Danielle A. Southern

Comparison of the Elixhauser and Charlson/Deyo methods of comorbidity measurement in administrative data.

Background:Comorbidity risk adjustment methods have been used widely with administrative data, and the Charlson/Deyo method is perhaps the most commonly used in the literature. However, a new method defined by Elixhauser et al. has been introduced recently and could be superior, although it has not been validated widely. Objectives:We compared the Charlson/Deyo and Elixhauser methods using Canadian administrative data on patients with myocardial infarction (MI). Research Design:We conducted a historical cohort study. Subjects:We used administrative hospital discharge data from a large Canadian city for all cases with acute MI coded as most responsible diagnosis between January 1, 1995, and March 31, 2001. Measures:We used each of the 2 methods to define comorbidity variables based on the International Classification of Diseases, 9th Revision, Clinical Modification codes present in each case record. We then compared 2 models predicting in-hospital mortality based on presence or absence of the variables defined by each of the methods. Frequency tables were produced and c-statistics and changes in −2 log likelihood (−2LogL) were calculated. We also visually assessed model performance by plotting observed and expected percentages of death for increasing risk categories defined by the 2 models. Results:The Elixhauser model outperformed the Charlson/Deyo model in predicting mortality, with higher c-statistic values (0.793 vs. 0.704). Superior performance of the Elixhauser method is confirmed when plotting the expected and observed risks of death across groupings of increasing risk, in which the Elixhauser method yields a wider range of predicted and observed probabilities of death across groupings (2.5%–33%) than does the Charlson/Deyo method (5%–25%). Conclusions:The Elixhauser comorbidity measurement method performs better than the widely used Charlson/Deyo method in the Canadian acute MI cases studied.

Survival After Coronary Revascularization Among Patients With Kidney Disease

Background—The optimal approach to revascularization in patients with kidney disease has not been determined. We studied survival by treatment group (CABG, percutaneous coronary intervention [PCI], or no revascularization) for patients with 3 categories of kidney function: dialysis-dependent kidney disease, non–dialysis-dependent kidney disease, and a reference group (serum creatinine <2.3 mg/dL). Methods and Results—Data were derived from the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH), which captures information on all patients undergoing cardiac catheterization in Alberta, Canada. Characteristics and patient survival in 662 dialysis patients (1.6%) and 750 non–dialysis-dependent kidney disease patients (1.8%) were compared with the remainder of the 40 374 patients (96.6%). For the reference group, the adjusted 8-year survival rates for CABG, PCI, and no revascularization (NR) were 85.5%, 80.4%, and 72.3%, respectively (P<0.001 for CABG versus NR; P<0.001 for PCI versus NR). Adjusted survival rates were 45.9% for CABG, 32.7% for PCI, and 29.7% for NR in the nondialysis kidney disease group (P<0.001 for CABG versus NR; P=0.48 for PCI versus NR) and 44.8% for CABG, 41.2% for PCI, and 30.4% for NR in the dialysis group (P=0.003 for CABG versus NR; P=0.03 for PCI versus NR). Conclusions—Compared with no revascularization, CABG was associated with better survival in all categories of kidney function. PCI was also associated with a lower risk of death than no revascularization in reference patients and dialysis-dependent kidney disease patients but not in patients with non–dialysis-dependent kidney disease. The presence of kidney disease or dependence on dialysis should not be a deterrent to revascularization, particularly with CABG.

Association of socio-economic status with diabetes prevalence and utilization of diabetes care services

BackgroundLow income appears to be associated with a higher prevalence of diabetes and diabetes related complications, however, little is known about how income influences access to diabetes care. The objective of the present study was to determine whether income is associated with referral to a diabetes centre within a universal health care system.MethodsData on referral for diabetes care, diabetes prevalence and median household income were obtained from a regional Diabetes Education Centre (DEC) database, the Canadian National Diabetes Surveillance System (NDSS) and the 2001 Canadian Census respectively. Diabetes rate per capita, referral rate per capita and proportion with diabetes referred was determined for census dissemination areas. We used Chi square analyses to determine if diabetes prevalence or population rates of referral differed across income quintiles, and Poisson regression to model diabetes rate and referral rate in relation to income while controlling for education and age.ResultsThere was a significant gradient in both diabetes prevalence (χ2 = 743.72, p < 0.0005) and population rates of referral (χ2 = 168.435, p < 0.0005) across income quintiles, with the lowest income quintiles having the highest rates of diabetes and referral to the DEC. Referral rate among those with diabetes, however, was uniform across income quintiles. Controlling for age and education, Poisson regression models confirmed a significant socio-economic gradient in diabetes prevalence and population rates of referral.ConclusionLow income is associated with a higher prevalence of diabetes and a higher population rate of referral to this regional DEC. After accounting for diabetes prevalence, however, the equal proportions referred to the DEC across income groups suggest that there is no access bias based on income.

Prediction of stroke or TIA in patients without atrial fibrillation using CHADS2 and CHA2DS2-VASc scores

Objectives To determine the accuracy of CHADS2 and CHA2DS2-VASc tools for predicting ischaemic stroke or transient ischaemic attack (TIA) and death in patients without a history of atrial fibrillation or flutter (AF). Methods The study included 20 970 patients without known AF enrolled in the Alberta Provincial Project for Outcomes Assessment in Coronary Heart disease (APPROACH) prospective registry who were discharged after an acute coronary syndrome (ACS) between 2005 and 2011. The outcome measures were incident ischaemic stroke, TIA or death from any cause. Results Over a median follow-up of 4.1 years, 453 patients (2.2%) had a stroke (n=297) or TIA (n=156) and 1903 (9.0%) died. The incidence of stroke or TIA increased with increases in each risk score (p<0.001), with an absolute annual incidence ≥1% with CHADS2 ≥3 or CHA2DS2-VASc ≥4. Both CHADS2 and CHA2DS2-VASc scores had acceptable discrimination performance (C-statistic=0.68 and 0.71, respectively). The mortality rate was also greater in patients with higher CHADS2 and CHA2DS2-VASc scores (p<0.0001). Conclusions In patients with ACS but no AF, the CHADS2 and CHA2DS2-VASc scores predict ischaemic stroke/TIA events with similar accuracy to that observed in historical populations with non-valvular AF, but with lower absolute event rates. Further study of the utility of the CHADS2 and CHA2DS2-VASc scores for the assessment of thromboembolic risk and selection of antithrombotic therapy in patients without AF is warranted.

Living Alone, Patient Sex and Mortality After Acute Myocardial Infarction

BACKGROUNDPsychosocial factors, including social support, affect outcomes of cardiovascular disease, but can be difficult to measure. Whether these factors have different effects on mortality post-acute myocardial infarction (AMI) in men and women is not clear.OBJECTIVETo examine the association between living alone, a proxy for social support, and mortality postdischarge AMI and to explore whether this association is modified by patient sex.DESIGNHistorical cohort study.PARTICIPANTS/SETTINGAll patients discharged with a primary diagnosis of AMI in a major urban center during the 1998–1999 fiscal year.MEASUREMENTSPatients’ sociodemographic and clinical characteristics were obtained by standardized chart review and linked to vital statistics data through December 2001.RESULTSOf 880 patients, 164 (18.6%) were living alone at admission and they were significantly more likely to be older and female than those living with others. Living alone was independently associated with mortality [adjusted hazard ratio (HR) 1.6, 95% confidence interval (CI) 1.0–2.5], but interacted with patient sex. Men living alone had the highest mortality risk (adjusted HR 2.0, 95% CI 1.1–3.7), followed by women living alone (adjusted HR 1.2, 95% CI 0.7–2.2), men living with others (reference, HR 1.0), and women living with others (adjusted HR 0.9, 95% CI 0.5–1.5).CONCLUSIONSLiving alone, an easily measured psychosocial factor, is associated with significantly increased longer-term mortality for men following AMI. Further prospective studies are needed to confirm the usefulness of living alone as a prognostic factor and to identify the potentially modifiable mechanisms underlying this increased risk.

Individual-level and neighborhood-level income measures: agreement and association with outcomes in a cardiac disease cohort.

Background:Census-based measures of income often are used as proxies for individual-level income. Yet, the validity of such area-based measures relative to ‘true’ individual-level income has not been fully characterized. Objectives:The objectives of this study were (1) to determine whether area-based measures of household income are a suitable proxy for self-reported household income and (2) to assess whether these measures are associated with outcomes in a cardiac disease cohort. Research Design:We used a prospective cohort from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH©) cardiac catheterization registry. Subjects:A total of 4372 patients having undergone cardiac catheterization and who also completed a 1-year follow-up questionnaire on self-reported income level were studied. Measures:Our measurements were survival to 2.5 years after catheterization and health-related quality of life (EuroQoL). Results:Agreement between the 2 income measures generally was poor (unweighted Kappa = 0.07), particularly for the low-income patients. Despite this poor agreement, both income measures were positively associated with survival and EuroQoL scores. An outcome analysis that simultaneously considered individual level income and area-based income revealed that low-income individuals have poorer survival and lower quality of life scores if they live in low income neighborhoods, but not if they live in high income neighborhoods. Conclusions:The area-based estimates of household income in these data demonstrate poor agreement with self-reported household income at the level of individual patients, particularly for low-income patients. Despite this, both income measures appear to be prognostically relevant, perhaps because individual and neighborhood income measure different constructs.

Lower extremity peripheral arterial disease in individuals with coronary artery disease: Prognostic importance, care gaps, and impact of therapy

BACKGROUND Our objective was to examine the effect of concomitant lower extremity peripheral arterial disease (PAD) on long-term prognosis and pharmacotherapy in patients with coronary artery disease (CAD). METHODS Prospective cohort study enrolling all patients with angiographically proven CAD between April 1, 2000, and December 31, 2004, in Alberta, Canada. RESULTS Of 28,649 patients (mean age 64 years) with CAD, 2509 (9%) had a physician-assigned diagnosis of lower extremity PAD. Mortality was higher in the patients with CAD and PAD over a mean follow-up of 3.1 years, even after adjusting for the fact that patients with PAD had more severe CAD and more comorbidities (adjusted hazard ratio [HR] 1.41, 95% CI 1.28-1.55). Fewer patients with CAD and PAD received antiplatelet agents (83% vs 86%, odds ratio 0.86, 95% CI 0.77-0.97) or beta-blockers (63% vs 67%, odds ratio 0.89, 95% CI 0.82-0.98), but users of these agents exhibited lower mortality (adjusted HR 0.68, 95% CI 0.60-0.77, for antiplatelet agents and adjusted HR 0.72, 95% CI 0.64-0.80, for beta-blockers). Approximately half of these patients were prescribed statins or angiotensin-converting enzyme inhibitors, and 27% were using all 3 evidence-based anti-atherosclerotic therapies (antiplatelets, statin, and angiotensin-converting enzyme inhibitor). CONCLUSIONS In patients with CAD, lower extremity PAD is independently associated with poorer outcomes. Although all evidence-based therapies are underused in patients with CAD, patients with concomitant PAD are less likely to be prescribed antiplatelet agents or beta-blockers--both agents are associated with improved survival in patients with CAD and PAD.

Women's Recovery from Sternotomy-Extension (WREST-E) Study: Examining Long-Term Pain and Discomfort Following Sternotomy and their Predictors

Objective: To examine incision and breast pain and discomfort, and their predictors in women 12 months following sternotomy. Design: Extension survey following participation in a clinical trial. Setting: 10 Canadian centres. Patients: Women (n = 326) who completed the Women’s Recovery from Sternotomy Trial. Interventions: None. Main outcome measures: Pain and discomfort data (numeric rating scales) collected by standardised interview at 5 days, 12 weeks and 12 months following sternotomy. Results: More patients reported having incision or breast discomfort (46.6%) than pain (18.1%) at 12 months postoperatively. No symptoms at 5 days postoperatively were significantly associated with symptom presence at 12 postoperative months. However, having incision pain and discomfort as well as breast pain and discomfort at 12 postoperative weeks was associated with incision pain (odds ratio (OR) = 3.26, 95% confidence interval (CI) 1.51 to 7.07), incision discomfort (OR = 4.87, 95% CI 3.01 to 7.88), breast pain (OR = 9.36, 95% CI 3.91 to 22.38) and breast discomfort (OR = 6.42, 95% CI 3.62 to 11.37), respectively, at 12 postoperative months. Increasing chest circumference was associated with having ongoing incision pain (OR = 1.12, 95% CI 1.03 to 1.21) and breast pain (OR = 1.10, 95% CI 1.00 to 1.22). Harvesting of bilateral internal mammary arteries (IMAs) was associated with having ongoing incision pain (OR = 4.71, 95% CI 1.54 to 14.3), while harvesting only the left IMA was associated with having ongoing breast pain (OR = 2.78, 95% CI 1.06 to 7.32) and breast discomfort (OR 1.80, 95% CI 1.02 to 3.19). Conclusions: Patients reported incision and breast pain and discomfort as long as 12 months post-sternotomy. Improved management of postoperative pain and discomfort up to at least 12 weeks following surgery may render reduced long-term pain and discomfort symptoms.

Characterizing Types of Readmission After Acute Coronary Syndrome Hospitalization: Implications for Quality Reporting

Background Thirty‐day readmission rates have been tied to hospital reimbursement in the United States, but remain controversial as measures of healthcare quality. We profile the timing, main diagnoses, and survival outcomes of inpatient and emergency department readmissions after acute coronary syndrome (ACS), based on a large regional database. Methods and Results Patients enrolled in the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) registry with an ACS hospitalization between April 2008 and March 2010 (n=3411) were included. Primary outcomes were inpatient and emergency department–only readmissions, at 30 days and 1 year. Predictors of 30‐day readmission were identified, and the association between 30‐day readmission status and mortality was evaluated. A total of 1170 (34.3%) patients had ≥1 hospital readmission within 30 days, reaching 2106 (61.7%) within 1 year of ACS discharge. Of first readmissions, 45% were emergency department only and 53% were for cardiovascular or possibly related diagnoses. Renal disease and diabetes predicted all‐cause readmissions at 30 days and 1 year, but there were no robust predictors of cardiovascular readmissions. Thirty‐day inpatient, but not emergency department, readmissions were associated with increased mortality. Conclusions Hospital readmissions within 30 days after discharge for ACS are common, and associated with increased mortality. However, our findings underline that readmissions are quite heterogeneous in nature, and that many readmissions are unrelated to index stay and thus not easily predicted with common clinical variables. All‐cause 30‐day readmission rates may be too simplistic, and perhaps even misleading, as a hospital performance metric.

Sex, Socioeconomic Status, Access to Cardiac Catheterization, and Outcomes for Acute Coronary Syndromes in the Context of Universal Healthcare Coverage

Background—Sex and neighborhood socioeconomic status (nSES) may independently affect the care and outcomes of acute coronary syndrome, partly through barriers in timely access to cardiac catheterization. We sought to determine whether sex modifies the association between nSES and the receipt of cardiac catheterization and mortality after an acute coronary syndrome in a universal healthcare system. Methods and Results—We studied 14 012 patients with acute coronary syndrome admitted to cardiology services between April 18, 2004, and December 31, 2011, in Southern Alberta, Canada. We used multivariable logistic regression to compare the odds of cardiac catheterization within 2 and 30 days of admission and the odds of 30-day and 1-year mortality for men and women by quintile of neighborhood median household income. Significant relationships between nSES and the receipt of cardiac catheterization and mortality after acute coronary syndrome were detected for women but not men. When examined by nSES, each incremental decrease in neighborhood income quintile for women was associated with a 6% lower odds of receiving cardiac catheterization within 30 days (P=0.01) and a 14% higher odds of 30-day mortality (P=0.03). For men, each decrease in neighborhood income quintile was associated with a 2% lower odds of receiving catheterization within 30 days (P=0.10) and a 5% higher odds of 30-day mortality (P=0.36). Conclusions—Associations between nSES and receipt of cardiac catheterization and 30-day mortality were noted for women but not men in a universal healthcare system. Care protocols designed to improve equity of access to care and outcomes are required, especially for low-income women.