of outpatient acute oncology care on the rate of PAHs in cancer patients remains unknown and is an area of ongoing research.

In summary, we found that PAHs represent a meaningful proportion of dollars spent caring for OCM patients with prostate cancer. Given the numerous adverse effects of unnecessary hospitalization among cancer patients, prevention of PAHs offers an attractive opportunity to simultaneously reduce healthcare expenditures and improve patient outcomes and satisfaction. Investment in specialized ambulatory acute care services for cancer patients could lead to meaningful cost savings by shifting avoidable inpatient care to the outpatient setting. We project that shifting such care could result in a mean cost savings of at least $12,000 per PAH. Additional research investigating the effect of oncology-specific ambulatory acute care services on the rate and associated costs of PAHs is needed to verify these estimates.

Highlights.

• Potentially avoidable hospitalizations (PAH) represent a cost savings opportunity.

• Unavoidable hospitalizations were more costly than PAHs

• PAHs accounted for 5.8% of total oncology care model expenditures.

• Shifting PAHs to the ambulatory setting may result in significant cost savings.