Evaluation of Ambulatory Geriatric Rehabilitation (EAGER): study protocol of a matched cohort study based on claims data
© The Author(s). 2017
Received: 19 November 2016
Accepted: 16 February 2017
Published: 2 March 2017
Ambulatory geriatric rehabilitation (AGR) is a community based outpatient intervention which aims to improve physical function, maintain independent living of geriatric patients, avoiding hospitalisation and institutionalisation. It should therefore reduce health care costs. The objective of our study is to evaluate the effectiveness of AGR for frail elderly patients insured by the statutory health insurance AOK Nordost compared to care as usual. Outcome variables are progression to higher nursing care levels, admission to nursing home, incident fractures, hospital admission, ambulatory care sensitive hospital admissions, days spent in hospital, and health care costs.
This matched cohort study aims to estimate average treatment effects of AGR. For this purpose we will compare patients receiving AGR with matched patients receiving care as usual. Patients in the intervention group were treated between the years 2009 and 2013 from three centres in Mecklenburg-Vorpommern, Germany. Matching will be conducted using propensity score techniques. Claims data will be provided by the statutory health insurance AOK Nordost. The primary outcomes are the progression of nursing care levels, incident fractures, and admission to nursing home. Secondary outcomes are total and ambulatory care sensitive hospital admissions, and health care costs from the statutory health insurance perspective. Data will be analysed using appropriate regression models.
This study aims to quantify the effectiveness of AGR. Results will be important for providers of AGR, policy makers and stakeholders to make informed decisions on whether to continue, modify or extend AGR.
German Clinical Trials Register (DRKS) S00008926, registered 29.07.2015
KeywordsAmbulatory geriatric rehabilitation Geriatric multimorbidity Health claims data Matched cohort study Propensity score matching
Many elderly will experience a reduction in physical function, leading to more falls and injuries. This leads to a loss of independence, hospitalisation, long-term nursing home care as well as premature death [1, 2]. In 2013, 2.63 million people in Germany were in need of nursing care. Roughly two third of them received ambulatory nursing care and one third received care in a nursing home. From the years 2011 to 2013, people receiving nursing care increased by 5% . In 2014, 27% of the population aged 65–79 received either ambulatory or institutionalised nursing care . Given the projected demographic changes in Germany, the population in the age group ≥65 years will increase from 21% (17.3 million) in the year 2015 to 27% (21.8 million) in the year 2030 . Long term nursing care and institutionalisation in a nursing home can be associated with a significant reduction of quality of life, mainly due to loss of autonomy and social contacts . The increased need of long term nursing care poses a major economic challenge . Thus measures to prevent, minimise or delay long term nursing care for elderly are urgently needed.
Germany has mandatory nursing care insurance attached to statutory health insurance since 1995. Elderly with disabilities or dementia can apply for a nursing care level [Pflegestufe]. To identify elderly in need, a basic geriatric assessment performed in general practice was introduced in 2005 . Although elderly are entitled to rehabilitative services as codified in the Book V (SGB V) and XI (SGB XI) of the German social code general practitioners have only limited access to specialised rehabilitative services for geriatric patients. While the number of hospitals providing geriatric services is increasing, the demand for ambulatory services is not met . Elderly patients with a need for rehabilitation prefer to stay close to their home and relatives, maintaining their everyday life . Consequently, ambulatory rehabilitation is preferred. Rehabilitative services were and are still mainly available after hospitalisation e.g. for stroke or fracture after a fall.
Preventive ambulatory geriatric rehabilitation (AGR [Ambulante Geriatrische Komplexbehandlung]) was introduced in 2008 within the legal frame (§ 140 Book V of the social code) of selective contracts for integrated care. Therefore it is only available as a model intervention in some areas for holders of specific statutory health insurances (e.g. AOK Nordost). AGR is not part of regular health care.
It is intended as a community based outpatient intervention to improve patient’s physical function, increase patient’s safety and quality of life as well as to prevent falls and injuries, to avoid and delay hospitalisation, the progression of nursing care level and admission to nursing home.
A systematic review of controlled trials of ambulatory and hospital interventions to improve physical function and maintain independent living in elderly people concluded that they were effective to achieve the goal . This review comprised only one German trial which included geriatric patient post hospital discharge . However, AGR is primarily intended to prevent hospitalisation and not as a post-discharge rehabilitation. The effectiveness of German AGR programs has not been evaluated rigorously yet. Previous studies have relied on uncontrolled study designs .
Objectives and hypotheses
The aim of our study is to evaluate the effectiveness of AGR regarding patient’s progression to higher nursing care levels, incident fractures, admission to nursing home, hospital admissions as well as health care costs. For this purpose we compare patients receiving AGR with patients receiving care as usual. We will estimate average treatment effects based on a cohort design using propensity score techniques to match cases and controls. The follow-up period will be up to 2 years.
AGR reduces and delays progression to higher nursing care levels.
AGR reduces and delays nursing home admissions.
AGR reduces the risk of incident fractures.
AGR decreases and delays hospital admissions and reduces the days spent in hospital during follow-up time.
AGR decreases and delays ambulatory care sensitive hospital admissions.
AGR decreases total health care costs from the statutory health insurance perspective.
On an exploratory basis we will investigate the effect on drug prescriptions.
The conduct of a randomised controlled trial to assess the effectiveness of AGR is currently limited due to logistic and ethical reasons. Therefore we will conduct a matched cohort study using claims data. Anonymised data will be provided by the statutory health insurance AOK Nordost which comprises basic demographic data, data on nursing care level, admission to a nursing home, billing data for ambulatory services (EBM position numbers) and for hospital services (DRG-codes/OPS-codes), as well as diagnoses (ICD-10 codes), and all health care costs, including costs for hospitalisation, remedies and aids, ambulatory costs and costs for medication. To balance potential confounders, we will apply a propensity score matching. Controls will be matched patients insured by the AOK Nordost.
The observation period comprises 4 billing periods (each 3 months, corresponding to 1 year) prior to the intervention, the intervention (index) billing period, and up to 8 billing periods post intervention, resulting in a total observation period of up to 13 billing periods. The billing period covering the most days of the intervention will be considered as the index billing period. Participants in the intervention group received a 4 weeks AGR in between the years 2009 and 2013.
Description of the AGR intervention and the setting
Eligibility criteria for AGR
Aged 70 and older
at least two geriatric multimorbidity listed in Table 1
impairment or handicap with functional deficits
at least one of the health conditions listed in Table 2
M96.8, M62.3, M62.5
G30, F00 – F07
R32, N39, R15
L89, L97, I83, L98
R64, E41, E43, E44
Disturbances in fluid and electrolyte balance
E86, E87, R60
Depression and Anxiety
F30 – F33, F40, F41
R20, G50 – G59, G60 – G64
severe visual or hearing impairment
H25, H28, H52-H54, H90, H91
Eligibility criteria for participation in AGR
Stroke and other cerebrovascular disorders
Status post fracture
Arterial obstructive disease with amputation or other surgery
Cox and osteoarthritis with Implantation of an endoprosthesis
Exacerbated chronic obstructive pulmonary disease
Pneumonia and other respiratory tract infections
Other fractures and injuries
Spondylopathies and Discopathies, possibly with laminectomy
Coronary heart disease and other heart diseases with cardiac surgery
Delirium and other organic brain psychosis
Symptoms, effecting the nervous system and musculoskeletal system
R29.5, R29.6, R29.8
Patients are not eligible for AGR if the assessment indicates a need for hospital admission, if they are not able to participate due to a poor health status or if they are unable to provide informed consent.
Exclusion criteria from the analyses
Criteria for the exclusion of AGR participants for study analysis
- Age <70 or >95 years in the intervention billing period
Prior to the intervention billing period:
- nursing care >2
- <360 insured days in the four previous billing periods
- living in a nursing home
- hospital costs without out of pocket spending at the last billing period >33.000 €
- hospital costs without out of pocket spending during the four last billing periods ≥44.000 €
- ambulatory costs during the last billing period ≥2.200 €
- ambulatory costs during the four last billing periods ∑ ≥5.500€
- remedy costs without out of pocket spending during the four previous billing periods ≥2.200 €
- costs of aid without out of pocket spending during the four previous billing periods ≥4.000 €
- drug costs without out of pocket spending during the four previous billing periods AGR ≥11.000 €
- total health care costs without out of pocket spending during the four previous billing periods ≥44.000 €
- diagnosed AIDS/HIV in the four previous billing periods
- chemotherapy in the four previous billing periods
- organ transplantation during the four previous billing periods
- dialysis during the four previous billing periods
The intervention group consists of all AGR participants, receiving the AGR in Mecklenburg-Vorpommern during the years 2009–2013. This will comprise approximately 700 patients. Controls will be chosen from a pool of around 250.000 members of the AOK Nordost aged 70 years and older. Approximately 2800 controls will be selected from the pool.
Outcome measures and data collection
Claims data will comprise the billing periods from 01.01.2008 until 31.12.2014, thus ensuring a minimal observation period of 12 months prior and after the index billing period. All variables are provided for each billing period during the observation period.
The primary outcomes are ‘progression of nursing care level’, ‘admission to nursing home’ and ‘incident fractures’.
Definitions of the nursing care levels 
Nursing care level
total daily help
(including help in household)
personal help (included in total daily help)
minimum 1,5 h
minimum 3 h
≥2 h, 3 times a day
minimum 5 h
≥4 h permanent help
The outcomes ‘admission to nursing home’ and ‘incident fractures’ are both coded as binary variables, stating whether the patients experienced the event after the index billing period or not.
Ambulatory care sensitive conditions
Ischaemic heart diseases
I25.0, I25.1, I25.5, I25.6, I25.8, I25.9
Other diseases of the circulatory system
I05, I06, I08.0, I49.8, I49.9, I67.2, I67.4, I70, I73, I78, I80.0, I80.80, I83, I86, I87, I95, R00.0, R00.2
Bronchitis & COPD
J20, J21, J40-J44, J47
Mental and behavioural disorders due to use of alcohol or opioids
Back pain [dorsopathies]
M42, M47, M53, M54
I10 - I15
Gastroenteritis and other diseases of intestines
K52.2, K52.8, K52.9, K57, K58, K59.0
Intestinal infectious diseases
A01, A02, A04, A05, A07-A09
Influenza and pneumonia
J10, J11, J13, J14, J15.3, J15.4, J15.7, J15.8, J15.9, J16.8, J18.0, J18.1, J18.8, J18.9
Ear nose throat infections
H66, H67, J01-J04, J06, J31, J32, J35
E10.2-E10.6, E10.8, E10.9, E11, E13.6, E13.7, E13.9, E14, E16.2
Gonarthrosis [arthrosis of knee]
M17.0, M17.1, M17.4, M17.5, M17.9
Soft tissue disorders
G56.0, M67.4, M71.3, M75-M77, M79
Other avoidable mental and behavioural disorders
F40, F41, F43, F45, F50.0, F50.2, F60
Diseases of the eye
Diseases of urinary system
N30, N34, N39.0
Diseases of the skin and subcutaneous tissue
A46, L01, L02, L04, L08.0, L08.8, L08.9, L60.0, L72.1, L98.0
E03 - E05, E89.0
Melanoma and other malignant neoplasms of skin
Gastritis and duodenitis
K21, K29.7, K29.9, K30, K31
Migraine and headache syndromes
G43, G44.0, G44.1, G44.3, G44.4, G44.8, R51
Malnutrition & nutritional deficiencies
E40 - 64, R63.6, D50, D51-D52, D53.1, D56
Alcoholic liver disease
K02, K04-K06, K08, K12, K13
Inflammatory diseases of female pelvic organs and disorders of female genital tract
N70-N72, N75, N76, N84.1, N86, N87
Diseases of male genital organs
N41, N45, N48.4
Avoidable infectious and parasitic diseases
A15.3, A15.4, A15.9, A16.2, A16.3, A16.5, A16.8, A16.9, A34 - A37, A50-A58, A63, A64, A80, B05 - B07, B15, B16.1, B16.9, B17, B18.0, B18.1, B20 - B24, B26, B34.9, B51 - B54, B77, B86
Convulsions, not elsewhere classified
Decubitus ulcer and pressure area
Rare diseases with <5000 cases each
F80, R63.0, R63.3, R63.8, Z73
L03, L04, L08.0, L08.8, L08.9, L88, L98.0, I891, L010, L011, L020 - L024, L028, L029
I20, I24.0, I24.8, I24.9, I25, R072, R073, R074, Z034, Z035
Convulsions and epilepsy
G25.3, G40, G41, O15, R56, R568
Dehydration and infections
A02, A04, A09, A05.9, A07.2, A08.0, A08.1, A08.3, A08.4, A08.5, E86, K52.0, K52.1, K52.2, K52.8, K52.9
D46.0, D46.1, D46.3, D46.4, D50.1, D50.8, D50.9, D51.0–D51.3, D51.8, D52.0, D52.1, D52.8, D52.9, D53.1, D57.1, D58.0, D58.1, D59.0 – D59.2, D59.9, D60.1, D60.8, D60.9, D61.0, D61.1, D64.0 - D64.4, D64.8
Pelvic inflammatory disease
N70, N73, N74
K20, K21.0, K21.9, K22.1, K22.6, K25.0 – K25.2, K25.4 – K25.6, K25.9, K26.0 – K26.2, K26.4 – K26.6, K27,K28.0 – 28.2, K28.4 – K28.6, K92.0, K92.1, K92.2, L97
N10, N11, N12, N13.6, N15.9, N30.0, N30.8, N30.9, N39.0,
Atrial fibrillation and flutter
I47.1, I47.9, I49.5, I49.8, I49.9, R00.0, R00.2, R00.8
Dyspepsia and other stomach function disorders
E10, E13.6 – E13.9, E14.9
A15, A16, A17, A18, A19
F20, F21, F23.2, F25
I61, I62, I63, I64, I66, I67.2, I69.8, R47.0
‘Total health care costs’ comprises expenditures for hospitalisation, remedies and medical aids, ambulatory costs, and medication. The variables concerning costs refer to costs excluding out-of-pocket spending except for remedies and medical aids where the available data does not allow for any separate analysis of out-of-pocket spending.
Matching and statistical analyses
To balance the distribution of potential confounders among cases and controls we will conduct a propensity score matching using a many-to-one matching . Variables for the estimation of the propensity score will be selected based on their expected importance to predict AGR participation as well as the outcomes of interest.
x ± 2 years
Area of residence
Days being insured
Level of nursing care
Hospital admission yes/no
Charlson Comorbidity index (CCI)
Days spent in the hospital
Hospital costs without out-of-pocket spending
Costs of remedy
Costs of medical aid
Drug costs without out-of-pocket spending
Total costs with out-of-pocket spending
Main diagnoses before AGR
Status post fracture or joint replacement
Cox- or gonarthrosis with endoprothesis
Other fractures and injuries
Spondylopathies and Discopathies, possibly with laminectomy
Pneumonia and other lung inflammations
Chronic obstructive pulmonary disease (COPD)
Arterial obstructive disease with amputation or other surgery
Coronary heart diseases with surgery
Stroke and other cerebrovascular diseases
Delirium and other organic brain psychosis
Symptoms, effecting the nervous system and musculoskeletal system
Charlson Comorbidity Index
Chronic pulmonary disease
Congestive heart failure
Metastatic solid tumor
Hemiplegia or paraplegia
Mild liver disease
Peripheral vascular disease
Severe visual/hearing impairment
Subsequently, propensity scores will be calculated using a logistic regression model using coded morbidity and costs under the scenarios a.) and b.), based on all variables listed in Table 6, taking statistical interactions and nonlinear associations into account. Up to four controls may be assigned to one case without repetition.
Appropriate regression models (e.g. time-event models, mixed models, two-part models) will be applied to study effects on our primary and secondary outcomes. Because treatment might also affect censoring due to mortality, competing risks models (using the Fine-Gray approach) will be applied . Patients dying during the follow-up period will not be excluded from the analyses.
AGR is currently only available in few areas for elderly people from selected statutory health insurances which opted to offer AGR to their beneficiaries. Evaluation of this intervention was previously limited to uncontrolled study designs . To the best of our knowledge, this will be the first study to evaluate AGR using a quasi-experimental design. This study may provide an estimation of the effectiveness of AGR on progression to higher nursing care levels and hospitalisation and other endpoints of clinical relevance. Our results will be important for providers of AGR, policy makers and stakeholders to make informed decisions on whether to continue, modify or even expand AGR to other areas in Germany. Additionally, our results might help to optimise AGR by identifying subgroups of patients who are more likely to benefit from AGR.
A limitation will be the restriction to claims data. Clinical measurements from instruments used for the geriatric assessment are not available for the control group. This might impair the quality of the matching as potential imbalance between clinical data and individual motivation to participate in AGR cannot be ruled out even if a high balance on claims data is achieved. Therefore, residual confounding may still be an issue after our matching. Final decisions on the applied methods need to account for the precise properties of the data.
Ambulatory geriatric rehabilitation
Charlson comorbidity index
German Diagnosis related Groups/Operationen- und Prozedurenschlüssel, billing data for hospital services
- EBM position numbers:
Uniform assessment standard, billing data for ambulatory Services (Einheitlicher Bewertungsmaßstab)
- ICD-10 code:
International Classification of Diseases, 10th Revision
German Social Code (Sozialgesetzbuch)
We would like to acknowledge Katrin Reber for her help to coordinate the study as well as Christoph Wagner for advice and support on data management. We are grateful to Sabine Meinhold, M. D., Holger Streich, M.D., and Dieter Hotzelmann, M.D. who offered AGR in Mecklenburg-Vorpommern. We are also grateful to the department of Epidemiology of Health Care and Community Health, Institute of Community Medicine, University Medicine Greifswald who provided the map of Mecklenburg-Vorpommern.
The evaluation is funded by the Federal Ministry of Education and Research (BMBF—Bundesministerium für Bildung und Forschung, Förderkennzeichen: 01GY1344).
Availability of data and material
The supervising authority ‘Ministry of Environment, Health and Consumer Protection of the Federal State of Brandenburg (MUGV)’ of the statutory health insurance which will provide the data (AOK Nordost), approved data transmission and analysis. Claims data will be anonymized before scientific analyses. The data are stored according to the data safety and management plan of the Institute for Community Medicine. The data will not be used for any other purpose than stated in the grant proposal and will not be transmitted to any other third party. Data will not be shared publicly due to legal restrictions regarding claims data according to SGB XI.
The study was conceived and funding was obtained by Jean-François Chenot and Carsten Oliver Schmidt. All authors contributed to data collection, data management, and the development of the study protocol. The manuscript was drafted by Simone Kiel, Jean-François Chenot and Carsten Oliver Schmidt. All authors finalised, provided critical review, and approved the final manuscript.
The authors declare that they have no competing interest. The AOK Nordost provided the data but has no influence on the analysis and the decision to publish.
Consent for publication
Ethics approval and consent to participate
The study protocol was reviewed and approved by the ethical review board of the University Medicine Greifswald. Patients participating in model projects like AGR are informed that their data will be used for scientific purposes.
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