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Treatment of hypercholesterolemia at discharge from hospital after acute myocardial infarction in a coronary heart disease low incidence area: Galicia (Northwest of Spain).
Muñiz Javier; Juane Rafael; García Manuel; Virgós A; Vázquez José Manuel; Castro Beiras Alfonso for the RIGA Investigators Group
Asociación de Estudios Biomédicos de Galicia
(BIOMEGA), A Coruña.
Complejo Hospitalario Juan Canalejo - Teresa Herrera, A Coruña.
Instituto Universitario de Ciencias de la Salud, Universidade da Coruña.
Complejo Hospitalario Cristal Piñor, Ourense. Hospital Xeral de Galicia, Santiago.
Objective: To examine adequacy to current recomendations of lipid lowering drug therapy at discharge from hospital among acute myocardial infarction patients (AMI).
Design: Hospital-based registry of AMI patients
Setting: 19 hospitals in Galicia, northwest of Spain.
Patients: 660 discharged AMI patients out of 778 admitted (February 1-July 31, 1995).
Measurements: Percent of discharged patients receiving lipid lowering drug therapy at discharge and percent among those who should be treated (personal history of lipid lowering drug therapy and/or total cholesterol > 220 mg/dl at this admission). Logistic regression of treatment at discharge.
Results: 13.2% of males and 6.3% of females (95% confidence interval of the difference=1.7-12.1) are discharged from hospital with lipid lowering drug treatment. 16.1% of patients below 70 years old and 4.8% of those 70+ (6.5-16.1) were treated. Among those meeting treatment criteria, 26.5% of males, 11.9% of females (0.3-28.9), 27% of patients under 70 and 12.5% of 70+ (0.5-28.5) are treated at discharge. There is a greater absolute number of patients treated who did not meet the criteria than that of patients who did in any age and sex group. Univariate analysis: being a male, smoker, previous lipid lowering drug treatment and total cholesterol levels above 220 mg/dl at this admission are directly and age inversely related to the odds of receiving treatment at discharge. Multivariate analysis: previous lipid lowering drug treatment and total cholesterol levels above 220 mg/dl at this admission are associated with an increased likelihood receiving treatment and age with a decreased likelihood.
Conclusions: Improvements can be made in the treatment of cholesterol levels at discharge after AMI. There is an undesirable dissociation between scientific evidence and clinical practice.
Introduction: It has been proven repeatedly that reducing serum cholesterol in persons with coronary heart disease reduces morbility and mortality.
Despite the consistency of these evidences, little information is available on to what extent lipid lowering drug therapy is incorporated into the clinical practice, particularly at the time of discharge from the hospital, the first and very important opportunity of secondary prevention in those who have suffered a myocardial infarction. Information is even more scarce when considering countries with low incidence of coronary heart disease, like Spain3, where practicing physicians may be less motivated to treat.
This study investigates to what extent patients in Galicia who have suffered an AMI and should be treated with lipid lowering drugs under current criteria, are actually being treated.
Methods: It is based on data from the RIGA study (Registry of Infarctions in Galicia), a hospital-based registry of AMI hospitalizations in Galicia, established to specifically monitor in-hospital treatment and procedures undergone by AMI patients, as well as their short term prognosis.
778 patients admitted to any of the 19 participating hospitals in Galicia (an autonomous community in the northwest of Spain, Figure 1) and table 1 between February 1st and July 31st, 1995, with confirmed AMI who survived the first hours in the emergency room were included. No intervention of any kind regarding appropriate management of these patients was done prior to or during the period of field work.
In this study, a patient falls into the category of "should be treated" if he/she meets at least one of the following criteria: personal history of hypercholesterolemia with drug treatment and/or a total serum cholesterol level (determined in the first 24 hours of the AMI) above 220 mg/dl. This figure was selected because the 4-S reported that cholesterol lowering in coronary patients with a concentration of ³ 5.5 mmol/l (213 mg/dl) by diet and simvastatin reduced coronary morbidity and mortality and improved survival7.
Point prevalence and 95% confidence intervals are presented where applicable.
Univariate and multivariate logistic regression with computation of the odds ratio of being treated at discharge depending on a selection of characteristics, as well as 95% confidence intervals of the odds ratio, have been done. The logistic regression method used has been stepwise forward. The statistical package used has been SPSS 6.1.3 for Windows.
Results: Galicia is an autonomous community in the northwest of Spain with a population of 2,700,000 habitants. Access to all levels of medical healthcare has been made extensive to include practically the entire population. The medical centers provide over 5,000 hospital beds, 75% of which are public and 25% private. There are three public hospitals and one private that have hemodynamics laboratories and cardiac surgery. There is a very active cardiac transplantation program (around 40 transplantations per year) in one of the public hospitals mentioned.
There is a wide variation among the 19 participating centers in the number of AMI attended per year. 26 centers were invited to participate in the study, 25 of which accepted the invitation, and 19 of these sent data on a regular basis. Only one center regularly attending AMIs refused to participate. The remainder non participating centers was made up of hospitals that attended very few AMIs (less than 5 in each case during the study period). The 778 patients came from 193 different municipalities out of the 315 existing in Galicia.
Table 2, Table 3 and Table 4 show general characteristics of the population, personal history and some details of this infarction and how it was treated.
The data on "appropriateness of lipid lowering therapy (tables 5 and 6) are based in 660 patients (550 men and 160 women.
Discussion: The sample group studied here had certain characteristics in common with other groups studied. The delay of onset of AMI among females compared to males is one. In this study, females are 10 years older on average than males. This difference is greater than that observed in countries with higher AMI incidence rates3 , like USA4 and Great Britain5, where the difference between genders is around 6 years, but very similar to what it is observed in closer countries (in terms of AMI incidence) like France6. These 10 years of delay appear also in CHD mortality statistics in Spain7. Data from "distant" countries may not, therefore, be applicable to our reality.
No differences were observed when referring to patients with a personal history of hypercholesterolemia, with or without drug treatment. In more than 70% of patients, CHD was diagnosed upon admission to the hospital, with no differences between genders.
Women are less likely to receive thrombolysis, partly due to their delay in reaching the hospital as compared to men and partly due to their age.
In-hospital mortality among females almost doubles male mortality. Again, when age is considered, female sex is no longer a deleterious condition.
Serum cholesterol levels in the first 24 hours of evolution are determined in less than half the AMI patients that are admitted to the hospital. This, together with the very little proportion of patients on lipid lowering therapy prior to this event, in whom there is clear justification to continue the treatment, results in that in half the number of patients we do not have judgement elements to establish lipid lowering drug therapy at discharge. Although the two post-miocardial infarction studies that have demonstrated benefits of lowering cholesterol were initiated several months after discharge (4-S1 six months and CARE2 three months), current guidelines suggest that aggressive cholesterol management should be started as soon as the diagnosis of clinical atherosclerotic disease is established4. The "tracking" effect of hospital treatments at discharge on later treatments, probably very variable between countries and diseases, appears to be strong in our case, with very few patients having their treatments changed by their primary care physicians after discharge, what it is an additional reason to start treatment at discharge.
As expected, the percent of patients under treatment among those who meet the criteria to be treated is higher than among those who do not meet those criteria, but the absolute number of patients treated who do not meet the criteria is higher than that of patients treated and meet the criteria (Table 5). This is true for both genders and age groups (<70 and ³ 70 years old). These data indicate that an intervention of unproved efficacy had, to a certain extent, already been incorporated into the clinical practice.
Nearly one out of every nine AMI patients are discharged from the hospital and put on lipid lowering drug therapy. Huge differences between genders and age groups are observed, but when both variables are considered simultaneously in estimating the odds of receiving this type of pharmacological treatment when patients are discharged, differences between genders disappear. Again, age is a confounding factor of the observed relationship.
Information from other countries concernig this topic is scarce. In a recent survey in Great Britain9, where the estimates for AMI treatment are based in 249 males and 240 females, only 6% of males and 10% of females receive lipid lowering drugs six months after the event. This survey was done prior to the 4-S. The only other close reference available, to the best of our knowledge, appears in a very recent guidelines from the American Heart Association8, where it is stated that up to two thirds of the patients with clinical manifestations of atherosclerosis receive no therapy to lower LDL cholesterol levels. This relevant assertion is based on unpublished data of 1995 from the National Heart, Lung and Blood Institute, what emphasize the scarcity of data available. In other study done in Spain10 prior to the 4-S publication and to our study, 6,7% of patients discharged with AMI are in drug treatment for hypercholesterolemia when learing the hospital
Conclusions: The results of this study show that there is a wide margin of improvement in the treatment of serum cholesterol levels at discharge from hospital after an AMI. It suggests that, in this topic, there is an undesirable dissociation between scientific evidence and clinical practice. Although in this particular case it may have resulted in a benefit to the "overtreated" (under current information available), this may not be the case in other diseases and/or treatments. Improvement in diagnosis is also needed and can be easily done introducing a routine serum cholesterol (and fractions) determination at the moment of admission for acute myocardial infarction.
This study has been possible through an investigation contract with MSD España
1.- Scandinavian Simvastatin Survival Study Group. Randomized trial of cholesterol-lowering in 4444 patients with coronary heart disease: The Scandinavian Simvastatin Survival Study (4S). Lancet 1994;344:1383-1389.2.- Sacks FM, Pfeffer MA, Moye LA, Rouleau JL, Rutherford JD, Cole TG, et al. The effect of pravastatin on coronary events after myocardial infarction in patients with average cholesterol levels. N Engl J Med 1996;335:1001-1009. 3.- Tunstall-Pedoe H, Kuulasmaa K, Amouyel P, Arveiler D, Rajakangas AM, Pajak A. Myocardial infarction and coronary deaths in the World Health Organization MONICA Project. Registration procedures, event rates, and case-fatality rates in 38 populations from 21 countries in four continents. Circulation 1994;90:583-612. 4.- Rogers WJ, Bowlbly LJ, Chandra NC, French Wj, Gore JM, Lambrew CT et al. for the participants in the National Registry of Myocardial Infarction, treatment of myocardial infarction in the United States (1990 to 1993). Circulation 1994;90:2103-2114.
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