Biomedical subjects

Marc Saez

Publications and source records attributed to Marc Saez.

9 recordsLinked to original sources

PubMed2007

A multilevel analysis on the determinants of regional health care expenditure: a note.

Health care in most countries is a rather "local good" for which the fiscal decentralization theory applies and heterogeneity is the result. In order to address the issue of multijurisdictional health care in estimating income elasticity, we constructed a unique sample using data for 110 regions in eight Organisation for Economic Co-operation and Development (OECD) countries in 1997. We estimated this sample data with a multilevel hierarchical model. In doing this, we tried to identify two sources of random variation: within- and between-country variation. The basic purpose was to find out whether the different relationships between health care spending and the explanatory variables are country specific. We concluded that to take into account the degree of fiscal decentralization within countries in estimating income elasticity of health expenditure proves to be important. Two plausible reasons lie behind this: (a) where there is decentralization to the regions, policies aimed at emulating diversity tend to increase national health care expenditure and (b) without fiscal decentralization, central monitoring of finance tends to reduce regional diversity and therefore decrease national health expenditure. The results of our estimation do seem to validate both these points.

Age Factors↗

PubMed2006

Use of primary health care services according to the different degrees of obesity in the Girona Health Region, Spain.

Our main hypothesis in this paper was that, once controlled for age and gender, the use of primary health care services of people in each of the groups defined by their degree of obesity (i.e. normal weight, overweight and obese) did not correspond to the need for care implied by the level of risk of the group he/she belonged to. This fact could reflect some inequity in the utilisation of such services. Using a survey of the general population from the Girona Health Region, Spain, carried out during the fourth quarter of 2002, we have found that: first, the probability of primary health care use decreased with income for GPs (until 1200 Euro) and increased for specialists (from 1500 Euro). Second, we could conclude by confirming our hypothesis, i.e. there was more probability of obese individuals using general practice care, public in particular, and less probability of them using specialists, private in particular, than the rest of individuals. Third, we conclude that the use of multilevel (also hierarchical or mixed) models could explain most of our original findings in this paper.

Adolescent↗

PubMed2006

Assessment of self-monitoring of blood pressure in the diagnosis of isolated clinic hypertension.

BACKGROUND: There are no studies assessing cardiovascular morbidity, morality in patients with isolated clinical hypertension (ICH) with self-blood pressure monitoring (SBPM). OBJECTIVES: To determine the value of SBPM in the diagnosis of ICH. METHODS: Cohort study. New hypertensive and normotensive patients 15-75 years, without cardiovascular events history. VARIABLES: Oriented anamnesis hypertension; blood pressure measurements (BP): clinical BP, SBPM and ambulatory BP monitoring (ABPM); evaluation of target organ damage (TOD); electrocardiogram; retinography and microalbuminuria (MA). RESULTS: One hundred and thirty-five patients, 95 hypertensive (62.1% males; mean age 59.08+/-16.8 years), 40 normotensive (37.5% males; mean are 56.32+/-10.22 years). BP measurements (mmHG) in normotensives vs hypertensives: clinical BP, 125.36/76.74 vs 149.81/87.86 mmHg (p<0.0001) and SPPM, 114.90/69.96 vs 142.06/86.31 (p<0.0001). Twenty-four-hour ABPM: 135.41/81/81.74. Prevalence of TOD in hypertensive: 23.10% left ventricular hypertrophy (LVH), sustained hypertension (SH): clinic BP, 149.88/86.34 vs 152.51/89.55 (p>0.10); SBPM: 147.895/88.95 vs 128.17/79 (p<0.0001) and ABPM, 141.72/88.22 vs 131.66/80 (p=0.053 for systolic). TOD in SH vs ICH: LVH, 24.6% vs 19.2% (p=0.814); exudates or haemorrhages, 7.7% vs 9.8% (p=0.580). The risk of an occurrence of any TOD in ICH patients is lower for 125/80 (OR=2.5). CONCLUSIONS: VAMPAHICA will provide information about value SBPM in the diagnosis of ICH. Advanced retinopathy is relative frequent in ICH patients. If TOD is accepted as a surrogate endpoint, the diagnostic values of ICH will be probably decreased.

Adolescent↗

PubMed2005

Analysis of case-crossover designs using longitudinal approaches: a simulation study.

BACKGROUND: Application of case-crossover designs provides an alternative to time-series analysis for analyzing the health-related effects of air pollution. Although some case-crossover studies can control for trend and seasonality by design, to date they have been analyzed as matched case-control studies. Such analyses may exhibit biases and a lower statistical efficiency than traditional time series analyzed with Poisson. METHODS: In this article, case-crossover studies are treated as cohort studies in which each subject is observed for a short period of time before and/or after the event, thus making possible analyzing with Andersen-Gill and generalized linear mixed models. We conducted a simulation study to compare the behavior of these models applied to case-crossover designs with time series analyzed with Poisson and with case-crossover analyzed by conditional logistic regression. To this end, we created a random variable that follows a Poisson distribution of low (2/day) and high mean events (22/day). This variable is a function of an unobserved confounding variable (that introduces trend and seasonality) and data on small particulate matter (PM10) from Barcelona. In addition, scenarios were created to assess the effect on exposure exerted by autocorrelation and the magnitude of the pollutant coefficient. RESULTS: The full semisymmetric design analyzed with generalized linear mixed models yields good coverage and a high statistical power for air-pollution effect magnitudes close to the real values but shows bias for high effect magnitudes. This bias seems to be attributable to autocorrelation in the exposure variable. CONCLUSIONS: Longitudinal approaches applied to case-crossover designs may prove useful for analyzing the acute effects of environmental exposures.

Air Pollutants↗

PubMed2003

Np.OR: an S-Plus function for pointwise nonparametric estimation of odds-ratios of continuous predictors.

Calculating odds ratios (OR) and corresponding confidence intervals (CI) for exposures that have been measured using a continuous scale, presents important limitations in the traditional practice of epidemiology. Our objective is to describe an S-Plus function, that we called np.OR, that allows the computation of the pointwise estimates of the ORs as well as their corresponding CIs of continuous predictors introduced nonlinearly in a generalised model. The function can also be generalised to compute the pointwise estimates of categorical predictors that were introduced nonlinearly. To illustrate usage of the program we analyse the relationship between ambient temperature and total mortality in Barcelona for the period 1991-1995, while controlling for observed and unobserved confounders.

Confidence Intervals↗

PubMed2002

A combined analysis of the short-term effects of photochemical air pollutants on mortality within the EMECAM project.

In recent years, some epidemiologic studies have attributed adverse effects of air pollutants on health not only to particles and sulfur dioxide but also to photochemical air pollutants (nitrogen dioxide and ozone). The effects are usually small, leading to some inconsistencies in the results of the studies. Furthermore, the different methodologic approaches of the studies used has made it difficult to derive generic conclusions. We provide here a quantitative summary of the short-term effects of photochemical air pollutants on mortality in seven Spanish cities involved in the EMECAM project, using generalized additive models from analyses of single and multiple pollutants. Nitrogen dioxide and ozone data were provided by seven EMECAM cities (Barcelona, Gijón, Huelva, Madrid, Oviedo, Seville, and Valencia). Mortality indicators included daily total mortality from all causes excluding external causes, daily cardiovascular mortality, and daily respiratory mortality. Individual estimates, obtained from city-specific generalized additive Poisson autoregressive models, were combined by means of fixed effects models and, if significant heterogeneity among local estimates was found, also by random effects models. Significant positive associations were found between daily mortality (all causes and cardiovascular) and NO(2), once the rest of air pollutants were taken into account. A 10 microg/m(3) increase in the 24-hr average 1-day NO(2)level was associated with an increase in the daily number of deaths of 0.43% [95% confidence interval (CI), -0.003-0.86%] for all causes excluding external. In the case of significant relationships, relative risks for cause-specific mortality were nearly twice as much as that for total mortality for all the photochemical pollutants. Ozone was independently related only to cardiovascular daily mortality. No independent statistically significant relationship between photochemical air pollutants and respiratory mortality was found. The results in this study suggest that, given the present levels of photochemical pollutants, people living in Spanish cities are exposed to health risks derived from air pollution.

Adolescent↗

PubMedDate not supplied

[The EMECAS Project: Spanish multicentre study on short-term health effects of air pollution].

UNLABELLED: The EMECAM Project demonstrated the short-term effect of air pollution on the death rate in 14 cities in Spain throughout the 1990-1995 period. The Spanish Multicentre Study on Health Effects of Air Pollution (EMECAS) is broadening these objectives by incorporating more recent data, information on hospital disease admissions and totaling 16 Spanish cities. This is an ecological time series study in which the response variables are the daily deaths and the emergency hospitalizations due to circulatory system diseases and respiratory diseases among the residents in each city. Pollutants analyses: suspended particles, SO2, NO2, CO and O3. Control variables: meteorological, calendar, seasonality and influenza trend and incidence. STATISTICAL ANALYSIS: estimate of the association in each city by means of the construction of generalized additive Poisson regression models and metanalysis for obtaining combined estimators. The EMECAS Project began with the creation of three working groups (Exposure, Epidemiology and Analysis Methodology) which defined the protocol. The average levels of pollutants were below those established under the current regulations for sulfur dioxide, carbon monoxide and ozone. The NO2 and PM10 values were around those established under the regulations (40 mg/m3). This is the first study of the relationship between air pollution and disease rate among one group of Spanish cities. The pollution levels studied are moderate for some pollutants, although for others, especially NO2 and particles, these levels could entail a problem with regard to complying with the regulations in force.

Air Pollution↗

PubMedDate not supplied

[Cancer cluster analysis. The case of the Campdorà District in Girona, Spain].

A conglomerate of cases may be defined as the onset of a number of cases of a disease larger than would be expected for a certain population group, geographical area or a certain timeframe. In the case of cancer, the study of conglomerates entails a number of specific characteristics as compared to other groups of diseases. This work is aimed at proposing a protocol affording the possibility of conducting the study of cancer conglomerates in time and/or space. This article is illustrated with a practical application in the case of the Campdorà District in Girona. Following a proposed protocol for the study of conglomerates, a description is provided of several statistical tools making it possible to draw a comparison among the existence of time-related groupings, as well as the related risk. During the period studied (1994-2002), no excessive statistically significant number of cancer cases seemed to have occurred in the Campdorà District in Girona.

Cluster Analysis↗

PubMedDate not supplied

[Research protocol for the mortality atlas of the provincial capitals of Andalusia and Catalonia (AMCAC Project)].

The aim of this work is to make known the multicentric project AMCAC, whose objective is to describe the geographical distribution of mortality from all causes in census groups of the provincial capitals of Andalusia and Catalonia during 1992-2002 and 1994-2000 respectively, and to study the relationship between the sociodemographic characteristics of the census groups and mortality. This is an ecological study in which the analytical unit is the census group. The data correspond to 298,731 individuals (152,913 men and 145,818 women) who died during the study periods in the towns of Almeria, Barcelona, Cadiz, Cordoba, Girona, Granada, Huelva, Jaen, Lleida, Malaga, Seville and Tarragona during the study periods. The dependent variable is the number of deaths observed per census group. The independent variables are the percentage of unemployment, illiteracy and manual workers. Estimation of the moderated relative risk and the study of the associations among the sociodemographic characteristics of the census groups and the mortality will be done for each town and each sex using the Besag-York-Mollie model. Dissemination of the results will help to improve and broaden knowledge about the population's health, and will provide an important starting point to establish the influence of contextual variables on the health of urban populations.

Algorithms↗