June 20, 2008
Non-Cardiac Arterial Disease in Catalonia
By Castellote, M A Cairols Batalla, S Riera; De Mercado, P Lazaro Y; Conesa, M D Aguilar
Aim. Non-cardiac arterial disease (NCAD) is a frequent cause of hospital admission. The aim of this study was to investigate differences in patient profiles and clinical records as a function of the size of the Vascular Surgery Unit (VSU). Methods. Retrospective observational study. Stratified cluster sampling and selection of patients hospitalized for NCAD. Analysis: 1 ) description of patient profiles, quality of clinical records, and VSU [availability of diagnostic (DR) and therapeutic (TR) resources, and of written protocols (WP)]; 2) association between these variables and size of VSU.
Results. The sample consisted of 14 hospitals, 6 with a VSU of 15 or fewer beds (VSU 15 beds (VSU > 15B). The mean number of DRs, TRs and WPs was 9, 2.8 and 2 in VSUs 15B. The proportion of patients older than 70, female, with ischemic disease, or with coexisting diabetes was significantly higher in VSUs 15B (58%, 22%, 69% and 48%). Comorbid conditions and treatment during admission and at discharge were documented significantly less frequently in the clinical records in VSUs
Conclusion. Patient profiles and the quality of clinical records vary by size of VSU. Under-reporting of risk factors may hinder the implementation of prevention and treatment measures.
[Int Angiol 2008;27:124-34]
Key words: Peripheral vascular diseases - Quality of health care - Hospital records - Spain.
The term non-cardiac arterial disease (NCAD) includes a number of different pathologies such as transient ischemic attack (TIA)1 stroke, aneurysm, and peripheral arterial disease (PAD). All these conditions are highly prevalent, share the same risk factors, and relatively frequently require surgical procedures such as endarterectomy, embolectomy, bypass, endovascular techniques or amputation.
PAD, defined as an obstruction of blood flow in the arterial tree, is the most prevalent non-cardiac arterial pathology at the hospital level. Population studies in the United States and Europe indicate a PAD prevalence of around 4% in persons over 40 years of age, and 13-14% in those over 60, although prevalences of 20% have been published in the latter group, depending on the definition used and type of population studied.1-4 The prevalence of risk factors associated with PAD is also very high.5, 6 If these data are extrapolated to Spain, with a population of nearly 9.7 million persons aged 60 or older in 2006,7 over 1.4 million persons in this age group are estimated to suffer from PAD.
The Guidelines for the Management of Patients with PAD developed by the ACC/AHA Task Force define the various diagnostic and therapeutic options for PAD as a function of different criteria.8 The TransAtlantic Inter-Societal Consensus (TASC) guidelines contain a new classification system for treatment of PAD.9 In general, the treatment objectives are to halt the progression of systemic arteriosclerotic disease, avoid clinical cardiovascular events, prevent limb loss in the case of PAD, and improve patients' functional capacity. Consequently, treatment should cover three areas: risk factor modification (stopping smoking and controlling hyperlipidemia, diabetes and arterial hypertension), secondary prevention measures (platelet inhibitors such as aspirin and clopidogrel to prevent clinical cardiovascular events), and treatment of symptoms (physical exercise and drugs such as cilostazol). At more advanced stages of the disease process, it may be necessary to resort to revascularization techniques, preferably bypass or stent implantation.
Lifestyle and risk factor modification, early diagnosis and initiation of 'best medical treatment', together with referral to a vascular specialist when indicated, can result in improved cardiovascular function and increased exercise tolerance, allowing the patient to maintain the ability to walk-necessary to carry out the activities of daily living-and to preserve quality of life and functional capacity. Moreover, these interventions may reduce the rate of amputations.10, 11
All these reasons explain why good management of NCAD depends in large measure on the availability of structural resources and of specialists with specific training in this disease. Variability in the availability of these two types of resources may produce variability in patient management and, consequently, different results depending on the hospital where the patient is treated.
The problem of variability in clinical practice has been widely debated in recent years. Variability has been described among countries, regions, centers and even physicians for reasons related with patient and physician characteristics, the distribution of morbidity, and the quality of scientific evidence underlying decision making.12 One source of variability closely related with all the foregoing is the lack of, or failure to follow, clinical protocols or practice guidelines. In this regard, the results of the Spanish Atherothrombosis Diagnosis and Action (ADA) study have shown the need for adequate protocols for the diagnosis and treatment of patients at risk of clinical manifestations of atherothrombosis.13 The relation between hospital characteristics and the outcome of a particular medical procedure has been the object of numerous studies, with inconsistent results. Some studies have shown an association between the size of the center and clinical outcomes,14- 16 whereas others have not confirmed these findings.17, 18 The differences between centers could be due, among other reasons, to unequal availability of diagnostic or therapeutic measures, different complexity of the patients treated, or the quality of the patient's clinical record.
Knowledge of the sources of variability is fundamental to be able to diminish its potentially harmful effect on health and the quality of care. This study aimed to investigate differences in patient profiles and the quality of clinical records as a function of hospital characteristics which may be sources of variability in the hospital management of NCAD. The two main objectives were: 1) to study the profile of patients hospitalized for NCAD in hospitals in Catalonia, and 2) to evaluate possible differences in the quality of the clinical records of these patients as a function of the size of the Vascular Surgery Unit (VSU).
Materials and methods
This was a retrospective, multicenter, observational study of patients hospitalized for NCAD in public hospitals in Catalonia, a region comprising 4 provinces in North-Eastern Spain. The inclusion criteria were: admission for NCAD in any of the selected hospitals in the months before January 2004, and age 18 or older. Stratified cluster sampling was carried out, with random selection proportional to the size of the stratum. The clusters consisted of hospitals included in the public health network of Catalonia (even if privately owned), which were grouped into 16 strata: by health region (all 8 existing regions) and by number of beds in the VSU [15 or fewer beds (VSU 15 beds (VSU >15B)]. Hospitals with <150 beds were not included in the target population, because they do not perform the vascular surgery procedures considered in this study. Within each stratum one hospital was randomly selected for about each 4 hospitals. In the end, 14 VSUs were selected (6 with 15B) since two strata were empty. In each center, the last 40 patients who met the inclusion criteria and who had been admitted before January 2004 were selected. The sample size (240 patients in VSUs 15B) was calculated to permit detection of differences of at least 10% in the study variables between the two types of VSU.
Clinical record data and data on each center's infrastructure and equipment were used. The patient variables were: age, gender, ischemic dis ease (location: suprainguinal, infrainguinal, upper limbs; type: chronic, acute; and severity: no symptoms, claudication, or critical limb ischemia); stroke or TIA (location: carotid, vertebral; aneurysm (location: abdominal aorta, suprarenal, infra-renal, other); and diameter (>5 cm, /=30 kg/m^sup 2^; hypertension:20 SBP >/=140 mmHg or DBP >90 mmHg; diabetes:2' baseline glycemia >/=126 mg/dL; hyperlipidemia:22 cholesterol: high risk >/=240 mg/dL; moderate risk >/=2000 -239 mg/ dL; HDL: high risk <35 mg/dL; moderate risk >/=35-<45 mg/dL; LDL: high risk >/=160 mg/dL; moderate risk >/=130-159 mg/dL; triglycerides: high risk >200 mg/dL; moderate risk >/=150-200 mg/ dL. The variables related with the centers were hospital characteristics: number of beds (<300; >/=300), ownership (public, private), undergraduate teaching center (yes/no), and post-graduate teaching center (yes/no); VSU characteristics: number of beds ( 15), teaching center [residents (yes/no)], number of vascular surgeons, availability of diagnostic tools (treadmill, duplex, transcranial Doppler, conventional angiography, digital arc in the operating theatre, computed tomography-scan, magnetic resonance angiography), availability of written protocols, and availability of therapeutic resources (conventional and endovascular surgery, day hospital, Intensive Care Unit, postsurgical reanimation unit, other). Data collection
Data were collected by physicians working in the VSUs, who received specific training for this study. A pilot study was carried out with 30 cases to evaluate the reliability of the data collection questionnaire and inter-observer consistency.
A descriptive study was made of patient variables, hospital and VSU characteristics, and documentation of relevant parameters in the clinical records. For the descriptive study, we used measures of central tendency (mean and standard deviation) in the case of quantitative variables, and proportions in the case of qualitative variables. We also studied the association between VSU size and the documentation of these parameters in the clinical records, and between VSU size and patient characteristics, using techniques of bivariate association (chi^sup 2^ and Students t-test for independent data) and multivariate association (logistic regression).
The final sample included 545 patients, which represented 95% of the projected initial sample. The results of the pilot study showed good reliability for the data collection questionnaire and high inter-observer consistency (>90%).
Most participating hospitals were publicly owned (12/14) and had >300 beds (8/14) (Table I). Eleven were undergraduate teaching centers and 12 were postgraduate. About 1/3 of the VSUs (5/14) had residents in Angiology and Vascular Surgery, and all of these units had >15 beds. Eight hospitals had >15 beds in the VSU, and the other 6 had 15 or fewer. Most hospitals (12/14) had at least 10 of the 12 diagnostic devices considered, and 10 hospitals had at least 4 of the 7 therapeutic resources studied. Six VSUs had no written protocols, 3 had 1-3 protocols, and 5 had >3.
As shown in Table II, VSU size was positively associated with the availability of diagnostic devices (mean of 9 devices in VSUs 15B; P<0.05) and therapeutic resources (2.8 and 6.5, respectively; P<0.05). No VSU with 15 or fewer beds had endovascular procedures. No significant differences were found in the availability of written protocols as a function of VSU size.
Table III shows the data on the documentation of different parameters in the clinical record as a function of VSU size, as well as the measure of association (odds ratio [OR]) adjusted for the presence of medical residents in the unit. Practically all the clinical records included the patient's age, gender, and etiology and type of current arterial disease. In 6% of the records there was no mention of the location of arterial disease, with no differences observed by VSU size. With regard to comorbidity, the lack of data ranged from 4% for arterial hypertension to 17% for dyslipidemia. The frequency with which these data were recorded differed by VSU size: those with > 15 beds were more likely to document whether the patient had co-existing ischemie cardiopathy, cerebrovascular ischemia, chronic obstructive lung disease (COPD) or dyslipidemia, whereas no differences were found in information on hypertension and diabetes. With respect to treatment, in 16% of the clinical records there was no mention of medication received before admission (with no differences by VSU size), 95% included information on medication administered during admission, and only 77% mentioned medication prescribed at discharge, with significantly more frequent documentation of the last two items in units with >15 beds. Finally, information on many cardiovascular risk factors was found to be under-recorded in the clinical files, especially for lipoproteins (about 20% for LDL and HDL), height (31%) and weight (40%). No differences by unit size were found in the frequency of documentation of most risk factors, although the probability of recording height, tobacco use and blood pressure was significantly higher in the records of patients treated in units with >15 beds (OR: 1.7, 3.4 and 5.7, respectively).
Some 74% of patients were men, with significant differences by unit size (69% in VSUs <15B and 78% in VSUs > 15B) (Table IV). About 62% of patients were aged 70 or older, and patients in this age group were more frequently found in units with fewer beds (67% vs 58%). Mean patient age was 72 years, although those treated in smaller units were older (73 vs 71 years; P<0.05), especially in the case of stroke (81 vs 68 years; P<0.01), aneurysm (77 vs 72 years; P<0.05) and major amputation (78 vs 71 years) (Table V).
The etiology of arterial disease (arteriosclerotic in 96% of cases) as well as the prevalence of carotid (29%) and abdominal aorta involvement (26%) were independent of unit size (Table VI). In contrast, an association was seen between VSU size and type of arterial disease: ischemic disease (80% of patients) was significantly more frequent in units with 15 or fewer beds (95% V5 69%), whereas aneurysm, stroke and asymptomatic forms were much more common in units with >15 beds (20% V5 4%, 8% vs 3%, and 4% vs 0%, respectively). The most frequent location of ischemic disease was infrainguinal (90%), with no differences by unit size, followed by suprainguinal (22%), which was significantly more common in units with >15 beds (28% vs 17%). Chronic ischemic disease was the most frequent type (80%), followed by acute (20%); an association was found with unit size, with a significantly larger proportion of chronic forms in units with 15 or fewer beds (84% vs 76%). Trophic lesions (64%) were significantly more frequent in patients treated in units with 15 or fewer beds (79% vs 48%), whereas claudication (15%) was more common in the larger units (21% vs 9%). The location of stroke, TTA or aneurysm, as well as aneurysm diameter were independent of unit size; most commonly, stroke/TIA occurred in the carotid area (98%), and aneurysm in the abdominal aorta (56%) or the infra-renal area (51%).
The most frequent comorbidities were arterial hypertension and diabetes (66% and 52%, respectively), while COPD was the least common (26%) (Table VII). No association was seen between unit size and the presence of the different comorbidities, although the relation almost reached statistical significance in the case of diabetes and dyslipidemia (P-0.06).
VSU size was found to be associated with arterial hypertension (59%), lack of physical activity (48%), and diabetes (35%): the first was more frequent in larger units while the latter two were more common in units with 15 or fewer beds (Table VIII). With regard to the remaining risk factors, 25% of patients were frankly obese, about 1/3 had serum concentrations of cholesterol, lipoproteins or triglycerides above the risk threshold, and 27% were current smokers. All of these factors were independent of unit size.
This study examined the quality of clinical records and the profiles of patients admitted for NCAD as a function of the size of the VSU in hospitals of Catalonia, Spain. The sample is representative of patients admitted for NCAD in Catalonian hospitals, given that it was based on the stratification of health areas and hospital size, all the selected hospitals participated in the study, and each unit provided a number of patients very close to what was targeted.
In general terms, we found that the diagnostic devices studied were widely available, while availability of the therapeutic resources was medium to high (all the hospitals with >15 beds and over half of those with fewer beds had most of the therapeutic procedures studied), and that of written protocols was low. The fact that larger VSUs are better equipped with diagnostic devices and therapeutic resources may be due to reasons of efficiency: these centers treat patients with more complex conditions, thus they require more sophisticated diagnostic and therapeutic procedures such as endovascular techniques, which are not available in any of the units with 15 or fewer beds. On the other hand, the lack of written protocols may be an important source of variability in the management of these patients.
A successful therapeutic procedure is the result of a complex interaction among hospital characteristics, volume of procedures performed in the hospital, physician experience and patient characteristics. The probability of making correct clinical decisions depends, among other things, on the availability of the necessary clinical information, thus the completeness of clinical records is an indicator of the quality of care. In this study, we found that the quality of the clinical records was poor, as defined by the low level of documentation of cardiovascular risk factors. Poor clinical record quality has been shown in several medical disciplines and scenarios, and investigators have recognized the difficulty of evaluating them, the lack of standards of quality, and the need to improve the information contained in these records.23,24 The under-recording of risk factors seen in this study could lead to differences in patient outcomes, because it reduces the likelihood of implementing important prevention and treatment measures in these patients, and may indirectly worsen their prognosis. Other authors have shown that incomplete information in the clinical record could reduce opportunities for prevention.25 These results demonstrate the need to improve the completeness of clinical record reporting by developing standards, as well as by educating physicians and increasing their awareness of the need to fully document the clinical variables on which their preventive, diagnostic and therapeutic decisions depend.26 This study also found differences in patient profiles as a function of VSU size. Patients treated in units with 15 or fewer beds were older and more frequently diabetic, with advanced chronic ischemic lesions. In contrast, strokes and aneurysms were more frequently treated in units with > 15 beds; these patients also more frequently suffered from chronic limb ischemia, and were more likely to have dyslipidemia and arterial hypertension as their main risk factors. The differences in patient profiles could be due to the different distribution of the reference population, to unequal availability of diagnostic or therapeutic measures and/or to different patient complexity. Hospital complexity is one of the main determinants of the use of different cardiovascular procedures.27 This would explain why, in our study, older patients with advanced ischemic lesions who did not require sophisticated treatment resources are hospitalized in smaller units which lack these resources, whereas younger dyslipidemic patients, with stroke, aneurysm or acute ischemic disease-who require more difficult diagnostic and therapeutic measures-are sent to larger units where these complex techniques, in particular endovascular, are available. This hypothesis implies a system patient transfer between Catalonian hospitals according to the characteristics of each case. The more complex conditions in patients treated in units with > 15 beds may explain why these larger units have better documentation of comorbidity, as well as treatment prescribed during and after hospitalization, in the clinical record than do the smaller units.
Knowledge of the sources of variability is fundamental for optimal patient management and reduction of differences in outcomes. The lack of written protocols, the poor quality of clinical records, and the different patient profiles found in this work could be sources of variability. Additional studies are needed to evaluate the degree to which these situations influence the management of NCAD in Catalonia.
The sample obtained in this study is a good representation of the population of patients with NCAD treated in Catalonian hospitals. In general, the hospitals are adequately equipped with diagnostic and therapeutic resources, especially those with >15 beds in the VSU. The quality of the clinical records is poor, particularly with regard to reporting of risk factors, which may hinder the implementation of prevention and treatment measures. Patient profiles vary according to unit size. Smaller units generally treat older patients, who are often diabetic and with advanced ischemic disease. Larger units generally admit younger patients with acute stroke or aneurysm, who are more frequently dyslipidemic or hypertensive.
Fundings.-This study was supported by Sanofi-Aventis.
Acknowledgements.-This study was made possible thanks to the collaboration of the Vascular Surgery Units of the following centers: Hospital Dos de Maig (Barcelona), Hospital del Mar (Barcelona), Hospital Clinic i Provincial (Barcelona), Hospital Municipal (Badalona), Hospital Universitari Gemans Trias i Pujol (Badalona), Hospital General (Granollers), Hospital St. Joan de Deu (Manresa), Corporacio Sanitaria del Pare Tauli (Sabaclell), Fundacio Sanitaria d'lgualada (Igualada), Hospital Universitari Doctor Josep Trueta (Girona), Hospital Universilari Arnau dc Vilanova (Lleida), Hospital de Sant Pau i Santa Tecla (Tarragona), Hospital Universitari Joan XXIII (Tarragona), and Hospital Universitari dc Bellvitge (Barcelona).
Received on January 24, 2007; sent for revision on May 22, 2007; resubmitted July 10, 2007; accepted for publication September 20, 2007.
1. Selvin E, Erlinger T. Prevalence of and risk factors for peripheral arterial disease in the United Stales. Circulation 2004;110:738-43.
2. Murabilo JM, Evans JC, Nieto K, Larson MG, Levy D, Wilson PW. Prevalence and clinical correlates of peripheral arterial disease in the Framingham Offspring Study. Am Heart J 2002;143:961-5.
3. Ogren M, Hedblad B, Engstrom G, Janzon L. Prevalence and prognostic significance of asymptomatic peripheral arterial disease in 68-year-old men with diabetes. Results from the population sludy "Men born in 1914" from Malmo, Sweden. Eur J Vas Endovasc Surg 2005;29:182-9.
4. Ness J, Aronow WS, Newkirk E, McDanel D. Prevalence of symptomatic peripheral arterial disease, modifiable risk factors, and appropriate use of drugs in the treatment of peripheral arterial disease in older persons seen in a university general medicine clinic. J Gerontol A Biol Sci Med Sci 2005;60:255-7.
5. Baena Diez JM, del Val Garcia JL, Tomas Pelegrina J, Martinez Martinez JL, Martin Penacoba R, Gonzalez Tejon I et al. [Cardiovascular disease epidemiology and risk factors in primary care]. Rev Esp Cardiol 2005;58:338-40.
6. Bhatt DL, Steg PG, Ohman EM, Hirsch AT, Ikeda Y, Mas JL et al.; REACH Registry Investigators. International prevalence, recognition and treatment of cardiovascular risk factors in outpatients with atherothrombosis. JAMA 2006;295:180-9.
7. National Statistics Institute. Website http://www.ine.es/ inebase/: Avance del Padron a 1 de enero de 2006 [Census forecast to 1 January 2006]. Provisional data. Accessed September 2006.
8. Collaborative report from the American Associations for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (writing committee to develop guidelines for the managemente of patients with peripheral arterial disease). ACC/AHA 2005 Practice Guidelines for the Management of Patients with Peripheral Arterial Disease (lower extremity, renal, mesenteric, and abdominal aortic): Executive Summary. Circulation 2006;113:1474- 547.
9. Norgren L, Hiatt WR, Dormandy JA, Nehler MR, Hams KA, Fowkes FG; TASC II Working Group; TASC II Working Group. Inter-Society Consensus for the Management of Peripheral Arterial Disease. Eur J Endovasc Surg 2007;33 Suppl 1:S1-75.
10. Zwierska I, Walter RD, Choksy SA, Male JS, Pockley AG, Saxton JM. Upper- vs lower-limb aerobic exercise rehabilitation in patients with symptomatic peripheral arterial disease: a randomized controlled trial. J Vasc Surg 2005;42:122-30.
11. Tsai JC, Chan P, Wang CH, Jeng C, Hsieh MH, Kao PF et al. The effects of exercise training on walking function and perception of health status in elderly patients with peripheral arterial disease. J Int Med 2002;252:448-55.
12. Gomez de la Camara A. [Scientific evidence-based medicine: myth and reality of variability in clinical practice and its impact on health outcomes]. Anales Sis San Navarra 2002;25:11-26.
13. Castillo J, Barrios V, Ros E, Llobet X. [Guidelines for action and diagnosis of atherothrombosis in Spain: the ADA (Atherothrombosis Action and Diagnosis) study]. Rev Clin Esp 2002;202:202-8.
14. Pearce WH, Parker MA, Feinglass J, Ujiki M, Manheim LM. The importance of surgeon volume and training in outcomes for vascular surgical procedures. J Vasc Surg 1999;29:768-78.
15. Carbonell AM, Lincourt AE, Kercher KW, Matthews BD, Cobb WS, Sing RF el al. Do patient or hospital demographics predict cholecyslectomy outcomes? A nationwide study of 93,578 patients. Surg Endosc 2005;19: 767-73.
16. Galan Gonzalez-Serna JM, Rodriguez Becerra E, Llanes Ruiz F, Rosado Martin M, Castillo Gomez J. [Evaluating the influence of hospital size on respiratory health care efficiency in Andalusia]. Arch Bronconeumol 1999;35:202-7.
17. Freixinet JL, Julia-Serda G, Rodriguez PM, Santana MB, Rodriguez de Castro R, Fiuza MD et al., and the Bronchogenic Carcinoma Cooperative Group of the Spanish Society of Pneumology and Thoracic Surgery GCCB-S. Hospital volume: operative morbidity, mortality and survival in thoracotomy for lung cancer. A Spanish multicenter study of 2994 cases. Eur J Cardiothorac Surg 2006;29:20- 5.
18. Thompson AM and Park KGM for the Scottish Audit of Gastric and Oesophageal Cancer. Does hospital size influence the outcome of patients with gastric cancer undergoing surgery? Br J Surg 2002;Suppl 1:89.
19. World Health Organisation. Physical status: the use and interpretation of anthropometry. Report of a WHO Expert Committee. Technical Report Series no. 854. Geneva 1995.
20. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr et al. The Seventh Report of the Joint National Commitee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure. The JNC 7 Report. JAMA 2003;289:2560-72.
21. Alberti KGMM, Zimmet PZ for the WHO Consultation. Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: Diagnosis and classification of diabetes mellitus. Report of a WHO consultation. Diabet Med 1996;15:539-53.
22. The American Association of Clinical Endocrinologists. Medical Guidelines for Clinical Practice for the diagnosis and treatment of dyslipidemia and prevention of atherogenesis. AACE Lipid Guidelines. Endocr Prac 2000; 6(No.2).
23. Lopez Rodriguez A, Hidalgo Santos JC, Segovia Perez C, Main Perez A, Corral Cuevas L, Gonzalez Maria E et al. [Metabolic control of diabetes mellitus in relation to the quality of clinical records]. Aten Primaria 2000;26:670-6.
24. Weyer SM, Konrard N, Esola D, Goodwin M, Stange KC, Flocke SA. Features of medical records in community practices and their association with preventive service delivery. Med Care 2005;43:28- 33.
25. Cox JL, Zitner D, Coutney K, MacDonald DL, Paterson G, Cochrane B et al. Undocumented patient information: an impediment to quality of care. Am J Med 2003;114: 211-6.
26. Molinier L, Aziza R, Baillet D, Bombail M, Daubert E, Gladieff L et al. Assessing the quality of patients' medical records at the Claudius-Regaud. Bull Cancer 2001;88:793-803. 27. Mirvis DM, Graney MJ. Variations in the use of cardiac procedures in the Veterans Health Administration. Am Heart J 1999;137(4 Pt 1):588-9.
M. A. CAIROLS CASTELLOTE 1, S. RIERA BATALLA 1, P. LAZARO Y DE MERCADO 2 M. D. AGUILAR CONESA 2, M. J. GARCIA DE YEBENES Y PROUS 2
1 Catalan Society of Angiology and Vascular Surgery, Barcelona, Spain
2 Tecnicas Avanzadas de Investigacion en Servicios de Salud (TAISS), Madrid, Spain
Address reprint requests to: Ma Dolores Aguilar Conesa, TAISS, C/ Cambrils 41-2, 28034 Madrid, Spain.
E-mail: [email protected]
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