Identification of Readmission Predictors in Elderly Patients with Acute Coronary Syndrome

Background: Readmission in elderly patients with acute coronary syndrome (ACS) is often associated with decreased functional capacity and quality of life, besides being an indicator of hospital care quality. Objectives: To identify clinical and sociodemographic profile of elderly patients with ACS, the hospital readmission predictors and the time that may influence the readmission-free survival curve; to describe the most prevalent nursing diagnoses. Methods: Retrospective longitudinal study with purposive sample of elderly patients with ACS based on retrospective analysis of 2012 medical records, considering the following variables: date of admission, cause, time interval between readmissions and hospital length of stay. Data were expressed in frequencies and means ± standard deviation. The readmission-free survival (p <0.05) was evaluated by the Kaplan-Meier curve. Results: Seventy-five elderly patients with ACS were studied: average of 72.0±8.3 years old, 61.3% male, 89,0% with hypertension. The readmission predictors were: ACS and percutaneous procedures. The period between readmissions ranged from 7 to 60 days, where 53.5% ranged from 31 to 60 days after hospital discharge. Nursing Diagnoses (NDs): impaired tissue integrity presented 25-day readmission average (p=0.04); 77 days (p=0.01) for impaired physical mobility, and 86 days (p=0.02) for risk for constipation. Conclusions: Clinical and sociodemographic characteristics of elderly patients with ACS under study: male, mean age of 72 years, low level of education, with multiple comorbidities. ACS and percutaneous procedures were the most frequent readmission predictors. NDs indicating possibility for readmission: impaired tissue integrity, risk for constipation and impaired physical mobility.


Introduction
The elderly population is growing rapidly with increasing life expectancy.According to DATASUS 1 , the population projection for elderly people over 60 years old in 2010 was of 19 million; this figure is expected to increase by 2060, reaching 73 million.This demographic transition led to changes in the epidemiological profile of such population, especially in terms of morbidity and mortality, with the progressive decrease in deaths from infectious diseases and the increase in the number of deaths from chronic diseases, entailing major challenges for health systems 2 .Today the most common cause of death in individuals over 65 years old are noncommunicable chronic diseases, particularly cardiovascular diseases 3 .
Diseases of the circulatory system are considered nowadays the third cause of hospitalization.In 2010, ischemic heart diseases accounted for 210,046 hospital Identification of Readmission Predictors Int J Cardiovasc Sci.2015;28 (2):139-147 Original Manuscript

ABBREVIATIONS AND ACRONYMS
• ACS -acute coronary syndrome • ND -nursing diagnosis admissions in Brazil 4 , where coronary heart disease was the most common cause of acute coronary syndrome (ACS) 5 .A group of clinical symptoms compatible with acute myocardial ischemia characterizes acute coronary syndrome.The clinical spectrum comprises unstable angina, acute myocardial infarction with ST-segment elevation, and acute myocardial infarction without ST-segment elevation 6 .
An international study 7 carried out with 1,271 patients diagnosed with myocardial infarction with ST elevation, during the period from 2006 to 2011, found increased risk factors for readmission at 30 days after discharge: age ≥80 years, diabetes mellitus, chest pain, cardiac arrest and (involvement) of three coronary arteries: the right coronary artery, the anterior descending artery, and the left circumflex artery found on the initial angiography 7 .
In addition, other studies suggest that hospital admissions can be associated with frail elderly with functional decline, loss of independence, low cognitive instruction at the time of hospital discharge, presence of heart disease, especially ACS 8,9 .
In such context, the nurse must act consistently, ensuring the identification of issues to guide the planning of interventions, safe practice and health care outcomes.
Moreover, knowing the nursing diagnoses as predictors of hospital readmission contributes to the implementation of early actions that prevent potential complications 10 .The scarcity of research at national level on predictors for hospital readmission in elderly patients with ACS is then evidenced.In this sense, it is necessary to identify the main predictors in order to contribute to the development of strategies that can reduce the number of readmissions on medium and long term.
This study aims to identify the clinical and sociodemographic profile of elderly patients with ACS; identify key predictors for readmission of elderly patients with ACS according to the time of readmission that can influence the readmission-free survival curve; and describe the most prevalent nursing diagnoses.

Methods
This is a retrospective longitudinal study, part of the project: Readmission of patient in cardiology hospital: For the identification of patients readmitted in 2012, a retrospective analysis of medical records from the database of the Statistical and Medical File Service was carried out considering the following variables: date of admission, cause, time interval between readmissions, and hospital length of stay.
The following inclusion criteria were adopted: patients >60 years, admitted to any hospital sector, diagnosed with ACS in the first admission.The sample consisted of 75 patients, excluding the patients whose medical records were not available at the time of collection.
The following variables were analyzed: age, sex, marital status, level of education, employment status, comorbidities, medical diagnosis of ACS, time interval between readmissions, hospital length of stay, number of readmissions, nursing diagnosis, and nursing evolution upon patient discharge.
The nursing diagnoses of NANDA Taxonomy 11 were progressively implemented and adapted to this institution since 1990, in all units, being daily registered in the patient's medical records, enabling the evolution during hospitalization.Twenty-five different nursing diagnoses were taken into account, from taxonomy II of NANDA-I (2009-2011) adapted to the reality of the institution, only in the period of admission and hospital discharge of the patient.
The SPSS (Statistical Package for the Social Sciences) program analyzed the data gathered.Qualitative variables were expressed as absolute and relative frequencies; quantitative variables were expressed as averages and standard deviations.The Kaplan-Meier curve was used to evaluate readmission-free survival curves; and the log-rank test verified the difference of curves.The significance level assumed was of p<0.05.

Results
In 2012, 75 elderly patients readmitted for ACS were identified.The mean age was of 72.0±8,3 years, ranging from 60 to 100 years old.Prevailing features: males (n=46;

Figure 1
Readmission-free survival curve of patients admitted with coronary syndrome, according to ND: Impaired tissue integrity.

Figure 2
Readmission-free survival curve of patients discharged, according to ND: risk for constipation.
By analyzing the Kaplan-Meier curve as for the readmission time and the relationship with the ND of the corresponding hospital admission period, it was observed that patients admitted with ND: Impaired tissue integrity can predict an average for readmission of 25 days (p=0.04) when compared to those who did not present such diagnosis (Figure 1).
As for the hospital discharge period, two ND were identified in the log rank analysis: impaired physical mobility (p=0.01) and risk for constipation (p=0.02).In this analysis, there was an increased curve between the time to experience a readmission, whose average was 77 days and 86 days, respectively, showing late readmission for patients with these diagnoses.Patients, however, are not readmission-free, as shown in Figures 2 and 3.

Figure 3
Readmission-free survival curve of patients discharged, according to ND: impaired physical mobility.

Discussion
The clinical and sociodemographic characteristics found: advanced age, male, low level of education and multiple comorbidities of readmitted patients under this study are consistent with previous descriptions of the field's literature [12][13][14][15][16][17][18] .
Regarding the readmission rate, a superiority was observed in this study when compared to other scientific evidence 19,20 .This occurred because the readmissions within one year after hospital discharge were taken into account, not limiting the time for readmission, as in many international researches based on readmission rates of up to 30 days 12,13,15,21 .
According to the cohort study carried out with 62,394 patients with acute myocardial infarction, only 19.1% were readmitted within 30 days 12 .However, another study showed that the greater the time between one readmission and the other, the greater the readmission rate: a 58.6%rate was observed in the period from two to six months 22 .
Nearly half of the readmitted patients had ACS (41.6%) as the main cause of readmission.A similar study involving 1,271 patients in an emergency care service in the United States found that 43.0% had ischemic heart disease as the main cause of readmission 7 .Another retrospective observational study carried out in New York City with 503 patients diagnosed with unstable angina and/or acute myocardial infarction showed that 51.0% of patients were readmitted due to heart problems (chest pain, shortness of breath, decreased exercise tolerance) 16 .
In this study, the hospital length of stay was high, similar to the retrospective study in a public hospital in Hong Kong, with 603 unplanned readmissions, whose average hospital length of stay was of 9 days 17 .
In most cases, such long hospital stay entails lack of available beds in hospitals, negatively influencing the resolution of cases, consuming more human and material resources, and becoming a challenge for the Unified Health System (SUS).
The NDs observed in this study, both in hospital admission and discharge periods, are in accordance with previous descriptions of the field's literature [23][24][25] .However, it was observed that in both periods, whether in hospital admission or hospital discharge, most of these diagnoses is repeated, a fact that should be highlighted, as the lack of resolution to these cases could possibly lead to a preventable readmission.
Preventable readmission is one that could be avoided if the patient's clinical profile had been better managed, with home care following hospital discharge, planning of the hospital discharge and provision of resources that meet patient needs at home 26 .
Moreover, as this is an elderly population, suffering from different comorbidities, it is plausible to infer that the NDs can be repeated by such chronic degenerative condition that will require nursing intervention to minimize potential repercussions.A study aiming to identify NDs related to geriatric syndromes in elderly hospitalized has selected 394 diagnoses and computed two syndromes on average per individual.This finding confirms the process of fragility of the elderly before hospitalization, increasing the chances of complications and rehospitalizations 27 .
Comprehensive observation and the implementation of a feasible care plan, encompassing health promotion, disease prevention and health maintenance must be part of nursing interventions for this population.
By analyzing the Kaplan-Meier curves and the log rank test, it was observed that the occurrence of ND: impaired tissue integrity during hospital admission period can predict patient readmission in less than 30 days.
The skin is the organ that most shows signs of aging.
It is where the loss of connective tissue, subcutaneous fat and glands occurs.Elderly patients with ACS develop limitations of their physical activities, besides having more dry and fragile skin, making them more vulnerable to the appearance of lesions.
An integrative review of the field's literature identified 22 nursing diagnoses, 36 interventions related to 15 skin changes, typical of the aging process 28 .The NDs: impaired skin integrity, impaired tissue integrity, impaired physical mobility, risk for infection, sensory/perception changes, decreased peripheral tissue perfusion, urinary incontinence, imbalanced nutrition, less than body needs and urinary incontinence were related to skin changes typical of the aging process 28 .
In this study the nursing interventions such as examining the skin, observing signs of infection, stimulating movement and walking, maintaining personal hygiene and promoting nutritional and water intake can prevent the emergence of ND: impaired tissue integrity, as it is a predictor of early readmission.
Also in readmission, another ND found was the risk for constipation.According to NANDA 11 definition, it means the risk for a decrease in the normal frequency of defecation, increased by the difficulty in passing hard, dry stools.
During the aging process, changes in sensory functions and chewing ability can interfere with food consumption.
Reducing the intake of meat, vegetables and fruit, and giving preference for more pasty and/or liquid consistencies can compromise the consumption of dietary fiber, minerals and vitamins 29 .As a result, changes in bowel habits can be commonly identified.Based on another study, authors confirm that the educational intervention in changing eating habits by increasing the intake of fiber, such as fruits and vegetables, helps to reduce the severity of constipation symptoms 30 .
In this study, patients with ACS possibly underwent invasive procedures (cardiac catheterization and coronary angioplasty), cardiac surgery (CABG), besides presenting clinical and physiological characteristics, such as loss of independence, insufficient physical activity, increased time stay in bed during hospitalization, decreased motility in the gastrointestinal tract caused by prolonged fasting and/or constipating medications, changes in habitual diet patterns, and the aging process itself.
Promoting the health of this population comes as nurses use health education with emphasis on nutritional education still during the hospitalization process, and the joint action with the nutrition team will provide a more adequate diet, improving bowel habit 29 .
Regarding the clinical conditions associated with the elderly, the following was identified: systemic arterial hypertension, sedentary lifestyle, dyslipidemia, diabetes mellitus, stress, smoking habits and obesity.These risk factors for ACS may have triggered the need for coronary artery bypass graft (CABG) surgery, coronary percutaneous intervention procedures, and several other invasive and noninvasive diagnostic tests that can entail patient's lower mobility during hospitalization.It is noteworthy that the ND: impaired physical mobility, according to the definition of NANDA 11 means limitation in independent and voluntary physical movement of the body or of one or more extremities.
Other factors that may be related to the presence of this diagnosis is the appearance of chest discomfort during physical exercise, limiting the patient's activity due to physical discomfort and fear of myocardial infarction; other factors that may also be present: fatigue, limited cardiovascular resistance, loss of integrity of bone structures and decreased muscle strength, resulting in loss of mobility.
In situations of movement restriction, when relative rest is recommended to the patient to decrease myocardial oxygen consumption, the nursing staff can perform passive exercises in bed preventing muscle disuse and fatigue.Moreover, the preparation of hospital discharge planning with the family and/or caregiver must provide information related to mobility limitations imposed by the disease itself.

Conclusions
The main sociodemographic characteristics and comorbidities of the elderly with ACS found were: male, mean age of 72 years old, married, retired, low level of education, with multiple comorbidities (systemic arterial hypertension, diabetes mellitus, sedentary lifestyle, dyslipidemia, stress, smoking habits, obesity).
The nursing diagnoses that indicated the possibility for readmission through the readmission-free survival curve were: impaired tissue integrity, risk for constipation, and impaired physical mobility.
The identification of these hospital admission predictors in elderly patients with ACS indicate areas of prioritization of nursing actions, which help in reducing the rate and frequency of readmissions, impact on the quality of life and functional capacity, as well as on health system costs.
It is emphasized that therapeutic measures should be aimed at all patients with ND identified at hospital admission.Such actions will enable possible resolutions or improved diagnostics during hospitalization, and even those identified during hospital discharge process, reducing the risks for readmission.
This study is limited by a restricted sample of a period of one year, with evaluation of entries in patients' medical records.Further studies are recommended to be carried out with longitudinal monitoring, including home care.

Potential Conflicts of Interest
No relevant potential conflicts of interest.

Sources of Funding
This study had no external funding sources.

Academic Association
This study is related to the Residency Program in Cardiovascular Nursing of EEUSP/IDPC.
occurrence and nursing care.The study was carried out in a public hospital of the State Secretariat of Health of São Paulo, a benchmark in the cardiovascular field.The study was approved by the Committee for Ethics in Research of the same institution under No. 4351/2013.

Table 1 Sociodemographic characteristics and comorbidities of the population under study
Identification of Readmission Predictors Int J Cardiovasc Sci.2015;28(2):139-147 Original Manuscript