Gema Vega

Variabilidad en el manejo hospitalario del infarto agudo de miocardio en España. Estudio IBERICA (Investigación, Búsqueda Específica y Registro de Isquemia Coronaria Aguda)*

Introduccion y objetivos Los datos sobre el manejo de los pacientes con infarto agudo de miocardio (IAM) que llegan a un hospital en Espana no garantizan la exhaustividad en el registro. El objetivo de este trabajo es conocer las caracteristicas y el manejo de los pacientes con IAM que llegan a todos los hospitales de distintas areas de 8 comunidades autonomas espanolas. Metodos El estudio IBERICA es un registro poblacional de IAM entre 25 y 74 anos de edad realizado en ocho comunidades autonomas espanolas. Para este trabajo se incluyeron los casos de IAM que llegaron vivos al hospital durante 1997. Se recogen las caracteristicas, tratamiento y evolucion a los 28 dias del episodio. Se realizo un analisis descriptivo y se calculo el coeficiente de variacion. Resultados Se registraron 4.041 casos de IAM: el 79,9% eran varones y la edad media fue de 61,1 anos. El 10,9% (IC del 95%: 9,9-11,9%) no ingresaron en una unidad de cuidados intensivos cardiologicos, existiendo una gran variabilidad entre las zonas (coeficiente de variacion del 53%). Existe tambien una gran variabilidad en la realizacion e indicacion de tecnicas diagnosticas y terapeuticas invasivas y no invasivas, asi como en el tratamiento farmacologico empleado: unicamente la utilizacion de antiagregantes (91,5%) y trombolisis (41,8%) presenta un coeficiente de variacion Conclusion Las caracteristicas de los pacientes varian entre las zonas estudiadas. Las diferencias geograficas en el manejo y pronostico sugieren que puede existir desigualdades en la atencion al enfermo con IAM en Espana.

Regional variability in population acute myocardial infarction cumulative incidence and mortality rates in Spain 1997 and 1998

Background: Myocardial infarction (MI) incidence and mortality display a high geographic variation. Aims: The objective of the present study was to analyze MI mortality, cumulative incidence rate variability in seven regions of Spain from 1997 to 1998. Methods and Results: Standardized methods were used to identify, find, register, and classify MI cases that were classified as definite, possible,insufficient-dataMI, and non-MI. The total population of the seven monitored regions was 7,364,682 inhabitants. Of the 11,256 cases fulfilling eligibility criteria to investigate, 10,660 were selected to calculate MI rates: 6554 (61.5%)non-fatal definite MI, 1179 (11.1%)fatal definite MI, 1859 (17.4%)fatal possible MI, 1068 (10.0%)fatal cases with insufficient data. The IBERICA 25–74 years age-standardized cumulative incidence rates for men and women, were 207 (range: 175–252) and 45 (range: 36–65) per 100,000, respectively. The age-standardized mortality rates for men and women, were 73 (range: 62–94) and 20 (range: 13–29) per 100,000, respectively. Age-standardized case-fatality was 31.4 and 24.2% in men aged 25–74 and 35–64 years, respectively, and 32.7 and 27.0%, respectively, in women. Conclusions: MI cumulative incidence and mortality rates are low compared with other industrialized countries but, vary considerably among regions in a Mediterranean country like Spain.

Recursos hospitalarios y letalidad por infarto de miocardio. Estudio IBERICA

Determinar el porcentaje depacientes con infarto agudo de miocardio (IAM) que noingresan en una unidad de cuidados intensivos corona-rios (UCIC), las variables asociadas al ingreso en unaUCIC y si el ingreso en una UCIC, su disponibilidad y lade hemodinamica en el hospital se asocian a la letalidada 28 dias.

Hospital resources and myocardial infarction case fatality. The IBERICA study

INTRODUCTION AND OBJECTIVES To determine the proportion of patients with myocardial infarction (MI) not admitted to a coronary care unit (CCU), the variables associated with admission into a CCU, and whether admission to a CCU, and the availability of coronary angiography in the same hospital, were associated with 28-day case fatality. PATIENTS AND METHOD Population-based registry of MI in patients 25 to 74 years of age, admitted during 1996-1998. Demographic and clinical characteristics were recorded, as well as management, clinical course and survival after 28 days. Hospitals were classified according to the availability of a CCU and catheterization laboratory (advanced hospital), CCU only (intermediate hospital) or neither (basic hospital). Admission to the CCU was also recorded. RESULTS In all, 9046 cases of MI were recorded; in 11.3% the patient was not admitted to a CCU. Age, smoking (OR=1.33; 95% CI, 1.08-1.64), non-Q MI (OR=0.62; 95% CI, 0.49-0.78) or undetermined location of MI (OR=0.34; 95% CI, 0.23-0.50), Killip 4 score on admission (OR=0.63; 95% CI, 0.40-1.00) and delay in arrival at the hospital >6 h were associated with CCU admission. Patients admitted to a CCU showed a lower case fatality in the first 24 h (4.2% vs 23.5%), which was independent of comorbidity, severity and treatment. The 24-hour survivors admitted to a basic hospital had higher case fatality (17.3% vs 7.8%) than other groups, which was related to differences in treatment. CONCLUSIONS CCU admission is associated with a lower case fatality in the first 24 h. Admission to a basic hospital is associated with a higher 28-day case fatality even in patients who survive 24 h.

Smoking and myocardial infarction case-fatality: hospital and population approach

Background Smoking is a risk factor for coronary heart disease, but it has been associated with better short-term prognosis in hospitalized patients with acute myocardial infarction. The aims of this study were to determine the association between smoking and myocardial infarction 28-day case-fatality in hospitalized patients and at the population level; and, whether smokers presenting with fatal myocardial infarction are more likely to die before reaching a hospital. Design and methods Population-based myocardial infarction registry, carried out in 1997-1998 in seven regions of Spain, used standardized methods to find and analyze suspected myocardial infarction patients (10 654 patients; 7796 hospitalized). Four categories of smoking status were defined: never-smokers, former smokers for more than 1 year, former smokers for less than 1 year, and current smokers. Results The main end-point was 28-day case-fatality, found to be 20.1, 17.1, 15.6, and 8.9%, in the four smoking status categories, respectively, for hospitalized patients; and 37.4, 33.0, 24.5, and 23.2%, respectively, at population level. Hospitalized current smokers had lower age, sex, and comorbidity-adjusted 28-day case-fatality than never-smokers (odds ratio = 0.71; 95% confidence interval: 0.56-0.90). This association held at population level (odds ratio = 0.68; 95% confidence interval: 0.60-0.76), in which former smoking was also associated with lower case-fatality. In fatal cases, recent former smokers presented a lower risk of out-of-hospital death than never-smokers (odds ratio = 0.47; 95% confidence interval: 0.29-0.77), whereas current smoking was marginally associated with out-of-hospital death (odds ratio = 1.22; 95% confidence interval: 0.99-1.50). Conclusions Current smoking is associated with lower 28-day case-fatality in hospitalized myocardial infarction patients. This association held at population level. Among fatal cases, smoking is associated with higher and recent former smoking with lower risk of dying out-of-hospital.

Dose-response association of physical activity with acute myocardial infarction: Do amount and intensity matter?

OBJECTIVE The aims of this study were to analyze the dose-response association between leisure time physical activity (PA) practice and myocardial infarction (MI), considering not only the total amount but also the amount of PA at different levels of intensity, and to determine whether these associations were modified by age. METHOD In a population-based age- and sex-matched case-control study, all first acute MI patients aged 25 to 74 years were prospectively registered in four Spanish hospitals between 2002 and 2004. Controls were randomly selected from population-based samples recruited during the same period of time. The Minnesota PA questionnaire was administered to assess total energy expenditure in PA and in light-, moderate-, and high-intensity PA. RESULTS Finally, 1339 cases and 1339 controls were included. The association between PA and MI likelihood was non-linear, with significantly lower MI odds at low practice levels (≥ 500 MET·min/week), lowest odds around 1500 MET·min/week, and a plateau thereafter. Light- (in subjects older than 64 years), moderate-, and high-intensity PA produced similar benefits. CONCLUSION Most of the population could reduce their likelihood of MI by engaging in PA at a moderate level of intensity or, in individuals older than 64 years, at a light level of intensity.

Association Between Paraoxonase-1 and Paraoxonase-2 Polymorphisms and the Risk of Acute Myocardial Infarction

INTRODUCTION AND OBJECTIVES Two particular polymorphisms, namely PON1-192 and PON2-311, in the genes encoding the antioxidant enzymes paraoxonase-1 (PON1) and paraoxonase-2 (PON2) have been associated with an increased risk of acute myocardial infarction (AMI). However, previous findings have been contradictory. The aim of this study was to investigate the association between the PON1-192 and PON2-311 polymorphisms and their interaction on AMI risk. METHODS This case-control study involved 746 consecutive AMI patients and 1796 control subjects without cardiovascular disease, who were randomly selected from the same population from which the patients came. All participants were recruited between 1999 and 2000 from four Spanish autonomous regions. All were assessed for the presence of PON1-192 and PON2-311 and for classical cardiovascular risk factors. Multivariate analysis was carried out using logistic regression modeling. RESULTS The odds ratios (OR) of AMI for patients with the PON1-192 QQ and PON2-311 SS genotypes (who comprised 50% and 66% of the population, respectively) were 1.26 (95% confidence interval [CI], 1.02-1.55) and 1.25 (95% CI, 1.04-1.50), respectively, compared with R and C allele carriers. Moreover, in patients with both QQ and SS genotypes, the adjusted OR of AMI increased to 1.41 (95% CI, 1.13-1.76). CONCLUSIONS Our results indicate that the PON1-192 and PON2-311 polymorphisms were independent risk factors of AMI in our population.

Análisis de la asociación entre un tratamiento y un acontecimiento de interés en estudios observacionales utilizando la probabilidad de recibir el tratamiento (Propensity Score). Un ejemplo con la reperfusión miocárdica

Introduccion y objetivos. Determinar el efecto de un tratamiento en estudios observacionales es problematico por las diferencias existentes entre tratados y no tratados. Un metodo propuesto para controlar estas diferencias es calcular la probabilidad condicionada por covariables de recibir el tratamiento, Propensity Score (PS). Presentamos una aplicacion de este metodo analizando la asociacion entre reperfusion y letalidad a 28 dias en pacientes con infarto agudo de miocardio (IAM). Metodo. Se presenta como calcular la PS de recibir reperfusion y las diferentes estrategias para analizar posteriormente su asociacion con la letalidad mediante modelos de regresion y apareamiento. Utilizamos datos de un registro poblacional de IAM realizado en Espana entre 1997 y 1998 que incluyo 6.307 IAM. Resultados. Se calculo la PS de reperfusion en 5.622 pacientes. En el analisis multivariado la reperfusion se asocio con menor letalidad (odds ratio [OR] = 0,59; intervalo de confianza [IC] del 95%, 0,46-0,77); al ajustar ademas por la PS de reperfusion esta asociacion no fue significativa (OR = 0,76; IC del 95%, 0,57-1,01). En el subgrupo de pacientes apareados, tratados y no tratados con PS de reperfusion similar (n = 3.138), este tratamiento no se asocio con letalidad (OR = 0,95; IC del 95%, 0,72-1,26). Controlando el impacto de los casos con datos insuficientes en la PS de reperfusion, esta se asocio con menor letalidad (OR = 0,66; IC del 95%, 0,55-0,80). Conclusiones. El calculo de la PS es un metodo para controlar las diferencias entre los grupos tratado y no tratado. Tiene limitaciones cuando el apareamiento es incompleto o hay datos insuficientes en la PS calculada. Los resultados del ejemplo presentado indican que la reperfusion reduce la letalidad del IAM.

Asociación de los polimorfismos de la paraoxonasa 1 y la paraoxonasa 2 con el riesgo de infarto agudo de miocardio

Introduccion y objetivos La paraoxonasa 1 (PON1) y la paraoxonasa 2 (PON2) son enzimas antioxidantes cuyos polimorfismos PON1-192 y PON2-311 se han relacionado con el riesgo de infarto agudo de miocardio, con resultados discordantes. El objetivo de este estudio es determinar la asociacion con el riesgo de infarto agudo de miocardio (IAM) de los polimorfismos PON1-192 y PON2-311 y su interaccion. Metodos Se realizo un estudio de casos y controles en el que se recluto a 746 pacientes consecutivos con IAM y 1.796 controles libres de enfermedad cardiovascular seleccionados al azar de la misma poblacion de la que provenian los casos, en 4 comunidades autonomas espanolas entre 1999 y 2000. Se determinaron los polimorfismos PON1-192 y PON2-311, ademas de los factores clasicos de riesgo cardiovascular. Se estimaron modelos de regresion logistica para los analisis multivaribles. Resultados Las odds ratio (OR) del genotipo QQ del polimorfismo PON1-192 y el SS del PON2-311 (presen-tes en el 50 y el 66% de la poblacion, respectivamente) de presentar un IAM fueron 1,26 (intervalo de confianza [IC] del 95%, 1,02-1,55) y 1,25 (IC del 95%, 1,04-1,50), respectivamente, en comparacion con los portadores de los alelos R y C. Ademas, para los sujetos que presentan ambos genotipos QQ y SS, la OR ajustada de tener un IAM se incremento hasta 1,41 (IC del 95%, 1,13-1,76). Conclusiones Nuestros resultados indican que los polimorfismos PON1-192 y PON2-311 son factores de riesgo de IAM independientes en nuestra poblacion.

Analysis with the propensity score of the association between likelihood of treatment and event of interest in observational studies. An example with myocardial reperfusion

INTRODUCTION AND OBJECTIVES Analysis of the effect of treatment in observational studies is complex due to differences between treated and nontreated patients. Calculating the probability of receiving treatment conditioned on relevant covariates (propensity score [PS]) has been proposed as a method to control for these differences. We report an application of PS to assess the association between reperfusion treatment and 28-day case fatality in patients with acute myocardial infarction (AMI). METHOD We describe the procedure used to calculate PS for receiving reperfusion treatment, and different strategies to analyze the association between PS and case fatality with regression modeling and matching. Data were from a population-based registry of 6307 patients with AMI in Spain during 1997-98. RESULTS The PS for reperfusion was calculated in 5622 patients. In the multivariate analysis, reperfusion was associated with lower case fatality (OR = 0.59; 95% confidence interval [95% CI]: 0.46-0.77). When PS was included as a covariate, this association became non- significant (OR = 0.76; 95% CI: 0.57-1.01). In the subgroup of matched patients with a similar PS (n = 3138), treatment was not associated with case fatality (OR = 0.95; 95% CI: 0.72-1.26). When the influence of cases with missing data on PS was controlled for, reperfusion treatment was associated with lower fatality (OR = 0.66; 95% CI: 0.55-0.80). CONCLUSIONS Calculating propensity score is a method that controls for differences between treated and nontreated patients. This score has limitations when matching is incomplete and when data are missing. Results of the present example suggest that reperfusion treatment reduces AMI case fatality.