International Journal for Quality in Health Care Advance Access originally published online on March 23, 2005
International Journal for Quality in Health Care 2005 17(3):255-258; doi:10.1093/intqhc/mzi026
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Differences in quality of care among patients hospitalized with atrial fibrillation as primary or secondary cause for admission
1 Saint Louis University, Saint Louis, MO, USA, 2 Michigan Peer Review Organization, Farmington Hills, MI, USA, 3 National Research Council, Brindisi, Italy, 4 The Duke Clinical Research Institute, Durham, NC
Objective. Several factors have been linked to the variation in the quality of care for patients with atrial fibrillation (AF). Whether hospitalization primarily for AF (primary diagnosis of AF) as opposed to another primary diagnosis but having concomitant AF (secondary diagnosis of AF) impacts quality of care for AF is not known. Accordingly, we sought to evaluate the differences in quality of care of Medicare patients admitted with primary diagnosis versus secondary diagnosis of AF.
Design and setting. We studied a random sample of Medicare fee-for-service discharges from Michigan’s acute care hospitals over a 1-year period with a primary or secondary diagnosis of AF (ICD-9-CM 427.31).
Main outcome measure. Warfarin use at the time of discharge.
Results. Of 5993 patients in the study, 772 had a primary diagnosis of AF and 5221 had a secondary diagnosis of AF. Patients with a secondary diagnosis of AF were older, more likely to be male, and less likely to be hypertensive. Patients with a secondary diagnosis of AF ‘ideal’ for anticoagulation (n = 1648) were less likely to receive warfarin compared with ‘ideal’ patients with primary diagnosis of AF (n = 363) (52.6% versus. 59.8%, P < 0.001). Adherence to test indicators was lower in patients with secondary diagnosis of AF.
Conclusion. Secondary diagnosis of AF rather than AF as a primary diagnosis appears to account for most Medicare patients with AF admitted to hospitals. Whereas quality of care is lower in patients with secondary diagnosis of AF, opportunity for quality improvement exists for both groups of patients with AF.
Keywords: atrial fibrillation, Medicare, quality of care
Address reprint requests to Rajendra H. Mehta, MD, MS; 2802 Leslie Park Circle; Ann Arbor, MI 48105. Tel: 734 668 7192; Fax: 734 668 7192. E-mail: mehta007{at}dcri.duke.edu
Accepted for publication January 5, 2005.
Randomized controlled trials of warfarin therapy have conclusively demonstrated that long-term anticoagulation therapy can effectively reduce the risk of thromboembolic complications in patients with atrial fibrillation (AF), including a two-thirds reduction in the risk of ischemic stroke [1–7]. This evidence supporting the benefit of warfarin led to incorporation of this therapy as a Class I recommendation for the prevention of stroke in patients with AF [8]. Unfortunately, there remains considerable variation in the use of anticoagulant therapy in patients with AF [9–13]. Physician surveys have identified patient (age, perceived risk of bleeding), physician (lack of knowledge of the guidelines, fear of complications), and health care system (lack of expertise or dedicated resources) -related factors that are associated with lower use of warfarin [14]. Yet, it is not known whether admission to a hospital with a primary diagnosis of AF (AF-primary) or for another primary reason where AF is a concomitant diagnosis (AF as a secondary cause for admission, AF-secondary) impacts the quality of care of these patients.
We investigated the quality of care of Medicare patients discharged with AF-primary compared with those with AF-secondary. We hypothesized that quality of care would not be affected by whether AF was a primary or secondary cause of admission, because of national guidelines [7] recommending similar treatments for both of these subgroups.
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We included Medicare fee-for-service discharges from all Michigan’s acute care (excluding Veteran’s Administration) hospitals (n = 136) from 1 July 1998 to 30 June 1999 with a primary or secondary discharge diagnosis of AF [International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 427.31]. Patients less than 65 years of age were excluded from the analysis.
The study population consisted of a 20% sample with a 5% over-sample of cases from each hospital. A limit of 85 cases was imposed on each hospital-specific sample. Medical records for each sampled hospitalization were forwarded to a national clinical data abstraction center, and data, including patient medical history, symptoms on arrival, electrocardiographic examination, in-hospital treatment, and discharge-treatment and disposition, were collected. Data quality was ensured through the use of trained technicians and software abstraction modules. Data abstraction accuracy was monitored by random record re-abstraction.
Quality of care was assessed by evaluating the proportion of patients in whom there was adherence to quality of care and test indicators among those that were considered ‘ideal’ for these indicators. The ‘ideal candidates’ for warfarin therapy included those patients meeting national guidelines for anticoagulant therapy [7], and without any contraindications to warfarin therapy. These contraindications included lone AF, planned surgery within 7 days of discharge or recent surgery, physician documentation of risk for falls, alcoholism/drug abuse (history or current), dual chamber pacemaker (history or current), schizophrenia/active psychosis (history or current), terminal illness, allergy to warfarin, complication related to warfarin, hepatic failure (history or current), endocarditis/pericarditis (within 6 months before hospitalization or current), extensive metastatic cancer (history or current), brain/central nervous cancer (history or current), seizures (history or current), malignant hypertension (history or current), CVA hemorrhagic (history or current), peptic ulcer (current), intracranial surgery/biopsy (current), hemorrhage (history or current), and physician documentation of rationale for not prescribing warfarin. The use of warfarin was determined among the ‘ideal’ patient cohort as the proportion of these patients receiving warfarin. Education regarding the risks and benefits of warfarin, and written discharge instructions were measured among patients discharged on warfarin. Patients with documented ‘new-onset’ AF were considered ideal candidates to be tested for thyroid function abnormality and left ventricular systolic dysfunction by echocardiography. Planned follow-up prothrombin time in those patients prescribed warfarin was assessed.
Statistical analysis
Summary statistics of the two groups (AF-primary versus AF-secondary) are presented as frequencies and percentages, mean ± standard deviation or as median and interquartile range. In all cases, missing data were not defaulted to negative and denominators reflect cases reported. Bivariate associations among the two groups for nominal variables are compared using Pearson 
2 tests, two-sided Fisher’s exact 2 testing, or two-tailed Student’s t-testing, as appropriate. Multivariate logistic regression analysis was performed using demographic variables and comorbid conditions to determine independent predictors of lack of warfarin use at discharge. SAS Version 8.1 (SAS Institute, Cary, NC, USA) was utilized for all analysis.
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Of 5993 patients with AF, 772 (13%) had AF-primary and 5221 (87%) had AF-secondary. The ‘ideal’ population for warfarin therapy consisted of 2011 patients (38.5% of the sample), of which 82% (1648) had AF-secondary. Within the ideal cohort, patients with AF-secondary were older (80 versus 76 years, P = 0.013) and were more likely to be male (43% versus 33%, P < 0.001) compared with patients with AF-primary. A higher proportion of patients with AF-secondary was admitted from (11% versus 3%, P < 0.001) or discharged to (22% versus 6%, P < 0.001) a skilled nursing facility, extended care facility, or an intermediate care facility. Most comorbid conditions were similar in the two groups with the exception of hypertension (37% versus 52%, P < 0.001) and stroke/transient ischemic attack (20% versus 25%, P = 0.042), which was less common among patients with AF-secondary. There were no significant differences in the history of congestive heart failure, coronary artery disease, diabetes, chronic obstructive pulmonary disease, or pneumonia between the two groups. Mortality rates at 30 days and at 1 year were higher in patients with AF-secondary than in patients with AF-primary (5.8% versus 2.5%, P < 0.01 and 28.3% versus 11%, P < 0.001, respectively).
Table 1 shows the compliance in the two comparison groups with regard to quality of care indicators. Patients with AF-secondary were less likely to receive warfarin at discharge than those with AF-primary among the ‘ideal’ cohort. After multivariate adjustments, AF-secondary remained independently associated with less use of warfarin (odds ratio 1.27, 95% confidence interval 1.10–1.61, P = 0.048). Documented education regarding warfarin, a scheduled follow-up for the measurement of prothrombin time, documentation of the performance of an echocardiogram, or thyroid function testing was lower among patients with AF-secondary than among those with AF-primary.
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Our data show that only one of seven patients discharged from a hospital with AF had this condition as a primary diagnosis. In contrast, in the vast majority of patients with AF, the primary reason for admission was not AF, but other non-cardiac and cardiac conditions. Despite the older age of patients with AF-secondary most comorbid conditions did not differ between the two groups and yet mortality at 30 days and 1 year was significantly higher in patients with AF-secondary than in those with AF-primary. Contrary to our hypothesis, quality of care for these high-risk patients with AF-secondary was generally inferior to those admitted with AF-primary. The adherence to the use of warfarin at discharge (quality of care indicator) and all test indicators were consistently lower in these patients than for patients with AF-primary. After adjustment for differences in age, gender, race, comorbidities, and the teaching status of the hospitals, AF-secondary remained the only independent predictor of warfarin non-use. Nonetheless, we would like to point out that even of those patients with AF-primary, 40% were not prescribed warfarin at discharge despite no contraindications for it, identifying the opportunity for further quality improvement efforts in both these groups of AF patients.
Although we are unable to determine the reason for the lower adherence to warfarin and other test indicators in patients with AF-secondary, we believe that this may be due to the fact that physicians may be focusing on the primary and the more immediate life-threatening problem, ignoring the coexisting more chronic problems that may not have an immediate impact on short-term or in-hospital outcome. It is also likely that in the current era of managed-care and the push to decrease in-patient length of stay, physicians may just be addressing the primary reason for admission, leaving secondary issues/problems to be resolved in an outpatient setting. Additionally, this may be related to differences in the documentation of contraindication to warfarin between the two groups.
Finally, strategies to improve adherence to key indicators should be directed towards care-givers and patients and include the use of automated physician treatment reminders, continuing physician and nursing education, patient education as to the benefits and risks of anticoagulation and importance of monitoring, nursing critical-care pathways, and the use of reprinted orders and discharge instructions, preferably in combination for all patients with AF [15,16]. Each institution should customize these tools to fit their own needs to improve care-giver buy-in and target all patients with AF.
Our study should be viewed in the light of its limitations. Only Medicare fee-for-service patients were included and caution needs to be exerted while generalizing data to other non-Medicare patients with AF. Retrospective analysis was performed through chart review and as such is subject to ascertainment bias. No follow-up data were available, thus limiting our ability to identify patients who were started on coumadin as outpatients. Nonetheless, data from recent study suggest that if the opportunity for care is missed in-hospital, then these life-saving therapies are not very likely to be started as outpatients.
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CMS Disclaimer: The analyses on which this publication is based were performed under contract number 500-02-MI-02, Utilization and Quality Control Quality Improvement Organization for the State of Michigan and sponsored by the Centers for Medicare & Medicaid Services (CMS), Department of Health and Human Services. The content of this article does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. government. The authors assume full responsibility for the accuracy and completeness of the ideas presented. The article is a result of the Health Care Quality Improvement Program initiated by the CMS, which has encouraged identification of quality improvement projects derived from analysis of patterns of care, and therefore required no special funding on the part of this contractor. Ideas and contributions to the authors concerning experience is engaging with issues presented are welcomed.
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