The Palliative Outcome Scale (POS) applied to clinical practice and research: an integrative review

ABSTRACT Objective: to identify and evaluate the evidence found in the international scientific literature on the application of the Palliative Outcome Scale (POS) in clinical practice and research in Palliative Care (PC). Method: integrative literature review, through the search of publications in journals indexed in PubMed / MEDLINE, LILACS, SciELO and CINAHL databases, between the years 1999 and 2014. Results: the final sample consisted of 11 articles. In the data analysis, the articles were classified into 2 units of analysis (studies using the POS as a resource in research and studies using the POS in clinical practice), in which the information was presented in the form of sub-themes related to publications of the selected studies, highlighting the synthesis of the results. Conclusion: POS emerged as an important tool for measuring outcomes to assess the quality of life of patients and families, of the quality of care provided and the PC service organization. The international scientific literature on the application of POS proved to be relevant to the advancement and consolidation of the field of knowledge related to PC.


Introduction
Among the clinical outcomes studied in oncology, evaluations of the survival curves and quality of life (QoL) are needed to direct the actions of health professionals (1) . However, to be reliable from a quantitative point of view, these assessments should be made using instruments to measure constructs that are valid, reliable and culturally adapted (2)(3) .
Originally developed by a group of researchers from King's College London (4) , the Palliative Outcome Scale (POS) is a multi-dimensional assessment scale of QoL widely used, both in teaching and research as well as in clinical practice, applied in people suffering lifethreatening chronic diseases in Palliative Care (PC) (1) .
These are essential for the humane treatment to people with life-threatening clinical conditions whose treatment is not longer a modifier of the disease (5) .
The POS has two versions: the self, which is points, being 0 a better QoL and 40, the worse QoL (6)(7)(8) .
The process of cultural adaptation and validation of POS has been completed in different countries and cultures in the following languages: Portuguese (of Portugal), Italian, Spanish (Spain and Argentina), German, French, Mandarin, Punjabi and Urdu. It is currently developing the validation of POS self version for the Brazilian Portuguese (POS-Br), which will enable the availability of the scale to be used as a data collection tool in scientific research and as a resource for clinical practice in the country (9) . PC must be seen as one of the mainstays of comprehensive care treatment for people with advanced (and life-threatening) disease. However, in Brazilian culture, there is a shortage of specific assessment tools that can measure the importance of early referral to a PC service and its impact on QoL. In addition, the POS is an important tool for measuring outcomes that can foster the advancement of knowledge in PC, promote and optimize care in PC services and its results can help to minimize the suffering of patients with advanced disease.
This study is shaped as an integrative review, aiming to identify and evaluate the evidence found The evidence found in this study will enable researchers and health professionals to understand and acknowledge the importance of the use of POS in the treatment of patients with life-threatening diseases.

Methodological Pathway
Through an integrative review, this study examined the scientific literature on the use of POS in the context of PC. This review followed the steps as suggested in the literature (10)(11)(12)(13) : selection of the guiding question,  (4) .
The descriptors "palliative care" (descriptor that encompasses the terms "hospice care" and "terminal care"), "Palliative Outcome Scale", "outcome assessment health care" and "quality of life" were combined via the Boolean connectors "AND" and "OR" in Portuguese and Spanish. It is worth mentioning that during the initial search, two records of integrative review were found, one of which addressed the POS validation studies (14) and the other, the impact of APCA POS as a tool to improve patient care quality and their Rugno FC, De Carlo MMRP. families (15) (though, been secondary sources of data, these two studies were not eligible).  Using as a starting point the adaptation of an assessment instrument (12) , it was performed the synthesis of the included articles. Data collection captured the following information: year of publication; study title; name of the authors; journal of publication; instruments used and results found.

Results
The consultation in 4 multidisciplinary databases and the findings ensured scientific and methodological    Caregiver assessment of patients with advanced cancer: Concordance with patients, effect of burden and positivity (24) Higginson IJ and Gao W.
Health Qual Life Outcomes
(the Figure 2  (POS) control group -higher scores for: "pain" (self and proxy versions), "information given about disease" (self version), "to share feelings with family" (proxy version) "to feel life is worth living" (self, proxy versions). Online course -71 (86,6%) physicians -intervention group, Face-to face course 11 (13,4%) physicians -control group. the Herth Hope Index (18) . PC should also be offered in the early stages to patients with Parkinson's disease, multiple system atrophy or progressive supranuclear palsy (23) . Using the The maintenance / improvement of QoL is among the most expected outcomes in the PC services, and QoL assessments allow the appreciation of the information reported by the patients themselves ("patient-reported outcomes"). This perception of the patient is essential to guide the clinical practice of professionals (19) . Some domains of the questionnaires used to assess the Rev. Latino-Am. Enfermagem 2016;24:e2764 symptoms and QoL in patients with advanced cancer can measure similar dimensions or constructs.

POS and Palliative Outcome Scale-Parkinson Disease
As there are few studies comparing the dimensions of instruments that have equivalent dimensions or constructs, an assessment of concurrent validity of these instruments may increase the knowledge of its psychometric properties and "interchangeability of equivalent areas" (17)(18)(19) . It is important to point out that this information was found in the subtopic 2 of unit 1. Nevertheless, the correlation between the areas of POS with EuroQoL scales (EQ-5D) and the Herth Hope Index (18)  Regarding the POS, RSCL and BPI (19) , its limitations are Despite the limitations already described, there was a high correlation between the POS and the HOPE-SP-CL, and also between POS and ACPDS (the correlation coefficients were higher than 0.6).
The use of POS can also contribute to the increase of the eligible patients to PC, whose target audience is still the cancer patients. The results found in Unit 2 (subtopic 1) proved the efficiency of this instrument for assessing QoL in non-oncologic patients and showed the need for QoL assessments -survival and multi-functional evaluations for patients with progressive neurological diseases (23) and COPD ( 22) (29) .
Often these discussions and QoL assessments take into account only the perception of the caregiver (such as the progression of disease -not enabling the self-assessment of the patient). As it was presented in unit 2 (subtopic 2), the caregiver assessments were considered valid and reliable compared to patient assessments, especially when using the POS scale (scale considered easy to understand for both) (24) . However, the caregivers' burden and how they consider the care, can affect their understanding of the patient's QoL. It is also noteworthy that the analysis of the results did not allow identifying the real impact of the burden on the which is justified by the increased use of strong opioids) (26) . It is well known that education and development of capacities in PC (online or face-to-face) should be offered regularly to the medical and nonmedical staff.
Through these activities, the team's attention would not be focused only on the patient's medical records, but also on his life story, desires and choices, resulting in greater agreement between "patient-reported outcomes" and proxy reviews (26) .
Communication skills should also be integrated and addressed in the courses. As evidenced in the subtopic 3, there is also an overestimation of the prognoses of patients in PC; this fact was even a limitation to the size of the sample (professionals had trouble in referring eligible patients for the study) (25) .