Disponível em: http://dx.doi.org/10.12707/RIII13101 RESEARCH PAPERS Study of the cut-off point of the Morse Fall Scale (MFS) Estudo do ponto de corte da Escala de Quedas de Morse (MFS) Estudio del punto de corte de la Escala de Caídas de Morse (MFS) Maria José Martins da Costa-Dias*; Teresa Martins**; Fátima Araújo*** Abstract Theoretical framework: The Morse Fall Scale (MFS) is a scale for assessing fall risk. It is designed for adults and widely used in Portugal. The scale should be calibrated for each particular setting so that fall prevention strategies are targeted to patients most at risk. Objective: To analyse the cut-off point of the scale that best distinguishes between people with and without fall risk in a hospital inpatient setting. Methodology: The receiver operator curve (ROC) was used to determine the optimal cut-off point. The predictive validity of the MFS was assessed through sensitivity and specificity, positive and negative predictive values, the ROC area under the curve (AUC) and also the Youden Index. Results: The cut-off point of 45 was identified as the optimal cut-off value, where 78% of the participants were identified as true positives and 22% as false negatives. It presented an OR of 3.8 (95%CI=2.17-6.51). Conclusion: The MFS is a good instrument for identifying patients with high fall risk in hospital settings, particularly in medical and surgical, long-term and palliative care inpatient wards. Keywords: accidental falls; risk management; hospital services. Resumo Resumen Enquadramento: A Escala de Quedas de Morse (MFS) é uma Marco contextual: la Escala de Caídas de Morse (MFS) es una escala de avaliação do risco de queda, desenhada para adultos e escala para evaluar el riesgo de caídas, diseñada para adultos y amplamente utilizada no nosso país. A escala deve ser calibrada ampliamente utilizada en Portugal. La escala debe ser calibrada para cada contexto para que as estratégias de prevenção sejam para cada contexto, con el fin de que las estrategias de prevención dirigidas aos doentes que estão em maior risco. se dirijan a los pacientes que están en mayor riesgo. Objetivo: Analisar o ponto de corte da escala que melhor Objetivo: identificar el punto de corte de la escala que mejor discrimine as pessoas sem risco das com risco de queda quando discrimine a las personas que no tienen riesgo de caída de las que internadas em contexto hospitalar. sí lo tienen cuando están internas en un contexto hospitalario. Metodologia: Foi utilizada para definir o melhor ponto de corte Metodología: para determinar el mejor punto de corte, se utilizó a receiver operator curve (ROC). A validade preditiva da MFS la curva del receptor operador (ROC). La validez predictiva de la foi avaliada através da sensibilidade e especificidade, do valor MFS se evaluó por medio de la sensibilidad y la especificidad, del preditivo positivo e negativo, da área abaixo da curva (AUC) de ROC e ainda através do Índice de Youden. valor predictivo positivo y negativo, del área bajo la curva (AUC) Resultados: O ponto de corte 45 foi identificado como o melhor de ROC y también a través del Índice de Youden. ponto de corte, no qual 78% dos participantes são identificados Resultados: el punto de corte de 45 fue identificado como como verdadeiros positivos e 22% como falsos negativos e el mejor punto de corte, en el que se identifica el 78 % de los apresenta um OR de 3,8 (IC95%=2,17-6,51). participantes como verdaderos positivos y el 22 % como falsos Conclusão: A MFS revela ser um bom instrumento para negativos, y tiene un OR de 3,8 (IC95%=2,17-6,51). identificar doentes com alto risco de queda, em contexto Conclusión: la MFS es un buen instrumento para identificar hospitalar, particularmente em internamentos médico-cirúrgicos, pacientes con alto riesgo de caídas en el ámbito hospitalario, de cuidados continuados e paliativos. sobre todo en pacientes hospitalizados en servicios médicos y quirúrgicos, así como de cuidados continuos y paliativos. Palavras-chave: acidentes por quedas; controle do risco; serviços hospitalares. Palabras clave: accidentes por caídas; control de riesgo; servicios hospitalarios. * Enfermeira Especialista em Saúde Infantil e Pediátrica. Aluna do Doutoramento em Enfermagem do Instituto de Ciências da Saúde da Universidade Católica Portuguesa. Morada: Avenida Lusíada, 100, 1500-650 Lisboa, Portugal [[email protected]]. ** Professora Coordenadora, Escola Superior de Enfermagem do Porto. Doutora em Ciências da Educação, 4200-072 Porto, Portugal[[email protected]]." *** Professora Adjunta. Doutora em Ciências da Educação. Escola Superior de Enfermagem do Received for publication: 10.04.13 Porto, 4200-072 Porto, Portugal[[email protected]]. Accepted for publication: 18.01.14 Revista de Enfermagem Referência Série IV - n.° 1 - Fev./Mar. 2014 pp.63-72 Introduction specificity scores (true negatives, or the proportion of non-fallers correctly classified as without or Fall risk assessment scales are tools that assign low fall risk), as well as the positive predictive numerical values to various risk factors. They are values (likelihood that a person assessed with fall added up to assess the patient’s likelihood of falling. risk has of falling) and negative predictive values Assessing the predictive validity of scales (Morse, (likelihood that a person assessed with no fall risk has 2009) allows to identify whether they fulfil their of not falling). purpose, i.e., if they distinguish well enough between The purpose of this study was to analyse the cut-off patients with and without risk of falling in a given point of the MFS for acute adult inpatient services of a population (Oliver, Healey, & Haines, 2010). The hospital in central Lisbon. Morse Fall Sacle (MFS) is one of most commonly used scales, taking into account its extensive development and comparative studies in patients hospitalised in Theoretical Framework different hospitals (Schwendimann, De Geest, & Milisen, 2006). Lamb, Jorstad-Stein, Hauer, and Becker (2005) define As any other assessment tool, a fall risk assessment accidental fall as an unexpected event in which the scale needs to be culturally and linguistically adapted patient comes to rest on the ground, floor, or lower and validated for Portuguese to be used in our level. Falls are the most common non-fatal injuries contexts (Almeida, Abreu, & Mendes, 2010). Ideally, in acute care hospitals (Perell, Nelson, Goldman, scales should be calibrated for each unit, so that fall Prieto-Lewis, & Rubenstein, 2001), affecting mainly prevention strategies are targeted to those most at the elderly (Oliver, 2007) and being an adverse event risk, i.e., the cut-off points or values that distinguish that is preventable. Simple risk assessment scales between patients with and without fall risk may can predict up to 70% of falls (Oliver, Daly, Martin, & differ depending on whether the scale is being used McMurdo, 2004). The first stage of any fall intervention in acute or chronic care settings. Even within the program is risk assessment. The nurse ought to same organisation, the scale may have different cut- use adequate assessment tools to identify both real off points (Morse, 2009). Fall risk varies according to and potential risks for patients, a competence that the type of patient, the different periods of the day is defined by the Ordem dos Enfermeiros (Nurses and the patient’s situation (Morse, 2009). The cut-off Association) (2004) at care management level within points as defined by the author of the scale are set the safe environment domain. The MFS is one of the between 25 and 55 points, suggesting that the high most widely disseminated and used scales in Portugal fall risk cut-off point in acute or surgical care settings (Soares & Almeida, 2008). Its predictive validity and where few patients have a high fall risk, is set at score interrater reliability have been demonstrated (Morse, 25. On the contrary, in hospitals or units for patients 2006; Morse, 2009). with chronic or cerebrovascular diseases, the author The MFS is described by its author as a simple and suggests that the high risk of falling be at score 45. quick method to assess the patient’s likelihood of Morse (2009) also recommends that the cut-off point falling, and counts with two decades of research. It of the scale should not to be above 55 points. This was developed by Janice Morse in 1985 in Canada, at value was identified by Schwendimann et al. (2006) the University of Alberta, to identify fall-prone patients in a cohort prospective study carried out in two (Morse, Morse, & Tylko, 1989). medicine inpatient departments of a hospital for The scale was developed based on a study composed acute patients as the most appropriate cut-off point of a random sample of 100 fallers and 100 non-fallers. for patients hospitalised in these services. The scale consists of six assessment items: (1) According to Morse (2009), the best method to define previous history of falling; (2) secondary diagnosis; the cut-off point is to assess the fall risk of patients (3) ambulatory aid; (4) intravenous therapy; (5) gait who are hospitalised in a given service and analyse and transferring; (6) mental status. the distribution of risk, thus obtaining the scale’s Items 1, 2, 4 and 6 are measured on a dichotomous sensitivity scores (true positives, or the proportion scale (No/Yes). A ‘No’ answer is always scored zero, of fallers correctly classified as high fall risk) and the while a “Yes” answer is scored 15 (in items 2 and 6), 20 Revista de Enfermagem Referência - IV - n.° 1 - 2014 Study of the cut-off point of the Morse Fall Scale (MFS) 64 (item 4) or 25 (item 1). Possible answers for item 3 are associated with a confidence interval of [0.80; 0.88].