Population aging and the increased burden of disability in middle and high income nations pose unique challenges to health care systems. The lives of frail elderly individuals and persons with disability are affected by complex interactions of physical, social, medical and environmental factors that necessitate multidisciplinary approaches to care. Services tend to be provided by a variety of health and social service agencies including both community and facility-based settings. For example, persons who are experiencing cognitive loss or decline of functional ability may receive support from home care agencies, supportive housing, rehabilitation services, or nursing homes. Similarly, persons with mental health problems may receive psychiatric services in primary care, community mental health programs, mental health group homes, or in-patient psychiatric units of hospitals. At the end of life, palliative care may be provided by community-based agencies or by residential hospices, but periodic contact with acute hospitals is also not uncommon. For each of these populations, health and social services are intended to be provided through an integrated system of care rather than through a singular organization.
The need to receive support from multiple service agencies has important implications for persons with complex care needs. At the individual level, there may be a risk of discontinuity of care if information systems are not compatible or if clinically relevant information is not shared between agencies. This may mean that needs are not identified when transitions are made between service providers, longitudinal change in functional status may go undetected as the person moves between service settings, or care plans are not followed through when the person receives care from another sector. The lack of coordination of information gathering can result in duplication of effort, increased assessment burden, and frustration among care recipients and their support network. For these reasons, there is a clear need for an integrated, multi-sectoral approach to assessment for persons with complex care needs.
The interRAI family of assessment instruments http://www.interrai.org was designed to be used with a variety of vulnerable populations [2, 3]. The first interRAI instrument was the Resident Assessment Instrument (RAI), developed in the United States in response to the Omnibus Reconciliation Act of 1987 . The interRAI network was established initially based on the international collaborative efforts of clinicians and researchers to apply the RAI to nursing home residents in other countries . By 1996, interRAI released the RAI-Home Care with the aim of establishing a compatible assessment approach in community based care settings that served populations at risk of nursing home placement or required post-acute or long term home care services [6–8]. The RAI-Mental Health instrument [9, 10] was the first interRAI instrument designed to be used with a general adult population in psychiatric hospital settings including, but not limited to, geriatric psychiatry. Other interRAI instruments developed in the 1990's include the RAI-Acute Care [11, 12], RAI-Post Acute Care , and RAI-Palliative Care .
The development of all these assessment instruments was guided by the design principles for the original RAI. The assessments were intended to use all sources of information available. Judgments were to be based on observable traits, have operational definitions and coding instructions that specified inclusion and exclusion criteria, and use clearly delimited time frames for observations anchored to a specific assessment reference date. In addition, each of these instruments was intended to support applications for multiple audiences including care planning, outcome measurement, quality improvement, and resource allocation. To this end, efforts were made to retain the capacity to derive or extend existing outcome measures (e.g., scales related to cognition, ADL, pain, depression, behaviour) and decision support algorithms (e.g., case mix algorithms, quality indicators).
The initial set of RAI instruments was developed in a serial process. For new instruments, this meant that lessons learned from the use of earlier instruments were taken into account in the development of subsequent instruments. However, the need to refine older instruments became apparent as innovations were identified. Also, it was recognized that the family of instruments should be refined in parallel, treating the collective set of instruments as an integrated system rather than as complementary, but independent assessments for specialized care settings.
In the year 2000, interRAI launched a multinational effort to update the entire family of RAI instruments and to develop new instruments for sectors not yet addressed by the existing instruments. The result of this effort is an integrated suite of instruments providing compatible assessment approaches for nursing homes, home care, acute care, post acute care, palliative care, assisted living, supportive housing, services for persons with intellectual disabilities, community mental health, emergency psychiatry, and inpatient psychiatry. The initial focus of the redevelopment effort for the interRAI suite of assessment instruments was to identify a common core set of about 70 items that would be present in all instruments, with exceptions permitted only for specialized settings where prevalence rates for the item will be negligible (e.g., pressure ulcers in in-patient psychiatry). Examples include items such as cognitive skills for decision making, activities of daily living (e.g., personal hygiene, toilet use, eating), mood (e.g., negative statements, persistent anger, crying/tearfulness), behaviour problems (e.g., verbal abuse, resisting care), falls, and health symptoms (e.g., pain frequency and intensity, fatigue). The next step was to identify over 100 optional items that would appear in many, but not all, instruments. These items were expected to be relevant to several service settings, but not pervasive enough in all service settings to warrant inclusion in the list of core items. Examples include long-term memory, situational memory, hearing aid use, family/close friends feeling overwhelmed by the person's illness, instrumental activities of daily living (e.g., meal preparation, financial management, phone use), stamina, additional health conditions (e.g., extrapyramidal symptoms, abnormal thought processes, delusions), medication adherence, and preventive interventions and screening (e.g., influenza vaccination, breast screening). Finally, specialized items that would only appear in specific instruments were also identified. For example, the in-patient psychiatry instrument has 170 unique measures (e.g., number of lifetime psychiatric admissions, command hallucinations, suicidality, illicit drug use, police intervention for criminal behaviour, history of sexual violence or assault as perpetrator, problem gambling) whose prevalences would be too low to warrant their use in non-mental health settings.
Once the initial item set was identified for the interRAI instruments, a 12-country effort was launched to evaluate the psychometric properties of the instruments in different health care settings. The present paper reports on the results of that cross-national effort with a particular emphasis on inter-rater reliability. There have been several studies of the reliability and validity of the early versions of interRAI instruments for nursing homes [15–20], home care[6, 7, 21], mental health , acute care , and palliative care . The general trend of these studies has been to show improved reliability over time with newer versions of these instruments, and they provided consistent evidence of good psychometric properties across populations and service settings. The multinational effort described here was launched in 2005 and included five instruments from the new suite designed for use in the following care settings: nursing homes, home care, rehabilitation, palliative care, and in-patient psychiatry Results for the new interRAI Acute Care  and interRAI Intellectual Disability  have been reported elsewhere. Reliability and validity results for new instruments in the suite (e.g., interRAI Community Mental Health) will be reported in future publications.