Epidemiology of idiopathic dilated cardiomyopathy in the elderly: Pooled results from two case-control studies

Although idiopathic dilated cardiomyopathy is often viewed as an affliction of young or middle-aged adults, morbidity and mortality rates from idiopathic dilated cardiomyopathy rise sharply with age and are highest in the elderly. To learn more about the determinants of this increasingly important cause of heart failure in the elderly, the authors conducted a pooled analysis of data from two case-control studies of idiopathic dilated cardiomyopathy carried out in Baltimore, Maryland (1984-1986), and Washington, DC (1990-1992). Identical diagnostic criteria and interviewing procedures had been used in both studies. All of the cases of idiopathic dilated cardiomyopathy had evidence of ventricular dilatation and hypokinesis, with a left ventricular ejection fraction of <40%. Cases with a history of coronary artery disease were excluded along with those with known secondary forms of cardiomyopathy. Up to two neighborhood controls of the same sex and approximate age (±5 years) were selected for each case using a random digit dialing technique. The subjects or a suitable surrogate was interviewed by telephone to obtain medical history information. The present analysis was limited to 94 cases and 152 matched controls who were at least 60 years of age. Conditional logistic regression methods were used in the analysis. Significant associations were observed with lower educational attainment and a history of hypertension (p < 0.05). The association with hypertension (relative odds = 2.2, 95% confidence interval 1.1-4.6) persisted after adjustment for race, education, and diabetes and was not accounted for by coronary angiography utilization patterns. The association with diabetes was of borderline significance (p < 0.10). The pattern of risk factors identified in this analysis may allow for the early identification of elderly persons who are at increased risk of idiopathic dilated cardiomyopathy.