Positive predictive value of the diagnosis of acute myocardial infarction in an administrative database

Adolescent overweight and future adult coronary heart disease

BACKGROUND

The effect of adolescent overweight on future adult coronary heart disease (CHD) is not known.

METHODS

We estimated the prevalence of obese 35-year-olds in 2020 on the basis of adolescent overweight in 2000 and historical trends regarding overweight adolescents who become obese adults. We then used the CHD Policy Model, a state-transition computer simulation of U.S. residents who are 35 years of age or older, to project the annual excess incidence and prevalence of CHD, the total number of excess CHD events, and excess deaths from both CHD and other causes attributable to obesity from 2020 to 2035. We also modeled the effect of treating obesity-related increases in blood pressure and dyslipidemia.

RESULTS

Adolescent overweight is projected to increase the prevalence of obese 35-year-olds in 2020 to a range of 30 to 37% in men and 34 to 44% in women. As a consequence of this increased obesity, an increase in the incidence of CHD and in the total number of CHD events and deaths is projected to occur in young adulthood. The increase is projected to continue in both absolute and relative terms as the population reaches middle age. By 2035, it is estimated that the prevalence of CHD will increase by a range of 5 to 16%, with more than 100,000 excess cases of CHD attributable to the increased obesity. Aggressive treatment with currently available therapies to reverse modifiable obesity-related risk factors would reduce, but not eliminate, the projected increase in the number of CHD events.

CONCLUSIONS

Although projections 25 or more years into the future are subject to innumerable uncertainties, extrapolation from current data suggests that adolescent overweight will increase rates of CHD among future young and middle-aged adults, resulting in substantial morbidity and mortality.

Effects of statin therapy on preventing atrial fibrillation in coronary disease and heart failure

BACKGROUND

Statins are associated with decreased incidence of life-threatening arrhythmias in patients with cardiomyopathy and reduce death and hospitalization in congestive heart failure (CHF). We hypothesized that statin use will reduce incident atrial fibrillation (AF) in patients with coronary heart disease (CHD), including those with CHF.

METHODS

A cohort of 17,741 patients with CHD examined between 1994 and 1997 at 5 Veterans Affairs medical facilities was assembled. Patients with known AF, warfarin treatment, liver disease, or no follow-up visits were excluded. The final cohort included 13,783 patients. The primary outcome was time to development of AF. Propensity scores were used to balance statin-treated and untreated patients with respect to baseline characteristics. Time from the initial visit to development of AF was analyzed with a Cox regression model, using statin treatment as a time-varying covariate.

RESULTS

Among the 13,783 patients, 5417 (39%) received statin treatment. Statin-treated patients were younger with fewer comorbid conditions. After propensity adjustment, the baseline characteristics of the statin-treated and untreated patients were similar. During an average follow-up of 4.8 years, 1979 (14%) patients developed AF. In the overall study population there was no difference in AF incidence with statin treatment (hazard ratio 1.0, 95% CI 0.88-1.14, P = .9). However, AF was less common among statin-treated patients with CHF (hazard ratio 0.57, 95% CI 0.33-1.00, P = .04).

CONCLUSIONS

We did not find any effect of statin treatment on AF incidence in patients with CHD; however, AF was reduced in a subset of patients with CHF.

A comparison of pioglitazone and rosiglitazone for hospitalization for acute myocardial infarction in type 2 diabetes

BACKGROUND

Recent studies have raised concerns about potential increased cardiovascular (CV) risk in type 2 diabetes patients treated with some peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonists.

OBJECTIVE

To ascertain the risk of hospitalization for acute myocardial infarction (AMI) in type 2 diabetes patients treated with pioglitazone relative to rosiglitazone.

METHODOLOGY

Using data covering 2003-2006 from a large health care insurer in the US, a retrospective cohort study was conducted in patients who initiated treatment with pioglitazone or rosiglitazone. The hazard ratio (HR) of incident hospitalization for AMI after initiation of treatment with these drugs was estimated from multivariate Cox's proportional hazards survival analysis; similarly, the HR was ascertained for hospitalization for the composite endpoint of AMI or coronary revascularization (CR).

RESULTS

A total of 29 911 eligible patients were identified in the database; 14 807 in the pioglitazone and 15 104 in the rosiglitazone group. Baseline demographics, medical history, and dispensed medications were generally well balanced between groups. The unadjusted HR for hospitalization for AMI was 0.82, 95%CI: 0.67-1.01. After adjustment for baseline covariates the HR was 0.78, 95%CI: 0.63-0.96. The adjusted HR for the composite of AMI or CR was 0.85, 95%CI: 0.75-0.98.

CONCLUSION

This retrospective cohort study showed that pioglitazone, in comparison with rosiglitazone, is associated with a 22% relative risk reduction of hospitalization for AMI in patients with type 2 diabetes.

Quality of care for gout in the US needs improvement

OBJECTIVE

To examine evidence-based quality indicators (QIs) in US veterans with gout diagnosis, and to examine the effect of demographics, heath care utilization/access, comorbid conditions, or physican characteristics as predictors of quality of gout care.

METHODS

Using the Minneapolis Veterans Affairs electronic medical record system, we identified a cohort of veterans receiving medication to treat gout between January 1, 1999 and December 31, 2003, and evaluated 3 recently published evidence-based QIs for gout management: QI 1 = allopurinol dose <300 mg in gout patients with renal insufficiency, QI 2 = uric acid check within 6 months of starting a new allopurinol prescription, and QI 3 = complete blood count and creatine kinase check every 6 months for gout patients receiving prolonged colchicine therapy. We calculated the proportion of patients whose therapy adhered to each QI and to all applicable indicators (overall physician adherence). Logistic regression analysis examined association of overall physician adherence with sociodemographics, health care utilization, comorbidity, and provider characteristics.

RESULTS

Of 3,658 patients with a diagnosis of gout, 663 patients qualified for examination of >/=1 QI. Of these 663 patients, therapy in only 144 (22%) adhered to all applicable QIs; 59 (78%) of 76 adhered to QI 1, 155 (24%) of 643 adhered to QI 2, and 18 (35%) of 52 adhered to QI 3. Overall physician adherence to QIs was significantly lower in older veterans and in those with more inpatient visits per year, but was higher in those with more primary care visits or more health care providers.

CONCLUSION

Suboptimal physician adherence to QIs was seen for all 3 QIs tested in this cohort of veterans with gout. These findings can guide quality improvement efforts.

Cyclooxygenase-2 selectivity of non-steroidal anti-inflammatory drugs and the risk of myocardial infarction and cerebrovascular accident

AIM

To assess degree of cyclooxygenase-2 (COX-2) selectivity of a non-steroidal anti-inflammatory drug (NSAID) and risk of myocardial infarction (MI) or cerebrovascular accident (CVA).

METHODS

Prescription fill data were linked to medical records of a merged VA-Medicare dataset. NSAIDs were categorized by Cox-2 selectivity. Incidence of CVA and MI within 180 days of index prescription was assessed using Cox-proportional hazards models adjusted for gender, race, cardiovascular and pharmacological risk factors and propensity for prescription of highly COX-2 selective NSAIDs.

RESULTS

Of 384,322 patients (97.5% men and 85.4% white), 79.4% were prescribed a poorly selective, 16.4% a moderately selective and 4.2% a highly selective NSAID. There were 985 incident cases of MI and 586 cases of CVA in >145 870 person-years. Highly selective agents had the highest rate of MI (12.3 per 1000 person-years; [95% CI: 12.2-12.3]) and CVA (8.1 per 1000 person-years; [95% CI: 8.0-8.2]). Periods without NSAID exposure were associated with lowest risk. In adjusted models, highly selective COX-2 selective NSAIDs were associated with a 61% increase in CVA and a 47% increase in MI, when compared with poorly selective NSAIDs.

CONCLUSIONS

The risk of MI and CVA increases with any NSAID. Highly COX-2 selective NSAIDs confer the greatest risk.

Validity of gout diagnoses in administrative data

OBJECTIVE

To determine the utility of using administrative data for epidemiologic studies of gout by examining the validity of gout diagnoses in claims data.

METHODS

From a population of approximately 800,000 members from 4 managed care plans, we identified patients who had at least 2 ambulatory claims for a diagnosis of gout between January 1, 1999 and December 31, 2003. From this group, a random sample of 200 patients was chosen for medical record review. Trained medical record reviewers abstracted gout-related clinical, laboratory, and radiologic data from the medical records. Two rheumatologists independently evaluated the abstracted information and assessed whether the gout diagnosis was probable/definite or unlikely/insufficient information. Discordant physician ratings were adjudicated by consensus. Based on record reviews, patients were also classified according to the American College of Rheumatology (ACR), Rome, and New York gout criteria and these results were compared with the physician global assessments.

RESULTS

There were 121 patients rated as having probable/definite gout by physician consensus, leading to a positive predictive value of >or=2 coded diagnoses of gout of 61% (95% confidence interval 53-67). There was low concordance between physician assessments and established gout criteria including ACR, Rome, and New York criteria (kappa = 0.17, 0.16, and 0.20, respectively).

CONCLUSION

Use of administrative data alone in epidemiologic and health services research on gout may lead to misclassification. Medical record reviews for validation of claims data may provide an inadequate gold standard to confirm gout diagnoses.

Health care resource utilization and expenditures associated with the use of insulin glargine

BACKGROUND

Newer insulins, such as long-acting analogues, offer promise of better glycemic control, reduced risk for diabetes complications, and moderation of health care use and costs.

OBJECTIVE

We studied initiation of insulin glargine to evaluate its association with subsequent health service utilization and estimated expenditures.

METHODS

Patients of the Veterans Health Administration, US Department of Veterans Affairs (VA) who initiated insulin glargine (n=5064) in 2001-2002 were compared with patients receiving other insulin (n=69,944), matched on prescription month (index date). Inpatient and outpatient VA care in the 12 months after a patient's index date was evaluated using Tobit regression, controlling for prior utilization, demographic characteristics, comorbidities, glycosylated hemoglobin (HbA(1c)) levels, and diabetes severity. National average utilization costs and medication acquisition costs were used to estimate the value of VA expenditures.

RESULTS

Compared with other insulin users, insulin glargine initiators had higher HbA(1c) values (8.72% vs 8.16%) prior to the index date, but greater subsequent HbA(1c) reduction (-0.50% vs -0.22%). After adjustment for age, prior utilization, HbA(1c) levels, and other factors, insulin glargine initiation was associated with 2.4 (95% CI, 1.1-3.7) fewer inpatient days for patients with any hospital admission (US $820 lower costs per initiator), 1.6 (1.2-1.9) more outpatient encounters ($279 higher costs per initiator), and $374 ($362-$387) higher costs for diabetes medications. The net difference was an average lower VA cost of $166 (-$290 to $622) per patient.

CONCLUSIONS

Insulin glargine use was associated with decreased inpatient days but increased outpatient care, and the value of the net change in utilization to VA offset the additional medication expenditures. Initiation of insulin glargine improves glycemic control and may reduce time in hospital without additional use of health resources.

Suboptimal control of atherosclerotic disease risk factors after cardiac and cerebrovascular procedures

BACKGROUND AND PURPOSE

Undergoing a carotid endarterectomy, a coronary artery bypass graft, or a percutaneous coronary intervention provides an opportunity to optimize control of blood pressure and low-density lipoprotein.

METHODS

Using Veterans Administration databases, we determined whether patients who underwent a carotid endarterectomy (n=252), coronary artery bypass graft (n=486), or percutaneous coronary intervention (n=720) in 2002 to 2003 at 5 Veterans Administration Healthcare Systems had guideline-recommended control of blood pressure and low-density lipoprotein in 12-month periods before and after a vascular procedure. Postprocedure control of risk factors across procedure groups was compared using chi(2) tests and multivariate logistic regression.

RESULTS

The proportion of patients undergoing carotid endarterectomy who had optimal control of both blood pressure and low-density lipoprotein increased from 23% before the procedure to 33% after the procedure (P=0.05) compared with increases from 32% to 43% for coronary artery bypass graft (P=0.001) and from 29% to 45% for percutaneous coronary intervention (P=0.002). Compared with the carotid endarterectomy group, the percutaneous coronary intervention group was more likely to achieve optimal control of blood pressure (OR: 1.92, 95% CI: 1.42 to 2.59) or low-density lipoprotein (OR: 1.51, 95% CI: 1.01 to 2.26) and the coronary artery bypass graft group was more likely to achieve optimal control of blood pressure (OR: 1.53, 95% CI: 1.42 to 2.59). Postprocedure cardiology visits, increase in medication intensity, and greater frequency of outpatient visits were also associated with optimal postprocedure risk factor control.

CONCLUSIONS

Although modest improvements in risk factor control were detected, a majority of patients in each vascular procedure group did not achieve optimal risk factor control. More effective risk factor control programs are needed among most vascular procedure patients.

Adherence to cardioprotective medications and mortality among patients with diabetes and ischemic heart disease

BACKGROUND

Patients with diabetes and ischemic heart disease (IHD) are at high risk for adverse cardiac outcomes. Clinical practice guidelines recommend multiple cardioprotective medications to reduce recurrent events. We evaluated the association between cardioprotective medication adherence and mortality among patients with diabetes and IHD.

METHODS

In a retrospective cohort study of 3,998 patients with diabetes and IHD, we evaluated use of ACE inhibitors or angiotensin receptor blockers, beta-blockers, and statin medications. Receipt of cardioprotective medications was based on filled prescriptions. Medication adherence was calculated as the proportion of days covered (PDC) for filled prescriptions. The primary outcome of interest was all-cause mortality.

RESULTS

The majority of patients (92.8%) received at least 1 cardioprotective medication. Patients receiving any medications had lower unadjusted mortality rates compared to patients not receiving any medications (7.9% vs. 11.5%; p = 0.03). In multivariable analysis, receipt of any cardioprotective medication remained associated with lower all-cause mortality (OR 0.65; 95% CI 0.43-0.99). Among patients receiving cardioprotective medications, the majority (80.3%) were adherent (PDC > or = 0.80). Adherent patients had lower unadjusted mortality rates (6.7% vs. 12.1%; p < 0.01). In multivariable analysis, medication adherence remained associated with lower all-cause mortality (OR 0.52; 95% CI 0.39-0.69) compared to non-adherence. In contrast, there was no mortality difference between patients receiving cardioprotective medications who were non-adherent compared to patients not receiving any medications (OR 1.01; 95% CI 0.64-1.61).

CONCLUSION

In conclusion, medication adherence is associated with improved outcomes among patients with diabetes and IHD. Quality improvement interventions are needed to increase medication adherence in order for patients to maximize the benefit of cardioprotective medications.

Clinical teaching and clinical outcomes: teaching capability and its association with patient outcomes

BACKGROUND

There is little research on the impact of medical education on patient outcome. We studied whether teaching capability is associated with altered short-term patient outcomes.

METHODS

We performed a multicentre retrospective cross-sectional study involving 40 clinician teachers who had attended on the general internal medicine services in hospitals affiliated with the University of Toronto along with the clinical outcomes of consecutive patients treated for community-acquired pneumonia, congestive heart failure, chronic obstructive pulmonary disease and gastrointestinal bleeding (n = 4377) between 1999 and 2001. Doctors were characterised by teaching effectiveness scores (n = 677) as high-rated or low-rated according to house staff ratings.

RESULTS

There was no correlation between the teaching effectiveness scores and the mean length of stay for those patients treated for community-acquired pneumonia (high-rated = 10.3 versus low-rated = 8.1 days, P = 0.058), congestive heart failure (high-rated = 10.1 versus low-rated = 9.9 days, P = 0.978), chronic obstructive pulmonary disease (high-rated = 9.4 versus low-rated = 9.9 days, P = 0.419) and gastrointestinal bleeding (high-rated = 6.3 versus low-rated = 6.8 days, P = 0.741). In addition, we observed no significant correlation between teaching effectiveness scores and 7-day, 28-day and 1-year readmission rates for all pre-specified diagnoses.

CONCLUSION

There is no large correlation between teaching effectiveness scores and short-term patient outcomes, suggesting that doctor teaching capabilities, as perceived by house staff, does not generally impact clinical care.

Revascularization and cardioprotective drug treatment in myocardial infarction patients: how do they impact on patients' survival when delivered as usual care

Background

Randomized clinical trials showed the benefit of pharmacological and revascularization treatments in secondary prevention of myocardial infarction (MI), in selected population with highly controlled interventions. The objective of this study is to measure these treatments' impact on the cardiovascular (CV) mortality rate among patients receiving usual care in the province of Quebec.

Methods

The study population consisted of a "naturalistic" cohort of all patients ≥ 65 years old living in the Quebec province, who survived a MI (ICD-9: 410) in 1998. The studied dependant variable was time to death from a CV disease. Independent variables were revascularization procedure and cardioprotective drugs. Death from a non CV disease was also studied for comparison. Revascularization procedure was defined as percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass graft (CABG). The exposure to cardioprotective drugs was defined as the number of cardioprotective drug classes (Acetylsalicylic Acid (ASA), Beta-Blockers, Angiotensin-Converting Enzyme (ACE) Inhibitors, Statins) claimed within the index period (first 30 days after the index hospitalization). Age, gender and a comorbidity index were used as covariates. Kaplan-Meier survival curves, Cox proportional hazard models, logistic regressions and regression trees were used.

Results

The study population totaled 5596 patients (3206 men; 2390 women). We observed 1128 deaths (20%) within two years following index hospitalization, of them 603 from CV disease. The CV survival rate at two years is much greater for patients with revascularization, regardless of pharmacological treatments. For patients without revascularization, the CV survival rate increases with the number of cardioprotective drug classes claimed. Finally, Cox proportional hazard models, regression tree and logistic regression analyses all revealed that the absence of revascularization and, to a lower extent, absence of cardioprotective drugs were major predictors for CV death, even after adjusting for age, gender and comorbidity.

Conclusion

Considering usual care management of MI in the province of Quebec in 1998, CV survival is positively correlated to the presence of a revascularization procedure and to the intensity of cardioprotective pharmacological treatment. These results are coherent with data from randomized control trials.

Access to myocardial revascularization procedures: closing the gap with time?

Background

Early access to revascularization procedures is known to be related to a more favorable outcome in myocardial infarction (MI) patients, but access to specialized care varies widely amongst the population. We aim to test if the early gap found in the revascularization rates, according to distance between patients' location and the closest specialized cardiology center (SCC), remains on a long term basis.

Methods

We conducted a population-based cohort study using data from the Quebec's hospital discharge register (MED-ECHO). The study population includes all patients 25 years and older living in the province of Quebec, who were hospitalized for a MI in 1999 with a follow up time of one year after the index hospitalization. The main variable is revascularization (percutaneous transluminal coronary angioplasty or a coronary artery bypass graft). The population is divided in four groups depending how close they are from a SCC (<32 km, 32–64 km, 64–105 km and ≥105 km). Revascularization rates are adjusted for age and sex.

Results

The study population includes 11,802 individuals, 66% are men. The one-year incidence rate of MI is 244 individuals per 100,000 inhabitants. At index hospitalization, a significant gap is found between patients living close (< 32 km) to a SCC and patients living farther (≥32 km). During the first year, a gap reduction can be observed but only for patients living at an intermediate distance from the specialized center (64–105 km).

Conclusion

The gap observed in revascularization rates at the index hospitalization for MI is in favour of patients living closer (< 32 km) to a SCC. This gap remains unchanged over the first year after an MI except for patients living between 64 and 105 km, where a closing of the gap can be noticed.

Cardiovascular morbidity associated with nonadherence to statin therapy

STUDY OBJECTIVE

To measure the extent of cardiovascular morbidity associated with nonadherence to 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) therapy.

DESIGN

Retrospective cohort study.

DATA SOURCE

Linked administrative health databases in Saskatchewan, Canada.

PATIENTS

A total of 1221 patients aged 30-70 years who received a new prescription for a statin drug between 1994 and 2001, within 1 year of their first cardiovascular event (i.e., myocardial infarction, unstable angina, ischemic stroke, percutaneous transluminal coronary angioplasty [PTCA], or coronary artery bypass graft [CABG]).

MEASUREMENTS AND MAIN RESULTS

Adherence was measured by the fill frequency (number of prescriptions filled during the observation period divided by months of observation). Patients with a fill frequency of 80% or greater were classified as adherent (661 patients); those with a fill frequency of 60% or less were classified as nonadherent (395 patients). The remaining 165 patients who had adherence rates of 61-79% were excluded from the analysis. The primary end point included a composite of myocardial infarction, unstable angina, PTCA, CABG, and death. Among 1056 patients, adherence was not associated with a reduction of the primary end point. However, patients in the adherent group were half as likely to experience a subsequent myocardial infarction as the patients in the nonadherent group (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.20-0.99, p=0.047). In patients younger than 65 years (both adherent and not), the associated reduction in myocardial infarction was even more profound (HR 0.14, 95% CI 0.04-0.46, p=0.001) and was accompanied by a trend for a lower frequency of unstable angina (HR 0.37, 95% CI 0.13-1.03, p=0.06). In patients 65 years or older (301 patients), adherence was not associated with significant changes in cardiovascular end points.

CONCLUSION

A detectable excess of cardiovascular morbidity appears to be associated with nonadherence to statin therapy. Our analysis suggests that many occurrences of myocardial infarction could be prevented with improvements in adherence. Larger studies are necessary to determine the association between adherence and other cardiovascular end points.

Potentially inappropriate prescribing in elderly veterans: are we using the wrong drug, wrong dose, or wrong duration?

OBJECTIVES

To identify the extent of inappropriate prescribing using criteria for proper use developed by the Agency for Healthcare Research and Quality (AHRQ) and dose-limitation criteria defined by Beers, as well as to describe duration of use and patient characteristics associated with inappropriate prescribing for older people.

DESIGN

Retrospective national Veterans Health Administration (VA) administrative database analysis.

SETTING

VA outpatient facilities during fiscal year 2000 (FY00).

PARTICIPANTS

Veterans aged 65 and older having at least one VA outpatient visit in FY00 (N=1,265,434).

MEASUREMENTS

Operational definitions of appropriate use were developed based on recommendations of an expert panel convened by the AHRQ (Zhan criteria). Inappropriate use was identified based on these criteria and inappropriate use of drugs per Beers criteria for dose-limitations in older people. Furthermore, duration of use and patient characteristics associated with inappropriate use were described.

RESULTS

After adjusting for diagnoses, dose, and duration, inappropriate prescribing decreased from 33% to 23%. Exposure to inappropriate drugs was prolonged. Pain relievers, benzodiazepines, antidepressants, and musculoskeletal agents constituted 61% of inappropriate prescribing. Whites, patients with psychiatric comorbidities, and patients receiving more medications were most likely to receive inappropriate drugs. Women were more likely to receive Zhan criteria drugs; men were more likely to receive dose-limited drugs

CONCLUSION

For the most part, the Zhan criteria did not explain inappropriate prescribing, which includes problems related to dose and duration of prescriptions. Interventions targeted at prescriptions for pain relievers, benzodiazepines, antidepressants, and musculoskeletal agents may dramatically decrease inappropriate prescribing and improve patient outcomes.

Accuracy of coding for possible warfarin complications in hospital discharge abstracts

BACKGROUND

Hospital discharge abstracts could be used to identify complications of warfarin if coding for bleeding and thromboembolic events are accurate.

OBJECTIVES

To measure the accuracy of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9CM) codes for bleeding and thromboembolic diagnoses.

SETTING

University affiliated, tertiary care hospital in Ottawa, Canada.

PATIENTS

A random sample of patients discharged between September 1999 and September 2000 with an ICD-9-CM code indicating a bleeding or thromboembolic diagnosis.

METHODS

Gold-standard coding was determined by a trained chart abstractor using explicit standard diagnostic criteria for bleeding, major bleeding, and acute thromboembolism. The abstractor was blinded to the original coding. We calculated the sensitivity, specificity, positive, and negative predictive values of the original ICD-9CM codes for bleeding or thromboembolism diagnoses.

RESULTS

We reviewed 616 medical records. 361 patients (59%) had a code indicating a bleeding diagnosis, 291 patients (47%) had a code indicating a thromboembolic diagnosis and 36 patients (6%) had a code indicating both. According to the gold standard criteria, 352 patients experienced bleeding, 333 experienced major bleeding, and 188 experienced an acute thromboembolism. For bleeding, the ICD-9CM codes had the following sensitivity, specificity, positive and negative predictive values [95% CI]: 93% [90-96], 88% [83-91], 91% [88-94], and 91% [87-94], respectively. For major bleeding, the ICD-9CM codes had the following sensitivity, specificity, positive and negative predictive values: 94% [91-96], 83% [78-87], 87% [83-90], and 92% [88-95], respectively. For thromboembolism, the ICD-9CM codes had the following sensitivity, specificity, positive and negative predictive values: 97% [94-99], 74% [70-79], 62% [57-68], and 98% [96-99], respectively. By selecting a sub-group of ICD-9CM codes for thromboembolism, the positive predictive value increased to 87%.

CONCLUSION

In our centre, the discharge abstract could be used to identify and exclude patients hospitalized with a major bleed or thromboembolism. If coding quality for bleeding is similar in other hospitals, these ICD-9-CM diagnostic codes could be used to study population-based warfarin-associated hemorrhagic complications using administrative databases.

Spatial variation in the management and outcomes of acute coronary syndrome

Background

Regional disparities in medical care and outcomes with patients suffering from an acute coronary syndrome (ACS) have been reported and raise the need to a better understanding of links between treatment, care and outcomes. Little is known about the relationship and its spatial variability between invasive cardiac procedure (ICP), hospital death (HD), length of stay (LoS) and early hospital readmission (EHR). The objectives were to describe and compare the regional rates of ICP, HD, EHR, and the average LoS after an ACS in 2000 in the province of Quebec. We also assessed whether there was a relationship between ICP and HD, LoS, and EHR, and if the relationships varied spatially.

Methods

Using secondary data from a provincial hospital register, a population-based retrospective cohort of 24,544 patients hospitalized in Quebec (Canada) for an ACS in 2000 was built. ACS was defined as myocardial infarction (ICD-9: 410) or unstable angina (ICD-9: 411). ICP was defined as the presence of angiography, angioplasty or aortocoronary bypass (CCA: 480–483, 489), HD as all death cause at index hospitalization, LoS as the number of days between admission and discharge from the index hospitalization, and EHR as hospital readmission for a coronary heart disease ≤30 days after discharge from hospital. The EHR was evaluated on survivors at discharge.

Results

ICP rate was 43.7% varying from 29.4% to 51.6% according to regions. HD rate was 6.9% (range: 3.3–8.2%), average LoS was 11.5 days (range: 7.5–14.4; median LoS: 8 days) and EHR rate was 8.3% (range: 4.7–14.2%). ICP was positively associated with LoS and negatively with HD and EHR; the relationship between ICP and LoS varied spatially. An increased distance to a specialized cardiology center was associated with a decreased likelihood of ICP, a decrease in LoS, but an increased likelihood of EHR.

Conclusion

The main results of this study are the regional variability of the outcomes even after accounting for age, gender, ICP and distance to a cardiology center; the significant relationships between ICP and HD, LoS and EHR, and the spatial variability in the relationships between ICP and LoS.

Depressive symptoms have an independent, gradient risk for coronary heart disease incidence in a random, population-based sample

PURPOSE

Depression is a risk factor for incident coronary heart disease (CHD), and predicts poor prognosis for patients post-myocardial infarction (MI). Few population-based, prospective studies have tested a gradient risk for depressive symptoms on CHD incidence.

METHODS

The sample (n=1302) was derived from the Nova Scotia Health Survey-1995 (NSHS95), an age- and sex-stratified, random, population-based health survey. All subjects were 45 years or older, free of overt CHD at baseline, and completed the Center for Epidemiological Studies-Depression (CES-D) scale. Covariates included age, sex, body mass index, physical activity level, family history of premature CHD, diastolic blood pressure, lipids, smoking, alcohol use, diabetes, and education level. For the 4 years following NSHS95, MI-related hospitalizations (ICD-9-CM code 410) and CHD-related deaths (ICD-9-CM codes 410-414) were extracted from the provincial, universal healthcare registry.

RESULTS

Fifty-two participants experienced a CHD event. A one standard-deviation increase in CES-D score was associated with a 1.32 hazard risk (confidence interval, 1.01-1.71) of CHD events, controlling for established CHD risk factors.

CONCLUSIONS

An independent, gradient association between depression and incident CHD was detected in a population-based sample with complete 4-year CHD data. This evidence supports the value of investigating mechanisms linking depression and CHD.

Mental disorders and revascularization procedures in a commercially insured sample

OBJECTIVE

The objective of this study was to determine if receipt of revascularization was similar among commercially insured adults with mental disorders compared with people without mental disorders.

METHODS

This was a retrospective analysis of a 100% sample of Blue Cross/Blue Shield of Iowa administrative claims data, 1996 to 2001. Logistic regression was used to calculate unadjusted and adjusted odds ratios (OR) for receipt of angioplasty (PTCA) and bypass graft surgery (CABG) within 30 days of discharge.

RESULTS

A total of 3368 adults, aged 18 to 64 years, were hospitalized for myocardial infarction (MI) and 40% (n = 1342) had a mental disorder. Subjects with mental disorders were more likely to be younger, female, urban residents, and to have increased cardiovascular and medical comorbidity. They were similarly likely as subjects without mental disorders to have received PTCA (OR, 1.10; 95% confidence interval [CI], 0.95-1.29) and CABG (OR, 0.89; 95% CI, 0.71-1.11) in analyses adjusted for demographic and clinical characteristics. Revascularization rates did not differ by mental disorder type, with few exceptions.

CONCLUSIONS

Receipt of revascularization was similar for patients with and without mental disorders. Our results may differ from previous findings as a result of the younger population studied and increased comorbidity in people with mental disorders, which may have resulted in a contraindication for surgical intervention. Conversely, the increased burden of comorbidity could suggest that these patients should have received PTCA at higher rates because of the better prognosis associated with revascularization as compared with medical management. Prospective analyses with review of clinical data and behavioral risk factors are necessary to determine why some patients with mental illness may be less likely to receive cardiac interventions.

Accuracy of ICD-9-CM codes for identifying cardiovascular and stroke risk factors

OBJECTIVES

We sought to determine which ICD-9-CM codes in Medicare Part A data identify cardiovascular and stroke risk factors.

DESIGN AND PARTICIPANTS

This was a cross-sectional study comparing ICD-9-CM data to structured medical record review from 23,657 Medicare beneficiaries aged 20 to 105 years who had atrial fibrillation.

MEASUREMENTS

Quality improvement organizations used standardized abstraction instruments to determine the presence of 9 cardiovascular and stroke risk factors. Using the chart abstractions as the gold standard, we assessed the accuracy of ICD-9-CM codes to identify these risk factors.

MAIN RESULTS

ICD-9-CM codes for all risk factors had high specificity (>0.95) and low sensitivity (< or =0.76). The positive predictive values were greater than 0.95 for 5 common, chronic risk factors-coronary artery disease, stroke/transient ischemic attack, heart failure, diabetes, and hypertension. The sixth common risk factor, valvular heart disease, had a positive predictive value of 0.93. For all 6 common risk factors, negative predictive values ranged from 0.52 to 0.91. The rare risk factors-arterial peripheral embolus, intracranial hemorrhage, and deep venous thrombosis-had high negative predictive value (> or =0.98) but moderate positive predictive values (range, 0.54-0.77) in this population.

CONCLUSIONS

Using ICD-9-CM codes alone, heart failure, coronary artery disease, diabetes, hypertension, and stroke can be ruled in but not necessarily ruled out. Where feasible, review of additional data (eg, physician notes or imaging studies) should be used to confirm the diagnosis of valvular disease, arterial peripheral embolus, intracranial hemorrhage, and deep venous thrombosis.

Effect of cardiovascular comorbidities and concomitant aspirin use on selection of cyclooxygenase inhibitor among rheumatologists

OBJECTIVE

To evaluate the effects of cardiovascular comorbidities and aspirin coprescription on cyclooxygenase (COX)-2 inhibitor (coxib) prescribing patterns among rheumatologists.

METHODS

A prospective cohort study was carried out with rheumatoid arthritis and osteoarthritis patients in the Consortium of Rheumatology Researchers of North America registry. Medication and comorbidity data were obtained prospectively from physician and patient questionnaires between March 2002 and September 2003. Multivariate adjusted associations between coxib use and specific cardiovascular variables, including aspirin use, were examined.

RESULTS

A total of 3,522 arthritis patients were included. COX inhibitors, including coxibs, nonselective nonsteroidal antiinflammatory drugs (NSAIDs), and meloxicam, were prescribed to a larger proportion of osteoarthritis patients (68.4%) than rheumatoid arthritis patients (47.1%) in our study (P < 0.001). COX inhibitors were prescribed to the majority of aspirin users (51.5%) and a similar proportion of nonusers (49.8%). In multivariate analyses, independent predictors of coxib use versus nonselective NSAID use included diagnoses of osteoarthritis (odds ratio [OR] 2.52, 95% confidence interval [95% CI] 1.81-3.52) and diabetes (OR 1.63, 95% CI 1.06-2.51). Conversely, aspirin use independently predicted selection of a nonselective NSAID rather than a coxib (OR 0.73, 95% CI 0.55-0.98). Neither a history of myocardial infarction nor stroke predicted utilization of a coxib. Similarly, cardiovascular variables did not predict the use of rofecoxib versus celecoxib.

CONCLUSION

Our data indicate that COX inhibitor coprescription among aspirin users is frequent. Despite cardiovascular concerns regarding the coxibs, our data suggest that aspirin use, but not cardiovascular comorbidities, predicted the selection of nonselective NSAIDs over coxibs.

Assessing the accuracy of administrative data in health information systems

BACKGROUND

Administrative data play a central role in health care. Inaccuracies in such data are costly to health systems, they obscure health research, and they affect the quality of patient care.

OBJECTIVES

We sought to prospectively determine the accuracy of the primary and secondary diagnoses recorded in administrative data sets.

RESEARCH DESIGN

Between March and July 2002, standardized patients (SPs) completed unannounced visits at 3 sites. We abstracted the 348 medical records from these visits to obtain the written diagnoses made by physicians. We also examined the patient files to identify the diagnoses recorded on the administrative encounter forms and extracted data from the computerized administrative databases. Because the correct diagnosis was defined by the SP visit, we could determine whether the final diagnosis in the administrative data set was correct and, if not, whether it was caused by physician diagnostic error, missing encounter forms, or incorrectly filled out forms.

SUBJECTS

General internal medicine outpatient clinics at 2 Veterans Administration facilities and a large, private medical center participated in this study.

MEASURES

A total of 45 trained SPs presented to physicians with 4 common outpatient conditions.

RESULTS

The correct primary diagnosis was recorded for 57% of visits. Thirteen percent of errors were caused by physician diagnostic error, 8% to missing encounter forms, and 22% to incorrectly entered data. Findings varied by condition and site but not by level of training. Accuracy of secondary diagnosis data (27%) was even poorer.

CONCLUSIONS

Although more research is needed to evaluate the cause of inaccuracies and the relative contributions of patient, provider, and system level effects, it appears that significant inaccuracies in administrative data are common. Interventions aimed at correcting these errors appear feasible.

Serum phosphate levels and mortality risk among people with chronic kidney disease

Elevated serum phosphate levels have been linked with vascular calcification and mortality among dialysis patients. The relationship between phosphate and mortality has not been explored among patients with chronic kidney disease (CKD). A retrospective cohort study was conducted from eight Veterans Affairs' Medical Centers located in the Pacific Northwest. CKD was defined by two continuously abnormal outpatient serum creatinine measurements at least 6 mo apart between 1999 and 2002. Patients who received chronic dialysis, those with a present or previous renal transplant, and those without a recent phosphate measurement were excluded. The primary end point was all-cause mortality. Secondary end points were acute myocardial infarction and the combined end point of myocardial infarction plus death. A total of 95,619 veterans with at least one primary care or internal medicine clinic contact from a Northwest VA facility and two or more outpatient measurements of serum creatinine, at least 6 mo apart, between January 1, 1999, and December 31, 2002, were identified. From this eligible population, 7021 patients met our definition of CKD. After exclusions, 6730 CKD patients were available for analysis, and 3490 had a serum phosphate measurement during the previous 18 mo. After adjustment, serum phosphate levels >3.5 mg/dl were associated with a significantly increased risk for death. Mortality risk increased linearly with each subsequent 0.5-mg/dl increase in serum phosphate levels. Elevated serum phosphate levels were independently associated with increased mortality risk among this population of patients with CKD.

Accuracy of Medicare claims-based diagnosis of acute myocardial infarction: estimating positive predictive value on the basis of review of hospital records

BACKGROUND

Many cardiovascular epidemiologic studies rely on diagnosis codes in health care claims databases. Despite important changes in the care and diagnosis of acute myocardial infarction (AMI), the validity of hospital discharge diagnosis codes for AMI in the US Medicare system has not been recently examined. Our objective was to examine the accuracy of International Classification of Diseases--ninth revision--Clinical Modifications (ICD-9-CM) discharge diagnosis codes and diagnosis-related groups (DRG) codes for AMI in a Medicare claims database.

METHODS

We sampled hospitalization episodes from Medicare beneficiaries in Pennsylvania during 1999, 2000, or both. We used Medicare data to identify patients with hospitalizations containing indicators of AMI (ICD-9-CM diagnosis codes 410.X0 and 410.X1 or DRG codes 121, 122, and 123). Hospital records for these episodes were reviewed by trained abstractors using World Health Organization criteria for diagnosing AMI. We then calculated the positive predictive value of Medicare claims-based definitions of AMI.

RESULTS

Of 2200 hospitalization episodes with Medicare diagnosis codes suggestive of AMI, 2022 hospital records (91.9%) were obtained. The positive predictive value for a primary Medicare claims-based definition was 94.1% (95% CI, 93.0%-95.2%). Positive predictive values for alternative claims-based definitions ranged slightly, with the definition including DRG codes and length-of-stay restrictions yielding the highest positive predictive value, 95.4% (95% CI, 94.3%-96.4%). Subjects with a history of myocardial infarction had a significantly lower positive predictive value than subjects without a history of myocardial infarction (88.1% vs 94.6%, P <.001).

CONCLUSIONS

In this study, we observed high positive predictive values for a Medicare claims-based diagnosis of AMI and a diagnosis based on structured hospital record review.

Relationship Between Selective Cyclooxygenase-2 Inhibitors and Acute Myocardial Infarction in Older Adults

Background— Although cyclooxygenase-2 inhibitors (coxibs) were developed to cause less gastrointestinal hemorrhage than nonselective nonsteroidal antiinflammatory drugs (NSAIDs), there has been concern about their cardiovascular safety. We studied the relative risk of acute myocardial infarction (AMI) among users of celecoxib, rofecoxib, and NSAIDs in Medicare beneficiaries with a comprehensive drug benefit.

Methods and Results— We conducted a matched case-control study of 54 475 patients 65 years of age or older who received their medications through 2 state-sponsored pharmaceutical benefits programs in the United States. All healthcare use encounters were examined to identify hospitalizations for AMI. Each of the 10 895 cases of AMI was matched to 4 controls on the basis of age, gender, and the month of index date. We constructed matched logistic regression models including indicators for patient demographics, healthcare use, medication use, and cardiovascular risk factors to assess the relative risk of AMI in patients who used rofecoxib compared with persons taking no NSAID, taking celecoxib, or taking NSAIDs. Current use of rofecoxib was associated with an elevated relative risk of AMI compared with celecoxib (odds ratio [OR], 1.24; 95% CI, 1.05 to 1.46; P =0.011) and with no NSAID (OR, 1.14; 95% CI, 1.00 to 1.31; P =0.054). The adjusted relative risk of AMI was also elevated in dose-specific comparisons: rofecoxib ≤25 mg versus celecoxib ≤200 mg (OR, 1.21; 95% CI, 1.01 to 1.44; P =0.036) and rofecoxib >25 mg versus celecoxib >200 mg (OR, 1.70; 95% CI, 1.07 to 2.71; P =0.026). The adjusted relative risks of AMI associated with rofecoxib use of 1 to 30 days (OR, 1.40; 95% CI, 1.12 to 1.75; P =0.005) and 31 to 90 days (OR, 1.38; 95% CI, 1.11 to 1.72; P =0.003) were higher than >90 days (OR, 0.96; 95% CI, 0.72 to 1.25; P =0.8) compared with celecoxib use of similar duration. Celecoxib was not associated with an increased relative risk of AMI in these comparisons.

Conclusions— In this study, current rofecoxib use was associated with an elevated relative risk of AMI compared with celecoxib use and no NSAID use. Dosages of rofecoxib >25 mg were associated with a higher risk than dosages ≤25 mg. The risk was elevated in the first 90 days of use but not thereafter.

Effectiveness of lipid-lowering medications in outpatients with coronary heart disease in the Department of Veterans Affairs System

Lipid therapy aimed at reducing low-density lipoprotein cholesterol has been shown, in several large-scale randomized controlled trials, to reduce coronary heart disease (CHD) morbidity and mortality and all-cause mortality in patients with established CHD. However, lipid therapy's effectiveness in usual clinical settings has not been extensively studied. The purpose of this study was to determine the effect of prescription lipid-lowering medication (LLM) on all-cause mortality in a cohort of patients with known CHD. We conducted a retrospective cohort study using linked administrative and clinical databases. Sixteen thousand four hundred seventy patients with CHD who were outpatients at 1 of 5 Veterans Affairs medical facilities in the upper midwest between 1994 and 1996 were identified and then followed until death or the end of the study (December 31, 2000). Pharmacy databases were used to determine whether patients had been prescribed LLMs. Demographics, co-morbid conditions, cardiac medications, and lipid levels were collected. Time-dependent Cox proportional hazards analyses, adjusted for confounding variables, and the propensity score for LLM use were performed to compare survival between those prescribed and those not prescribed LLM. During an average follow-up of 5.9 years, there were 4,821 recorded deaths in patients not prescribed LLM (51%) and 1,245 deaths in patients prescribed LLM (18%). On average, the treated cohort survived 15 months longer than the untreated group (p<0.0001). The age-adjusted hazards ratio associated with LLM use was 0.59 (95% confidence interval 0.55 to 0.63, p=0.0001). After adjusting for propensity score, age, and previous use of LLM, the hazard ratio associated with prescription of LLM was 0.77 (95% confidence interval 0.70 to 0.85, p<0.0001). This study confirms, in a standard clinical setting, the beneficial effects of LLM on total mortality in patients with established CHD. These data suggest that the benefits of lipid therapy observed in highly controlled randomized trials are attainable in usual clinical settings.

Cardiovascular and thromboembolic events following hypertensive pregnancy

BACKGROUND

Hypertension is a common complication of pregnancy. Previous evidence has linked pregnancy-related hypertension to maternal cardiovascular disease. We conducted a population-based cohort study to estimate the risks for cardiovascular and thromboembolic events in women with pregnancy-related hypertension.

METHODS

We analyzed data from all singleton births recorded in Washington State from 1987 to 1998. Mothers were classified as having gestational hypertension, preeclampsia, or chronic hypertension based on hospital discharge and birth record information. Birth records were linked to subsequent hospitalizations within Washington State. Proportional hazards models were used to estimate the relationship between each form of pregnancy-related hypertension and subsequent risk for cardiovascular and thromboembolic events.

RESULTS

We identified 31,239 eligible hypertensive pregnancies from 807,010 births. During follow-up, there were 118 hospitalizations for a first acute cardiovascular event and 172 hospitalizations for a first thromboembolic event. Gestational hypertension, mild preeclampsia, and severe preeclampsia were associated with 2.8-fold (95% confidence interval [CI], 1.6 to 4.8), 2.2-fold (95% CI, 1.3 to 3.6), and 3.3-fold (95% CI, 1.7 to 6.5) greater risks for cardiovascular events, respectively. Severe preeclampsia was associated with a 2.3-fold (95% CI, 1.3 to 4.2) greater risk for thromboembolic events.

CONCLUSION

Preeclampsia and gestational hypertension are associated with increased risk for cardiovascular events. Pregnancy-induced hypertension appears to be an important risk factor for the development of future cardiovascular disease in young women.

Accuracy of Medicare claims data for rheumatologic diagnoses in total hip replacement recipients

This analysis was performed to examine whether Medicare claims accurately document underlying rheumatologic diagnoses in total hip replacement (THR) recipients. We obtained data on rheumatologic diagnoses including rheumatoid arthritis (RA), avascular necrosis (AVN), and osteoarthritis (OA) from medical records and from Medicare claims data. To examine the accuracy of claims data we calculated sensitivity and positive predictive value using medical records data as the "gold standard" and assessed bias due to misclassification of claims-based diagnoses. The sensitivities of claims-based diagnoses of RA, AVN, and OA were 0.65, 0.54, and 0.96, respectively; the positive predictive values were all in the 0.86-0.89 range. The sensitivities of RA and AVN varied substantially across hospital volume strata, but in different directions for the two diagnoses. We conclude that inaccuracies in claims coding of diagnoses are frequent, and are potential sources of bias. More studies are needed to examine the magnitude and direction of bias in health outcomes research due to inaccuracy of claims coding for specific diagnoses.

Regionalization and the underuse of angiography in the Veterans Affairs Health Care System as compared with a fee-for-service system

BACKGROUND

Policies to concentrate or regionalize invasive procedures at high-volume medical centers are under active consideration. Such policies could improve outcomes among those who undergo procedures while increasing their underuse among those who never reach such centers. We compared the underuse of needed angiography after acute myocardial infarction in a traditional Medicare fee-for-service system with underuse in the regionalized Department of Veterans Affairs (VA) health care system.

METHODS

We studied 1665 veterans from 81 VA hospitals and 19,305 Medicare patients from 1530 non-VA hospitals, all of whom were elderly men. We compared adjusted angiography use and one-year mortality among patients for whom angiography was rated as clinically needed. We compared underuse in models before and after controlling for the on-site availability of cardiac procedures.

RESULTS

After adjustment for the need for angiography, underuse was present in both groups, but VA patients remained significantly less likely than Medicare patients to undergo angiography (43.9 percent vs. 51.0 percent; odds ratio, 0.75; 95 percent confidence interval, 0.57 to 0.96). After also controlling for on-site availability of cardiac procedures at the admitting hospital, we found no significant difference in the underuse of angiography among VA patients as compared with Medicare patients (odds ratio, 1.02; 95 percent confidence interval, 0.82 to 1.26) or in one-year mortality (odds ratio, 1.08; 95 percent confidence interval, 0.89 to 1.28).

CONCLUSIONS

There is underuse of needed angiography after acute myocardial infarction in both the VA and Medicare systems, but the rate of underuse is significantly higher in the VA. These differences appear to be associated with limited on-site availability of cardiac procedures in the regionalized VA health care system. Further work should focus on how regionalization policies could be improved with effective referral and triage processes.

Process of care and outcome after acute myocardial infarction for patients with mental illness in the VA health care system: are there disparities?

OBJECTIVE

To compare process of care and outcome after acute myocardial infarction, for patients with and without mental illness, cared for in the Veterans Health Administration (VA) health care system.

DATA SOURCES/SETTING

Primary clinical data from 81 VA hospitals.

STUDY DESIGN

This was a retrospective cohort study of 4,340 veterans discharged with clinically confirmed acute myocardial infarction. Of these, 859 (19.8 percent) met the definition of mental illness. Measures were age-adjusted in-hospital and 90-day cardiac procedure use; age-adjusted relative risks (RE) of use of thrombolytic therapy, beta-blockers, angiotensin converting enzyme (ACE) inhibitors, or aspirin at discharge; risk-adjusted 30-day and one-year mortality.

RESULTS

Patients with mental illness were marginally less likely than those without mental illness to undergo in-hospital angiography (age-adjusted RR 0.90 [95 percent confidence interval: 0.83, 0.98]), but there was no significant difference in the age-adjusted RR of coronary artery bypass graft surgery in the 90 days after admission (0.85 [0.69, 1.05]), or in the receipt of medications of known benefit. For example, ideal candidates with and without mental illness were equally likely to receive beta-blockers at the time of discharge (age-adjusted RR 0.92 [0.82, 1.02]). The risk-adjusted odds ratio (OR) for death in patients with mental illness versus those without mental illness within 30 days was 1.00 (0.75, 1.32), and for death within one year was 1.25 (1.00, 1.53).

CONCLUSIONS

Veterans Health Administration patients with mental illness were marginally less likely than those without mental illness to receive diagnostic angiography, and no less likely to receive revascularization or medications of known benefit after acute myocardial infarction. Mortality at one year may have been higher, although this finding did not reach statistical significance. These findings are consistent with other studies showing reduced health care disparities in the VA for other vulnerable groups, and suggest that an integrated health care system with few financial barriers to health care access may attenuate some health care disparities. Further work should address how health care organizational features might narrow disparities in health care for vulnerable groups.

Geographic variation in health care utilization and outcomes in veterans with acute myocardial infarction

OBJECTIVES

To examine regional variation in health care utilization and outcomes during acute and chronic care of veterans following acute myocardial infarction (AMI), identifying potentially modifiable variables and processes of care that influence patient outcomes.

METHODS

Using national VA databases, we identified all veterans hospitalized at any VA Medical Center (VAMC) for AMI between October 1990 and September 1997. Demographic, inpatient, outpatient, mortality, and readmission data were extracted for 4 regions: Northeast, South, Midwest and West. Multivariable Cox proportional hazards regression models, controlled for comorbidity, were used to assess predictors of time to death and readmission.

RESULTS

We identified 67,889 patients with AMI. Patient demographic characteristics by region were similar. Patients in the Northeast had more comorbid conditions and longer lengths of stay during the index AMI hospitalization. Region of the country independently predicted time to death, with lower risk of death in the Northeast (hazard ratio [HR] = 0.875; 95% confidence interval [95% CI], 0.834 to 0.918; P < .0001) and West (HR = 0.856; 95%CI, 0.818 to 0.895; P = .0001) than in the South. Patients in the Northeast and West also had more cardiology or primary care follow-up within 60 days and at 1 year post-discharge than patients in the South and Midwest. Outpatient follow-up accounted for a significant portion of the variation in all-cause mortality.

CONCLUSION

Substantial geographic variation exists in subsequent clinical care and outcomes among veterans hospitalized in VAMCs for AMIs. Outpatient follow-up was highly variable and associated with decreased mortality. Further studies are needed to explore the causes of regional variation in processes of care and to determine the most effective strategies for improving outcomes after AMI.

Comparing performance of multinomial logistic regression and discriminant analysis for monitoring access to care for acute myocardial infarction

One way to monitor patient access to emergent health care services is to use patient characteristics to predict arrival time at the hospital after onset of symptoms. This predicted arrival time can then be compared with actual arrival time to allow monitoring of access to services. Predicted arrival time could also be used to estimate potential effects of changes in health care service availability, such as closure of an emergency department or an acute care hospital. Our goal was to determine the best statistical method for prediction of arrival intervals for patients with acute myocardial infarction (AMI) symptoms. We compared the performance of multinomial logistic regression (MLR) and discriminant analysis (DA) models. Models for MLR and DA were developed using a dataset of 3,566 male veterans hospitalized with AMI in 81 VA Medical Centers in 1994-1995 throughout the United States. The dataset was randomly divided into a training set (n = 1,846) and a test set (n = 1,720). Arrival times were grouped into three intervals on the basis of treatment considerations: <6 hours, 6-12 hours, and >12 hours. One model for MLR and two models for DA were developed using the training dataset. One DA model had equal prior probabilities, and one DA model had proportional prior probabilities. Predictive performance of the models was compared using the test (n = 1,720) dataset. Using the test dataset, the proportions of patients in the three arrival time groups were 60.9% for <6 hours, 10.3% for 6-12 hours, and 28.8% for >12 hours after symptom onset. Whereas the overall predictive performance by MLR and DA with proportional priors was higher, the DA models with equal priors performed much better in the smaller groups. Correct classifications were 62.6% by MLR, 62.4% by DA using proportional prior probabilities, and 48.1% using equal prior probabilities of the groups. The misclassifications by MLR for the three groups were 9.5%, 100.0%, 74.2% for each time interval, respectively. Misclassifications by DA models were 9.8%, 100.0%, and 74.4% for the model with proportional priors and 47.6%, 79.5%, and 51.0% for the model with equal priors. The choice of MLR or DA with proportional priors, or DA with equal priors for monitoring time intervals of predicted hospital arrival time for a population should depend on the consequences of misclassification errors.

Impact of race on cardiac care and outcomes in veterans with acute myocardial infarction

OBJECTIVES

The goal of this study was to assess racial differences in process of care and outcome for acute myocardial infarction in the VA health care system.

DESIGN

Retrospective cohort study using clinical data.

SETTING

Eighty-one acute care VA hospitals.

PATIENTS

Four thousand seven hundred sixty veterans discharged with a confirmed diagnosis of acute myocardial infarction. The analysis was restricted to 606 black and 4005 white patients.

MAIN OUTCOME MEASURES

Comparison of use of guideline-based medications, invasive cardiac procedures, and all-cause mortality at 30 days, 1 year, and 3 years.

RESULTS

Black patients were equally likely to receive beta-blockers, more likely than white patients to receive aspirin (86.8% vs. 82.0%; P <0.05), and marginally more likely to receive angiotensin converting enzyme inhibitors (55.7% vs. 49.6%; P = 0.07) at the time of discharge. In contrast, black patients were less likely than white patients to receive thrombolytic therapy at the time of arrival (32.4% vs. 48.2%; P <0.01). There was no significant difference in refusal of angiography or percutaneous transluminal coronary angioplasty between black patients and white patients, or in crude rates of either of these procedures. There was also no difference overall in the percentage of patients who refused coronary artery bypass graft surgery. However, black patients were less likely than white patients to undergo bypass surgery (6.9% vs. 12.5% by 90 days; P <0.001). Black patients remained less likely to undergo bypass surgery even when high-risk specific coronary anatomy subgroups were examined. There was no difference in mortality in the two groups.

CONCLUSIONS

In this integrated health care system, no significant racial disparities in use of noninterventional therapies, diagnostic coronary angiography, or short- or long-term mortality was found. Disparities in use of thrombolytic therapy and coronary artery bypass surgery existed, however, even after accounting for differences in clinical indications for treatment and patient refusals. Further work should assess the role of the medical interaction and physician behavior in racial disparities in use of health care.

Comparison of use of medications after acute myocardial infarction in the Veterans Health Administration and Medicare

BACKGROUND

There is concern that care provided in the Veterans Health Administration (VA) may be of poorer quality than non-VA health care. We compared use of medications after acute myocardial infarction in the VA with that in non-VA healthcare settings under fee-for-service (FFS) Medicare financing.

METHODS AND RESULTS

We used clinical data from 2486 VA and 29 249 FFS men >65 years old discharged with a confirmed diagnosis of acute myocardial infarction from 81 VA hospitals and 1530 non-VA hospitals. We reported odds ratios (ORs) for use of thrombolytics, beta-blockers, ACE inhibitors, or aspirin among ideal candidates adjusted for age, sample design (hospital academic affiliation, availability of cardiac procedures, and volume), and within-hospital clustering. Ideal VA candidates were more likely to undergo thrombolytic therapy at arrival (OR [VA relative to Medicare] 1.40 [1.05, 1.74]) or to receive ACE inhibitors (OR 1.67 [1.12, 2.45]) or aspirin (OR 2.32 [1.81, 3.01]) at discharge and equally likely to receive beta-blockers (OR 1.09 [1.03, 1.40]) at discharge.

CONCLUSIONS

Ideal candidates in VA were at least as likely as those in FFS to receive medical therapies of known benefit for acute myocardial infarction.

A comparison of emergency medical services times for stroke and myocardial infarction

OBJECTIVE

Since stroke symptoms are often vague, and acute therapies for stroke are more recently available, it has been hypothesized that stroke patients may not be treated with the same urgency as myocardial infarction (MI) patients by emergency medical services (EMS). To examine this hypothesis, EMS transport times were examined for both stroke and MI patients who used a paramedic-level, county-based EMS system for transportation to a single hospital during 1999.

METHODS

Patients were first identified by their hospital discharge diagnosis as stroke (ICD-9 430-436, n = 50) or MI (ICD-9 410, n = 55). Trip sheets with corresponding transport times were retrospectively obtained from the 911 center. A separate analysis was performed on patients identified by dispatchers with a chief complaint of stroke (n = 85) or MI (n = 372).

RESULTS

Comparing stroke and MI patients identified by ICD-9 codes, mean EMS transport times in minutes did not meaningfully differ with respect to dispatch to scene arrival time (8.3 vs 8.9, p = 0.61), scene time (19.5 vs 21.4, p = 0.23), and transport time (13.7 vs 16.2, p = 0.10). Mean total call times in minutes from dispatch to hospital arrival were similar between stroke and MI patients (41.5 vs 46.4, p = 0.22). Results were similar when comparing patients identified by dispatchers with a chief complaint indicative of stroke or MI.

CONCLUSION

In this single county, EMS response times were not different between stroke and MI patients. Replication in other EMS settings is needed to confirm these findings.

Administrative data for public health surveillance and planning

Electronically available administrative data are increasingly used by public health researchers and planners. The validity of the data source has been established, and its strengths and weaknesses relative to data abstracted from medical records and obtained via survey are documented. Administrative data are available from a variety of state, federal, and private sources and can, in many cases, be combined. As a tool for planning and surveillance, administrative data show great promise: They contain consistent elements, are available in a timely manner, and provide information about large numbers of individuals. Because they are available in an electronic format, they are relatively inexpensive to obtain and use. In the United States, however, there is no administrative data set covering the entire population. Although Medicare provides health care for an estimated 96% of the elderly, age 65 years and older, there is no comparable source for those under 65.

Outcome of myocardial infarction in Veterans Health Administration patients as compared with medicare patients

BACKGROUND

Some have the opinion that patients cared for in Veterans Health Administration (VHA) hospitals receive care of poorer quality than those cared for in non-VHA institutions. To assess the quality of care in VHA hospitals, we compared the outcome of acute myocardial infarction among patients in VHA and non-VHA institutions while controlling for potential confounders, including coexisting conditions and severity of illness.

METHODS

We studied 2486 veterans discharged from 81 VHA hospitals and 29,249 Medicare patients discharged from 1530 non-VHA hospitals, restricting our samples to men at least 65 years of age who were discharged with confirmed acute myocardial infarction. We compared coexisting conditions, severity of illness, and 30-day and 1-year mortality in the two samples.

RESULTS

VHA patients were significantly more likely than Medicare patients to have a recorded history of hypertension (64.3 percent vs. 57.3 percent), chronic obstructive pulmonary disease or asthma (30.9 percent vs. 23.5 percent), diabetes (34.8 percent vs. 29.0 percent), stroke (20.4 percent vs. 14.2 percent), or dementia (7.2 percent vs. 4.8 percent) (P<0.001 for all comparisons). According to both multivariate logistic regression and an analysis using 2265 matched pairs of VHA and Medicare patients, there were no significant differences in 30-day or 1-year mortality. The matched-pairs analysis found that the difference in mortality at 30 days (the mortality rate among Medicare patients minus the mortality rate among VHA patients), averaged over the 5-year age groups, was -0.8 percent (95 percent confidence interval, -2.8 percent to 1.3 percent), and the difference in mortality at 1 year was -1.3 percent (95 percent confidence interval, -3.9 percent to 1.3 percent).

CONCLUSIONS

VHA patients had more coexisting conditions than Medicare patients. Nevertheless, we found no significant difference in mortality between VHA and Medicare patients, a result that suggests a similar quality of care for acute myocardial infarction.

Evaluating the predictive value of osteoarthritis diagnoses in an administrative database

OBJECTIVE

To assess the positive and negative predictive values of osteoarthritis (OA) diagnoses contained in an administrative database.

METHODS

We identified all members (> or =18 years of age) of a Massachusetts health maintenance organization with documentation of at least one health care encounter associated with an OA diagnosis during the period 1994-1996. From this population, we randomly selected 350 subjects. In addition, we randomly selected 250 enrollees (proportionally by the age and sex of the 350 subjects) who did not have a health care encounter associated with an OA diagnosis. Trained nurse reviewers abstracted OA-related clinical, laboratory, and radiologic data from the medical records of both study groups (all but 1 chart was available for review). Pairs of physician reviewers evaluated the abstracted information for both groups of subjects and rated the evidence for the presence of OA according to 3 levels: definite, possible, and unlikely.

RESULTS

Among the group of patients with an administrative diagnosis of OA, 215 (62%) were rated as having definite OA, 36 (10%) possible OA, and 98 (28%) unlikely OA, according to information contained in the medical record. The positive predictive value of an OA diagnosis was 62%. In those without an administrative OA diagnosis, 44 (18%) were assigned a rating of definite OA. The negative predictive value of the absence of an administrative OA diagnosis was 78%.

CONCLUSION

Use of administrative data in epidemiologic and health services research on OA may lead to both case misclassification and under ascertainment.