Anxiety Express Report

Publication date: 2005-12-31

Adherence Patterns in Elderly Patients on SSRI Therapy for Anxiety

Expert Commentary

Provided by David V. Sheehan, MD, MBA, Professor of Psychiatry, Director of Psychiatric Research, University of South Florida College of Medicine, Tampa, Florida

Anxiety and depression are very prevalent in the elderly population, with 20% of patients (≥65 years of age) experiencing depressive disorder or subsyndromal depression,¹ and up to 20% of elderly patients experiencing some form of anxiety disorder.^2-4 Moreover, 37% of elderly individuals with a diagnosed anxiety disorder also have comorbid depression.^5-7 In addition to significant morbidity, anxiety and depression may diminish desired clinical and economic outcomes in treating other comorbidities in the elderly patient, such as congestive heart failure, coronary heart disease and diabetes. ^8,9

Diagnosis and subsequent treatment of anxiety disorders in the elderly patient is essential, as these disorders interfere with patient well being and daily functioning. ^10,11 Recent data has revealed a correlation between late life anxiety and subjective memory loss;¹² predictive of future cognitive decline. ¹²

The primary issues in the pharmacologic treatment of anxiety disorders in elderly patients are efficacy, safety, tolerability, and adherence to therapy. Benzodiazepines have been the most widely used pharmacologic agents for anxiety for a number of years. ^13,14 However, the use of benzodiazepines require special care in geriatric patients due to increased drug absorption and volume of distribution, as well as decreased hepatic metabolism, protein binding, and renal excretion. ¹⁵ Moreover, a recent US consensus panel concluded that benzodiazepines were potentially inappropriate for use in the elderly, independent of diagnosis or condition. ¹⁶ Accordingly, benzodiazepines will not be covered under the Medicare Prescription Drug, Improvement, and Modernization Act. ¹⁷

Selective serotonin reuptake inhibitors (SSRIs) are considered first-line therapy because of their ability to effectively improve the symptoms of anxiety; with established safety and tolerability profiles. Of the available SSRIs to treat anxiety disorders (fluox-etine, sertraline, citalopram, escitalopram), immediate-release paroxetine is the only FDA-approved agent indicated in all anxiety disorders, including post-traumatic stress disorder, obsessive-compulsive disorder, generalized anxiety disorder, panic disorder, and social anxiety disorder. ¹⁸

Despite the clinical efficacy of SSRIs for anxiety disorders, patients experience anxiety relapse rates as high as 27% to 39%.^13,19 A major factor in relapse may be the early discontinuation of therapy due to adverse events. Furthermore, the efficacy of any SSRI, including immediate-release paroxetine, is dependent on patient adherence to the medical regimen. Non-adherence with pharmacotherapy in the treatment of psychiatric disorders is common and has been reported in up to 60% of psychiatric patients. ²⁰ Such high rates of non-adherence result in poor clinical outcomes as well as increased treatment costs for relapse. ^20,21

Controlled-release (CR) paroxetine (Paxil CR) is the only extended-release SSRI that has a delayed and slower rate of absorption in the gastrointestinal tract, possibly reducing the likelihood of common SSRI adverse side effects that could lower discontin-uation rates. Indeed, CR paroxetine has been associated with superior patient adherence in naturalistic samples compared with immediate-release paroxetine, fluoxetine, sertraline, and citalopram. ²² A subsequent analysis that included escitalopram found similar results. ²³ Although these studies suggest improved adherence with CR paroxetine compared to immediate-release paroxetine in the general population, there are no studies that directly compare the two formulations of paroxetine in elderly patients. Such assessments are critically needed in elder