The One-Year Attributable Cost of Post-Stroke Aphasia

Abstract

Background and Purpose

Little is known about the contribution of aphasia to the cost of care for patients who experience stroke.

Methods

We retrospectively examined a cohort of South Carolina Medicare beneficiaries who experienced an ischemic stroke in 2004 to determine the attributable cost of aphasia. Univariate analyses were used to compare demographic, comorbidity, and severity differences between individuals with post-stroke aphasia and those without aphasia. Differences in payments by Medicare due to stroke were examined using a Gamma distributed generalized linear multivariable model.

Results

3,200 Medicare beneficiaries experienced an ischemic stroke in South Carolina in 2004 and 398 had post-stroke aphasia. Patients with aphasia experienced longer length of stays, greater morbidity, and greater mortality. In adjusted models that controlled for relevant covariates, the attributable one-year cost of aphasia was estimated at $1703.

Conclusions

Aphasia adds to the cost of stroke-related care, above the cost of stroke alone.

INTRODUCTION

Stroke is a leading cause of long-term disability in the U.S. and the cost of stroke-related care is substantial. Approximately 100,000 individuals who suffer a stroke will be left with aphasia, a higher-order disturbance of language ^{1, 2}. Aphasia is associated with higher mortality, morbidity and utilization of healthcare resources³. Higher-order skills such as language are believed to be associated with higher costs for post-stroke care and rehabilitation. However, few studies have examined cost issues related to aphasia despite such patients requiring extensive care in a range of medical settings⁴. We sought to examine the one-year attributable cost of aphasia among ischemic stroke survivors.

METHODS

Data for this study were obtained from the South Carolina Office of Research and Statistics from a state-wide cohort of Medicare participants. To identify patients with ischemic stroke, we used International Classification of Diseases and Health Related Problems (ICD-9) codes for stroke and aphasia. ICD-9 codes 434.xx, 436.xx were used for ischemic stroke ⁵ and 784.3 to identify those with aphasia. Stroke severity was defined based on a novel proxy measure as follows: (1) mild if no major stroke-related diagnoses (e.g. dysarthria), (2) moderate if one stroke-related diagnosis (excluding hemiplegia), and (3) severe if hemiplegia or two or more other stroke-related diagnoses. We then calculated: (1) the number of patients with stroke, (2) the number of patients with stroke and aphasia, (3) selected demographic and clinical variables, (4) the length of stay (LOS) in days, and (5) total charges submitted and payments made (US$) by Medicare for all patients.

The date of the index admission was used as the start date for the analysis. All billing data for patients in this inception cohort for any time, up to 365 days post index date were used. An analytical data set was created by summarizing resource use from six different healthcare provider sources that bill separately to Medicare for each individual patient and linking the summaries from these multiple administrative files: hospitals, Part B providers, nursing homes, outpatient, home health, and durable medical equipment.

Attributable costs of aphasia were defined as the cost of caring for patients with aphasia post-stroke over and above the cost of general stroke care. We calculated both the actual charges billed for the care of the patients and the payments made by Medicare based on 2004 dollars. The cost analysis for this study was primarily performed from the perspective of the payer (i.e. payments). The effect that each patient characteristic had on total charges and payments for our 2004 SC Medicare sample of ischemic stroke patients was initially assessed by univariate analysis. To assess 1-year attributable LOS and total cost of aphasia, multivariable analyses were conducted.

RESULTS

More than 12% of the total sample had aphasia. Patients with aphasia were older and had more comorbidity, more severe strokes, and longer LOSs (Supplemental Table 1; please see http://stroke.ahajournals.org). Medicare payments for the care of stroke survivors with aphasia averaged $20,734 compared to $18,683 for those without aphasia. In adjusted models, the estimated 1-year attributable cost of aphasia was $1703 (Table 1). Multivariable analysis indicated that aphasia resulted in an 8.5% increase in payments and a 6.5% increase in LOS. Stroke severity, race/ethnicity, and comorbidity were associated with greater costs and longer LOS (Supplemental Table 2).

Table 1.

1-Year Medicare Payments for Ischemic Stroke Patients

	Overall (n=3200)	Aphasic (n=398)	Non-Aphasic (n=2802)	p-value*
Hospital	6,549 (5364)	6,353 (3439)	6,577 (5584)	0.63
Provider	3,586 (4061)	3,432 (2994)	3,608 (4190)	0.73
Nursing Home	4,741 (8679)	6,135 (9550)	4,543 (8532)	<0.0001
Home Health	1,899 (3356)	2,140 (3753)	1,864 (3295)	0.78
Outpatient	1,478 (3547)	1,828 (4062)	1,429 (3466)	0.65
Durable Med. Equip.	686 (1607)	847 (2015)	663 (1539)	0.83
Total Charges($)	49,648 (39605)	54,492 (37495)	48,960 (39855)	<0.001
Total Payments($)	18,938 (14455)	20,734 (14242)	18,683 (14469)	<0.001
Est. Total Payments 95% Confidence Intervals		20,833 (19,336–22,447)	19,130 (18,204–20,104)	0.008

DISCUSSION

The cost of caring for post-stroke patients with aphasia was ~$1,700 more than the cost of caring for patients without aphasia. Those with aphasia also experienced longer LOSs than those without aphasia. Longer LOSs in this population contributes to increased costs thereby increasing the attributable cost of having aphasia. In addition, it is believed that patients with higher order cognitive deficits (i.e language comprehension, memory, naming, etc) experience longer LOSs due to the greater amount of time it takes to appreciate and remediate their deficits⁶.

It is also notable that patients with aphasia had different personal characteristics and discharge profiles than those without aphasia. Patients with aphasia were older and were more often discharged to a skilled nursing facility than persons without aphasia. This finding is important because age is a primary risk factor for stroke; therefore older patients are more likely to experience aphasia and at a greater cost⁷. These findings in total are significant because clinicians, third party payers, and medical administrators are all required to develop an accurate picture of the financial burden of post-stroke disorders as reimbursement dollars for the management of these conditions continues to decrease².

We acknowledge several limitations to this study. First, attributable cost analysis is limited by the absence of specific measures of quality. Second, the sample of patients with aphasia reported in this study is significantly lower than previous reports of 21–38% of all stroke patients³. This difference may represent limited use of ICD-9 coding for aphasia or undercoding relative to previous studies. Third, we used a non-standardized and un-validated proxy measure of stroke severity. Stroke severity is a significant predictor of LOS and cost, however currently no standardized measure of stroke severity for administrative data exists. Fourth, we reported costs from the perspective of Medicare (payments by Medicare) and this perspective may not capture the actual costs to society (e.g. out-of-pocket expenses and loss of earnings due to stroke).

However, the findings from this study demonstrated that the one-year attributable cost of aphasia post-stroke was higher than that for patients without aphasia due to costs related to LOS, age, and discharge site. These findings are important because dramatic changes are occurring in healthcare reimbursement ^8–12, specifically, imposed caps on Medicare reimbursement for outpatient rehabilitation services ¹³. Originally, Medicare beneficiaries were limited to a $1,500 cap for Part B Medicare therapy to be shared by speech-language pathology (SLP) and physical therapy (PT) while occupational therapy (OT) was granted its own cap. Although, the current therapy cap is $1,870 for SLP and PT the financial burden of the cap remains a major limiting factor to the access of long-term rehabilitative services for patients with persisting aphasia. We believe these findings are also important to understanding the complexity of variables that contribute to the cost of stroke-related care. The cost of stroke has been primarily linked to costs related to the LOS, hospital overhead, nursing salaries, physician salaries, therapists and medications¹⁴. The findings of this study suggest that other factors such as post-stroke disorders also contribute to higher costs of post-stroke care. Understanding these contributors is important to making informed decisions and advocating for patients with such disorders.