Los modelos de niveles múltiples: una estrategia analítica para el estudio de los problemas de salud de la población Multilevel models: an analysis strategy for the study of health problems in society

Se presenta una discusión teórico metodológica sobre la aplicabilidad de modelos de niveles múltiples para el estudio de los procesos de salud/enfermedad, sus determinantes y condicionantes, en función de la estratificación de la sociedad y de las condiciones de vida de sus habitantes. Se recupera una noción de población según la perspectiva de la teoría de los sistemas complejos jerárquicos que busca no reducir la realidad, sino una construcción del problema procurando identificar distintos niveles de abstracción para su abordaje. Estos modelos constituyen una opción que supera las experiencias previas, con la aplicación de técnicas estadísticas convencionales, dado que permiten analizar simultáneamente distintos niveles de agregación conservando su estructura jerárquica. Se consideran la influencia de las variables teniendo en cuenta su pertenencia a unidades mayores y la asociación potencialmente existente entre las unidades de un mismo nivel, es decir, la correlación intraclase entre variables relativas a individuos, familias, grupos, próximos entre sí, que comparten condiciones semejantes. Se evita de este modo sobredimensionar el efecto de las variables de macro nivel. Los modelos de niveles múltiples resultan particularmente adecuados para valorar desigualdades en el proceso salud/enfermedad/atención de los grupos poblacionales y analizar cómo los contextos sociales afectan los resultados y los riesgos de salud individuales. Se destaca la necesidad de desarrollar estrategias de producción de información y de análisis que posibiliten reconocer niveles de explicación y de intervención, para proveer insumos y desencadenar acciones adecuadas a las especificidades locales, a nivel de las micro-áreas, con miras a lograr una mayor equidad en salud.<br>This paper presents the theoretical-methodological discussion about the applicability of multiple level models in the study of the health/sickness process, its determinants and conditioning factors, as a function of the stratification of society and the living conditions of its inhabitants. It goes back to the concept of population according to the theory of hierarchical complex systems, which seeks not to reduce reality, but rather to build the problem trying to identify different levels of abstraction in its approach. These models are options to overcome prior experiences, with the application of conventional statistical techniques, given that they make it possible to simultaneously analyze different levels of aggregation, while keeping its hierarchical structure. They consider the influence of the variables taking into account their belonging to lager units and the potential association existing between the units of a same level, that is, the intraclass correlation among variables relative to individuals, families and groups, close amongst themselves, which share similar conditions. In this manner, it tries to avoid oversizing the effect of macro level variables. The multiple level models are particularly appropriate to evaluate inequalities in the health/sickness/care process of the population groups and to analyze how social contexts affect the results and health risks of people. It highlights the need to develop information production strategies and analyses that make it possible to recognize levels of explanation and intervention to provide inputs and trigger actions suited to local specificities, at the level of micro-areas, so as to have more equity in healthcare

The impact of rural residency on the expression and outcome of systemic lupus erythematosus: data from a multiethnic Latin American cohort

Objective: The objective of this paper is to examine the role of place of residency in the expression and outcomes of systemic lupus erythematosus (SLE) in a multi-ethnic Latin American cohort. Patients and methods: SLE patients (<two years of diagnosis) from 34 centers constitute this cohort. Residency was dichotomized into rural and urban, cut-off: 10,000 inhabitants. Socio-demographic, clinical/laboratory and mortality rates were compared between them using descriptive tests. The influence of place of residency on disease activity at diagnosis and renal disease was examined by multivariable regression analyses. Results: Of 1426 patients, 122 (8.6%) were rural residents. Their median ages (onset, diagnosis) were 23.5 and 25.5 years; 85 (69.7%) patients were Mestizos, 28 (22.9%) Caucasians and 9 (7.4%) were African-Latin Americans. Rural residents were more frequently younger at diagnosis, Mestizo and uninsured; they also had fewer years of education and lower socioeconomic status, exhibited hypertension and renal disease more frequently, and had higher levels of disease activity at diagnosis; they used methotrexate, cyclophosphamide pulses and hemodialysis more frequently than urban patients. Disease activity over time, renal damage, overall damage and the proportion of deceased patients were comparable in rural and urban patients. In multivariable analyses, rural residency was associated with high levels of disease activity at diagnosis (OR 1.65, 95% CI 1.06-2.57) and renal disease occurrence (OR 1.77, 95% CI 1.00-3.11). Conclusions: Rural residency associates with Mestizo ethnicity, lower socioeconomic status and renal disease occurrence. It also plays a role in disease activity at diagnosis and kidney involvement but not on the other end-points examined. Lupus (2012) 21, 1397-1404.211313971404Federico Wilhelm Agricola Foundation ResearchNational Institute of Arthritis and Musculoskeletal and Skin Diseases [P01 AR49084]STELLAR (Supporting Training Efforts in Lupus for Latin American Rheumatologists) ProgramRheuminations Inc.Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS)-Beca de Formacio i Contractacio de Personal InvestigadorNational Institute of Arthritis and Musculoskeletal and Skin Diseases [P01 AR49084

Mestizos with systemic lupus erythematosus develop renal disease early while antimalarials retard its appearance: Data from a Latin American cohort

Objectives The objective of this paper is to assess the predictors of time-to-lupus renal disease in Latin American patients. Methods Systemic lupus erythematosus (SLE) patients (n=1480) from Grupo Latino Americano De Estudio de Lupus (GLADEL's) longitudinal inception cohort were studied. Endpoint was ACR renal criterion development after SLE diagnosis (prevalent cases excluded). Renal disease predictors were examined by univariable and multivariable Cox proportional hazards regression analyses. Antimalarials were considered time dependent in alternative analyses. Results Of the entire cohort, 265 patients (17.9%) developed renal disease after entering the cohort. Of them, 88 (33.2%) developed persistent proteinuria, 44 (16.6%) cellular casts and 133 (50.2%) both; 233 patients (87.9%) were women; mean (+/- SD) age at diagnosis was 28.0 (11.9) years; 12.2% were African-Latin Americans, 42.5% Mestizos, and 45.3% Caucasians (p=0.0016). Mestizo ethnicity (HR 1.61, 95% CI 1.19-2.17), hypertension (HR 3.99, 95% CI 3.02-5.26) and SLEDAI at diagnosis (HR 1.04, 95% CI 1.01-1.06) were associated with a shorter time-to-renal disease occurrence; antimalarial use (HR 0.57, 95% CI 0.43-0.77), older age at onset (HR 0.90, 95% CI 0.85-0.95, for every five years) and photosensitivity (HR 0.74, 95% CI 0.56-0.98) were associated with a longer time. Alternative model results were consistent with the antimalarial protective effect (HR 0.70, 95% CI 0.50-0.99). Conclusions Our data strongly support the fact that Mestizo patients are at increased risk of developing renal disease early while antimalarials seem to delay the appearance of this SLE manifestation. These data have important implications for the treatment of these patients regardless of their geographic location.229899907Federico Wilhelm Agricola Foundation Research (BAPE)National Institute of Arthritis and Musculoskeletal and Skin Diseases [P01 AR49084]STELLAR (Supporting Training Efforts in Lupus for Latin American Rheumatologists) ProgramRheuminations IncInstitut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS)-Beca de Formacio i Contractacio de Personal Investigador (GPE)FONDECYT [1110395]National Institute of Arthritis and Musculoskeletal and Skin Diseases [P01 AR49084]FONDECYT [1110395