Introduction

According to the World Health Organization (WHO) rehabilitation is defined as “a set of interventions designed to optimize functioning and reduce disability in individuals with health conditions in interaction with their environment”1. Rehabilitation is considered a key health strategy in the 21st century. Demographic and epidemiological trends indicate that human functioning is one of the most important indicators of population health, apart from morbidity and mortality. Thus, it suggests that the main focus of healthcare will be on the real health needs generated by long-term treatment of chronic diseases, including comprehensive enhancement and intensification of rehabilitation1,2.

The aim of rehabilitation is to optimize functioning of patients. WHO indicates International Classifications and Terminologies including the International Statistical Classification of Diseases and Related Health Problems (ICD) and the International Classification of Functioning, Disability and Health (ICF) as the global standards for collecting data regarding health, clinical documentation and statistical data aggregation3. ICF and ICD provide health information in relation to diagnosis (ICD) as well as functioning and disability (ICF)4. In 2019, WHO launched an eleventh version of ICD (ICD-11), which was supplemented with a section presenting an assessment of functioning containing selected ICF categories5.

The ICF is based on a holistic biopsychosocial disability model that allows for a comprehensive and wide approach to the problems of an individual related to functioning in his /her living environment6. The model contains 6 components, including: (1) body functions which make up physiological and psychological functions of the body; (2) body structures that are its anatomical parts; (3) activity as performing actions or tasks by the individual; (4) participation meaning involvement in life situations; (5) environmental factors that constitute physical, social or attitudinal elements of the environment in which people live; (6) personal factors constituting the life background and the life situation of an individual, comprising the features not related to a health condition7. This approach provides a multifaceted and multidimensional view of human functioning. It also creates a useful framework for understanding the interaction between individual components of the biopsychosocial model.

The ICF was developed and approved in 2001 and many initiatives have been implemented since then4,5,8,9. In order to make the classification more suitable for everyday use, ICF Core Sets have been developed. The ICF Core Sets provide lists of core categories that are relevant to specific medical conditions and healthcare contexts10. The ICF Rehabilitation Set includes 30 ICF categories and is used in the context of describing functioning in various clinical populations among adults, at various stages of patient rehabilitation in inpatient and outpatient rehabilitation facilities, as well as in day care centres11. The rating system proposed in the ICF consists of so-called "qualifiers". They are used to code the severity of a functional problem. The qualifiers are as follows: 0 (0–4%), no problem; 1 (5–24%), mild problem; 2 (25–49%), moderate problem; 3 (50–95%), severe problem; 4 (96–100%), complete problem; 8, not specified; and 9, not applicable7. Environmental factors interact with all components of the biopsychosocial model, making a facilitating or hindering impact of physical and social world and attitudinal system. Qualifiers linked to the category of activity and participation, by determining the level of performance, make it possible to observe the extent to which environmental factors act as a barrier or a facilitator7.

The lack of detailed guidelines presenting how to use the qualifiers can make it difficult to assess the patients consistently. In order to solve this problem, it is important to collect the already existing data on the assessment of functioning by means of the ICF and to develop explanations for codes and qualifiers adapted to the clinical conditions in a given country.

The ICF as a classification is not an assessment tool in itself, but it is a framework based on a biopsychosocial model that enables a comprehensive description of functioning and disability of the examined person in the context of his/her life12. The Global Disability Action Plan (2014–2021) of the WHO recommends the use of the ICF as a superior component of the diagnosis and assessment related with the rehabilitation process13. The ICF is accepted by all the WHO Member States, but its use in clinical practice is still limited14. One of the reasons is the limited number of clinical tools that use language familiar to healthcare professionals while still following the ICF concept. Therefore, in order to facilitate the implementation of the ICF in daily practice, it is necessary to develop a universal and health worker-friendly assessment tool. Cooperative and uniform implementation of the ICF to the Polish healthcare system, as well as other public services, must be coordinated. It is very important to introduce a universal language that would allow us to transfer the information about the state of human functioning in healthcare systems. Consequently, the aim of the study is to create an initial reference guide for the assessment of the ICF Rehabilitation Set in Polish practice.

Materials and methods

The development of the Polish version of ICF Rehabilitation Set involved the following steps: (1) verification of ICF categories; (2) development of simple, intuitive descriptions; (3) development of the first Polish version of the rating reference guide.

Verification of ICF categories

The first stage in the verification of the ICF categories was to conduct a discussion panel consisting of rehabilitation experts with a minimum of 3 years of work experience in an inpatient rehabilitation department in a hospital or a rehabilitation centre, a day rehabilitation centre or an outpatient rehabilitation facility. The members of the discussion panel included: a medical rehabilitation physician, a primary care physician, physiotherapists, an occupational therapist, a psychologist, a speech therapist, a nurse, a social worker and members of the Polish Council for the ICF. Specialists were recruited from inpatient and outpatient rehabilitation centres in the country. Medical facilities conducting rehabilitation were drawn from the register of medical facilities. The inclusion criteria for these units was to have an expert in the field of rehabilitation with at least 3 years of experience at work with the patient. If the centre refused to participate in the study or did not have an expert with the above-mentioned experience, another centre was drawn from the pool.

The task of specialists was to assess the ICF categories in terms of their importance for rehabilitation. The expert survey was carried out in the form of an online questionnaire. This expert survey, consisted of open questions and the answers to the questions regarding the most common problems, barriers and facilitations of people participating in the rehabilitation process, were identified, distinguished and linked to the ICF. Selected categories were counted only once per expert. It was assumed that the ICF categories, which were considered very important by at least 3 experts, were included in the list of categories qualified for the next stage of verification.

The second step aims were to identify the most common problems experienced by patient with health condition that was documented in a clinical setting. The discussion panel was attended by 21 adults and older people. People participating in rehabilitation at the Donum Corde Rehabilitation Centre were included in the mentioned group. The group of 21 patients included 13 women and 8 men, their mean age was 45.8 ± 13.4 years. The reasons for participation in inpatient rehabilitation were: cardiological (n = 4), neurological (n = 8), pulmonary (n = 3) and orthopaedic diseases (n = 6).

People participating in rehabilitation took part in interviews carried out by physiotherapists. The interviews aimed to identify the most common problems with functioning related with the current state of health, recorded in a clinical setting. During the interviews, the subjects determined aspects specific to the rehabilitation process and a given health condition that were important to provide a comprehensive description of their functioning. ICF categories that were considered a problem, barrier or facilitator were included in the candidate categories. Interview protocols were developed by the principal investigator, supplemented with relevant medical data contained in patients' medical records relevant to ICD-10. During the analysis process, the physiotherapist also discussed the patients' problems in an interdisciplinary team consisting of: a physician, physiotherapist, nurse, pharmacist, occupational therapist, speech therapist and psychologist to determine their relationship with ICF. Categories that were identified as a problem, barrier or facilitator by at least 75% of interviewees were included in the list of proposed ICF categories.

The methodology of the discussion panel was compliant with the WHO guidelines15 and was also based on the experience of other researchers16,17.

The final verification of the ICF categories proposed for inclusion in the Polish version of ICF Rehabilitation Set was carried out by a research team consisting of 4 persons with the title of associate professor and PhD. All researchers had experience in the use of the ICF classification in scientific research and clinical practice and they dealt with treatment, rehabilitation, education or medical statistics. The team analysed the obtained proposed ICF categories from the stage of experts (in the field of rehabilitation) examination as well as patients participating in physical rehabilitation. Individual categories from the ICF Rehabilitation Set were considered confirmed if the same category emerged in the course of interviews with patients and a group of rehabilitation experts. In consequence, three groups of categories have been identified: (1) ICF categories identified as relevant by patients and experts, hence represented in the ICF Rehabilitation Set, (2) ICF categories that were represented in the ICF Rehabilitation Set but not identified as important by the discussion panel, and (3) ICF categories that were considered important by the members of the discussion panel, but were not included in the ICF Rehabilitation Set18. The ultimate list of ICF categories consisted of codes that were considered relevant by at least 75% of the participants of the discussion panel.

Development of simple, intuitive descriptions

To develop simple, intuitive descriptions of the Polish ICF Rehabilitation Set based on the original ICF category descriptions included in the classification, a consensus conference with multidisciplinary rehabilitation experts was conducted.

The consensus process included 3 groups of 7 experts with experience in clinical work with the patient. In each group, one moderator and an assistant for the ICF implementation team in Poland were appointed. The assistant was responsible for taking notes during the conference, but did not have the right to vote. Each group received initial suggestions for simple, intuitive descriptions of each ICF category. Descriptions were prepared on the basis of the results of previous conferences in Japan19, Italy15 and China20. The participants were asked to read and discuss the initial suggestions for descriptions. Then, each participant voted on whether the description was simple and intuitive enough to be used in everyday clinical practice. It was important to maintain the context of the original description of the ICF categories. During the first vote, consensus was achieved when the description of each ICF category reached 75% agreement in each group. The categories that did not reach consensus in the first vote were re-described, discussed and voted on again. A similar voting was conducted three times. The final versions of the ICF category descriptions were approved by the members of the Council for ICF Implementation in Poland and redirected for translation by a native English speaker.

Development of the first version of the rating reference guide

The rating reference guide Polish version of ICF Rehabilitation Set contains a description how to assess the different ICF categories and how to transfer the assessment results to qualifiers.

Rehabilitation experts have identified the main aspects to consider when rating ICF Body Functions, Activities and Participation, and Environmental Factors. The members of the working group proposed descriptive scales that can be used in practice to rate the categories. The proposed rating system was prepared during a discussion panel based on the applied methods of clinician assessment, cognitive interviews and reviews of available and already verified tools for the assessment of ICF categories. The available guide is also based on the results of the definitions developed by the Japanese Team19 and the Italian Team15.

Ethics

This study was approved by the Bioethics Committee of the University of Rzeszów (Resolution No. 33/05/2019). All participants provided written informed consent. All methods were performed in accordance with the relevant guidelines and regulations.

Results

A Polish version of ICF Rehabilitation Set to assess and verify functioning levels of patients was developed for 29 categories, including 8 categories (B130, B134, B152, B280, B455, B620, B710, B730) from Body Functions, 16 (D230, D240, D410, D415, D420, D450, D465, D510, D530, D540, D550, D570, D640, D710, D850, D920) from Activities and Participation, and 5 (E110, E115, E155, E310, E450) from Environmental Factors. Table 1 shows a comparison of ICF Rehabilitation Set and the initial Polish ICF Rehabilitation Set included the most important ICF categories from the point of view of rehabilitation experts and patients. The main difference between the sets concerns the inclusion of environmental factors in the assessment of patients participating in the rehabilitation process.

Table 1 Identification of ICF Rehabilitation Set categories.
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Development of simple, intuitive descriptions

As a result of the process of defining ICF categories, 6 initial description proposals were accepted in the first stage, and 15 proposals in the second stage. In the final third voting, the description of the remaining 8 definitions was settled. All participants agreed to the final simple, intuitive descriptions of the ICF categories indicated at the verification stage.

The Polish final version of the simple, intuitive description of the ICF categories was shown on Table 2.

Table 2 The Polish version of the simple, intuitive description of the ICF categories.
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Development of the rating reference guide

The assessment of all three components of the classification was proposed using the same scale described by WHO7. For “Body Functions”, a general qualifier that scores the extent of the problem or the extent of the impairment is shown on a scale from 0 to 4 (xxx.0 NO problem; xxx.1 MILD problem; xxx.2 MODERATE problem; xxx.3 SEVERE problem; xxx.4 COMPLETE problem xxx.8 not specified and xxx.9 not applicable).

For “Activities and Participation”, two qualifiers are presented: capacity and performance. Rating Capacity refers to the patient's ability to complete a task or take an action. It should be measured in a unified, standardized environment, so without the use of facilitators and specific barriers. Rating Performance refers to the patient's ability to perform a task or take an action in one’s own current environment, thus taking into account the facilitators or barriers posed by the social conditions in which the patient lives. Both qualifiers are scored using the following scale: xxx.0 NO problem; xxx.1 MILD problem; xxx.2 MODERATE problem; xxx.3 SEVERE problem; xxx.4 COMPLETE problem; xxx.8 not specified and xxx.9 not applicable.

The coding of "Environmental Factors" should be done by assessing the patient's perspective. A qualifier assessing environmental factors may indicate a barrier or facilitator. The rating scale is as follows: xxx.0 NO barrier; xxx.1 MILD barrier; xxx.2 MODERATE barrier; xxx.3 SEVERE barrier; xxx.4 COMPLETE barrier; xxx.+ 0 NO facilitator; xxx + 1 MILD facilitator; xxx.+ 2 MODERATE facilitator; xxx.+ 3 SUBSTANTIAL facilitator; xxx.+ 4 COMPLETE facilitator; xxx.8 barrier not specified; xxx.+ 8 unspecified facilitator and xxx.9 not applicable7.

For the analysis of limitations in the range of body functions related to B130, B134, B152, B445 and B620, an assessment by means of specially prepared questions and an assessment carried out by healthcare professionals were proposed. The description of the possible limitation makes it possible to qualify the patient's problem for the appropriate qualifier. The assessment of B280 (Sensation of pain), B710 (Mobility of joint functions) and B730 (Muscle power functions) was linked to existing methods and scales commonly used in clinical practice, i.e. pain assessment on the Visual Analog Scale21, goniometric assessment of the range motion22 and assessment of muscle strength using the Lovett Scale23.

In case of activity and participation, D230, D240, D465, D570, D710, D850 and D920 were assessed by means of questions asked by healthcare professionals. The assessment of categories D420 (Transferring oneself), D510 (Washing oneself), D530 (Toileting), D540 (Dressing), D550 (Eating) was based on the Activity of Daily Living Scale24, taking into account the range of patient limitations on a scale from 0 to 4, whereas the assessment of one of the complex daily activities D650 (Doing housework) was presented using the Lawton Instrumental Activities of Daily Living Scale25. For the analysis of categories D415 (Maintaining a body position) and D410 (Changing basic body position), the Berg Balance Scale was used26. With reference to mobility assessment D450 (Walking), the result of the Short Physical Performance Battery Test was used on the ICF scale27.

The assessment guide of environmental categories E110, E115, E155, E310 and E450 focused on the analysis of the existence of barriers and facilitations based on specially developed questions. Tables 3, 4 and 5 presents the rating reference guide Polish version of ICF Rehabilitation Set.

Table 3 Rating reference guide Polish version of ICF Rehabilitation Set (Body Functions).
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Table 4 Rating reference guide Polish version of ICF Rehabilitation Set (Activities & Participation).
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Table 5 Rating reference guide Polish version of ICF Rehabilitation Set (Environmental Factors).
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Discussion

The use of the ICF in clinical practice requires a precise definition of categories and rating system of qualifiers in a way that will allow for the standardization of the assessment regarding the effects of patients' rehabilitation. The development of the Polish version of ICF Rehabilitation Set included a process of codes verification, development of simple intuitive descriptions for individual ICF categories and a proposal of the rating system of qualifiers to support the implementation of ICF in clinical practice in Poland among patients participating in the rehabilitation process. Prepared descriptions do not exclude linking and using specific measurement and clinical tools in the future to assess a given code. Moreover, it is assumed that the prepared descriptions are used in a compatible manner and linked with data transformed from standardized measurement tools.

Verification and identification of the Polish version of ICF Rehabilitation Set showed 29 ICF categories: 8 categories related to body functions; 16 ones related to activities and participation, and 5 ones related to environmental factors. Comparing these categories to the generic set, the biggest change was the introduction of 5 environmental rating codes. According to the panel of experts, researchers and patients, the following categories were introduced, such as: products and technology for personal use in daily living (e115); immediate family (e310) or individual attitudes of healthcare professionals (e450). These categories are important due to the fact that they allow for the identification of facilitating factors or barriers related to the process of functional rehabilitation of patients15,28. Prodinger et al. also proposed the use of a set of 12 environmental categories as a supplement to the assessment of functioning aspects in clinical populations for reporting health conditions, including rehabilitation process20. Disability is not only a health problem; it is also the result of the interaction of health status with factors of the living environment and is an integral part of assessment in the field of patient rehabilitation29.

The development of a reliable rating tool increases the usefulness of the ICF classification for clinical and statistical purposes. The results on the patient's functioning can be transmitted to other specialists, as well as compared showing the effectiveness of rehabilitation in different institutions or regions19. Previous studies on the clinical implementation of the ICF Rehabilitation Set suggested that clinicians were unable to distinguish effectively the line between different qualifiers30. Moreover, in the study carried out by Senju et al., experts also indicated that it is difficult to distinguish the difference between mild and moderate ICF problems. The WHO states that a moderate problem ranges from 25 to 49% of problem percentages, whereas a mild problem is from 2 to 24%31. The existing explanation of the problem causes some difficulties in assessing patients in clinics32.

Therefore, international efforts have been made to develop ICF-based clinical tools. The development of tools includes the development of ICF sets as well as simple intuitive descriptions of ICF categories included in the sets17. What is more, some studies regarding the implementation of ICF sets were also carried out, however, the assessment of qualifiers differed from one study to another. The Chinese project used an intuitive rating scale ranging from 0 to 1033. The Japanese researchers developed a rating reference guide for the ICF Rehabilitation Set. They developed a rating system with a description for each answer and translated the assessment into ICF qualifiers19,34. The weighted kappa coefficient in the field studies was 0.61. The inter-rater reliability test showed moderate to high inter-rater agreement34. In the Polish version of the ICF Rehabilitation Set, apart from specially developed questions for the assessment of individual categories, the most frequently used scales in clinical conditions in Poland were also proposed.

One of the most important issues in interdisciplinary communication in healthcare is the use of common terminology35. The ICF classification is closely related to the ICD-10. The ICD-10 is a health classification system and etiological framework, while the ICF is used to classify health-related functioning and disability. Thus, the ICD-10 provides information on the diagnosis of the disease, while the ICF offers an additional explanation of how the medical condition affects the functioning of people with various diseases36. Combining the ICD-10 reporting with the ICF can improve the quality of data regarding patients collected in the healthcare system.

The World Health Organization and the World Confederation for Physical Therapy proposed the use of the ICF as a universal patient assessment in rehabilitation practice37. Therefore, the use of a unified rating system considering ICF qualifiers will be beneficial both in clinical and scientific discussion as well as in statistics38,39. The Polish version of ICF Rehabilitation Set proposed by us is a reference framework for the harmonization of existing information on the functioning and disability of people participating in the rehabilitation process.