Importance Older adults are particularly vulnerable to adverse events during hospitalization for acute medical problems. The Mobile Acute Care of the Elderly (MACE) service is a novel model of care delivered by an interdisciplinary team, designed to deliver specialized care to hospitalized older adults to improve patient outcomes.
Objective To evaluate the impact of the MACE service when compared with general medical service (usual care).
Design Prospective, matched cohort study.
Setting The Mount Sinai Hospital, an urban tertiary acute care hospital.
Participants Patients aged 75 years or older admitted because of an acute illness to either the MACE service or usual care. Patients were matched for age, diagnosis, and ability to ambulate independently.
Exposures Admission to the MACE service when compared with admission to usual care.
Main Outcome Measures Patient outcomes included incidence of adverse events, including falls, pressure ulcers, restraint use, and catheter-associated urinary tract infections, along with length of stay, rehospitalization within 30 days, functional status at 30 days, and patient satisfaction during care transitions, measured with the 3-item Care Transition Measure.
Results A total of 173 matched pairs of patients were recruited. The mean (SD) age was 85.2 (5.3) and 84.7 (5.4) years in the MACE and usual-care groups, respectively. After adjustment for confounders, patients in the MACE group were less likely to experience adverse events (9.5% vs 17.0%; adjusted odds ratio, 0.11; 95% CI, 0.01-0.88; P = .04) and had shorter hospital stays (0.8 days, 95% CI, 0.7-0.9; P = .001) than patients receiving usual care. Patients in the MACE group were not less likely to have a lower rate of rehospitalization within 30 days than those in the usual-care group (odds ratio, 0.91; 95% CI, 0.39-2.10; P = .83). Functional status did not differ between the 2 groups. Care Transition Measure scores were 7.4 points (95% CI, 2.9-11.9; P = .001) higher in the MACE group.
Conclusions and Relevance Admission to the MACE service was associated with lower rates of adverse events, shorter hospital stays, and better satisfaction. This model has the potential to improve care outcomes among hospitalized older adults.
Trial Registration clinicaltrials.gov Identifier: NCT00927160
Older adults are particularly vulnerable to adverse events during and after hospitalization for acute medical problems, including pressure ulcers, falls, hospital-acquired infections, functional decline, institutionalization, and readmission to the hospital after discharge.1 As health care reform is underway, with incentives and penalties to hospital systems in an effort to reduce medical complications specifically related to care for older adults, also known as “never events,”2 geriatric-focused models of inpatient care offer effective ways to transform inpatient care for older adults. These models, staffed by geriatricians and others trained in delivering care for older adults, have been associated with better outcomes, such as reduced risk of institutionalization and functional decline.3,4
In the 1990s, the Acute Care for Elderly (ACE) unit was designed and tested for its potential to improve patient outcomes in randomized controlled trials5-7 and is widely accepted as a prototype model to provide inpatient care for older adults.8,9 ACE units used a multidisciplinary approach to integrate principles of comprehensive geriatric assessment and quality improvement, incorporating a specifically designed hospital environment, patient-centered care, discharge planning, and review of medical care to reduce avoidable adverse events.9 Although unit-based care models have clear advantages for care, they have not been widely disseminated across institutions,10 particularly because of barriers in initial setup, including costs, staffing, and space needs.9,10 Furthermore, because of patient flow where hospitals are often at or near capacity and patient turnover is rapid, the physical ACE unit may not be able to reserve beds for patients for which the unit is designed, and the unit will sometimes be too full to accommodate patients deemed appropriate for its services.11
As a result, we modified the ACE unit model of care at our institution to deliver geriatric-oriented inpatient care to older patients without the limitations of a physical unit. The Mobile Acute Care of the Elderly (MACE) service consists of an interdisciplinary team of geriatricians, social workers, and clinical nurse specialists with a focus on reducing the risks of hospitalization, improving care coordination with outpatient practice, discharge planning, and patient and caregiver education. To examine its effectiveness, we conducted a prospective study with a matched cohort design to examine outcomes associated with the MACE service for hospitalized vulnerable older adults. We hypothesized that the MACE service, which included a transitional care component, may be associated with improved outcomes for hospital readmissions, adverse event incidence, length of stay, and patient satisfaction when compared with usual care.
This study was conducted at the Mount Sinai Hospital in New York, New York, an urban tertiary care hospital, from November 12, 2008, through August 10, 2011. The MACE service was developed as an inpatient service to care for older adults who were receiving care at the outpatient geriatrics practice at Mount Sinai, a geriatrics patient-centered medical home that delivers primary and geriatric care to older adults. These patients are routinely admitted to the MACE service during any inpatient admission at Mount Sinai for medical reasons. To evaluate its potential effects, we established a matching cohort drawing from patients admitted to the inpatient medical service using a prospective matching algorithm to reduce confounding from differences between the 2 populations of patients. This method has been used to establish a balanced control group in previous studies.12,13 The study was approved by Mount Sinai Institutional Review Board and was registered at ClinicalTrials.gov.
Description of mace service and usual care
Briefly, the MACE service team consisted of an attending geriatrician-hospitalist, geriatric medicine fellow, social worker, and clinical nurse specialist. The geriatrician-hospitalist was the attending physician of record for the elderly patient admitted for acute care in the hospital. The interdisciplinary team met daily to discuss the care of all patients with the nurse specialist acting as the “hospital coach” educating the patient or caregiver. The MACE service also adopted elements to improve care transitions, including medication reconciliation before discharge and communication with the primary care physician within 24 hours of discharge. Further description of the MACE service is included in the online supplement (eAppendix).
The usual-care group included patients admitted to the general medical unit. The usual-care team included an internal medicine attending physician, not a geriatrician, and did not have a clinical nurse specialist. In addition, usual care includes a unit-based social worker rather than a team-based social worker. All other aspects of care, including the number of hospital floors or units and comanagement with internal medicine house staff, were similar for the 2 patient groups.
Study design and inclusion
Our study sample included patients admitted to the MACE service or general medical service, aged 75 years or older, who were currently receiving primary care from a physician who was a member of the hospital faculty. We used this inclusion criterion because the vast majority of patients in the MACE group received primary care affiliated with the hospital, and we wanted a comparable control sample. Proxy respondents were contacted if the patient had a history of dementia, had delirium determined using the Confusion Assessment Method during eligibility verification,14 or did not score 4 or higher on a 6-item cognitive screen (3 items pertaining to orientation and 3 to recall). We excluded patients admitted to any nonmedicine unit or specialty service, including surgery, telemetry, and respiratory care because the MACE service does not manage patients in these units; we also excluded patients transferred from an outside hospital. Patients were contacted within 24 to 48 hours after admission to the MACE service or inpatient medical services.
For this prospective, matched cohort study, all eligible and consenting patients who were admitted to the MACE service were enrolled to establish a pool of patients for prospective matching. Eligible and consenting control patients were enrolled from the general medical service (usual care) if they were matched with yet-unmatched enrolled patients from the MACE service according to 4 characteristics: age (within 5 years); ability to ambulate independently; primary admitting diagnosis, categorized by body system; and admission dates within 180 days. Patients receiving usual care who met inclusion criteria but had no current matching patients from the MACE service were enrolled to a pool of unmatched usual-care recipients. If there were more than 10 patients in the unmatched usual-care pool, a computer-generated random number was used to select 50% of the eligible patients to be enrolled. Study flow is shown in the Figure.
Data collection and measures
Data were obtained by interviews on admission to the hospital and 15 and 30 days after discharge and by medical record review by a clinician investigator (W.W.H.); this investigator was not blinded to treatment assignment because medical records clearly indicated whether a patient was managed by the MACE service. The primary outcome measure was rehospitalization within 30 days after hospital discharge, determined in a telephone interview. Other outcome measures included rehospitalization within 15 days after hospital discharge and self-reported use of hospital-based acute care within 30 days, a composite that included hospitalizations, observation unit stays, and emergency department visits. The incidence of adverse events during incident hospitalization was collected through medical record review; adverse events included catheter-associated urinary tract infection (UTI), falls, and restraint use. Catheter-associated UTI was defined as UTI in a patient who had an indwelling urinary catheter, with onset no more than 48 hours after catheter removal. In addition, the incidence of pressure ulcer during hospitalization was obtained through self-report 15 days after discharge.
Functional status 30 days after discharge was assessed using the Functional Independence Measure (FIM) motor subscale15-17 and the Older Americans Resource Scale for Instrumental Activities of Daily Living (OARS-IADL).18 Patient satisfaction was measured with the 3-item Care Transition Measure19 and the Hospital Consumer Assessment of Healthcare Providers and Systems survey (HCAHPS),20,21 which have been validated in older adults to measure patient assessment of the quality of care transitions and satisfaction during hospitalization. Overall health-related quality of life was assessed using the Patient Reported Outcomes Measurement Information System (PROMIS) global 10-item instrument,22 a standardized, validated measurement for reliable measurement of patient-reported health status. The EQ-5D score, a standardized measurement of health status developed by the EuroQol Group, was calculated from the PROMIS instrument.23
Other covariates collected at baseline included age, sex, race, marital status, education level, insurance status, self-reported income, living alone, and having paid help before admission. The patient's history of chronic conditions was obtained from review of the inpatient medical record at admission, and chronic conditions were summarized using the Charlson Comorbidity Index.24,25 Delirium on admission was assessed using the Confusion Assessment Method, a validated tool for screening for delirium.14 The severity of illness was measured using the physiological measure of a modified Acute Physiology and Chronic Health Evaluation (APACHE) II scale,26 without the Glasgow Coma Scale. Functional status at baseline before hospital admission was obtained from patient interview using the FIM motor scale. The number of outpatient medications before hospitalization was determined through inpatient record review, as was the number of previous hospitalizations in the prior year.
Baseline characteristics and outcome measures were compared between care groups; McNemar, Stuart-Maxwell, and paired t tests were used to account for the matched cohort design. Next, we performed conditional logistic regression analysis for categorical outcomes, taking into account the matched-pair cohort design. We also performed fixed-effect linear regression for continuous outcomes to obtain point estimates with multivariable adjustment to account for matching.27 We included covariates in our multivariable models parsimoniously, based on whether they differed between groups, and we included other important covariates anticipated to have a strong effect on outcomes. Additional details on inclusion of covariates and sensitivity analyses are included in the eAppendix. All analyses were performed with Stata software, version 12.1 (StataCorp).
Our study procedures yielded a matching cohort of 173 patients in each group, drawing from a pool of 233 patients from the MACE service and 267 receiving usual care (Figure). Baseline characteristics of patients from the MACE service who were matched with patients receiving usual care did not differ substantially from characteristics in patients who were not matched, except that the latter patients were older (mean [SD] age, 88.9 [7.0] years). All subsequent analyses were carried out in the matched cohort.
Patients in the MACE group had a mean (SD) age of 85.2 (5.3) years, 76.3% were female, and 55.5% were white; they were well matched to the usual-care group (mean [SD] age, 84.7 [5.4]; 72.8% were female and 48.0% were white) (Table 1). Patients in the MACE and usual-care groups were equally likely to be Medicaid beneficiaries (34.7% and 36.4%). Only 31.8% in each group were able to ambulate independently at baseline. Patients in the MACE group were slightly more ill on admission than those in the usual-care group (mean [SD] APACHE score, 10.0 [3.5] vs 9.1 [2.8]; P = .004), had a higher prevalence of dementia (45.1% vs 34.1%; P = .03) or delirium at admission (22.5% vs 10.4%; P = .001), and were taking more prescribed medications at baseline (mean [SD], 10.0 [4.0] vs 8.0 [4.0]; P < .001). A total of 149 patients (86.1%) from the MACE service and 156 (90.2%) receiving usual care completed 30-day follow-up. Baseline characteristics did not differ between patients who did not complete 30-day follow-up and those who did.
Among patients in the MACE group, 15.4% were readmitted within 30 days of discharge compared with 22.4% in the usual-care group (odds ratio [OR], 0.67; 95% CI, 0.35-1.25) (Table 2). After multivariable adjustment, there was no difference between the 2 groups in readmission risk at 30 days (adjusted OR, 0.91; 95% CI, 0.39- 2.10; P = .83) (Table 3). Rates of acute care use, which combine visits to emergency departments and readmissions at 30 days, also did not differ (20.8% vs 25.6%; OR, 0.77; 95% CI, 0.36-1.64; P = .50).
The incidence of adverse events in the hospital was lower in the MACE group; 9.5% experienced adverse events, including falls, pressure ulcers, catheter-associated UTIs, and restraint use compared with 17.0% in the usual-care group (P = .02). After multivariable adjustment, adverse events remained less likely in the MACE group (adjusted OR, 0.11; 95% CI, 0.01-0.88; P = .04).
Length of stay and discharge destination
The mean (SD) length of stay among patients in the MACE group was 4.6 (3.3) days, which was shorter than that in the usual-care group (6.8 [7.6] days; P = .001) (Table 2). After multivariable adjustment, the mean length of stay was 0.8 days shorter among patients in the MACE group than for those in the usual-care group (95% CI, 0.7-0.9; P = .001). The distributions of discharge destination were similar in the 2 groups; approximately 24.9% in the MACE group were discharged to a skilled nursing facility compared with 22.5% in the usual-care group, although among those discharged to home, patients in the MACE group were more likely to receive postdischarge services at home, including skilled nursing and chore services (82.3% vs 68.9%; P = .01).
Functional status in performing basic activities of daily living was measured with the FIM motor scale 30 days after discharge; the mean (SD) score was 60.9 (21.1) in the MACE group and 56.5 (27.0) in the usual-care group (Table 2). The between-group difference after multivariable adjustment was 2.3 points (95% CI, −1.6 to 6.1; P = .24), which was not statistically significant. The ability to perform instrumental activities of daily living, assessed with OARS-IADL, also did not differ between the groups after multivariable adjustment (between-group difference, 0.01 point; 95% CI, −0.54 to 0.56; P = .98).
Patient satisfaction and health status
Patients in the MACE group were more likely than those receiving usual care to report that they talked about the help they would need after discharge (92.2% vs 67.6%; P = .005) (Table 2). Taken as a whole, patient satisfaction, measured with HCAHPS, did not differ substantially between care groups. However, satisfaction measured with the 3-item Care Transition Measure was 7.4 points (95% CI, 2.9-11.9) higher in the MACE group (P = .001) after multivariable adjustment. Overall health status, measured with the PROMIS tool at 30 days, did not differ between care groups, nor did the EQ-5D scores.
In this single-site study of a redesigned ACE program, we found that the MACE service was associated with better outcomes than usual care in several important areas and was not associated with worse outcomes, although readmission rates at 30 days and other measured outcomes did not differ significantly between the groups. Of note, the MACE service was associated with lower rates of adverse events, shorter hospital stays, and improved satisfaction with transitions of care. These findings suggest that providing inpatient care through a MACE service may be associated with better outcomes for this vulnerable older adult population.
The potential benefits of receiving care in a MACE service are probably multifactorial, because the service was built using an interdisciplinary approach, with a focus on multiple components, including avoiding hazards of hospitalization, improving care coordination, and providing patient and caregiver education. The higher use of home services in the MACE group at discharge may mediate the reduction in length of stay among these patients. Considering that few hospitals have dedicated units or floors for the care of older adults and the ACE unit model has had limited dissemination nationally, the MACE model may be a viable alternative because it can be seamlessly integrated in a hospital's work flow without the requirement for a dedicated unit.
The only new role that requires staffing is the nurse coordinator, because the social worker and geriatrics physician are obtained from reallocating existing resources.11 This cost may be offset by improved patient outcomes, including a reduction in length of stay and adverse event rates; the latter may lead to better reimbursement as payment is increasingly linked to outcomes. Further studies are needed to compare the effects and barriers to implementation between MACE and other types of inpatient geriatric models, such as consultative models. Of note, MACE was established as an inpatient care model integrated with an outpatient geriatric practice, which was a patient-centered medical home, and is now part of an accountable care organization. MACE may be a valuable component program of such organizations as more health care organizations adopt this model.
Although prior studies in physical ACE units demonstrated that functional status at hospital discharge could be improved through ACE unit care, the effect was not long lasting.28 This finding is consistent with our results, which showed little benefit associated with the MACE service in patient functioning 30 days after discharge.
A main limitation of the study is due to its observational design and its potential bias; patients in the MACE service were also receiving care at a geriatrician-based primary care practice. Although we have taken steps to reduce potential imbalances between the comparison groups by using a prospective matching method, it is possible that some of the effects associated with the MACE service may be related to its association with a geriatric primary care practice. Through our matching strategy, we were able to establish a control group that differed from the MACE group for a few measured variables. However, these differences suggested that patients in the MACE group were sicker than the comparison group, which may imply that our results underestimate the effectiveness of receiving care from the MACE service. Another limitation is that for the outcome of hospital adverse events, medical records were reviewed by a single investigator who could not be blinded to group assignment. Finally, our study was a single-center study in an urban tertiary medical center; further studies in other settings are needed to demonstrate its generalizability.
In conclusion, the MACE service is a readily adaptable model of inpatient care that may be associated with better outcomes for hospitalized older adults. As hospital systems devise ways to improve the delivery and quality of care for older adults, the MACE service model should be considered.
Correspondence: William W. Hung, MD, MPH, Mount Sinai School of Medicine, 1 Gustave L Levy Pl, PO Box 1070, New York, NY 10029 (william.hung@mssm.edu).
Accepted for Publication: December 27, 2012.
Published Online: April 22, 2013. doi:10.1001/jamainternmed.2013.478
Author Contributions: All authors had full access to all the data in the study. Dr Hung takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Hung, Ross, and Siu. Acquisition of data: Hung. Analysis and interpretation of the data: Hung, Ross, and Farber. Drafting of the manuscript: Hung. Critical revision of the manuscript for important intellectual content: All authors. Statistical analysis: Hung. Obtained funding: Hung and Sui. Administrative, technical, or material support: Siu. Study supervision: Ross and Siu.
Conflict of Interest Disclosures: Dr Ross reports that he is a member of a scientific advisory board for FAIR Health, Inc, and receives grant funding from Medtronic, Inc, to develop methods of clinical trial data sharing, from the Centers for Medicare & Medicaid Services to develop and maintain performance measures used for public reporting, and from the Pew Charitable Trusts to examine regulatory issues at the US Food and Drug Administration. Dr Ross is supported by the National Institute on Aging (grant K08 AG032886) and by the American Federation for Aging Research through the Paul B. Beeson Career Development Award Program.
Funding/Support: Support for this project was provided by the John A. Hartford Center of Excellence and in part by the Claude D. Pepper Older Americans Independence Center at Mount Sinai School of Medicine (grant P30-AG028741).
Role of the Sponsors: The sponsor played no role in the design of the study, analysis or interpretation of findings, or drafting the manuscript and did not review or approve the manuscript prior to submission. The authors assume full responsibility for the accuracy and completeness of the ideas presented.
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