Introduction

Cerebrovascular diseases, such as stroke, are among the greatest challenges in healthcare [23, 24]. In Germany, about 196,000 first-ever strokes occur every year. In addition, about 66,000 recurrent strokes take place [21]. In the context of the demographic development with an ageing population, the number of stroke patients is expected to increase significantly in the coming years [14]. In parallel with the increasing incidence and decreasing mortality, however, it is above all the impairments caused by a stroke that are of great interest to health care practitioners and other health care actors [33, 41].

Stroke, the second leading cause of death worldwide, represents one of the main reasons for long-term disability [45]. In high-income countries, stroke is even the most common cause of acquired impairment in adulthood, and some of those affected are confronted with dramatic changes in patients’ everyday lives [17, 43]. Data on long-term disability and recovery after stroke vary widely and depend on various influencing factors, like age or type of stroke [6, 46]. However, motor impairments after stroke are found in about 80% of all cases [27], which are associated with persisting disability and dependency in over 30% [12].

The importance of neuro-rehabilitative research becomes obvious in regard to these numbers [5]. The main aim of neurological rehabilitation is to improve function and independence in activities of daily living, and to enable social participation [12]. The understanding of rehabilitation must not only be based on the underlying disease mechanisms, but must above all be based on the consequences of the disease according to the International Classification of Functioning, Disability and Health [44]. This concept divides the disease consequences into three main areas: (a) damage to body functions and structure (e.g. paresis of the hand), (b) activity (e.g. learning activities, exercise of skills) and (c) participation (e.g. participation in professional and social life). In addition to pathophysiological classification, this system offers the possibility of classifying and specifically treating patients with regard to their functional state of health, the degree of limitation and their social effects.

Stroke research is often focused on the acute treatment phase as well as on the first weeks of rehabilitation – usually the phase of inpatient rehabilitation [40]. Data on long-term disability and recovery after stroke is limited. Few studies have explored functionality based on the ICF conceptual model [38].

In stroke patients, a wide range of individual variability of recovery extent and rate can be observed clinically. However, it is still open which factors contribute to functional recovery. Detailed data describing the long-term development of stroke patients after being discharged from rehabilitation programs are rare. To date, it is not fully described how stable the effects of rehabilitation are and how much clinical improvement can be seen in the time period following inpatient rehabilitation, especially with regard to ICF functionality. Even less is known about the patients’ perspective on long-term recovery from stroke.

This lack of data is also due to a missing link between research institutions and rehabilitation centers [19, 39]. Therefore, the IMPROVE-platform was established as a research collaboration between an Universitary Stroke Center, i.e., the department of neurology at the University Medical Center Hamburg-Eppendorf (UKE) and five rehabilitation clinics, to address the mentioned questions in future research projects.

This first study of the IMPROVE platform is a multicenter observational prospective study to investigate the main factors influencing the functional recovery of stroke patients with regard to the ICF-dimensions in a long-term view with a focus on hand function.

Methods

Aim of the study

The overall goal of this study is to identify and understand factors that influence the course of recovery following focal brain lesions within the framework of standard neurorehabilitation in Germany. In this observational longitudinal study, the long-term recovery processes of stroke patients will be investigated. The influence of motor function, cognition, care situation, depression, fatigue as well as information and knowledge about the disease on functional recovery, participation, autonomy and quality of life will be assessed. The assessment of motor function focuses on hand-function, which represents a crucial function for independence and participation in activities of daily living. The current state of subjective as well as objective parameters is surveyed. The development of hand function 1 year after rehabilitation and the main factors influencing it will be analyzed. Ideally, the results obtained can be used to identify opportunities and improvement potentials for future rehabilitation strategies. More targeted planning and individualized therapy courses could be results of this development.

Study description and study design

IMPROVE is an observational, longitudinal, multicenter study in an Universitary Stroke Center and five rehabilitation centers in northern Germany (NCT04119479). The applied set of assessments includes self-reported outcome measures as well as objective scores representing the ICF dimensions body function and structure, activity and participation. Initial measures are conducted during the end of inpatient rehabilitation in the cooperating study centers. Follow-up examinations take place three, six and 12 months after inclusion (Fig. 1). Measures include standardized state of the art motor and cognitive function assessments carried out by trained health care specialists. In addition, questionnaires are provided covering a number of stroke specific health care topics. If available, routine magnetic resonance imaging data from the acute care phase is collected as well. Before inclusion, patients are informed thoroughly about the study structure and the ability to opt-out at any given point. Data collection is carried out according to European data protection law.

Fig. 1
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Stroke patients with an ischemic or hemorrhagic stroke with a still remaining deficit (mRS ≥1) during the end of inpatient rehabilitation are included in the study. In addition, a group of patients with craniocerebral trauma from the rehabilitation centers as well as a group of chronic stroke patients is recruited as a comparison group. All groups undergo the same examinations and ICF-orientated assessments

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The IMPROVE research platform

For this research project, rehabilitation centers suitable for implementation were sought and approached. The general study structure was discussed in preparatory meetings and developed together with the participating centers. In the first months of 2017, the last adjustments to the study design were made, particularly with regard to the selection of assessors.

For the implementation in clinical everyday life of the rehabilitation clinics, an intensive exchange with the cooperation clinics took place via visits and various meetings. Task force meetings are hold, which are attended by one representative of each of the partner clinics. In addition, joint cooperation meetings involving the local medical study management and representatives of the therapy areas of all clinics are performed. At the same time, there are regular telephone and E-mail exchanges, covering individual questions and assessment contents. A monthly IMPROVE newsletter is set up to inform all participants about current activities and the current recruitment status.

An initial standardized on-site training was given to the staff in each of the participating rehabilitation clinics, covering the topics inclusion, documentation, the exact performance of assessments and the exchange of data between the rehabilitation clinic and UKE. Only trained personnel are allowed to carry out the study in order to ensure a standardized implementation. A test run of one to two patients per clinic was initially carried out for quality assurance and in order to integrate the study into the processes of the clinics. If new members join the study team, they are also trained in the IMPROVE standards. An electronic Case Report Form is set up for the IMPROVE study. All follow-up examinations are carried out at the UKE by the same trained study team. In order to enable all patients to participate, travel costs are reimbursed or transport to the study center is organized.

Study arms

Three groups are included in the study. Mainly subacute stroke patients with an ischemic or hemorrhagic stroke at the end of their inpatient rehabilitation period. Only patients with a still remaining deficit are included. In one rehabilitation center, craniocerebral trauma patients at the end of the inpatient rehabilitation are recruited as a second group. Additionally, a cohort of chronic stroke patients is recruited by the post stroke clinic of the UKE Neurology department. The chronic stroke group as well as the group of craniocerebral trauma patients represent a comparison group. All groups undergo the same examinations.

Eligibility criteria

Patients admitted to the cooperating rehabilitation centers following cerebral infarction and/or cerebral hemorrhage (ICD 10 I61-I69) are screened by a physician for eligibility. Patients from the rehabilitation centers are included at the end of rehabilitation phases C and D according to the criteria of the Bundesarbeitsgemeinschaft für Rehabilitation [3].

Inclusion criteria are:

  • Ischemic or hemorrhagic stroke according to ICD 10 I61-I69

  • Patients in or after completion of rehabilitation phases C and D according to BAR criteria

  • Age ≥  18

  • Sufficient knowledge of German

  • Existing declaration of consent

  • Deficit still existing (modified Rankin score of at least 1 at inclusion)

Exclusion criteria are:

  • Need for care prior stroke

  • Subarachnoid hemorrhage, craniocerebral trauma, transient ischemic attack as primary diagnosis

  • Severe pre-existing psychiatric disease

  • Participation in follow-up examination not possible

For the chronic stroke group as well as the craniocerebral trauma group the same inclusion/exclusion criteria are applied. For the chronic stroke group patients are included in an outpatient setting after completing inpatient rehabilitation. For the craniocerebral trauma group patients with craniocerebral trauma (ICD 10 S06.1-S06.9) as a primary diagnosis are included.

Sample size estimation

As this is an explorative observational study, no classical calculation of sample sizes is eligible. Based on the annual treatment numbers of the participating clinics, an initial estimate of 300 inclusions was made. Eighteen months after the beginning of the study we performed a sample size calculation based on the available data on recovery of the hand function in the Stroke Impact Scale (SIS) and the dropout rate of the patients included until then. Based on these data we estimated that we would need N = 225 to be able to identify a difference with Cohens d = 0.3. The recruitment goal could be reduced to 225 patients.

Outcome measures

The primary outcome measure is a hand motor score built by the sum of the hand items of the Fugl-Meyer upper limb motor score as an objective measurement of hand function after 1 year [15]. This subdomain covers seven performance tasks rated in a three-point scale from 0 = cannot perform, 1 = performs partially and 2 = performs fully. The seven tasks include Finger flexion (1), Finger extension (2), Extension of metocarpophalangeal joints, flexion of proximal and distal interphalangeal joints (3), Thumb adduction (4), Thumb opposition (5), Grasp cylinder (6), Grasp tennis ball (7). The maximal possible score is 14.

Further outcome measures include assessments and scores that are regularly used in rehabilitation settings and are designed to reflect the three components of the International Classification of Functioning, Disability and Health (Tables 1, 2 and 3).

Table 1 Assessments used in the study reflecting the component body structure of the International Classification of Functioning, Disability and Health
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Table 2 Assessments used in the study reflecting the component activities of the International Classification of Functioning, Disability and Health
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Table 3 Assessments used in the study reflecting the components participation of the International Classification of Functioning, Disability and Health
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In addition, medical history is recorded at each examination time point. Questionnaires about health care structure (ZAPA) [36], level of information and information needs and sociodemographic information [18] are included.

Certain data regarding sociodemographic information and clinical characteristics of stroke are collected at the first examination. Questionnaires which are just applicable for patients, which have left the hospital environment (like the SIS) are added to the assessments starting from the first follow-up after 3 months.

If available, magnetic resonance imaging from the acute phase are acquired and stroke volume and location is analyzed using semi-automatic segmentation software.

Contacts

The study is conducted as a multicenter study by the Department of Neurology of the University Medical Center Hamburg-Eppendorf in collaboration with the departments for neurological rehabilitation of RehaCentrum Hamburg, MEDICLIN Klinikum Soltau, Klinikum Bad Bramstedt, VAMED Klinik Geesthacht and VAMED Rehaklinik Damp. The study is funded by the University Medical Center Hamburg-Eppendorf and the Deutsche Rentenversicherung Nord.

Perspective

While stroke rehabilitation research often focuses on the acute treatment phase and the time period of inpatient rehabilitation, we designed a study to investigate the long-term development of stroke patients after discharge from the rehabilitation clinic. Recruitment to the study was started in July 2017. The estimated primary completion date is July 2020.

The data of this study will provide an insight into the long-time course of stroke rehabilitation. The data collected have the potential to identify factors that influence recovery from stroke in the long term. This can be the basis for further treatment improvements in stroke rehabilitation by addressing potentially unknown factors and thus individualize therapy paths.

Besides that, investigating the long-term course of chronic stroke patients will give an important information about the recovery potential of these patients in a standard care setting. Quality of life at the end of the rehabilitation as well as changes in quality of life over 1 year will be investigated. Data on patients’ stroke-related health literacy and information needs over 1 year will be analyzed.

Overall, this study can contribute to a better understanding of the long-term course of stroke patients, thereby help health professionals dealing with stroke with an earlier prognosis and maybe provide data for patient-individualized treatment-protocols in the future.

With this study, the IMPROVE-Platform is established as an interdisciplinary platform for rehabilitation research for stroke patients. This first study addressing the actual practice of neurorehabilitation will be the basis for building new research hypotheses, which than can be tested in future studies within the IMPROVE-Platform. This platform connects experts from research and clinical practice of neurorehabilitation and thereby forms a network to build up future research projects in the area of neurorehabilitation.