Improvement of serum lipids concentration in a general population historical cohort. Why? / Mejora de la concentración de lípidos séricos en una cohorte histórica de población general. ¿Por qué?

Background: Knowledge about the harmful effects of high levels of low-density lipoprotein cholesterol (cLDL) in adults increased after the publication of various guidelines, leading to closer control and more treatment. We hypothesized that these health care changes would result in an overall improvement in the lipid profile of the population. Objective: To determine the evolution of the lipid profile in the population of Spain from the Diet and Risk of Cardiovascular Disease in Spain cohort. Methods: A comparison was made between the baseline population-based probabilistically sampled DRECE cohort (DRECE 1 study, 1992-1994, n=4787) and its 13 years later revisit (DRECE 3 study, 2005-2007). A cross-sectional comparison was made of the overall population of DRECE1 and DRECE3, including only individuals aged 20 to 60 years (inter-individual variations). For subjects participating in both DRECE1 and DRECE3 (n=1039), individual variations over time (intra-individual analyses) were examined. Results: In the overall population, the prevalence of lipid-lowering therapy increased from 3.8% in DRECE1 to 10.7% in DRECE3. Comparing the lipid profile of the population aged 20-60 years in DRECE1 with the same age group in DRECE3, an overall decrease is observed in total cholesterol from a mean of 203.31mg/dl (SD 43.51) in 1992-1994 to 196.31mg/dl (SD 38.53) in 2005-2007, and in cLDL from a mean of 125.78mg/dl (SD 38.53) to 121.37mg/dl (SD 34.22). The proportion of the population with total cholesterol >200mg/dl decreased from 51% in DRECE1 to 47% in DRECE3, although this difference did not reach statistical significance (p=0.077). As regards the intra-individual analyses, total cholesterol increased from DRECE1 to DRECE3 in men and women younger than 40 years at baseline, but decreased in those who were older. Index of individuality for total cholesterol, cLDL, cHDL and triglycerides ranged from 0.53 to 0.87. Conclusions: The lipid profile of the Spanish population improved between 1992-1994 and 2005-2007. Within individuals, lipid concentrations, especially total cholesterol and cLDL have increased, although the trend is favorable in the middle-age group (40-59 years). These changes seem to be due to several causes, impacted by dietary and lifestyle factors, and also by a greater emphasis in lipid-lowering therapy in middle-aged people. Lipid parameters had a low index of individuality, which limits their usefulness as population reference values (AU)

Antecedentes: Los efectos nocivos de los altos niveles de colesterol ligado a lipoproteínas de baja densidad (cLDL) han sido ampliamente difundidos en la literatura científica y popular. Nuestra hipótesis es que estas recomendaciones han influido eficazmente en el perfil lípido de la población española. Objetivo: Determinar la evolución del perfil de lípidos en la población de España a partir de la cohorte Dieta y riesgo de enfermedad cardiovascular en España (DRECE). Métodos: Se comparó la cohorte de partida DRECE (estudio DRECE1, 1992-1994, n=4.787), procedente de muestreo probabilístico poblacional, con su reevaluación a los 13 años (estudio DRECE3, 2005-2007). Se compararon de modo transversal las muestras DRECE1 y DRECE3, incluyendo solo sujetos entre 20 y 60 años (variaciones interindividuales). De los sujetos que participaron en ambos estudios (n=1.039) se examinaron las variaciones interindividuales a lo largo del tiempo (análisis intraindividual). Resultados: En la población general, la prevalencia de la terapia hipolipidemiante aumentó de 3,8% en DRECE1 a 10,7% en DRECE3. Al comparar el perfil lipídico de la población de 20 a 60 años en DRECE1 con el mismo grupo de edad en DRECE3 disminuye la media del colesterol total de 203,31mg/dl (DS 43,51) en 1992-1994 a 196,31mg/dl (DS 38,53) en 2005-2007, la media del cLDL disminuye de 125,78mg/dl (DS 38,53) a 121,37mg/dl (DS 34,22). La proporción de la población con colesterol total>200mg/dl se redujo de 51% en DRECE1 al 47% en DRECE3, aunque esta diferencia no fue significativa (p=0,077). Respecto del análisis intraindividual el colesterol total aumentó de DRECE1 a DRECE3 en hombres y mujeres menores de 40 años al inicio de la cohorte, y descendió en los mayores de 40. El índice de individualidad del colesterol total, cLDL, cHDL y triglicéridos osciló entre 0,53 y 0,87. Conclusiones: El perfil lipídico de la población española mejoró entre 1992-1994 y 2005-2007. La concentración intraindividual de lípidos aumentó ligeramente, especialmente el colesterol total y cLDL, pero la tendencia fue más favorable en los sujetos de edad media (40-59 años). Estos cambios parecen ser multicausales, influidos por factores dietéticos y de estilo de vida, y también por un mayor énfasis en la terapia hipolipidemiante en sujetos en edad media. Los parámetros lipídicos tenían un bajo índice de individualidad, lo que limita su utilidad como valores de referencia poblacionales (AU)

Improvement of serum lipids concentration in a general population historical cohort. Why?

BACKGROUND: Knowledge about the harmful effects of high levels of low-density lipoprotein cholesterol (cLDL) in adults increased after the publication of various guidelines, leading to closer control and more treatment. We hypothesized that these health care changes would result in an overall improvement in the lipid profile of the population. OBJECTIVE: To determine the evolution of the lipid profile in the population of Spain from the Diet and Risk of Cardiovascular Disease in Spain cohort. METHODS: A comparison was made between the baseline population-based probabilistically sampled DRECE cohort (DRECE 1 study, 1992-1994, n=4787) and its 13 years later revisit (DRECE 3 study, 2005-2007). A cross-sectional comparison was made of the overall population of DRECE1 and DRECE3, including only individuals aged 20 to 60 years (inter-individual variations). For subjects participating in both DRECE1 and DRECE3 (n=1039), individual variations over time (intra-individual analyses) were examined. RESULTS: In the overall population, the prevalence of lipid-lowering therapy increased from 3.8% in DRECE1 to 10.7% in DRECE3. Comparing the lipid profile of the population aged 20-60 years in DRECE1 with the same age group in DRECE3, an overall decrease is observed in total cholesterol from a mean of 203.31mg/dl (SD 43.51) in 1992-1994 to 196.31mg/dl (SD 38.53) in 2005-2007, and in cLDL from a mean of 125.78mg/dl (SD 38.53) to 121.37mg/dl (SD 34.22). The proportion of the population with total cholesterol >200mg/dl decreased from 51% in DRECE1 to 47% in DRECE3, although this difference did not reach statistical significance (p=0.077). As regards the intra-individual analyses, total cholesterol increased from DRECE1 to DRECE3 in men and women younger than 40 years at baseline, but decreased in those who were older. Index of individuality for total cholesterol, cLDL, cHDL and triglycerides ranged from 0.53 to 0.87. CONCLUSIONS: The lipid profile of the Spanish population improved between 1992-1994 and 2005-2007. Within individuals, lipid concentrations, especially total cholesterol and cLDL have increased, although the trend is favorable in the middle-age group (40-59 years). These changes seem to be due to several causes, impacted by dietary and lifestyle factors, and also by a greater emphasis in lipid-lowering therapy in middle-aged people. Lipid parameters had a low index of individuality, which limits their usefulness as population reference values.

Evaluación multicéntrica de distintos métodos para la determinación de colesterol HDL directo con respecto al colesterol HDL de precipitación / Multicentre evaluation of different methods for the determination of direct HDL-cholesterol compared to the precipitation method

Introducción. Los resultados de los programas de garantía de calidad indican que existen diferencias significativas entre los métodos homogéneos disponibles para la medición del colesterol HDL. Sin embargo, la posible influencia de efectos matriz en las muestras liofilizadas empleadas y la ausencia de un valor verdadero en estas muestras, hace difícil la valoración completa de estos métodos. En este estudio experimental multicéntrico hemos comparado los métodos homogéneos más utilizados en nuestro medio, con respecto al de precipitación de ácido fosfotúngstico-MgCl2. Material y métodos. Cada laboratorio procesó unas 100 muestras de suero de pacientes por uno o dos métodos homogéneos y envió alícuotas congeladas de las muestras analizadas al laboratorio central donde se procesaron por el método de precipitación. Resultados. Las imprecisiones de los métodos homogéneos fueron buenas e inferiores a las de precipitación, que cumplía las especificaciones de calidad para sesgo y error total (ET). Sin embargo, no todos los métodos homogéneos cumplían los objetivos de calidad mínimos, pues algunos procedimientos producían sesgos positivos muy altos (en relación al método de comparación) y uno un sesgo negativo muy bajo. El estudio de la concordancia, realizado estratificando a los pacientes según las concentraciones de colesterol HDL, mostró diferencias entre los métodos. Conclusiones. Estos resultados sugieren que existen discrepancias en la valoración de las magnitudes obtenidas con los métodos homogéneos, probablemente generada por una elevada inexactitud en algunos de ellos y que es conveniente que los laboratorios conozcan las caracteristicas de imprecisión y sesgo del metodo directo que utilizan con respecto al de referencia (AU)

Introduction. The results of quality assurance programs suggest that there are significant differences between the homogeneous methods available for the measurement of HDL cholesterol. However, the possible influence of matrix effects in the lyophilized samples used and the absence of a true value in these samples means that a full assessment of these methods cannot be made. In this multicentre pilot study we compared the most used homogeneous methods in our country with the phosphotungstic acid-MgCl2 method. Material and methods. Each laboratory processed about one hundred serum samples from patients with one or two homogeneous methods and sent frozen aliquots of the samples in special packaging with dry ice to the central laboratory where they were processed by the precipitation method. Results. The imprecision of homogeneous methods were good and lower than those of the precipitation method, and met the quality specifications for bias and total error (TE). However, not all homogeneous methods met the minimum quality objectives, as some procedures produced a very high positive bias (relative to the comparison method) and one, a low negative bias. In addition, the study of the agreement between methods, made by stratifying patients according to HDL cholesterol concentrations, showed differences. Conclusions. These results suggest that there are discrepancies in the assessment of the levels obtained with homogeneous methods, probably due to a high inaccuracy in some of them, and it is advised that the laboratories be aware of the characteristics of inaccuracy and bias of the direct method used compared to the reference method (AU)