Objectives: The aim of this study was to characterise the epidemiology of congestive heart failure namely assessing demographic, etiologic and prognostic aspects, and the hospital admission trends in the last 6 years.
Methods: Retrospective analysis of computerised data concerning patients with congestive heart failure admitted to the department of Internal Medicine.
Location: A central hospital in the North of Portugal.
Subjects: Two thousand five hundred and sixty-one patients older than 10 years, admitted to the Internal Medicine Department of a central hospital in the North of Portugal between January 1, 1989 and December 31, 1994 and discharged with the principal or first listed diagnosis of congestive heart failure (ICD-9-CM code 4280).
Results: Eighty per cent of the patients had more than 60 years of age and the mean age was 69 years (female: 70.40 +/- 12.65; male: 66.24 +/- 12.25; p < 0.0001). Fifty-four per cent were females and 46 per cent males. The prevalence of congestive heart failure in the Internal Medicine Department was 4.8%. Between the ages of 15 and 44 years the hospital age-specific prevalence was between 16.1/10,000/year and 26.7/10,000/year for women and between 14.5/10,000/year and 16.1/10,000/year for men. For ages equal or greater than 75 years it was between 508.9/10,000/year and 561.3/10,000/year for women and between 300.2/10,000/year and 421.8/10,000/year for men. Possible causes of congestive heart failure were: valve disease in 26 per cent of patients, coronary artery disease in 24 per cent and hypertension in 20 per cent. The average case-fatality rate was 15.15% (female: 15.54%; male: 14.69%; chi 2 = 0.36; p > 0.55) evolving from 19.45% in 1989 to 12.59% in 1994 (chi 2 = 6.85; p < 0.01). Between the ages of 15 and 44 years the hospital cause-specific mortality rate was 16.2/100,000 and for ages equal or greater than 75 years it was 743.6/100,000. Stepwise logistic regression produced the following odds ratios for the variables significantly associated with dead during hospital admission: age (> or = 70 years)--1.48; infectious diseases--1.37; central nervous system diseases--2.28; chronic renal diseases--1.96; cardiac arrest--24.1; pulmonary embolism--2.26; acute renal failure--7.93; clinical signs of severe sodium and water retention--1.49; hyponatremia--3.39; other electrolyte abnormalities and acid-base balance disturbances--1.78. The simple linear regression of daily admissions on time produced a positive slope of 0.0002 (p < 0.002).
Conclusions: The hospital prevalence of congestive heart failure is identical to other Western countries and is greater among the elderly patients. Valve disease, coronary artery disease and hypertension are the most frequent causes of congestive heart failure. An increasing trend in hospital admissions for congestive heart failure was observed. The hospital mortality was reduced in the last 6 years and was greater among the elderly patients. Age (> or = 70 years), the presence of comorbidity (infectious disease, central nervous system disease, acute renal failure, chronic renal disease and pulmonary embolism), hyponatremia, other electrolyte abnormalities and acid-base balance disturbances, resuscitated cardiac arrest and the presence of severe sodium and water retention have prognostic significance.