Eficacia de la dieta DASH en la prevención de las enfermedades cardiovasculares


Eficacia de la dieta DASH en la prevención de las enfermedades cardiovasculares

Fung TT, Chiuve SE, McCullough ML, Rexrode KM, Logroscino G, Hu FB. Adherence to a DASH-Style Diet and Risk of Coronary Heart Disease and Stroke in Women. Arch Intern Med 2008; 168: 713-720.  R TC PDF

Introducción

La dieta DASH (Dietary Approaches to Stop Hypertension) reduce la presión arterial (PA) y el colesterol LDL. Sin embargo, no se ha demostrado que sea capaz de prevenir las enfermedades cardiovasculares, dado que puede ser difícil llevar a cabo estudios de prevención primaria de las enfermedades cardiovasculares mediante la dieta.

Objetivo

Estudiar la asociación entre la adherencia a la dieta DASH y la incidencia de cardiopatía isquémica (CI) y AVC a lo largo de 24 años.

Perfil del estudio

Tipo de estudio: Estudio de cohortes

Área del estudio: Tratamiento

Ámbito del estudio: Comunitario

Métodos

Estudio de cohortes.

El Nurses´ Health Study es un estudio de cohortes que incluye a 121.700 enfermeras que tenían entre 30 y 55 años al inicio del estudio, en 1976 y cuyo seguimiento alcanza al 95% de la cohorte original en estos momentos. A las participantes se les envía un cuestionario cada 4 años en los que se interroga entre otras cosas sobre la frecuencia de consumo de 61 alimentos durante el año previo. Con estos datos se valoró el grado de adherencia a la dieta DASH mediante la construcción de una escala que incluía 8 componentes: frutas, hortalizas, frutos secos, legumbres, lácteos desnatados, cereales integrales, sodio, bebidas azucaradas y carnes rojas y procesadas. Se clasificó a las mujeres en quintiles en función del grado de consumo de cada uno de estos alimentos y se le asignaba 5 puntos a las que tenían el quintil óptimo y 1 punto a las que estaban en el peor quintil.

Las variables de resultado principales fueron los casos de CI y AVC ocurridos entre 1980 y 2004, confirmados mediante la revisión de los registros médicos de las participantes por investigadores que desconocían la puntuación de las mujeres. En 1990 se recogió una muestra de sangre en la que se mideron el perfil lipídico, la PCR y la interleukina 6. Otras variables analizadas fueron el IMC, el tabaquismo, el ejercicio físico de tiempo libre, la menopausia, y la ingesta de aspirina y multivitamínicos.

Resultados

Durante los 24 años de seguimiento se registraron 3.105 casos de IM y 2.317 casos de AVC (1.242 isquémicos, 440 hemorrágicos y el resto indeterminados). Las mujeres que presentaron una mejor adherencia a la dieta DASH también consumían más fibra, ácidos grasos omega-3 y multivitamínicos y menos ácidos grasos saturados, grasas trans y calorías, hacían más ejercicio, fumaban menos y era más probable que fueran hipertensas.

Se encontró una relación inversa entre la incidencia de CI y la puntuación de la escala de adherencia a la dieta DASH, que se mantuvo en el análisis multivariante (fig. 1).

Figura 1. Riesgo relativo de CI en función de la puntuación de la escala DASH en el análisis multivariante.

Lo mismo sucedió para los AVC, aunque en el análisis por separado de los AVC isquémicos y hemorrágicos, la tendencia no fue estadísticamente significativa para ninguno de ellos por separado (fig. 2).

Figura 2. Riesgo relativo de AVC en funcióln de la puntuación de la escala DASH en el análisis multivariante.

En los análisis de subgrupos se detectó una tendencia que no alcanzó la significación estadística a una mayor eficacia para los dos tipos de eventos en fumadoras, para la CI en obesas y para los AVC en hipertensas. No se detectó ninguna relación entre el grado de adherencia a la dieta DASH y el colesterol LDL o los triglicéridos, pero sí con menores niveles de proteína C reactiva y de interleukina 6.

Conclusiones

Los autores concluyen que, en mujeres de edad media, la adherencia a una dieta DASH se asocia a una menor incidencia de cardiopatía isquémica y AVC a largo plazo.

Conflictos de interés

Ninguno declarado. Financiado por una beca de los National Institutes of Health.

Comentario

La dieta DASH es un plan de alimentación propuesto por el National Heart, Lung, and Blood Institute para reducir la PA. Se trata de una dieta baja en grasas saturadas, colesterol y totales y rica en fruta, hortalizas y lácteos desnatados. En un ensayo clínico a corto plazo, se demostró que los pacientes asignados a una dieta de este tipo obtenían reducciones de la PA que en los hipertensos llegaban a los 11/5,5 mmHg comparados con los asignados a seguir una dieta americana estándar. En un estudio posterior se demostró que la restricción de sodio conseguía pequeñas reducciones de PA adicionales.

Sin embargo, estos estudios son de corta duración, por lo que es difícil que puedan detectar cambios en la morbimortalidad asociada a la HTA. Es bastante improbable que se pueda llevar a cabo un estudio de intervención a largo plazo para comprobar esta hipótesis. Por este motivo, resulta útil recurrir a los estudios observacionales. La cohorte del Nurses´ Health Study tiene la suficiente duración como para comprobarla. En este estudio se ha observado que la utilizacion de una dieta DASH se asocia a un menor riesgo a largo plazo de CI y AVC. El hecho de que los datos sobre la dieta se hayan recogido antes de los eventos de resultado hace que no se pueda dar un sesgo de recuerdo selectivo o de selección. Por contra, las mujeres que obtenían mejores puntuaciones en la escala de la dieta DASH también llevaban un estilo de vida “más sludable”, por lo que no se puede descartar que parte del efecto observado se deba a factores de confusión que se hayan escapado al análisis multivariante.

El principal inconveniente de este estudio es que sus participantes son muy homogéneas (mujeres de edad media con un nivel educativo alto) por lo que antes de extrapolar sus resultados es necesario llevar a cabo estudios en otras poblaciones. Tampoco puede deducirse que la dieta DASH sea la dieta ideal, puesto que la adhesión a otros modelos dietéticos como la dieta mediterránea también se han asociado a un menor riesgo de cardiopatía isquémica.

Bibliografía

  1. Elmer PJ, Obarzanek E, Vollmer WM, Simons-Morton D, Stevens VJ, Young DR, et al for the PREMIER Collaborative Research Group. Effects of Comprehensive Lifestyle Modification on Diet, Weight, Physical Fitness, and Blood Pressure Control: 18-Month Results of a Randomized Trial. Ann Intern Med 2006; 144: 485-495.  R TC (s) PDF (s) RC
  2. Sacks FM, Svetkey LP, Vollmer WM, Appel LJ, Bray GA, Harsha D, et al for the DASH–Sodium Collaborative Research Group. Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet. N Engl J Med 2001; 344: 3-10.  R TC (s) PDF (s)
  3. Appel LJ, Moore TJ, Obarzanek E et al for the DASH Collaborative Research Group. A clinical trial of the effects of dietary patterns on blood pressure. N Engl J Med 1997; 336: 1117-1124.  R TC PDF
  4. National Heart, Lung, and Blood Institute. Your Guide to Lowering Your Blood Pressure with DASH. National Institutes of Health. 2006.

Autor

Manuel Iglesias Rodal. Correo electrónico: mrodal@menta.net.

Influencia de las migraciones en Reino Unido sobre conducta materna


Influence of moving to the UK on maternal health behaviours: prospective cohort study

Summer Sherburne Hawkins, research fellow, Kate Lamb, MSc student, Tim J Cole, professor, Catherine Law, professor, the Millennium Cohort Study Child Health Group

1 Centre for Paediatric Epidemiology and Biostatistics, UCL Institute of Child Health, London WC1N 1EH

Correspondence to: S S Hawkins s.hawkins@ich.ucl.ac.uk<!–
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Abstract

Objective To compare health behaviours during pregnancy (smoking and alcohol consumption) and after birth (initiation and duration of breast feeding) between British/Irish white mothers and mothers from ethnic minority groups; and, in mothers from ethnic minority groups, to examine whether indicators of acculturation (generational status, language spoken at home, length of residency in the United Kingdom) were associated with these health behaviours.

Design Prospective nationally representative cohort study.

Setting England.

Participants 6478 British/Irish white mothers and 2110 mothers from ethnic minority groups.

Main outcome measures Any smoking during pregnancy; any alcohol consumption during pregnancy; initiation of breast feeding; breast feeding for at least four months.

Results Compared with British/Irish white mothers, mothers from ethnic minority groups were less likely to smoke (15% v 37%) or consume alcohol (14% v 37%) during pregnancy but more likely to initiate breast feeding (86% v 69%) and breast feed for at least four months (40% v 27%). Among mothers from ethnic minority groups, first and second generation mothers were more likely to smoke during pregnancy (odds ratio 3.85, 95% confidence interval 2.50 to 5.93, and 4.70, 2.49 to 8.90, respectively), less likely to initiate breast feeding (0.92, 0.88 to 0.97, and 0.86, 0.75 to 0.99), and less likely to breast feed for at least four months (0.72, 0.62 to 0.83, and 0.52, 0.30 to 0.89) than immigrants, after adjustment for sociodemographic characteristics. There were no consistent differences in alcohol consumption. Among immigrants, for every additional five years spent in the UK the likelihood of mothers smoking during pregnancy increased by 31% (4% to 66%) and they were 5% (0% to 10%) less likely to breast feed for at least four months.

Conclusions After immigration, maternal health behaviours worsen with length of residency in the UK. Health professionals should not underestimate women’s likelihood of engaging in risky health behaviours because of their ethnicity.

Introduction

The adverse effects of smoking1 2 and alcohol consumption3 during pregnancy and the beneficial effects of breast feeding4 on maternal and child health are well known. Many women from resource-rich countries, however, do not adhere to recommendations,1 5 6 7 8 9 10 including those to reduce smoking11 12 and stop drinking13 during pregnancy and breast feed exclusively for six months.14 Research from the United States has shown that maternal health behaviours vary by country of birth and length of residency, two indicators of acculturation.15 16 17 18 19 20 21 22 23 24 Acculturation is the adoption of health behaviours from the new dominant culture and loss of health behaviours from the original culture.25 26 In the US, acculturation has been associated with an increase in smoking15 16 17 18 and alcohol consumption15 16 17 during pregnancy as well as a reduction in initiation19 20 21 22 23 24 and duration19 23 24 of breast feeding.

Over the past 50 years immigration into the United Kingdom has increased, primarily from South Asia, the Caribbean, Europe, and Africa.27 In 2001-2, 7.6% of the population was from an ethnic minority group, an increase of 44% over the previous decade.28 Women from ethnic minority groups are less likely to smoke or consume alcohol than the general population in England29 and more likely to initiate and continue breast feeding than white mothers.7

We compared health behaviours during pregnancy (smoking and alcohol consumption) and after birth (initiation and duration of breast feeding) between British/Irish white mothers and mothers from ethnic minority groups in a nationally representative, contemporary cohort of mothers in England. We also examined how indicators of acculturation (measured by generational status, language spoken at home, length of residency in the UK) were associated with these health behaviours.

Methods

Participants
The millennium cohort study is a prospective study of children born in the UK in the new century. We used a stratified clustered sampling framework to over-represent children from ethnic minority groups and disadvantaged areas. In England, electoral wards (as established in 1998) were categorised as “ethnic” (based on the 1991 census, if at least 30% of residents were from an ethnic minority group) and the remainder as “disadvantaged” (the upper quarter of the child poverty index) or “advantaged” (all remaining wards). In Wales, Scotland, and Northern Ireland there was no “ethnic” stratum.30 Families were invited to participate if they were eligible for child benefit and resident in the UK when their child was aged 9 months. The original cohort comprised 18 819 children (18 553 families) born between September 2000 and January 2002 (72% response).30 About 80% (14 630) participated in the second contact, in September 2003 to January 2005, when the children were aged 3 years.31 At both contacts, information was collected through interviews of main respondents in the home. Translators were available.32

We focused on families in England because numbers were insufficient to analyse by ethnic group in Wales, Scotland, or Northern Ireland. Among the 11 695 mothers with singleton children at the first contact, 79% (9184) participated in the second. Families from “ethnic” and “disadvantaged” electoral wards were less likely to participate in the second contact,31 but non-response weights are available and were used to allow for differential attrition. Data were accessed through the UK Data Archive, University of Essex.

Among the 9184 mothers with singleton children in England at both contacts, we included 8588 in the analyses. We excluded families if information was missing on the main respondent’s ethnicity (46), the main respondent was not female (139) or a natural mother (53), there were two cohort children from the same family (8), or the main respondent had missing information on her generational status (370), language spoken at home (0), length of residency in the UK (193), initiation of breast feeding (15), duration of breast feeding (15), smoking during pregnancy (41), or alcohol consumption during pregnancy (16). Some families satisfied more than one exclusion criterion.

At the first contact, mothers reported their own ethnicity (out of 16 possible choices), which was classified according to guidelines from the Office for National Statistics.33 White women were categorised as either from any UK country or the Republic of Ireland (referred to as “British/Irish”) or from any other country (referred to as “other white”).5 To increase sample size we collapsed ethnic groups into British/Irish white, Pakistani or Bangladeshi, black (black African, black Caribbean, other black), Indian, other white (such as white European, North American), other (such as Sri Lankan, Arab), or mixed.

Sociodemographic characteristics were based on maternal self report at the first contact. Maternal socioeconomic circumstances were categorised according to the National Statistics socioeconomic classification,34 maternal education was defined as the highest academic qualification attained, and single motherhood status was defined as being a single mother when the child was aged 9 months. Mothers also reported whether the cohort child was their first live birth (parity), and their age at the birth of the cohort child. We included family income at the first contact; if it was missing we substituted values from the second contact (483).

Outcome measures
Smoking and alcohol consumption during pregnancy—At the first contact, mothers were asked about their smoking and drinking habits during pregnancy. Mothers reported their smoking habits before pregnancy and were asked whether they changed during pregnancy. Mothers were classified as having smoked if they reported smoking any number of cigarettes during pregnancy. Mothers also reported how often they drank alcoholduring pregnancy, ranging from never to every day. Mothers were classified as having consumed alcohol if they reported consuming any amount of alcohol during pregnancy. At the time when the mothers were pregnant, government recommendations were that pregnant women should drink no more than one or two units of alcohol once or twice a week and avoid intoxication.35

Initiation and duration of breast feeding—At the first contact, mothers were asked about their infant feeding practices. Initiation of breast feeding was defined as the baby having received any breast milk. Duration was categorised as being either fully or partially breast fed for at least four calendar months (≥17.4 weeks) or less than four months.5 At the time of the cohort births, the World Health Organization recommended that babies were breast fed for at least four months.36

Indicators of acculturation
Generational status—At the second contact, main respondents reported whether they, their mother, and their father were born in the UK or Republic of Ireland and, if not, their country of birth. Mothers were classified as immigrants (neither they nor either parent were born in the UK or Republic of Ireland), first generation (they were born in the UK or Republic of Ireland, but at least one parent was born outside the UK or Republic of Ireland), or second generation (both they and their parents were born in the UK or Republic of Ireland).

Language spoken at home—At the first contact, main respondents reported whether the language usually spoken at home was English, English and another language, or another language only.

Length of residency in the UK—At the second contact, main respondents who were not born in the UK or Republic of Ireland were asked the year when they arrived in the UK. This was subtracted from the year of the interview at the first contact to give the length of residency.

Statistical analyses
All analyses were conducted with STATA statistical software, version 9.2 SE (Stata Corporation, TX), with survey commands to account for the clustered sampling framework and obtain robust standard errors. We derived weighted percentages and conducted analyses using survey and non-response weights to allow for the clustered sampling and attrition between contacts. Proportions were compared with Pearson’s {chi}2 tests with the Rao and Scott second order correction.37 We included British/Irish white mothers to provide baseline characteristics of the majority ethnic group in England. Health behaviours during pregnancy (smoking and alcohol consumption) and after birth (initiation and duration of breast feeding) were compared by maternal ethnic group. Continue reading Influencia de las migraciones en Reino Unido sobre conducta materna