Abstract
INTRODUCTION
Time spent at home may aid in understanding recovery following traumatic brain injury (TBI) among older adults, including those with Alzheimer's disease and related dementias (ADRD). We examined the impact of ADRD on recovery following TBI and determined whether socioeconomic disadvantages moderated the impact of ADRD.
METHODS
We analyzed Medicare beneficiaries aged ≥65 years diagnosed with TBI in 2010–2018. Home time was calculated by subtracting days spent in a care environment or deceased from total follow‐up, and dual eligibility for Medicaid was a proxy for socioeconomic disadvantage.
RESULTS
A total of 2463 of 20,350 participants (12.1%) had both a diagnosis of ADRD and were Medicaid dual‐eligible. Beneficiaries with ADRD and Medicaid spent markedly fewer days at home following TBI compared to beneficiaries without either condition (rate ratio 0.66; 95% confidence interval [CI] 0.64, 0.69).
DISCUSSION
TBI resulted in a significant loss of home time over the year following injury among older adults with ADRD, particularly for those who were economically vulnerable.
Highlights
Remaining at home after serious injuries such as fall‐related traumatic brain injury (TBI) is an important goal for older adults.
No prior research has evaluated how ADRD impacts time spent at home after TBI.
Older TBI survivors with ADRD may be especially vulnerable to loss of home time if socioeconomically disadvantaged.
We assessed the impact of ADRD and poverty on a novel DAH measure after TBI.
ADRD‐related disparities in DAH were significantly magnified among those living with socioeconomic disadvantage, suggesting a need for more tailored care approaches.
Keywords: Alzheimer's disease, days at home, Medicaid eligibility, Medicare, traumatic brain injury
1. INTRODUCTION
Traumatic brain injury (TBI) is a common fall‐related injury that results in more than 123,000 hospitalizations and 485,000 emergency department visits annually among adults aged 65 years and older. 1 , 2 TBI increases risk of Alzheimer's disease and related dementias (ADRD) and a number of other health conditions (e.g., depression, insomnia). 3 , 4 , 5 , 6 In addition, TBI results in disproportionate disability and functional limitations among older adults relative to their younger counterparts. 7 , 8 , 9 Yet, despite its large public health impact, relatively little is understood about recovery following TBI among older adults or the factors that influence recovery.
Although TBI is a well‐established risk factor for ADRD, 3 , 4 , 10 , 11 ADRD can increase the risk of fall‐related injury including TBI. 12 , 13 In a large, nationally representative study (n = 154,151), older adults with incident TBI were four times more likely to have a baseline diagnosis of ADRD compared to older adults without TBI (13.0% vs 3.3%, p < .001). 14 ADRD likely complicates recovery following TBI among older adults; yet its influence is understudied. Prior studies of functional recovery following TBI have been conducted primarily in mixed‐age populations, severe TBI, or among individuals discharged to inpatient rehabilitation, and may not be representative of the experiences of most older adults with TBI. 7 , 15 , 16 , 17 , 18
Unfortunately, longitudinal studies needed to gain understanding of recovery among older adults, including those with ADRD, following TBI are challenging to conduct. Multiple factors influence participants’ ability to engage in research, including poor pre‐injury functioning, baseline ADRD, and structural and economic barriers to participation. 19 Administrative claims data can overcome some of these limitations and have been used to assess new‐onset depression, insomnia, and ADRD among older adults following TBI. 14 , 20 , 21 However, although understanding the risk of new disease associated with TBI is important, patient‐centered measures of functional recovery from TBI would better inform rehabilitation.
Home time is a novel, population‐based measure defined as the amount of time spent at home and not hospitalized or in a rehabilitation facility following a health‐related event. 22 , 23 Spending more time at home is an important patient‐centered outcome for older adults, and is associated with higher functional status, lower rates of depression, and increased quality of life. 22 , 24 , 25 , 26 Home time is sensitive to differences in patient demographics and comorbid status, making it a potentially useful population‐based measure to better understand functional recovery and the factors that influence it following TBI among older adults, including those with ADRD. 27 , 28 The effects of ADRD on recovery following TBI may be particularly marked among older adults experiencing socioeconomic disadvantage. ADRD is associated with elevated needs for caregiving and assistance with activities of daily living (ADLs) that are substantially more likely to go unmet among those who cannot afford additional resources or supports needed for successful aging in place. 29 , 30 Thus in the present study, our objectives were (1) to examine the impact of TBI on home time among older adults with ADRD and (2) to determine the extent to which socioeconomic disadvantage amplified the impact of ADRD on home time. We hypothesized that the negative association between ADRD and home time after TBI would be substantially greater among those experiencing socioeconomic disadvantage.
2. METHODS
We conducted a retrospective cohort study using Medicare administrative claims and assessment data obtained from the Center for Medicaid & Medicare Services (CMS) Chronic Conditions Warehouse (CCW). We obtained a 5% random sample for years 2010–2016 and a 20% random sample for years 2017–2018. Claims were available for hospitals, skilled nursing facilities, home health care agencies, and both freestanding and hospital‐based outpatient facilities. This study was exempted from review by the University of Maryland School of Medicine Institutional Review Board (IRB).
2.1. Study population
Community‐dwelling Medicare beneficiaries aged 65 and older who were hospitalized with a primary diagnosis of TBI between 2010 and 2017 and discharged alive to any non‐hospice settings (including skilled nursing facilities, rehabilitation hospital, or home) were eligible for the study. Only the first TBI was used among beneficiaries who had multiple TBI claims over the observation period. Beneficiaries who were not long‐stay residents (residence of more than 100 days in a long‐term care facility prior to admission), as identified by using assessment dates on the Medicare Minimum Data Set 3.0, were considered community dwelling. We defined TBI using the Centers for Disease Control and Prevention (CDC) International Classification of Diseases (ICD) version 9 (ICD‐9) and version 10 (ICD‐10) codes on inpatient claims, and the date of TBI was assigned as the index date. 1 Diagnoses codes indicating TBI sequelae or subsequent encounters were excluded. Continuous Medicare Parts A and B coverage for at least 6 months before the index date and for the entirety of the 12‐month follow‐up period or until death was required.
2.2. Exposure and covariates
The CCW contains annual flags and dates of first diagnosis since Medicare enrollment for 27 chronic conditions that are identified using CMS algorithms based on specific diagnosis or procedure codes. Diagnosis of ADRD is based on the CCW algorithm and has been shown to perform well in validation studies. 31 If the date the beneficiary met CCW criteria for diagnosis of ADRD occurred prior to the index date, the beneficiary was considered to have ADRD. Similarly, we determined whether all other CCW chronic conditions were present prior to the index date. In addition, we captured the original reason for entitlement code, dichotomized as age or disability (including end‐stage renal disease) and dual eligibility for Medicaid during any point in the 6 months prior to TBI as a proxy indicator of pre‐TBI economic disadvantage. Notably, community‐dwelling older adults are generally only eligible for Medicaid if they live near or below the poverty line or have high medical needs and limited income or financial assets (in most states <$3000 in assets for a couple, or $2000 for an individual). 32
2.3. Home time
Consistent with our prior work, home time was calculated by subtracting the number of days spent in an inpatient, skilled nursing facility, nursing home, emergency department observation, or outpatient observation setting (i.e., patient is in the hospital but has not been technically admitted), and the number of days spent deceased, from the total follow‐up available for each of the 12 follow‐up months (monthly level). 33 , 34 This definition of home time extends prior work to include emergency department and outpatient observation settings, which are technically not time spent at home. 22 , 35 Beneficiaries who died did not continue to contribute to home time following the month of their death (i.e., home time was set to missing).
2.4. TBI severity
Common TBI severity measures such as the Glasgow Coma Scale score, which measures neurological deficit, or the Abbreviated Injury Scale (AIS) score, which is a measure of anatomic injury severity associated with increased risk of mortality, are not available in administrative claims data. 36 , 37 In the present study, we have addressed this limitation by including a claims‐based estimate of the AIS score based on the ICD codes used to identify TBI. The AIS is rated on a scale from 1 to 6, with higher scores indicating greater injury severity. AIS scores of 6/6 are designated as unsurvivable. We used the R program IDCPIC‐R to covert ICD‐9 and ICD‐10 codes for TBI from the inpatient claim into AIS codes (head region) to provide a more granular measure of anatomic injury. 38 This program has been validated and shown to perform well for TBI and has been used in prior studies to estimate the head AIS score in TBI patients. 39 , 40 As in our prior work, we also used length of hospital stay, whether the hospitalization resulted in an intensive care unit stay, and discharge location (home vs rehabilitation) as proxies for injury severity. 41
RESEARCH IN CONTEXT
Systematic review: The authors reviewed publications on recovery following traumatic brain injury (TBI) among older adults and the use of days at home (DAH) as an outcome metric using common methods (e.g., PubMed, reference searches). There is little research on recovery from TBI among older adults and none that examines the impact of Alzheimer's disease and related dementias (ADRD) or socioeconomic disadvantage on a population‐level outcome metric such as DAH.
Interpretation: Medicare beneficiaries aged 65 and older with a diagnosis of ADRD and Medicaid eligibility (12%) spent significantly fewer DAH following TBI compared to beneficiaries without ADRD and Medicaid eligibility (adjusted rate ratio 0.66; 95% confidence interval 0.64, 0.69).
Future directions: Future work will investigate factors associated with successful aging in place among older adult survivors of TBI with ADRD.
2.5. Statistical analysis
We first described the distribution of clinical, demographic, and injury‐related characteristics in the entire sample and by ADRD and Medicaid eligibility status (four groups) and tested differences in distributions using chi‐square Goodness of Fit, analysis of variance (ANOVA), and the Kruskal–Wallis test. We plotted the mean home time per month pre‐ and post‐TBI by ADRD/Medicaid eligibility group status and calculated the proportion of days of home time in each group out of the total days spent alive during the 6 months before and 12 months after TBI. We calculated the average number of days post‐TBI spent in each of the following settings: home, inpatient, nursing home, and outpatient observation or emergency department stays. Next, we plotted the proportion of days spent in each location by ADRD/Medicaid eligibility status using the number of days alive as the denominator.
We modeled the unadjusted monthly count of home time over the 12 months post‐TBI as a function of ADRD and Medicaid eligibility and their interaction using generalized estimating equations with a negative binomial distribution and log link. To account for differing lengths of time spent alive following TBI, we weighted the models by the stabilized inverse probability of survival in each month. In contrast to using a monthly indictor of mortality in our regression models, this method helps account for the increased risk of mortality among some participants. Probability of survival was generated at the monthly level from a pooled logistic regression model fit for demographic, clinical, and injury‐related characteristics. In negative binomial models, the correlation matrix was autocorrelated (first order). Time was modeled as its inverse based on model fit using the quasilikelihood information criterion. We exponentiated effect estimates to generate the rate ratio (RtR) and 95% confidence interval (CI) for the effect of ADRD, Medicaid eligibility, and their interaction on home time using estimate statements in SAS Enterprise Release 3.71 (SAS Institute Inc., Cary, NC, USA). Next, we built the adjusted model by adding variables (TBI acuity [excluding hospital length of stay and discharge home, which were in the causal pathway], demographics with continuous age, comorbidities, and socioeconomic indicators) and the count of days at home during the month prior to TBI to the regression model. Finally, we used post‐estimation commands (proc plm in SAS) to estimate the adjusted mean number of days at home per month in each of the four groups.
3. RESULTS
We identified 32,560 Medicare beneficiaries with TBI meeting our enrollment criteria. Of these, 4740 (14.6%) were deceased at discharge, 5659 (17.5%) were discharged to locations other than a nonhospice community setting (e.g., hospice, long‐term acute care, or psychiatric hospital), and 1811 (5.6%) were younger than 65 years of age, leaving 20,350 (62.5%) beneficiaries in our study sample.
Mean age was 81.6 (SD 8.2) years (Table 1). The sample was 56% female and 88% White. Based on a head AIS score of 1–2, 14.6% had mild TBI and more than half were discharged home. Prevalence of comorbid conditions was high. For example, prevalence of anemia was 72.9%, prevalence of diabetes was 45.4%, and prevalence of ischemic heart disease was 68.2%. Over the 1‐year follow‐up, 23.7% died.
TABLE 1.
Characteristics of Medicare beneficiaries aged 65 years and older hospitalized with a traumatic brain injury (TBI) 2010–2017 at baseline (index date), by Alzheimer's disease and related dementias (ADRD) diagnosis and economic disadvantage (dual) status, n = 20,350.
| Total, n = 20,350 | No ADRD/No Dual, n = 10,666 | ADRD/No Dual, n = 4420 | No ADRD/Dual, n = 2801 | ADRD/Dual, n = 2463 | p‐value | |
|---|---|---|---|---|---|---|
| TBI acuity variables, n (%) | ||||||
| Head AIS a Score | <.001 | |||||
| 1–2 | 2965 (14.6) | 1470 (13.8) | 734 (16.6) | 375 (13.4) | 386 (15.7) | |
| 3 | 6349 (31.2) | 3506 (32.9) | 1296 (29.3) | 873 (31.2) | 674 (27.4) | |
| 4–5 | 10863 (53.4) | 5597 (52.5) | 2356 (53.3) | 1524 (54.4) | 1386 (56.3) | |
| TBI type | <.001 | |||||
| Other | 18,559 (91.2) | 9797 (91.9) | 3962 (89.6) | 2575 (91.9) | 2225 (90.3) | |
| Concussion | 1059 (5.2) | 573 (5.4) | 243 (5.5) | 138 (4.9) | 105 (4.3) | |
| Non‐specified TBI | 732 (3.6) | 296 (2.8) | 215 (4.9) | 88 (3.1) | 133 (5.4) | |
| Length of hospital stay | <.001 | |||||
| < 2 days | 2795 (13.7) | 1754 (16.4) | 550 (12.4) | 275 (9.8) | 216 (8.8) | |
| 2–3 days | 7287 (35.8) | 3873 (36.3) | 1721 (38.9) | 877 (31.3) | 816 (33.1) | |
| 4–5 days | 4580 (22.5) | 2324 (21.8) | 1032 (23.4) | 640 (22.9) | 584 (23.7) | |
| > 5 days | 5688 (28.0) | 2715 (25.5) | 1117 (25.3) | 1009 (36.0) | 847 (34.4) | |
| Intensive care unit stay | 7024 (34.5) | 3690 (34.6) | 1433 (32.4) | 1043 (37.2) | 858 (34.8) | <.001 |
| Discharge destination | <.001 | |||||
| Home | 10,316 (50.7) | 4477 (42.0) | 2551 (57.7) | 1611 (57.5) | 1677 (68.1) | |
| Rehabilitation | 10,034 (49.3) | 6189 (58.0) | 1869 (42.3) | 1190 (42.5) | 786 (31.9) | |
| Death during follow‐up | 4823 (23.7) | 1098 (10.3) | 968 (21.9) | 1370 (48.9) | 1387 (56.3) | <.001 |
| Time to death in days (SD) | 146.7 (128.1) | 212.3 (136.6) | 203.0 (133.0) | 97.7 (97.9) | 103.8 (103.3) | <.001 |
| Home time, 12 months post‐TBI (SD) | 313.3 (111.8) | 349.3 (63.8) | 329.5 (91.4) | 234.3 (150.2) | 217.9 (151.0) | <.001 |
| Demographic variables, n (%) or mean (SD) | ||||||
| Age in years (SD) | 81.6 (8.2) | 80.0 (8.0) | 84.5 (7.1) | 80.4 (8.9) | 84.3 (7.7) | <.001 |
| Sex | <.001 | |||||
| Male | 8891 (43.7) | 4935 (46.3) | 1785 (40.4) | 1237 (44.2) | 934 (37.9) | |
| Female | 11,459 (56.3) | 5731 (53.7) | 2635 (59.6) | 1564 (55.8) | 1529 (62.1) | |
| Race | <.001 | |||||
| White | 18,032 (88.6) | 9846 (92.3) | 4059 (91.8) | 2221 (79.3) | 1906 (77.4) | |
| Black | 994 (4.9) | 370 (3.5) | 199 (4.5) | 207 (7.4) | 218 (8.9) | |
| Asian | 460 (2.3) | 118 (1.1) | 49 (1.1) | 158 (5.6) | 135 (5.5) | |
| Hispanic | 342 (1.7) | 64 (0.6) | 34 (0.8) | 117 (4.2) | 127 (5.2) | |
| Other | 522 (2.6) | 268 (2.5) | 79 (1.8) | 98 (3.5) | 77 (3.1) | |
| Comorbid conditions, n (%) | ||||||
| ADRD | 6883 (33.8) | N/A | N/A | N/A | N/A | |
| Anemia | 14,844 (72.9) | 6932 (65.0) | 3692 (83.5) | 2081 (74.3) | 2139 (86.9) | <.001 |
| Asthma | 3300 (16.2) | 1517 (14.2) | 770 (17.4) | 502 (17.9) | 511 (20.8) | <.001 |
| Atrial fibrillation | 6222 (30.6) | 3044 (28.5) | 1496 (33.9) | 876 (31.3) | 806 (32.7) | <.001 |
| Cataracts | 16,160 (79.4) | 8201 (76.9) | 3876 (87.7) | 2051 (73.2) | 2032 (82.5) | <.001 |
| Cancer | 4390 (21.6) | 2208 (20.7) | 1059 (24.0) | 588 (21.0) | 535 (21.7) | <.001 |
| Chronic kidney disease | 8753 (43.0) | 3859 (36.2) | 2170 (49.1) | 1354 (48.3) | 1370 (55.6) | <.001 |
| COPD b | 7362 (36.2) | 3256 (30.5) | 1739 (39.3) | 1194 (42.6) | 1173 (47.6) | <.001 |
| Depression | 9438 (46.4) | 3866 (36.3) | 2714 (61.4) | 1247 (44.5) | 1611 (65.4) | <.001 |
| Diabetes | 9238 (45.4) | 4329 (40.6) | 2054 (46.5) | 1482 (52.9) | 1373 (55.8) | <.001 |
| Glaucoma | 5976 (29.4) | 3013 (28.3) | 1430 (32.4) | 760 (27.1) | 773 (31.4) | <.001 |
| Heart failure | 9136 (44.9) | 3974 (37.3) | 2256 (51.0) | 1447 (51.7) | 1459 (59.2) | <.001 |
| Hyperlipidemia | 17,500 (86.0) | 9065 (85.0) | 3944 (89.2) | 2326 (83.0) | 2165 (87.9) | <.001 |
| Hyperplasia (benign prostatic) | 5296 (26.0) | 2685 (25.2) | 1272 (28.8) | 674 (24.1) | 665 (27.0) | <.001 |
| Hypertension | 18,565 (91.2) | 9447 (88.6) | 4203 (95.1) | 2541 (90.7) | 2374 (96.4) | <.001 |
| Hypothyroid | 6863 (33.7) | 3305 (31.0) | 1787 (40.4) | 832 (29.7) | 939 (38.1) | <.001 |
| Ischemic heart disease | 13,869 (68.2) | 6698 (62.8) | 3338 (75.5) | 1929 (68.9) | 1904 (77.3) | <.001 |
| Osteoporosis | 6460 (31.7) | 2901 (27.2) | 1747 (39.5) | 798 (28.5) | 1014 (41.2) | <.001 |
| Rheumatoid/osteoarthritis | 14,390 (70.7) | 7000 (65.6) | 3512 (79.5) | 1899 (67.8) | 1979 (80.4) | <.001 |
| Stroke | 6352 (31.2) | 2546 (23.9) | 1928 (43.6) | 791 (28.2) | 1087 (44.1) | <.001 |
| Socioeconomic indicators, n (%) | ||||||
| OREC c | <.001 | |||||
| Age | 18,212 (89.5) | 9748 (91.4) | 4072 (92.1) | 2276 (81.3) | 2116 (85.9) | |
| Disability | 2138 (10.5) | 918 (8.6) | 348 (7.9) | 525 (18.7) | 347 (14.1) | |
| Dual | 5264 (25.9) | |||||
Abbreviated injury scale score.
Chronic obstructive pulmonary disease.
Original reason for entitlement code.
There were 4420 (21.7%) Medicare beneficiaries with a diagnosis of ADRD who were not eligible for Medicaid, 2801 (13.8%) without ADRD who were eligible for Medicaid, and 2463 (12.1%) with both ADRD and Medicaid eligibility (Table 1). Individuals with Medicaid eligibility, regardless of ADRD status, were more likely to have hospital stays of ≥5 days (36.0% of those without ADRD and 34.4% of those with ADRD) compared to beneficiaries without Medicaid (25.5% of those without ADRD and 25.3% of those with ADRD) (p‐value for comparison across groups < .001). Yet, beneficiaries without ADRD or Medicaid eligibility (n = 10,666) were more likely to be discharged to rehabilitation (58.0% vs 31.9%−42.3% for other ADRD/Medicaid groups, p < .001 across groups). Furthermore, beneficiaries with both ADRD and Medicaid eligibility were much more likely to die during follow‐up (56.3%) compared to other ADRD/dual groups (10.3%−48.9%) (p < .001 for comparison across groups).
We observed differences in home time pre‐ and post‐TBI by ADRD/Medicaid eligibility status (Figure 1 and Table 2). Across all groups, we observed a significant decrease in home time in the month of TBI followed by a rebound in home time over the year post‐TBI. Differences in home time between groups were exaggerated post‐TBI. For example, during the 6 months pre‐TBI, individuals with ADRD and Medicaid eligibility experienced on average 7% fewer days at home relative to beneficiaries without ADRD or Medicaid eligibility, equivalent to ≈13 days over the 6‐month period (Table 2). In contrast, during the 12 months post‐TBI and accounting for differential mortality, that disparity in home time widened to 39% fewer days.
FIGURE 1.
Days at home 6 months before and 12 months after traumatic brain injury among older Medicare beneficiaries by Alzheimer's disease and related dementias (ADRD) diagnosis and Medicaid eligibility (dual) status.
TABLE 2.
Proportion (standard deviation) of days of home time out of days spent alive among Medicare beneficiaries aged 65 years and older hospitalized with a traumatic brain injury (TBI) 2010–2017 6 months before and 12 months after TBI, by Alzheimer's disease and related dementias (ADRD) diagnosis and Medicaid eligibility status, n = 20,350.
| No ADRD/ No Medicaid, n = 10,666 | ADRD/ No Medicaid, n = 4420 | No ADRD/ Medicaid, n = 2801 | ADRD/ Medicaid, n = 2463 | p‐value | |
|---|---|---|---|---|---|
| 6 months pre‐TBI | 0.98 (0.07) | 0.94 (0.12) | 0.95 (0.10) | 0.91 (0.15) | <.001 |
| 12 months post‐TBI | 0.86 (0.20) | 0.75 (0.30) | 0.57 (0.38) | 0.47 (0.38) | <.001 |
In unadjusted negative binomial models including ADRD, Medicaid eligibility, and their interaction, beneficiaries with ADRD but without Medicaid spent fewer days at home following TBI compared to beneficiaries without ADRD or Medicaid eligibility (RtR 0.88; 95% CI 0.87, 0.89) (Table 3). Beneficiaries with Medicaid eligibility but without ADRD also spent fewer days at home post‐TBI compared to beneficiaries without Medicaid eligibility or ADRD (RtR 0.81; 95% CI 0.80, 0.83). Finally, beneficiaries with both ADRD and Medicaid eligibility were at home for 36% fewer days post‐TBI compared to beneficiaries without ADRD or Medicaid eligibility (RtR 0.64; 95% CI 0.62, 0.66).
TABLE 3.
Unadjusted and adjusted rate ratios and 95% confidence intervals of the associations between Alzheimer's disease and related dementias (ADRD) diagnosis, economic disadvantage (dual), and their interaction on home time over the year following hospitalization for traumatic brain injury 2010–2017 among Medicare beneficiaries aged 65 and older, n = 20,350.
| Unadjusted | Adjusted a | |
|---|---|---|
| ADRD | 0.88 (0.87, 0.89) | 0.93 (0.92, 0.95) |
| Dual | 0.81 (0.80, 0.83) | 0.82 (0.80, 0.84) |
| ADRD a Dual | 0.64 (0.62, 0.66) | 0.68 (0.66, 0.71) |
Adjusted for: Age, sex, race, inverse‐(months post‐TBI), Abbreviated Injury Scale score – head, home time in the month prior to TBI, intensive care unit stay, acute myocardial infarction, anemia, asthma, atrial fibrillation, cataract, cancer, chronic kidney disease, chronic obstructive pulmonary disease, depression, diabetes, glaucoma, heart failure, hip fracture, hyperlipidemia, hypertension, hypothyroid, ischemic heart disease, osteoporosis, rheumatoid and osteoarthritis, stroke, and original reason for Medicare entitlement (age vs other).
Following adjustment for covariates (see footnote, Table 3 for adjustment variables), beneficiaries with ADRD but without Medicaid eligibility spent fewer days at home following TBI compared to beneficiaries without ADRD or Medicaid eligibility (RtR 0.93; 95% CI 0.92, 0.95) (Table 3). Beneficiaries with Medicaid eligibility but without ADRD also spent fewer days at home post‐TBI compared to beneficiaries without Medicaid eligibility or ADRD (RtR 0.82; 95% CI 0.80, 0.84). Finally, beneficiaries with both ADRD and Medicaid eligibility were at home for significantly fewer days at home post‐TBI compared to beneficiaries without ADRD or Medicaid eligibility (RtR 0.68; 95% CI 0.66, 0.71). At 12 months, the estimated days at home was 319 in the group without ADRD or Medicaid eligibility, 299 among those with ADRD who were not Medicaid eligible, 263 among those without ADRD who were Medicaid eligible, and 218 among those with both ADRD and Medicaid eligibility.
Figure 2 displays the proportion of days alive spent in the different health care settings. Individuals with both ADRD and dual eligibility spent most of their time alive post‐TBI in a nursing home (including both skilled nursing and long‐term stays). Those without ADRD who were dually eligible also spent almost half of their time alive in a nursing home.
FIGURE 2.
Proportion of days alive spent in select health care settings, by Alzheimer's disease and related dementias (ADRD) and Medicaid eligibility (dual) status.
4. DISCUSSION
In this nationally representative study of community‐dwelling Medicare beneficiaries, TBI resulted in a significant loss of home time over the year following injury, a loss markedly worse among older adults with ADRD. The ADRD‐related disparity in outcomes was significantly wider for older adults who were also dually eligible for Medicaid. In total, older adults who were living with ADRD and dually eligible for Medicaid spent an average of 100 days less at home over the year following TBI than beneficiaries without ADRD or Medicaid eligibility. Our results highlight intersectionality between socioeconomic disadvantage and dementia among older adults recovering from traumatic injuries and underscore a need for urgency in developing new care pathways to improve aging in place for this vulnerable population. 30
Although the reasons for decreased home time following TBI among older adults with ADRD remain unexplored, prior literature offers a few possible mechanisms. Individuals with ADRD had a heavier comorbidity burden, which has been shown to interfere with recovery from disability. 42 Beneficiaries with ADRD may not be able to access or participate in restorative care activities, such as walking programs, that could facilitate successful aging in place. This is important because prior work has shown that once in rehabilitation, older adults with cognitive impairment have higher needs but make similar functional gains. 43
Amplification of the loss of home time among individuals with both ADRD and Medicaid dual eligibility following TBI is concerning. Economic disadvantage, both objectively measured and perceived, has been shown previously to be associated with underuse of needed medical care, instability at hospital discharge, and higher rates of hospital readmission and death after cardiac hospitalizations. 44 , 45 , 46 , 47 Furthermore, Medicaid eligible beneficiaries in our study were more likely to originally qualify for the Medicare benefit through disability. Pre‐existing disability could exacerbate sequelae of TBI, resulting in admission to long‐term care and decreasing days at home. Prior studies of community‐dwelling older adults suggest that individuals with greater disability in ADLs before a fall‐related injury are less likely to recover post‐injury. 48 Finally, older adults with high medical needs (such as those with dementia) who also lack financial resources may struggle to pay for additional supports and equipment needed for successful aging in place, and this may in turn contribute to the higher rates of nursing home admission observed in this study. Prior studies have shown that older adults with TBI are at increased risk of nursing home placement, 19 and our data highlight a particularly vulnerable subgroup: those with pre‐existing cognitive impairment and socioeconomic disadvantage.
Following TBI, home time increased during the first 4 months post‐injury but did not reach pre‐injury levels. These results are consistent with prior studies conducted among patients with hip fracture showing that most recovery is complete by 2–6 months post‐injury. 49 We have previously reported similar findings on rates of new mental health diagnoses among older adults with TBI. 20 , 41
This study is the first to estimate the impact of TBI on days at home, an important patient‐centered outcome. Recovery in home time was consistent with results from prior studies on recovery following hip fracture and TBI, suggesting that it may be a useful, population‐level metric for future studies of TBI. Furthermore, this is the first study to examine the impact of ADRD and Medicaid eligibility on recovery following TBI, despite the relatively high prevalence of these two conditions in this population (34% with ADRD and 26% Medicaid eligible in our study). Thus this study highlights heterogeneity in recovery following TBI and identified relatively common and vulnerable subgroups that may benefit from intensive rehabilitation and other interventions following injury.
Limitations of this study should also be considered. First, this study focused on older adults hospitalized with TBI, implying that individuals with mild injury may have been excluded. In fact, based on estimated AIS head scores, almost 85% of the sample sustained moderate‐severe TBI (AIS >2). Even so, home time among individuals without ADRD or dual rebounded to almost pre‐injury levels, suggesting that for up to half of older adults hospitalized with TBI, complete or near‐complete recovery is possible. This study relied on administrative claims data that are submitted for reimbursement purposes. Certain conditions, including ADRD, are known to be underdiagnosed in administrative data. 50 , 51 Because everyone in this study had TBI, this misclassification would bias toward the null. Although most older adults prefer to age at home, it is possible that time away from home for a small subset of older adults with substantial unmet needs at home is a beneficial, not a negative, outcome. Finally, this study included Medicare Fee for Service beneficiaries; thus individuals with Medicare Advantage plans are not represented.
5. CONCLUSION
Among community‐dwelling older Medicare beneficiaries, TBI resulted in a significant loss of home time over the year following injury that was exacerbated among individuals with ADRD. Beneficiaries with ADRD who were also economically vulnerable prior to their TBI lost 100 days at home over the year following TBI relative to beneficiaries without ADRD or Medicaid eligibility. In addition to investigating recovery from TBI among the vulnerable subgroups identified in this study, future studies should seek to investigate mechanisms of the loss of home time and develop interventions to increase home time among older adults following TBI.
CONFLICT OF INTEREST STATEMENT
The authors declare no conflicts of interest.
CONSENT STATEMENT
This study was exempted from review by the institutional review board of the University of Maryland School of Medicine due to the use of de‐identified data. Informed consent was not required.
Supporting information
ACKNOWLEDGMENTS
Dr. Albrecht was supported by National Institute on Aging grant R01AG076441. Dr. Falvey was supported during the work by the National Institute on Aging and the Maryland Claude D. Pepper Center (grant numbers K76AG074926 and P30AG028747). We acknowledge the support of the University of Maryland, Baltimore, Institute for Clinical & Translational Research and the National Center for Advancing Translational Sciences Clinical Translational Science Award grant number 1UL1TR003098 in helping secure Medicare data and providing support for analysis. The funder had no role in conduct of the research or preparation of the article.
Albrecht JS, Scherf A, Ryan KA, Falvey JR. Impact of dementia and socioeconomic disadvantage on days at home after traumatic brain injury among older Medicare beneficiaries: A cohort study. Alzheimer's Dement. 2024;20:2364–2372. 10.1002/alz.13666
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