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European Journal of Heart Failure 2002 4(6):779-786; doi:10.1016/S1388-9842(02)00116-2
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© 2002 European Society of Cardiology

Annual rates of admission and seasonal variations in hospitalizations for heart failure

Manuel Martínez-Sellésa,*, José A. García Roblesa, Luis Prietob, José A. Serranoa, Roberto Muñoza, Elisa Fradesa and Jesús Almendrala

a Cardiology Department, Hospital Universitario Gregorio Marañón, Dr. Esquerdo 46, 28007-Madrid, Spain
b Departamento de Estadística, Facultad de Medicina, Universidad Complutense de Madrid, Ciudad Universitaria 28040-Madrid, Spain

* Corresponding author. Tel.: +34-915-868-276; fax: +34-915-868-276. E-mail address: mmselles{at}navegalia.com


   Abstract
Top
 Abstract
1. Introduction
 2. Methods
 3. Results
 4. Discussion
 5. Conclusions
 Acknowledgments
 References
 
Aims: To investigate the annual hospitalization rate and seasonal variation in confirmed heart failure (HF) admissions.

Methods and Results: Records from all admissions to one hospital during 1 year with a HF diagnostic code were reviewed. From 1953 admissions, 595 were excluded because they did not fulfill the diagnostic criteria. A total of 1069 patients had 1358 admissions with confirmed HF. Mean age was 74.8±11.5 years, 42% were males. The admission data were matched with data from the municipal census with 537 666 people aged ≥15 years. There were 2.5 admissions per 1000 for the adult population and 26.5/1000 in those aged ≥80 years. There were 444 males and 625 females, giving a higher rate of admission for female patients 2.2/1000 vs. 1.7/1000 (P<0.0001), although age adjusted rates in females were higher only for ≥80 years. Echocardiogram was performed in 706 patients (66%), 325 (46%) had a normal ejection fraction. This proportion increased in females—64% vs. 29% males—and in older patients—55% in ≥75 vs. 39% in <75 years. Mortality during the first admission of 1996 was 8.3%. There was a seasonal variation in HF hospitalizations (P<0.0001) peaking at 25% above average in January and dipping to 33% below average in August.

Conclusion: The rate of HF admissions was 2.5/1000 with an elderly preponderance and a higher rate of admission in males <80 years and in females ≥80 years. A seasonal variation ranging from 25% above average in January to 33% below average in August was observed.

Key Words: Heart failure • Seasonality • Epidemiology • Ejection fraction

Received August 7, 2001; Revised November 15, 2001; Accepted February 5, 2002


   1. Introduction
Top
 Abstract
 1. Introduction
2. Methods
 3. Results
 4. Discussion
 5. Conclusions
 Acknowledgments
 References
 
The progressive aging of the population, combined with increased survival of patients with cardiovascular disease, as a result of therapeutic improvements, have led to an escalating prevalence of heart failure. Consequently, heart failure has become the most important public health problem in cardiovascular medicine, placing a heavy burden on health care systems [1,2]. Hospitalization of patients with heart failure consumes 74% of the total health care costs of heart failure [2]. Moreover, heart failure is the most common principal diagnosis among hospitalized adults aged 65 years and older [2–4]. In spite of these facts, the contemporary epidemiology of heart failure in Spain is not well documented, although there is an apparent ever increasing number of hospital admissions due to this condition [3], a situation similar to that of other developed countries [5–10].

Several methodological problems pose difficulties in the study of heart failure epidemiology. First, routinely collected data from primary care cannot be used to describe the epidemiology of heart failure because of the questionable validity of the clinical diagnosis of heart failure in this setting [11–17]. Second, although the initial presentation of heart failure is to a hospital in more than 80% of the cases [11] the miscoding problem in routine hospital discharge records [18] makes these data unsuitable for epidemiological studies. Third, most published epidemiological studies have relied on a clinical diagnosis (based just on signs and symptoms) of heart failure, only a few studies include a chest X-ray. Consequently, it is unclear whether all cases really had heart failure [7]. Fourth, little is known about seasonal variations in hospitalizations due to heart failure. Although seasonal variation in the incidence of acute myocardial infarction and in blood pressure is well known [19,20] there is an evident paucity of data about seasonal variation in heart failure [21–23].

The aim of this study was to investigate the rate of heart failure admissions in the health area served by our hospital and to define any seasonal variations in chronic heart failure hospitalizations.


   2. Methods
Top
 Abstract
 1. Introduction
 2. Methods
3. Results
 4. Discussion
 5. Conclusions
 Acknowledgments
 References
 
All data come from the HOLA project (Heart failure: Observation of Local Admissions). This registry involved all medical departments of the Gregorio Marañón University Hospital with 1917 beds [24] and a primary catchment population of 636 302, of which 537 666 are 15 years of age or older.

The study included all admissions to our center from 1 January 1996 to 31 December 1996, that received at least one of the International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) codes in Table 1 as principal diagnosis or any diagnosis (1953 admissions). The hospital records were collected and retrospectively reviewed. All available demographic and medical data, including left ventricular ejection fraction, were recorded for each patient.


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  		Table 1 Heart failure or related diagnosis (International Classification of Diseases 9—Clinical Modification)

 
2.1. Case definition
Since the evaluation was made retrospectively, it was decided to use criteria most likely to be found in the majority of records. Patients were included if they were 15 years of age or older and had:
  1. Ventricular dysfunction or valvular heart disease fitting the European Society of Cardiology guidelines for the diagnosis heart failure [25].
  2. Neither ventricular dysfunction nor valvular heart disease but, at least, one symptom (dyspnea or oliguria) plus one sign (high jugular venous pressure, rales or pedal edema) of heart failure and Chest Roentgenogram with evidence of heart failure (cardiomegaly, pulmonary edema or vascular redistribution).
  3. No echocardiographic study but at least one symptom of heart failure and one sign or Chest Roentgenogram evidence of heart failure.

Patients were excluded if:

  1. The presence of heart failure could not be objectively determined using the above criteria (454 admissions—23.3%).
  2. They had an acute myocardial infarction as primary reason for admission (69 admissions—3.5%).
  3. Their hospital records were incomplete or parts were not available for investigation (72 admissions—3.7%).

In total 1069 patients with 1358 admissions (1.27 admissions per patient) were included in the study.

2.2. Review
All data collected were reviewed by two cardiologists (MMS and JAGR—the case definition panel). Cases were included only if both cardiologists agreed that the case met the defining criteria. The reproducibility of the panel decisions for case definition, evaluated by random re-submission of 9% of the cases, was good, Cohen's k=0.89 (95%CI 0.77–0.99).

To study the seasonal variation in heart failure hospitalizations the mean of daily hospitalizations in the 12 months was compared.

To calculate age and sex-specific annual rate of hospitalizations the admission data were matched with the demographic data from the 1996 municipal census [26].

2.3. Statistical analysis
The {chi}2-test was used to compare discrete variables. Independent predictors of in-hospital mortality were examined with a logistic multivariate stepwise regression analysis that included all variables with a P value <0.15 in the univariate analysis.

The number of hospitalizations per month were assumed to follow a Poisson Distribution and the 95% Confidence Intervals for the parameter were calculated estimating its variance by the square root of the observed values. To express hospitalizations as daily rates, the monthly values are divided by the number of days in each month. To study the seasonal variation in heart failure hospitalizations, several Poisson Regression models were tested in order to find the simpler polynomial with which the data fitted.

All relevant proportions are reported with their Confidence Intervals. All tests were two-tailed.

A commercially available microcomputer statistics program (SPSS 10.0 for Windows, Chicago, IL, USA) was used to perform all statistical analysis.


   3. Results
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
4. Discussion
 5. Conclusions
 Acknowledgments
 References
 
The total population covered by our hospital in 1996 was 636 302 individuals [24]; 98 636 children (<15 years) were not included in the analysis. Thus, 537 666 people (255 089 males and 282 577 females) were included in the study population. The age and sex distribution, depicted in Table 2, shows that 17.8% were aged 65 years or over.


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  		Table 2 Age and sex distribution of the population

 
During the study period 1069 patients had 1358 admissions with confirmed heart failure (1.27 admissions per patient, 5.7% of all medical admissions). Another 595 admissions with diagnostic codes of heart failure that did not fulfill our diagnostic criteria were not included in the analysis.

There were 2.5 admissions/1000 for the entire adult population (95%CI: 2.4–2.6/1000) and 26.5/1000 (95%CI: 24.3–28.7/1000) for persons aged 80 years or over. Mean age was 74.8±11.5 years, with a median of 76 years; 42% were males. Table 3 depicts the age and sex distribution of these patients. There were 444 males and 625 females, giving a higher admission rate in females (males 1.7/1000, 95%CI 1.5–1.9; females 2.2/1000, 95%CI 2.0–2.4), P<0.0001, although age adjusted rates in females were higher only in the very old (80 years or over) (Fig. 1 and Table 4).


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  		Table 3 Age and sex distribution of patients admitted with heart failure

 


Figure 1
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  		Fig. 1 Rate of admission of patients with heart failure according to age (in years) and sex.

 


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  		Table 4 Rate of admissions/1000: hospitalizations and age/sex distribution of patients admitted with heart failure

 
3.1. Co-morbidity and in-hospital mortality
Mean hospital stay was 16±15.5 days (median 12 days). The majority of patients were admitted to the Internal Medicine Department (71%) and Cardiology (20%). Co-morbidity was frequent:
  • Risk factors: hypertension 43%, diabetes 30%, smoking 16%, hyperlipidemia 11%, and severe obesity 6%.
  • Systemic diseases: chronic pulmonary disease 30%, renal disease 14%, alcoholism 8%, ulcer disease 6%, dementia 6%, liver disease 5% and cancer 4%.
  • Cardiovascular diseases: previous myocardial infarction 15%, previous stroke 12%, severe coronary stenosis 9%, peripheral vascular disease 6% and CABG 4%.
  • ECG alterations: atrial fibrillation 49%, left bundle branch block 11%, right bundle branch block 8%, previous pacemaker implantation 7%.
  • Valvular heart disease: moderate or severe regurgitation: mitral 25%, aortic 6%, tricuspid 19%. Moderate or severe stenosis: aortic 9%, mitral 9%. Previous valvular surgery 7%.

Mortality during the first admission of 1996 was 8.3%, 9.8% in patients aged >75 years and 6.7% in those aged 75 years or younger. Independent predictors of in-hospital mortality are shown in Table 5.


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  		Table 5 Independent predictors of in-hospital mortality (multivariate analysis)

 
3.2. Left ventricular ejection fraction
An echocardiogram was performed in 706 patients (66%). Normal left ventricular ejection fraction (0.5 or over) was found in 325 patients (46%). This proportion was higher in females—64% vs. 29% males—and in older patients—55% in those aged 75 years or over vs. 39% in those below 75 years, both tests with P<0.001 (Fig. 2). Echocardiogram was performed less frequently in females, P<0.01 and in the elderly, P<0.001 (Fig. 3).


Figure 2
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  		Fig. 2 Distribution of left ventricular ejection fraction (LVEF) in different age (in years) and sex groups.

 


Figure 3
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  		Fig. 3 Percentage of patients in which echocardiogram was not performed. Age and sex distribution.

 
3.3. Treatment
Diuretics were the treatment most frequently administered at discharge (86%). ACE inhibitors, nitrates and digoxin were used in 50–53% of patients, while 25–30% of patients received antiplatelet therapy or anticoagulation. Other treatments, including beta-blockers, were used in less than 10% of patients admitted with heart failure during 1996. Treatment changed according to left ventricular ejection fraction (Table 6).


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  		Table 6 Discharge treatment according to left ventricular ejection fraction (LVEF)

 
Only two ACE inhibitors were used, due to availability in our hospital: captopril 45.5% and enalapril 7.5%. Mean daily doses were: 61±46 mg and 16.5±14 mg, respectively. Patients admitted to the cardiology department received ACE inhibitors more frequently than patients admitted to other departments, when left ventricular ejection fraction was moderately or severely depressed or not measured, while the contrary happened in patients with normal or near normal ejection fraction (Fig. 5).

3.4. Seasonal variation
The mean number of hospitalizations was 3.71±1.61 hospitalizations/day. Fig. 4 shows the mean number of hospitalizations per day and its Confidence Interval each month. There was a clear seasonal variation in heart failure hospitalizations (P<0.0001) peaking at 25% above average in January and dipping to 33% below average in August, without Confidence Intervals overlapping. When modeling these monthly variations by Poisson Regression a second order polynomial, with a minimum in summer time and maximal values in winter time, proved to be the best model.


Figure 4
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  		Fig. 4 Seasonal variations in heart failure hospitalizations.

 

   4. Discussion
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
5. Conclusions
 Acknowledgments
 References
 
Hospital surveys of confirmed heart failure prevalence in unselected populations are few. Much of our current knowledge of heart failure is based on highly selected hospital series, or patients selected for clinical trials. Such patients do not reflect the spectrum of heart failure as it presents in the population [27]. On the other hand, hospitalization for heart failure is a growing health problem in most developed countries [3–10], and represents a major burden for the Spanish health system that increased substantially in the period 1980–1993 [3] and probably continues to do so. A recent demographic study in Madrid based on the 1996 population data, predicted a 25% growth in the elderly population (65 years or more) and a 46% increase in the percentage of very old among this elderly population (≥85 years/≥65 years) in only 15 years (1996–2011) [29]. As we found that the rate of heart failure hospitalizations rises very steeply with age, the hospital burden of heart failure will increase dramatically in the next 15 years. Knowing that the direct cost of heart failure in developed countries is between 1% and 2% of total health care expenditure, and that at least two-thirds of the expenditure on heart failure is attributable to hospitalization [1,2], this increased hospital burden also means a great increase in the direct costs of heart failure.

A direct comparison with other hospital surveys of heart failure in unselected European populations is difficult because most published reports use no other criteria than diagnostic codes. Parameshwar and co-workers [8,18] surveyed all heart failure admissions to a district (community) hospital in Greater London, serving a population of approximately 155 000. In a 6-month period, they found 140 admissions with heart failure defined as evidence of heart disease with the development of fluid retention (4.9% of all medical admissions). Extrapolating their data to 1 year they found a prevalence of 1.86/1000, similar to the admission rate of 2.52/1000 that we found in a population aged ≥15 years.

Similar prevalences were found using only primary diagnostic codes in the USA in 1986 [6], and in Scotland in 1990 [7]. These studies suggested that 2.1–2.3/1000 population were hospitalized for heart failure. Using any diagnostic code position, rates of admission increased to 4.3–6.8/1000. A comparable prevalence was found by Rodríguez-Artalejo et al. [3] in Spain using broader diagnostic codes (5.1/1000), approximately double what we found. Due to frequent miscoding in routine hospital discharge records [18], it is possible that some of the cases in these studies did not have heart failure, and thus, these figures are overestimations. In fact, in our study, with well-defined inclusion and exclusion criteria only 69.5% of the patients with a heart failure code were included. However, we cannot exclude that mild forms of heart failure were excluded by our strict criteria, thus underestimating the true rate of admission.

One key finding of our study was the very old age of the population and the frequent multiple co-morbidity, confirming most recent studies from other countries. Most of these patients would not have been eligible for large heart failure trials [27]. It is well known that the heart failure hospitalization rate increases with age [3,4,7,28,30] but this increase was particularly dramatic in our study reaching 26.5/1000 in those aged 80 years and over. Women also had a higher rate of admission for heart failure (males 1.7/1000, females 2.2/1000, P<0.0001). The increased life expectancy of women—82.7 years vs. 75.3 years for males in 1996 in Madrid [31]—has a direct correlation with this finding. In fact, age adjusted admission rates in females were higher only in the very old (80 years or over). This age and female preponderance could be, in part, related to the high percentage of heart failure with a normal left ventricular ejection fraction, 64% for women vs. 29% for men and 55% in those aged 75 or more vs. 39% in those aged less than 75 years. Real differences might be even higher because left ventricular ejection fraction measurement was less frequently performed in females and in the elderly (Fig. 3).

Since in-hospital mortality increases with the presence of depressed left ventricular ejection fraction and valve stenosis, echocardiography is the best non-invasive diagnostic tool for risk stratification and pre-discharge treatment regimen selection in heart failure patients. In this regard, ACE inhibitor prescription was associated with systolic dysfunction, although this association was stronger in the cardiology department (Fig. 5).


Figure 5
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  		Fig. 5 ACE inhibitor use according to left ventricular ejection fraction (LVEF) and department of admission. No LVEF: patients without LVEF measurement.

 
From a clinical point of view, high jugular venous pressure, recently shown to be an independent risk factor in patients with heart failure [32], also increased in-hospital mortality in our study (OR 2.5). However, it had no independent effect on prognosis when data from the echocardiogram were introduced in the model, confirming the value of this diagnostic tool in patients with heart failure (Table 5).

Our report also describes and compares the seasonal variation in chronic heart failure hospitalizations showing a seasonal pattern ranging from a peak of 25% above average in January to 33% below average in August. There are three previous reports mentioning seasonality with regard to heart failure. Boulay et al. [22] in a retrospective national survey in France during a 2-year period showed that hospitalizations for heart failure followed a seasonal variation, ranging from +7 to +10% above average from December through April to –9 to –20% below average from July through September. A very similar pattern was also found by Allegra et al. [23] in a retrospective analysis of heart failure emergency department visits involving seven northern New Jersey hospitals over an 11-year period. These authors found that visits for heart failure increased in the winter months. Compared with the average of the other months, December was the highest (14.3% above) and August was the lowest (15.5% below). Our data display a similar but sharper monthly pattern. In contrast, Parry et al. [21] noted that patients from northern Nigeria with heart failure presented more frequently during the hot wet months than during the cooler dry months. Nevertheless, the different climatic environment and population (mainly peripartum heart failure) of this study precludes comparison with our data and the two previous studies.

Potential mechanisms underlying a seasonal pattern are other conditions with a well-known seasonal variation [22]: respiratory tract infections, myocardial infarction, blood pressure and acute arrhythmia. Cold climate mediated changes in hemodynamics and in sympathetic nervous system could also play an important role. In our population geographic movement due to the vacation period is another factor that could explain a small part of this variation in the summer months.

Finally, the Spanish national health system has some characteristics that make the data obtained in this study more reliable than similar studies in countries with a more diverse range of medical care, providers, and health insurance. Every Spanish citizen has health insurance irrespective of their financial status, but cannot choose providers at his own discretion. The system mandates attendance to assigned clinics, and hospital, but the hospital care is free of charge. All these characteristics permit us to obtain epidemiologically representative data when comparing the admissions with the population from the health area served by our hospital.

4.1. Limitations
The obvious drawbacks of using hospital records for research could not be totally avoided in this study. To minimize the impact of varying diagnostic criteria among different doctors, and services, the cases had to fulfill well-defined inclusion criteria, which were strict, highly reproducible and clinically recognizable. However, it is conceivable that these criteria while increasing the specificity could have reduced the sensitivity by excluding milder forms of heart failure, thus, underestimating the true rate of heart failure admissions.

The number of hospitalizations for persons with a diagnosis of heart failure does not necessarily represent prevalence of heart failure cases. Although our data could be close to an epidemiologically representative population, considering that approximately 80% of first diagnoses of heart failure occur at hospitalization [11], unrecognized cases of heart failure and patients with heart failure who were not hospitalized during 1996 (including patients dying suddenly outside the hospital) would be undetected in the present study.


   5. Conclusions
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 5. Conclusions
Acknowledgments
 References
 
A retrospective study of an unselected sample of patients admitted to a large metropolitan hospital with confirmed heart failure revealed an admission rate of 2.5/1000 population for this condition, with an elderly preponderance and a higher admission rate in females, although age adjusted rates in females were higher only in those aged 80 years or over. The percentage of heart failure patients with a normal ejection fraction was higher in women and in the elderly.

Clear seasonal variations in admissions with heart failure were found. Heart failure hospitalizations peaked in winter and ranged from a peak of 25% above average in January to 33% below average in August.


   Acknowledgments
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 5. Conclusions
 Acknowledgments
References
 
We are indebted to Antonio Martinez, MD, for critically reviewing the manuscript.


   References
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 5. Conclusions
 Acknowledgments
 References
 

  1. Murdoch D.R., McMurray J. Epidemiological perspectives on heart failure: common, costly, disabling, deadly. In: Heart failure management—Sharpe N., ed. (2000) Martin Dunitz.
  2. Ryden Bergsten T., Andersson F. The health care costs of heart failure in Sweden. J Int Med (1999) 246:275–284.[CrossRef][Web of Science][Medline]
  3. Rodríguez-Artalejo F., Guallar-Castillón P., Banegas Banegas Jr, Del Rey Calero J. Trends in hospitalization and mortality for heart failure in Spain, 1980–1993. Eur Heart J (1997) 18:1771–1779.[Abstract/Free Full Text]
  4. Ghalli J.K., Cooper R., Ford E. Trends in hospitalization rates for heart failure in the United States, 1973–1986: evidence for increasing population prevalence. Arch Int Med (150) 1990:769–773.
  5. Haldeman G.A., Croft J.B., Giles W.H., Rashidee A. Hospitalization of patients with heart failure: national hospital discharge survey 1985–1995. Am Heart J (1999) 137:352–360.[CrossRef][Web of Science][Medline]
  6. Gillum R.F. Epidemiology of heart failure in the United States. Am Heart J (1993) 26:1042–1047.
  7. McMurray J., McDonagh T., Morrison C.E., Dargie H.J. Trends in hospitalization for heart failure in Scotland 1980–1990. Eur Heart J (1993) 14:1158–1162.[Abstract/Free Full Text]
  8. Parameshwar J., Poole-Wilson P.A., Sutton G.C. Heart failure in a district general hospital. J R Coll Phys Lond (1992) 26:139–142.[Web of Science][Medline]
  9. Polanczyk C.A., Rohde L.E., Dec G.W., DiSalvo T. Ten year trends in hospital care for congestive heart failure: improved outcomes and increased use of resources. Arch Int Med (2000) 160:325–332.[Abstract/Free Full Text]
  10. Doughty R., Yee T., Sharpe N., et al. Hospital admissions and deaths due to congestive heart failure in New Zealand, 1988–91. N Z Med J (108) 1995:473–475.
  11. Cowie M.R., Wood D.A., Coats A.J.W., et al. Incidence and aetiology of heart failure. Eur Heart J (1999) 20:421–428. /doi:10.1053/euhj.1998.1280.[Abstract/Free Full Text]
  12. Gibson T.C., White K.L., Klainer L.M. The prevalence of congestive heart failure in two rural communities. J Chron Dis (1966) 19:141–152.[CrossRef][Web of Science][Medline]
  13. Royal College of General Practioners, Office of Population Census and Survey, and Department of Health and Social Security. Morbidity statistics from general practice: third national study, 1981–82 (1988) London: HMSO.
  14. Royal College of General Practioners, Office of Population Census and Survey, and Department of Health and Social Security. Morbidity statistics from general practice: third national study, 1991–92 (1995) London: HMSO.
  15. Phillips S.J., Whisnant J.P., O'Fallon W.M., Frye R.L. Prevalence of cardiovascular disease and diabetes mellitus in residents of Rochester, Minnesota. Mayo Clin Proc (1990) 65:344–359.[Web of Science][Medline]
  16. Mittelmark M.B., Psaty B.M., Rautaharju P.M., et al. Prevalence of cardiovascular diseases among older adults. The cardiovascular health study. Am J Epidemiol (1993) 137:311–317.[Abstract/Free Full Text]
  17. Remes J., Miettinen H., Reunanen A., Pyörälä K. Validity of clinical diagnosis of heart failure in primary health care. Eur Heart J (1991) 12:315–321.[Abstract/Free Full Text]
  18. Sutton G.C. Epidemiological aspects of heart failure. Am Heart J (1990) 6:1538–1540.
  19. Brennan P.J., Greenberg G., Miall W.E., Thompson S.G. Seasonal variation in arterial blood pressure. Br Med J (1982) 285:919–923.[Abstract/Free Full Text]
  20. Spencer F.A., Goldberg R.J., Becker R.C., Gore J.M. Seasonal distribution of acute myocardial infarction in the second national registry of myocardial infarction. J Am Coll Cardiol (1998) 31:1226–1233.[Abstract/Free Full Text]
  21. Parry E.H.O., Ladipo G.O.A., Davidson N.Mc.D., et al. Seasonal variation of cardiac heart failure in northern Nigeria. Lancet (1997) 1:1023–1025.
  22. Boulay F., Berthier F., Sisteron O., Gendreike Y., Gibelin P. Seasonal variation in chronic heart failure hospitalizations and mortality in France. Circulation (1999) 100:280–286.[Abstract/Free Full Text]
  23. Allegra J.R., Cochrane D.G., Biglow R. Monthly, weekly, and daily patterns in the incidence of congestive heart failure. Acad Emerg Med (2000) 8:682–685.[CrossRef][Web of Science]
  24. Anonymous. Hospital General Universitario Gregorio Marañón. Memoria 1996. Consejería de Sanidad y Servicios Sociales. Comunidad de Madrid, 1998.
  25. Task Force on heart failure of the European Society of Cardiology. Guidelines for the diagnosis of heart failure. Eur Heart J (1995) 16:741–751.[Free Full Text]
  26. Anonymous. Resultados provisionales detallados del padrón municipal de habitantes y estadística de población de la Comunidad de Madrid, 1996. Instituto de estadística. Consejería de Hacienda. Comunidad de Madrid. Área de regimen interior y personal. Ayuntamiento de Madrid, 1998.
  27. McMurray J. Heart failure: we need more trials in typical patients. Eur Heart J (2000) 21:699–700. /doi:10.1053/euhj.1999.1974.[Free Full Text]
  28. Rich M.W. Epidemiology, pathophysiology, and etiology of congestive heart failure in older adults. J Am Geriatr Soc (1997) 45:968–974.[Web of Science][Medline]
  29. Anonymous. Proyecciones de población y de hogares de la Comunidad de Madrid, 1996–2011. Tomo I: Proyecciones básicas por sexo y edad. Instituto de estadística. Consejería de Hacienda. Comunidad de Madrid, 1998.
  30. Khand A.U., Gemmell I., Rankin A.C., Cleland J.G.F. Clinical events leading to the progression of heart failure: insights from a national database of hospital discharges. Eur Heart J (2001) 22:153–164.[Abstract/Free Full Text]
  31. Anonymous. Memoria Área 1 de Madrid 1999. Dirección General Atención Primaria Área 1. Insalud, 2000.
  32. Drazner M.H., Rame E., Stevenson L.W., Dries D.L. Prognostic importance of elevated jugular venous pressure and a third heart sound in patients with heart failure. N Engl J Med (2001) 345:574–581.[Abstract/Free Full Text]

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 Eur J Heart FailHome page
A. U. Khand, M. Shaw, I. Gemmel, and J. G.F. Cleland
Do discharge codes underestimate hospitalisation due to heart failure? Validation study of hospital discharge coding for heart failure
Eur J Heart Fail, August 1, 2005; 7(5): 792 - 797.
[Abstract] [Full Text] [PDF]

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 Eur J Heart FailHome page
M. Martinez-Selles, J. A. G. Robles, R. Munoz, J. A. Serrano, E. Frades, M. D. Munoa, and J. Almendral
Pharmacological treatment in patients with heart failure: patients knowledge and occurrence of polypharmacy, alternative medicine and immunizations
Eur J Heart Fail, March 1, 2004; 6(2): 219 - 226.
[Abstract] [Full Text] [PDF]

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