An Analysis of the Interactions Between Individual Comorbidities and Their Treatments-Implications for Guidelines and Polypharmacy

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. (J Am Med Dir Assoc 2010; 11: 475-484)