Metabolic Syndrome: conceptual analysis in the nursing context

Objective to analyze the metabolic syndrome concept and to identify its essential features, antecedents, and outcomes within the context of nursing. Method conceptual analysis, based on the methodological steps of a model. We carried out an integrative review by accessing four databases online: Medical Literature Analysis and Retrieval System Online, Scientific Electronic Library Online, Latin American and Caribbean Health Sciences Literature, and Índice Bibliográfico Español en Ciencias de la Salud. Results the essential features most frequently involved the diagnostic criteria of metabolic syndrome. Inadequate nutrition and physical inactivity were highlighted as the most common antecedents of the syndrome, and the outcomes were occurrences of cardiovascular disease and diabetes mellitus type 2. As implication, we highlight relevant empirical data to the broad definition of the concept. Conclusion we could analyze the concept under study regarding essential features, antecedents, and outcomes, operationally defining it as a potential nursing phenomenon, which demands health care focusing on reducing risks and morbidity and mortality for cardiovascular diseases.


Introduction
The metabolic syndrome has drawn the attention of the scientific and professional community, not only due to the impact of each of their respective components, but mainly due to the high prevalence of cardiovascular risk factors (1) . According to a global estimate there is prevalence between 20 and 25% in the adult population (2) . In Brazil, the prevalence ranges around 9% in the adult and older-adult population, associated with the following variables: sociodemographic (age, education, marital status, and housing), behavioral (self-perception of health), and comorbidities (cerebrovascular accident, overweight, depression), in different ways between the sexes (3) .
This health condition has been widely studied by researchers, with varying criteria and existing definitions for diagnosis, particularities, and prevalence in population and age groups, aiming to discuss the accuracy of its assumptions (4)(5) and possible parameters that may be related such as neck circumference (6) and presence of Acanthosis nigricans (7) .
This syndrome was officially and primary described by Gerald Reaven in 1988, and was named "Syndrome X," which comprised insulin resistance, hypertension, dyslipidemia, and diabetes mellitus, and did not include obesity, currently considered one of the basal pathogenic factors (4,8) . Other concepts used to characterize it are mentioned such as insulin resistance syndrome, new world syndrome, plurimetabolic syndrome, deadly quartet syndrome, and dyslipidemia syndrome (9) .
Likewise, concerning the definition, the metabolic syndrome concept, currently accepted, is nonuniform on health literature, whether national (10) or international (11) , which evidences the understanding of disease or disorder, even though publications (1,12) spread the understanding that it is a set of cardiovascular risk factors. Hence, we highlight a gap in the knowledge about the idea that a broader definition for the metabolic syndrome concept would favor the development of health care in practice, teaching, and research, through innovative approaches (13) , by inserting nursing care in such.
Within the context of nursing, risk factors that compose the syndrome refer to the field of performance of the discipline, such as the measurement of waist circumference, blood pressure, and evaluation of laboratory parameters (14) , in order to comprise a nursing phenomenon, for which research should be developed to introduce new and relevant knowledge such as the analysis of the concept and applicability as human responses to inadequate life habits. Therefore, our objective was to analyze the metabolic syndrome concept and to identify its essential features, antecedents, and outcomes within the context of nursing.

Method
This is a conceptual analysis, based on the methodological steps of the Walker and Avant's Model (15) , covering the process of clarification of meanings of terms and their respective definition, in such a way that researchers and readers share a common language, especially, when a concept requires "clarification," as For the selection of the metabolic syndrome concept, we considered such identification in clinical practice and research, as a phenomenon of significant occurrence in people attended by nurses in the context of Primary Health Care. Moreover, since it is a condition that puts individuals at risk of complications, it demands deepening and clarifying the concept, the knowledge produced about the syndrome, and its insertion as a nursing phenomenon, and, thus, in line with the aforementioned model (15) . This analysis demand is directly related to the purpose of our study, previously presented. In order to achieve it, we question: what is the reason for this concept analysis? Regarding the identification of possible uses of the concept, we searched the literature for synthesis and for understanding how this knowledge is focused or applied, implicitly and explicitly.
In our study, in which we analyzed the concept within the context of nursing, some criteria were deemed relevant for identifying uses in articles: being produced by nurses and or published in nursing journals or related areas; directly contemplating the syndrome, cardiovascular risk factors, and/or overweight and obesity in the content; clearly presenting the concept in the title and or in the development of the article; exposing data relevant to the analysis for composing the concept as a nursing phenomenon; and prioritizing articles with higher level of scientific evidence.
Concerning antecedents, features, and outcomes, the model (15) define them, respectively, as: events that happen a priori to the phenomenon (required for its occurrence); words or expressions that repeatedly emerges in the literature, which demonstrates the essence of the concept; and events or situations that occur a posteriori to the phenomenon, respectively. We drew our attention to the exclusive criterion, according to which something cannot be, at the same time, a feature, an antecedent, and an outcome.
To follow this step, we conducted an integrative literature review, according to the development stages of this type of review in nursing (16) , because we understand the relevance of the systematic and operational approach of this process, in such a way we can achieve results according to our predetermined goal. In the productions selected for the review, we sought the use and definition of the concept, a sine qua non for inclusion in the study, besides frequency, adequacy, and direct correlation with the syndrome itself. In this selection, we established the inclusion criteria: full papers electronically available, in English, Portuguese, or Spanish, indexed in the last ten years, on human beings, regardless of age, population group, or correlation with diseases. We excluded from the studies repeated and editorial articles, dissertations, theses, point of views, and case studies. These criteria, in addition to the methodological strictness, were paramount to reduce biases of the study. For the search process and selection of the articles, specifically, we followed the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) (17) guide, which are detailed in Figure 1.
After the search procedure, we read the titles and abstracts of the selected articles to verify if they met the established inclusion criteria and, later, to read them in full. We used the PICO strategy, representing the acronym for "patients," "intervention," Rev. Latino-Am. Enfermagem 2019;27:e3154.

Excluded studies (editorials, dissertations, and point of views) (n=39)
Studies selected for initial reading (n=98)  Finally, empirical references were gathered to create a definition, understood as categories or classes of observable phenomena that demonstrate the occurrence of the concept by an operational definition of such (15) .

Studies selected for reading in full
Results were critically analyzed and arranged in a

Results
We selected 36 articles produced and/or published by nurses in nursing journals or related areas. These articles mostly involved cross-sectional (n=13) and descriptive (n=9) studies, with Level VI classification of scientific evidence, depicting the profile of nursing productions about the concept under study. In Figure 2 we present the profile of the selected articles, according to title, author, year of publication, type of study, and level of evidence.
Félix NDC, Nóbrega MML. Nursing diagnoses of ICNP ‡® for people with metabolic syndrome (14) 2018 Descriptive VI Anthropometric indicators that predict metabolic syndrome among adolescents (19) 2018 Cross-sectional IV Construction and validation of educational materials for the prevention of metabolic syndrome in adolescents (20) 2017 Descriptive VI Prevalence of metabolic syndrome in individuals with type 2 diabetes mellitus (21) 2017 Cross-sectional VI Lifestyle intervention on metabolic syndrome and its impact on quality of life: a randomized controlled trial (22) 2017 Randomized clinical trial III Risk factors associated with the development of metabolic syndrome in children and adolescents (23) 2016 Cross-sectional VI Metabolic syndrome in fixed-shift workers (24) 2015 Cross-sectional VI Neck circumference as a potential marker of metabolic syndrome among college students (25) 2014 Cross-sectional VI Prevalence of metabolic components in university students (26) 2014 Descriptive VI Alimentary habits, physical activity, and framingham global risk score in metabolic syndrome (27) 2014 Randomized clinical trial III Prevalence of metabolic syndrome in elderly and agreement among four diagnostic criteria (28) 2014 Cross-sectional VI Metabolic syndrome in overweight/obese female adolescents (29) 2012 Cross-sectional VI Nutrition and self-care practices of patients with chronic metabolic syndrome: a qualitative study (30) 2012 Descriptive VI

LILACS §
Overweight and obesity in students aging 6-10 yeas of a state school in Umuarama-PR-Brazil || (31)  2017 Descriptive VI Metabolic syndrome prevalence in patients with refractory schizophrenia (32) 2016 Cross-sectional VI Components of metabolic syndrome and associated factors in adolescents: a casecontrol study (33) 2016 Case-control study IV Persistence of metabolic syndrome in children and adolescents are overweight according to two diagnostic criteria: a longitudinal study (34) 2015 Longitudinal VI Prevalence of metabolic syndrome in metallurgical workers from different shifts (35) 2015 Cross-sectional VI Metabolic syndrome risk assessment in children: use of a single score (36) 2015 Cross-sectional VI Metabolic syndrome and its relationship with cardiovascular risk scores in adults with non-communicable chronic diseases (37) 2014 Cross-sectional VI Metabolic syndrome components in arterial hypertension (38) 2012 Cross-sectional VI Metabolic syndrome and breast cancer: systematic review (39) 2012 Systematic review III Prevalence of metabolic syndrome and its components in the menopausal transition: a systematic review (40) 2012 Systematic review III Metabolic syndrome in coronary artery and occlusive vascular diseases: a systematic review (41) 2010 Systematic review III Prevalence of metabolic syndrome in adolescents: a systematic review (42) 2009 Systematic review III

MEDLINE ¶
Metabolic syndrome and quality of life: a systematic review (43) 2016 Systematic review III Prevalence of metabolic syndrome among nursing personnel and its association with occupational stress, anxiety and depression (44) 2015 Descriptive VI A web-based health promotion program for patients with metabolic syndrome (45) 2014 Longitudinal VI Androgen-deprivation therapy and metabolic syndrome in men with prostate cancer (46) 2014 Longitudinal VI A randomized controlled trial undertaken to test a nurse-led weight management and exercise intervention designed for people with serious mental illness who take second generation antipsychotics (47) 2013 Randomized clinical trial III Bipolar disorder and metabolic syndrome: a systematic review (48) 2013 Systematic review III Implementing an evidence-based metabolic syndrome prevention and treatment program utilizing group visits (49)   in the publications, we observed that the expression "aggregation" was the most frequent initial term in definitions and, in our study, we used it to initially relate the essential features to the concept, antecedents, and outcomes. However, part of the studies conducted by the nursing field still defines the syndrome as a condition of disease, disorder, or abnormality, as shown in Figure 3.
The youth population was highlighted, in which there is a high prevalence of overweight and changes in the lipid profile of these individuals. These factors may pose risk for further metabolic syndrome and cardiovascular diseases (26) , which require nursing interventions to reduce them.
Therefore, the development of effective health care and the encouragement to public policies are suggested, policies which should act towards the awareness of a healthy lifestyle, focusing on the family, prioritizing older people without, however, disregarding younger people (28,(32)(33) . This comprises the nursing care that must Rev. Latino-Am. Enfermagem 2019;27:e3154.
be systematically provided and registered according to a standardized language, from a classification system.
For the older population, menopause transition promotes increase in the measurement of waist circumference, blood pressure, fasting blood glucose, triglycerides, and decrease in the high-density lipoprotein cholesterol, more expressive in the first two (40) . Hence, regarding the relation between the syndrome, menopause transition, and age, most studies showed that menopause transition was an independent predictor (29,40) ; however, there is need for studies with more robust designs to establish the relation of cause and effect.
Concerning behavioral factors, we identified more studies with high level of scientific evidence, especially publications in the nursing field and/or developed by nurses. Authors of national (14) and international (5) studies point that nurses need to consider such factors when planning and prescribing nursing interventions directed to this clinical profile and population, in such a way to achieve results relevant to the nursing practice.
According to results of another study (27)  Studies on several types of nursing interventions (22,43,47,(51)(52) , healthcare promotion programs, Web-based (45) , of visits (49) , and self-care (30) to changes in lifestyle and increased adherence among patients with the syndrome highlight impacts on the reduction of metabolic parameters and improvement in the quality of life, with beneficial effects on metabolic parameters, in particular, in weight loss and waist circumference.
As for the most frequent antecedents, their set negatively acts on the lipid profile and increases the prevalence of the syndrome and, therefore, the risk of cardiovascular disease (22,27,30,51) . Moreover, attention is draw to the effective development of healthcare actions, based on knowledge and adherence to preventive behaviors for decreasing diseases resulting from the syndrome (33) . Nurses are members of the participatory process of identifying these human responses and providing guidance for improving life habits and adherence to measures of healthcare promotion.
Concerning psychosocial and cultural factors, the literature (44) highlights the correlation between metabolic syndrome variables and anxiety (p=0.022), and between the syndrome and stress (p=0.008). Nursing staff must seek social and family support, in such a way it may help in identifying ways to communicate with professionals (50) .
In this situation, it is important to develop environments for nursing interaction, with families and community, for a healthy nutrition routine, practice of physical exercise, and weight and stress control (20) .
As for working factors, the syndrome can be related to some variables, such as work, poor sleep quality, poor diet, sedentary lifestyle, alcoholism, smoking, absenteeism, and dissatisfaction with the work (24,35) .
Concerning such factors, studies have been developed with nurses for understanding this phenomenon among these professionals, who will be attended by other nursing professionals, and that the phenomenon also occurs in this category, which needs to be recognized and monitored.
Infectious factors identified as antecedents to the syndrome, such as depression (22,(43)(44) , schizophrenia (32) , and bipolar disorder (48) , were found due to the number Hence, a multidisciplinary approach in health is necessary (22) in order to reduce factors responsible for the emergence of the syndrome and its respective outcomes. Nurses routinely deal with the imbalance of these factors and have an important role on the diagnosis, healthcare planning, strategy interventions, and control of this syndrome (21) .
Nursing professionals use knowledge from other fields in their professional practice and efficiently implement them, since they monitor, in a more longitudinal way, people affected by this syndrome.
These professionals, within a multidisciplinary work, must know the concept of the phenomenon and engage in developing actions that promote cardiovascular health in people affected with the syndrome and which reduce the consequent morbidity and mortality.
The categorized features enabled the creation of an operational definition for the metabolic syndrome concept as a nursing phenomenon, in order to be used in the planning and implementation of nursing care and in the field of teaching and research, in such a way to reduce the antecedents and the respective outcomes of short, medium, and long term -and in these last we evidenced high frequency of the outcome related to the occurrence of cardiovascular disease and diabetes mellitus type 2 (14, .
We understand that such outcome comprises a relevant