Josep L. Carrasco

The use of indexes evaluating the adherence to the Mediterranean diet in epidemiological studies: a review

The purpose of this paper is to review some of the methods that several epidemiological studies use to evaluate the adherence of a population to the Mediterranean diet pattern. Among these methods, diet indexes attempt to make a global evaluation of the quality of the diet based on a traditional Mediterranean reference pattern, described as a priori, general and qualitative. The Mediterranean diet indexes, hence, summarise the diet by means of a single score that results from a function of different components, such as food, food groups or a combination of foods and nutrients. The reviewed evaluation methods can be classified into three categories depending on the way they are calculated: (1) those based on a positive or negative scoring of the components, (2) those that add or substract standardised components, and (3) those that are based on a ratio between components. Dietary scores have been used to explore the multiple associations between the Mediterranean diet, as an integral entity, and health parameters such as life expectancy or the incidence of obesity, cardiovascular diseases and some types of cancers. Moreover, these indexes are also useful tools to measure food consumption trends and to identify the involved factors, as well as to develop comprehensive public health nutrition recommendations. A more precise and quantitative definition of the Mediterranean diet is required if the adherence to such a dietary pattern is intended to be more accurately measured. Other aspects of the Mediterranean diet indexes should also be taken into account, like the inclusion of typical Mediterranean foods such as nuts and fish and the validation of the dietary pattern approach by using biomarkers.

Effect of vertebroplasty on pain relief, quality of life, and the incidence of new vertebral fractures: A 12-month randomized follow-up, controlled trial

Uncertainty regarding the benefits of vertebroplasty (VP) for the treatment of acute osteoporotic vertebral fractures has recently arisen. A prospective, controlled, randomized single‐center trial (ClinicalTrials.gov registration number NCT00994032) was designed to compare the effects of VP versus conservative treatment on the quality of life and pain in patients with painful osteoporotic vertebral fractures, new fractures and secondary adverse effects were also analyzed during a 12‐month follow‐up period. A total of 125 patients were randomly assigned to receive conservative treatment or VP. The primary end point was to compare the evolution of the quality of life (Quality of Life Questionnaire of the European Foundation for Osteoporosis [Qualeffo‐41] and pain (Visual Analogue Scale [VAS]) during a 12 month follow‐up. Secondary outcomes included comparison of analgesic consumption, clinical complications, and radiological vertebral fractures at the same time points. Both arms showed significant improvement in VAS scores at all time points, with greater improvement (p = 0.035) in the VP group at the 2‐month follow‐up. Significant improvement in Qualeffo total score was seen in the VP group throughout the study, whereas this was not seen in the conservative treatment arm until the 6‐month follow‐up. VP treatment was associated with a significantly increased incidence of vertebral fractures (odds ratio [OR], 2 · 78; 95% confidence interval [CI], 1.02–7.62, p = 0.0462). VP and conservative treatment are both associated with significant improvement in pain and quality of life in patients with painful osteoporotic vertebral fractures over a 1‐year follow‐up period. VP achieved faster pain relief with significant improvement in the pain score at the 2‐month follow‐up but was associated with a higher incidence in vertebral fractures.

Maximizing association statistics over genetic models

The assessment of the association between a candidate locus and a disease may require the assumption of an inheritance model. Most researchers select the additive model and test the association with the Cochran‐Armitage trend test. This test assumes a dose‐response effect with regard to the number of copies of the variant allele. However, if there is reason to expect dominance or recessiveness in the effect of the variant allele, the heterozygous genotype may be grouped with one of the two homozygous, depending on the inheritance model, and a simple test on the 2 × 2 table can be used to assess independence. When the underlying genetic model is unknown, association may be assessed using the max‐statistic, which selects the largest test statistic from the dominant, recessive and additive models. The statistical significance of the max‐statistic has been previously addressed using permutation or Monte Carlo simulation approaches. We aimed to provide simpler alternatives to the max‐test to make it feasible in large‐scale association studies. Our simulations show that this procedure has an effective number of tests of 2.2, which can be used to correct the significance level or P‐values. We also derive the asymptotic distribution of max‐statistic, which leads to a simple way to calculate the significance level and allows the derivation of a formula for power calculations in the design of studies that plan to use the max‐statistic. A simulation study shows that the use of the max‐statistic is a powerful approach that provides safeguard against model uncertainty. Genet. Epidemiol. 2008 Wiley‐Liss, Inc.

Genetic polymorphism of glutathione S-transferase P1 gene and lung cancer risk.

Objectives: The human GSTTP1 gene is polymorphic with an A → G transition in exon 5 causing a replacement 105 Ile→Val in the GSTP1 protein. The two isoforms, encoded by the alleles GSTP1*A and GSTP1*B, respectively, show different catalytic efficiencies towards some carcinogenic epoxides. In this study we have addressed the possible role of the Ile105Val GSTP1 polymorphism in lung cancer susceptibility.Methods: The polymorphic site was genotyped by RFLP in a group of lung cancer patients (n=164) and in two control groups (healthy smokers, n=132; general population, n=200). All patients and controls were Northwestern Mediterranean Caucasians of the same ethnic origin.Results and Conclusions: The cancer patients showed frequencies of GSTP1*A/A; GSTP1*A/B and GSTP1*B/B (50%, 38%, 11%, respectively) very similar to those of both control groups (healthy smokers: 48%, 41%, 11%). After adjusting for age, sex and smoking status, no association was found between the GSTP1*B allele and lung cancer risk (OR: 1.18; 95% CI: 0.67–2.07). The Ile105val GSTP1 polymorphism was also analysed in combination with the GSTM1 and GSTT1 genes. The results showed that allelism at GSTP1 did not increase the risk associated with the GSTM1 or GSTT1 deletions.

Effects of cigarette smoke on endothelial function of pulmonary arteries in the guinea pig

BackgroundCigarette smoking may contribute to pulmonary hypertension in chronic obstructive pulmonary disease by altering the structure and function of pulmonary vessels at early disease stages. The objectives of this study were to evaluate the effects of long-term exposure to cigarette smoke on endothelial function and smooth muscle-cell proliferation in pulmonary arteries of guinea pigs.Methods19 male Hartley guinea pigs were exposed to the smoke of 7 cigarettes/day, 5 days/week, for 3 and 6 months. 17 control guinea pigs were sham-exposed for the same periods. Endothelial function was evaluated in rings of pulmonary artery and aorta as the relaxation induced by ADP. The proliferation of smooth muscle cells and their phenotype in small pulmonary vessels were evaluated by immunohistochemical expression of α-actin and desmin. Vessel wall thickness, arteriolar muscularization and emphysema were assessed morphometrically. The expression of endothelial nitric oxide synthase (eNOS) was evaluated by Real Time-PCR.ResultsExposure to cigarette smoke reduced endothelium-dependent vasodilatation in pulmonary arteries (ANOVA p < 0.05) but not in the aorta. Endothelial dysfunction was apparent at 3 months of exposure and did not increase further after 6 months of exposure. Smoke-exposed animals showed proliferation of poorly differentiated smooth muscle cells in small vessels (p < 0.05) after 3 months of exposure. Prolonged exposure resulted in full muscularization of small pulmonary vessels (p < 0.05), wall thickening (p < 0.01) and increased contractility of the main pulmonary artery (p < 0.05), and enlargement of the alveolar spaces. Lung expression of eNOS was decreased in animals exposed to cigarette smoke.ConclusionIn the guinea pig, exposure to cigarette smoke induces selective endothelial dysfunction in pulmonary arteries, smooth muscle cell proliferation in small pulmonary vessels and reduced lung expression of eNOS. These changes appear after 3 months of exposure and precede the development of pulmonary emphysema.

Evaluating associations between Mediterranean diet adherence indexes and biomarkers of diet and disease

OBJECTIVE We examined associations between two Mediterranean diet (MD) adherence indexes (the MD index, MDI, and the MD score, MDS) and several blood biomarkers of diet and disease. SUBJECTS We studied 328 individuals from Catalonia (Northeastern Spain), ages 18-75, who provided fasting blood samples, a subset of the 2346 individuals as part of a larger representative and random sample from the 1992-1993 Catalan Nutritional Survey. DESIGN AND METHOD Diet was measured using 24-h recalls. Biomarkers studied were plasma levels of beta-carotene, alpha-tocopherol, retinol, vitamins B12, C and folates as well as serum total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides. Multivariate linear regression was used to analyse associations of the nutrient biomarkers with the dietary pattern indexes, adjusting for potential confounders. RESULTS AND CONCLUSIONS Subjects with higher MD adherence, as measured by the two dietary indexes, had significantly higher plasma concentrations of beta-carotene, folates, vitamin C, alpha-tocopherol and HDL cholesterol. The most highly significant relationship was that between folates and the adherence to the MD Pattern, as determined by both indexes. These research findings suggest the potential usefulness of biomarkers as complementary tools for assessing adherence to a dietary pattern. This type of data not only informs the development of robust dietary adherence indexes, but it also provides specific clues about the potential physiological mechanisms that explain the beneficial effects of the MD pattern on chronic disease risk.

The Mediterranean diet in Spain: adherence trends during the past two decades using the Mediterranean Adequacy Index

OBJECTIVE The purpose of the present study was to analyse the evolution of the Spanish populations global and regional adherence to the Mediterranean diet (MD) since 1987. DESIGN A cross-sectional study was conducted analysing food consumption from the Spanish Household Consumption Surveys administered by the Spanish Ministry of Agriculture, Fisheries and Food. SETTING The Mediterranean Adequacy Index (MAI) was applied to measure the adherence to the MD. The significance of the MAI trend was evaluated using a regression model. SUBJECTS The sample comprises a household consumption data set, which consisted of 2500 households in 1987 and increased to 6200 in 2005. RESULTS There was a significant decrease in the MAI (P=0.001) during the past two decades in Spanish households. From 1987 to 1997, MD adherence significantly decreased, but since 1998 it appears to have stabilised. In recent years, the daily household availability of several of the food components of the MD has increased. The MAI was observed to be significantly higher during the entire period in some Mediterranean regions, such as Andalusia, and significantly lower in more inland regions, such as Castile-Leon. CONCLUSIONS During the past two decades, Spain has experienced a significant downward trend in adherence to the predominant dietary pattern, likely as a result of numerous socio-economic changes. However, a stabilisation and a recent slight recovery have been observed during the past decade.

Estimation of the concordance correlation coefficient for repeated measures using SAS and R

The concordance correlation coefficient is one of the most common approaches used to assess agreement among different observers or instruments when the outcome of interest is a continuous variable. A SAS macro and R package are provided here to estimate the concordance correlation coefficient (CCC) where the design of the data involves repeated measurements by subject and observer. The CCC is estimated using U-statistics (UST) and variance components (VC) approaches. Confidence intervals and standard errors are reported along with the point estimate of the CCC. In the case of the VC approach, the linear mixed model output and variance components estimates are also provided. The performance of each function is shown by means of some examples with real data sets.

The Concordance Correlation Coefficient for Repeated Measures Estimated by Variance Components

The concordance correlation coefficient (CCC) is an index that is commonly used to assess the degree of agreement between observers on measuring a continuous characteristic. Here, a CCC for longitudinal repeated measurements is developed through the appropriate specification of the intraclass correlation coefficient from a variance components linear mixed model. A case example and the results of a simulation study are provided.

Canine cognitive deficit correlates with diffuse plaque maturation and S100β (−) astrocytosis but not with insulin cerebrospinal fluid level

Like humans, canines develop with aging β-amyloid (Aβ) plaques and a progressive cognitive deficit on tasks similar to those used in diagnosis and follow-up of Alzheimer’s disease. Owing to that, dogs are quite unique to investigate the early events taking place in the diffuse Aβ plaque maturation and its relationship with cognitive deficit. The aim of the present investigation was to study the link between the diffuse Aβ plaque maturation and the astro- and microglial reactivity. The involvement of insulin and beta-subunit of S100 protein (S100β) overexpression in the process was also investigated. Aβ plaques were measured and counted in prefrontal cortex of 16 pet dogs of different breeds, weight and sex, classified as control and with a light or severe cognitive deficit. A correlation between canine graded cognitive deficit, diffuse plaque maturation, and S100β (−) astrocytosis, but not with cerebrospinal fluid insulin level, was found that may reflect the very early events of Aβ deposition in Alzheimer’s disease.