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IIR 04-104 – HSR Study

IIR 04-104
Modifiable Determinants of Anti-Depressant Adherence Among Older Veterans
Helen C. Kales, MD
VA Ann Arbor Healthcare System, Ann Arbor, MI
Ann Arbor, MI
Funding Period: March 2007 - February 2011
Geriatric depression is often chronic, recurrent, and associated with significant suffering, disability, suicide risk and decreased quality of life. Most geriatric depression is treated in primary care where a substantial treatment gap exists. Research examining this treatment gap has focused on provider and system factors. Despite the success of collaborative care models to treat late-life depression, patient-level factors including poor participation and non-adherence limit the extent to which older patients realize the benefits of efficacious depression treatments. Older patients often fail to take antidepressants as prescribed; as many as 40% discontinue antidepressants prematurely. To develop interventions to increase depression treatments' effectiveness, it is critical to understand late-life adherence behaviors. In particular, we must examine factors for which future interventions would have impact. In previous non-VA studies, comorbid anxiety has been identified as one factor that appears to put depressed older patients at substantial risk for treatment non-adherence. Other important factors likely impact late-life antidepressant adherence, but little research has investigated this area.

The primary aims of this study were to: 1) assess the impact of clinically significant anxiety on antidepressant adherence in older veterans with depression and, 2) use qualitative and quantitative methods to examine other potentially modifiable determinants of adherence (e.g. beliefs, attitudes, social support, etc.).

This study used a sequential mixed-methods approach to identify and examine factors that impede late-life antidepressant adherence. Qualitative methods (focus groups) were used to guide the development of a subsequent prospective quantitative structured interview in the following ways: 1) suggesting other domains not yet considered or studied; 2) revealing potential mechanisms for the impact of these factors on adherence; and 3) informing the structured interview questions. Based on the qualitative results, we refined a structured interview instrument that assessed comorbid anxiety and other key constructs potentially determining adherence. Anxiety in particular was assessed using the Anxiety Sensitivity Index (ASI) for somatic anxiety; the Hospital Anxiety and Depression Scale (HADS) for generalized anxiety; and the Post-Traumatic Stress Disorder Checklist Military Version (PCLM) for PTSD. Participants in both portions of the study were identified via an algorithm using VistA/Cache.

The primary analysis examined the effect of comorbid anxiety on acute phase (first 4 months) antidepressant adherence. Secondary exploratory analyses assessed the role of other factors on acute phase adherence.
Overall, 98% of the study subjects initiated (e.g. took at least 1 dose) their antidepressant medication while 72% were adherent (took 80% or more of the prescribed doses) at four-month followup. Adherence rates were lower for : 1) African-American (48.4%) than for white patients (73.6%); 2) for patients with high school or less education (67.3%) than for college-educated patients (74.8%); 3) for patients without a partner (59.7%) than for patients with a partner (80.1%); 4) for patients in the Detroit site (66.27%) as compared to the Battle Creek (73.2%) or Ann Arbor sites (75.0%); and 5) for patients in non-psychiatric treatment settings (70.7%) than for patients seen in psychiatry (74.8%).
Contrary to our primary hypothesis, the three measures of anxiety did not have any effect on adherence in the overall sample in either crude and adjusted analyses. However, in analyses stratified by treatment setting (psychiatric vs. non-psychiatric), higher somatic anxiety and lower PTSD symptoms were associated with non-adherence among patients seen in psychiatry. Examining treatment setting differences further, we found that while some factors associated with non-adherence were similar between psychiatric and non-psychiatric settings (e.g. non-adherence associated with patients who were more likely to be older, less educated, African-American, without partners, with more medical and substance abuse comorbidity), other factors were different. In psychiatric settings, non-adherence was also associated with lower rates of past antidepressant exposure. In non-psychiatric settings, non-adherence was associated with greater depression severity, with lower somatic anxiety symptoms and with higher PTSD symptoms.

This research provided us with an insight and understanding of factors associated with late-life depression adherence behaviors. Such an understanding is essential for developing and testing interventions that will increase the effectiveness of existing depression treatments and collaborative care models, improving depression outcomes for a substantial number of older veterans.

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Journal Articles

  1. Ilgen MA, Zivin K, McCammon RJ, Valenstein M. Pain and suicidal thoughts, plans and attempts in the United States. General hospital psychiatry. 2008 Nov 1; 30(6):521-7. [view]
  2. Kales HC, Kavanagh J, Chiang C, Kim HM, Bishop T, Valenstein M, Blow FC. Predictors of Antidepressant Nonadherence Among Older Veterans With Depression. Psychiatric services (Washington, D.C.). 2016 Jul 1; 67(7):728-34. [view]
  3. Leggett A, Kavanagh J, Zivin K, Chiang C, Kim HM, Kales HC. The Association Between Benzodiazepine Use and Depression Outcomes in Older Veterans. Journal of geriatric psychiatry and neurology. 2015 Dec 1; 28(4):281-7. [view]
  4. Gerlach LB, Chiang C, Kales HC. The Start Predicts the Finish: Factors Associated With Antidepressant Nonadherence Among Older Veterans During the Acute and Maintenance Treatment Phases. The Journal of clinical psychiatry. 2019 Mar 26; 80(3). [view]
Conference Presentations

  1. Kales HC. Beyond Later-Life Depression: The Next Generation of Diagnosis and Management. Paper presented at: American Association for Geriatric Psychiatry Professional Development Meeting; 2010 Nov 12; Santa Monica, CA. [view]
  2. Kales HC, Valenstein MT, McCarthy JF, Kavanagh JS, Newman D, Blow FC. Current PTSD symptoms among older veterans with depression. Presented at: American Association for Geriatric Psychiatry Annual Meeting; 2009 Mar 6; Honolulu, HI. [view]
  3. Bambauer KZ, McCammon RJ, Davis MM, Halasyamani LK, Kales HC. Medicare prescription drug plan costs for psychiatric medications. Paper presented at: National Institute of Mental Health Mental Health Services Research Annual Conference; 2007 Jul 24; Washington, DC. [view]

DRA: Mental, Cognitive and Behavioral Disorders, Aging, Older Veterans' Health and Care
DRE: Treatment - Observational
Keywords: Access, Depression
MeSH Terms: none

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