HSR&D Home » Research » IIR 04-248 – HSR&D Study
Stroke Prevention in Atrial Fibrillation: Impact of Mental Illness
Susan M Frayne, MD MPH
VA Palo Alto Health Care System, Palo Alto, CA
Palo Alto, CA
Funding Period: April 2005 - March 2010
Atrial fibrillation (AF) is a major cause of preventable stroke; anticoagulation with warfarin decreases stroke risk, but warfarin's narrow therapeutic window necessitates careful monitoring of labs (INR). Clinicians may have concerns that patients with mental health conditions (MHC) will not be able to take warfarin safely. It is not known how often patients with MHC receive anticoagulation therapy, nor how they fare on it.
Primary objectives were to characterize warfarin eligibility and to determine whether processes of care (receipt of warfarin, INR lab monitoring, Time in Therapeutic Range of INR [TTR]) and outcomes (strokes, hemorrhages, death) differ for patients with and without MHC.
For VA patients with AF (based on VA National Patient Care Database [NPCD] and Medicare administrative data), in FY04 we identified processes of care from Decision Support System, supplemented with Medicare data. We identified outcomes from VA's Vital Status file and from NPCD and Medicare data. Patients had one of 15 MHCs (derived from AHRQ's Clinical Classifications Software) if they had an ICD9 code for MHC prior to FY04 and a confirmatory ICD9 code during the study period.
In our main cohort, 22,261 had MHC and 103,442 had no MHC. Key findings were as follows:
(1) Most AF patients with MHC and without MHC (97% of each group) were warfarin-eligible based upon a CHADS2 stroke risk score of 1 or more. More of those with MHC than without MHC had high stroke risk: 83% versus 82% had a CHADS2 score of 2 or more, and 62% versus 57% had a score of 3 or more. However, risk factors for hemorrhage were also more common in patients with MHC: for example, 1.2% versus 0.5% had a history of intracranial hemorrhage, 27% versus 20% had a history of other hemorrhage, 17% versus 3% had a history of dementia, and 2% versus 1% had a history of cirrhosis.
(2) In unadjusted analyses, patients with MHC were less likely than those with no MHC to receive warfarin (48% versus 52%, respectively). This pattern remained even after adjusting for age, sex, race/ethnicity, CHADS2 stroke risk score, and bleeding risk: AOR 0.80. Among AF patients treated with warfarin, those with MHC had more regular INR monitoring (AOR 1.24 for monthly monitoring in patients with versus without MHC, adjusting for age, sex, race/ethnicity and physical comorbidity index). However, those with MHC spent less time in the therapeutic range of INR: median TTR was 0.61 versus 0.68, respectively. Furthermore, fewer patients with MHC (54%) than without MHC (62%) had a TTR above the desired threshold of 0.58; this finding persisted in adjusted analyses (AOR 0.78 after adjusting for sociodemographics and physical comorbidity).
(3) Among both warfarin-treated patients and among patients not treated with warfarin, those with MHC had worse outcomes (strokes, major hemorrhages, death) than did those without MHC. These differences persisted after adjustment for sociodemographic characteristics and comorbidity. Among those treated with warfarin, 20% of those with MHC versus 16% of those without MHC had at least one adverse outcome (adjusted OR 1.27). Among those who did not receive warfarin, adjusted OR was 1.46 for the composite outcome.
(4) The association between MHC and processes/outcomes of AF care varied by specific MHC type. Outcomes tended to be worst in those with alcohol use disorders or psychosis. For example, among warfarin-treated patients, for the composite outcome (stroke, hemorrhage or death), adjusted OR was depression 1.24, PTSD 1.32, other anxiety 1.07 (NS), psychotic disorders 1.51 and alcohol use disorders 1.40, respectively.
Clinicians should take MHC into account when developing a treatment plan for patients with MHC, since MHC may confer excess risk for adverse outcomes in anticoagulated patients. However, the risks versus benefits in an individual patient need to be carefully considered, and presence of MHC should not be considered an absolute contraindication to anticoagulation. The subset of warfarin-treated MHC patients who have alcohol use disorders or psychotic disorders may represent a group at particularly high risk of out-of-range INR values and adverse outcomes; if clinicians decide to treat them with warfarin, it is possible that adjunct measures, such as AF case management, may enhance safety of anticoagulation care. This study is part of an emerging body of evidence suggesting that processes and outcomes of medical care can be worse in patients with mental illness.
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DRA: Health Systems, Mental, Cognitive and Behavioral Disorders
Keywords: Patient outcomes, Stroke, VA/non-VA comparisons
MeSH Terms: none