An analysis of the interactions between individual comorbidities and their treatments--implications for guidelines and polypharmacy.

ABSTRACT

BACKGROUND: With aging there is an increase in frailty and chronic disease leading to a potential increase in medication use. Most clinical trials have excluded old, frail individuals and have failed to take into account the effects of outcome interaction. METHODS AND RESULTS: In this article we provide a mathematical model demonstrating that comorbidities, including old age, interact with therapies, reducing their effectiveness. CONCLUSION: These findings question the validity of single disease guidelines in old persons or in persons with multiple chronic diseases.