Possible influence of the prospective payment system on the assignment of discharge diagnoses for coronary heart disease

Current trends in stroke events, mortality, and case fatality in Switzerland: an epidemiologic update

BACKGROUND

Stroke is a major cardiovascular disease. The last epidemiologic update of stroke events, mortality, and case fatalities (CF) in Switzerland was performed in 2004. Between 2004 and 2017, traditional- and non-traditional cardiovascular risk factors changed, life expectancy increased, stroke units were implemented, and stroke treatment standardized. Therefore, we present an update of Swiss stroke epidemiology.

METHODS

Data were obtained from two databases, the Federal Hospital Discharge Statistics (HOST, n = 1 470 259) and the Cause of Death (CoD) database (n = 66 971), to analyze stroke diagnoses coded according to I60-I64 (ICD 10) in 2017 in Switzerland. Discharge- and event rates for stroke, in- and out-of-hospital CF, and mortality were calculated.

RESULTS

In 2017, there were 26 032 stroke discharges in Switzerland (45% women) compared to 13 996 discharges in 2004. The age-standardized event rate per 100 000 increased in women/men from 119.7/178.7 in 2004 to 265.1/396.7 in 2017. However, the absolute number of stroke deaths decreased between 2004 and 2017 from 3569 (60% women) to 2816 (59% women). The overall sex-stratified mortality rate approximately halved between 2004 and 2017 in women (from 77.5 to 38.5/100 000) and men (from 56.1 to 27.2/100 000). The overall CF halved between 2004 and 2017 from 22.7% to 10.5% and was higher in women (13.4%) compared to men (8.0%).

CONCLUSIONS

Compared to 2004, the rates of stroke events and discharges have increased in Switzerland. However, the overall CF rate and overall sex-stratified mortality rate has approximately halved. This suggests, among other factors, increased recognition and better treatments for stroke.

Vascular Risk Factor Prevalence and Trends in Native Americans with Ischemic Stroke

INTRODUCTION

Native Americans have a higher incidence and prevalence of stroke and the highest stroke-related mortality among race-ethnic groups in the United States. We aimed to analyze trends in the ischemic stroke (IS) vascular risk factor prevalence in Native Americans along with a comparison to the other race-ethnic groups.

METHODS

National Inpatient Sample (NIS) database was used to explore the prevalence of risk factors among hospitalized IS patients during 2000 - 2016. Prevalence estimates were calculated for each risk factor within each race-ethnic group in 6 time periods. Linear trends were explored using linear regression models, with differences in trends between the Native American group and the other race-ethnic groups assessed using interaction terms. The analysis accounted for the complex sampling design, including hospital clusters, NIS stratum, and trend weights for analyzing multiple years of NIS data.

RESULTS

Native Americans constituted 5472 of the 1,278,784 IS patients. The age-and-sex-standardized prevalence of hypertension (slope = 2.24, p < 0.001), hyperlipidemia (slope = 6.29, p < 0.001), diabetes (slope = 2.04, p = 0.005), atrial fibrillation/flutter (trend slope = 0.80, p = 0.011), heart failure (trend slope = 0.73, p = 0.036) smoking (trend slope= 3.65, p < 0.001), and alcohol (slope = 0.60, p = 0.019) increased among Native Americans. They showed larger increases in hypertension prevalence compared to Blacks, Hispanics, and Asian/Pacific Islanders and in smoking prevalence compared to Hispanics and Asian/Pacific Islanders. By the year 2015-2016, Native Americans had the highest overall prevalence of diabetes, coronary artery disease, smoking, and alcohol among all race-ethnic groups.

CONCLUSION

The prevalence of most vascular risk factors among ischemic stroke patients has increased in Native Americans over the last two decades. Significantly larger increases in hypertension and smoking prevalence were seen in Native Americans compared to other groups along with them having the highest prevalence in multiple risk factors in recent years.

Feasibility analysis of conducting observational studies with the electronic health record

Background

The secondary use of electronic health records (EHRs) promises to facilitate medical research. We reviewed general data requirements in observational studies and analyzed the feasibility of conducting observational studies with structured EHR data, in particular diagnosis and procedure codes.

Methods

After reviewing published observational studies from the University Hospital of Erlangen for general data requirements, we identified three different study populations for the feasibility analysis with eligibility criteria from three exemplary observational studies. For each study population, we evaluated the availability of relevant patient characteristics in our EHR, including outcome and exposure variables. To assess data quality, we computed distributions of relevant patient characteristics from the available structured EHR data and compared them to those of the original studies. We implemented computed phenotypes for patient characteristics where necessary. In random samples, we evaluated how well structured patient characteristics agreed with a gold standard from manually interpreted free texts. We categorized our findings using the four data quality dimensions “completeness”, “correctness”, “currency” and “granularity”.

Results

Reviewing general data requirements, we found that some investigators supplement routine data with questionnaires, interviews and follow-up examinations. We included 847 subjects in the feasibility analysis (Study 1 n = 411, Study 2 n = 423, Study 3 n = 13). All eligibility criteria from two studies were available in structured data, while one study required computed phenotypes in eligibility criteria. In one study, we found that all necessary patient characteristics were documented at least once in either structured or unstructured data. In another study, all exposure and outcome variables were available in structured data, while in the other one unstructured data had to be consulted. The comparison of patient characteristics distributions, as computed from structured data, with those from the original study yielded similar distributions as well as indications of underreporting. We observed violations in all four data quality dimensions.

Conclusions

While we found relevant patient characteristics available in structured EHR data, data quality problems may entail that it remains a case-by-case decision whether diagnosis and procedure codes are sufficient to underpin observational studies. Free-text data or subsequently supplementary study data may be important to complement a comprehensive patient history.

Increasing prevalence of vascular risk factors in patients with stroke: A call to action

OBJECTIVE

To evaluate trends in prevalence of cardiovascular risk factors (hypertension, diabetes, dyslipidemia, smoking, and drug abuse) and cardiovascular diseases (carotid stenosis, chronic renal failure [CRF], and coronary artery disease [CAD]) in acute ischemic stroke (AIS) in the United States.

METHODS

We used the 2004-2014 National Inpatient Sample to compute weighted prevalence of each risk factor in hospitalized patients with AIS and used joinpoint regression to evaluate change in prevalence over time.

RESULTS

Across the 2004-2014 period, 92.5% of patients with AIS had ≥1 risk factor. Overall age- and sex-adjusted prevalence of hypertension, diabetes, dyslipidemia, smoking, and drug abuse were 79%, 34%, 47%, 15%, and 2%, respectively, while those of carotid stenosis, CRF, and CAD were 13%, 12%, and 27%, respectively. Risk factor prevalence varied by age (hypertension: 44% in 18-39 years vs 82% in 60-79 years), race (diabetes: Hispanic 49% vs white 30%), and sex (drug abuse: men 3% vs women 1.4%). Using joinpoint regression, prevalence of hypertension increased annually by 1.4%, diabetes by 2%, dyslipidemia by 7%, smoking by 5%, and drug abuse by 7%. Prevalence of CRF, carotid stenosis, and CAD increased annually by 13%, 6%, and 1%, respectively. Proportion of patients with multiple risk factors also increased over time.

CONCLUSIONS

Despite numerous guidelines and prevention initiatives, prevalence of hypertension, diabetes, dyslipidemia, smoking, and drug abuse in AIS increased across the 2004-2014 period. Proportion of patients with carotid stenosis, CRF, and multiple risk factors also increased. Enhanced risk factor modification strategies and implementation of evidence-based recommendations are needed for optimal stroke prevention.

A cohort study on physician documentation and the accuracy of administrative data coding to improve passive surveillance of transient ischaemic attacks

BACKGROUND

Administrative health data are valuable in health research and disease surveillance, but have low to moderate sensitivity in identifying transient ischaemic attacks (TIA) in the emergency department (ED). We aimed to identify the predictors of coding accuracy for TIA.

METHODS

The study population was obtained from two ongoing studies on the diagnosis of TIA, minor stroke and stroke mimic. ED charts were manually reviewed by a stroke neurologist to obtain the clinical diagnosis, patient characteristics and content of physician documentation. Administrative data codes were compared with the chart-adjudicated diagnosis to determine cases of misclassification by administrative data. Univariable regression was used to evaluate candidate predictors of disagreement, and the significant variables were tested in a multivariable model to obtain an adjusted estimate of effect.

RESULTS

Among 417 patients (39.1% TIA, 37.2% minor stroke and 23.7% stroke mimics), there were 122 cases of disagreement between adjudications and administrative data codes for the diagnosis of TIA. The majority of disagreement (n=103/122, 84.4%) arose from adjudicated TIA cases that were misclassified as non-TIA in administrative data coding. There were 78 (18.7%) charts with documented uncertain diagnosis, and 73 (17.5%) charts had no definite diagnosis. The relative risk of disagreement between chart adjudication and administrative data coding when the final diagnosis was uncertain or absent was 1.82(1.36, 2.44) and the risk difference was 18.5%. Multivariable logistic regression analyses confirmed this association using different case definition algorithms.

CONCLUSIONS

In suspected patients with TIA and minor stroke presenting to the ED, physician documentation was the dominant factor in coding accuracy, supporting the concept that physicians are active participants in administrative data coding. Strategies to improve chart documentation are predicted to have a positive effect on coding accuracy.

On pump versus off pump coronary artery bypass grafting in patients with end-stage renal disease and coronary artery disease - A nation-wide, propensity score matched database analyses

OBJECTIVE

The usage of on or off cardiopulmonary bypass in patients with coronary artery disease receiving coronary artery bypass grafting (CABG) surgery had been debated and had not yet been investigated thoroughly in patients with end-stage renal disease (ESRD). We aimed to study cardiovascular outcomes and total mortality in these patients by using our National Health Insurance (NHI) database.

METHOD

By using our NHI ESRD claim database, we searched ESRD patients aged more than 18years, who received CABG and divided them into on pump and off pump groups. Baseline characteristics and underlying comorbidities were identified from the database. Propensity score (PS) method was used to match all the potential confounders between patients. Outcomes including mortality, myocardial infarction, stroke and repeat revascularization within 30days, 1year and whole follow-up period were also obtained.

RESULT

A total of 134,410 ESRD patients were identified in the database. We included 341 patients and 543 patients who received off pump and on pump CABG respectively. The hazard ratios of different outcomes at 30days, 1year and a median of 745days after CABG did not show significant different between on, or off pump groups before and after PS match.

CONCLUSION

ESRD patients with CAD undergoing either on pump or off pump CABG surgery showed similar outcomes in 30days, 1year and whole follow-up period.

Mortality Associated With Heart Failure After Myocardial Infarction: A Contemporary Community Perspective

BACKGROUND

Contemporary data are lacking on the prognostic importance of heart failure (HF) after myocardial infarction (MI). We evaluated the prognostic impact of HF post MI according to preserved/reduced ejection fraction and the timing of its occurrence.

METHODS AND RESULTS

All Olmsted County, Minnesota, residents (n=2596) with incident MI diagnosed in 1990 to 2010 and no prior HF were followed through March 2013. Cox models were used to examine (1) the hazard ratios for death associated with HF type and timing and (2) secular trends in survival by HF status. During a mean follow-up of 7.6 years, there were 1116 deaths, 634 in the 902 patients who developed HF (70%) and 482 in the 1694 patients who did not develop HF (28%). After adjustment for age and sex, HF as a time-dependent variable was strongly associated with mortality (hazard ratio =3.31, 95% confidence interval: 2.93-3.75), particularly from cardiovascular causes (hazard ratio =4.20, 95% confidence interval: 3.50-5.03). Further adjustment for MI severity and comorbidity, acute treatment, and recurrent MI moderately attenuated these associations (hazard ratio =2.49 and 2.94 for all-cause and cardiovascular mortality, respectively). Mortality did not differ by ejection fraction, but was higher for delayed- versus early-onset HF (P for heterogeneity =0.002). The age- and sex-adjusted 5-year survival estimates in 2001 to 2010 versus 1990 to 2000 were 82% and 81% among HF-free and 61% and 54% among HF patients, respectively (P for heterogeneity of trends =0.05).

CONCLUSIONS

HF markedly increases the risk of death after MI. This excess risk is similar regardless of ejection fraction but greater for delayed- versus early-onset HF. Mortality after MI declined over time, primarily as a result of improved HF survival.

The effect of physicians’ financial incentives on the diagnosis related group-based prospective reimbursement scheme in Taiwan

This study examines whether the implementation of a Physician Compensation Program (PCP) improved departmental performance in a large private not-for-profit hospital’s performance after it implemented the Taiwan Diagnosis Related Group-based (Tw-DRG) prospective reimbursement scheme. Because hospitals in Taiwan are structurally similar to staff-model HMOs, the effects of PCPs on hospital performance under the Tw-DRG scheme in Taiwan may have implications for staff-model HMOs. The data sample contains 624 monthly observations of the 26 departments in the case hospital for the period 2009–2010. Of the 26 departments, 18 have implemented the Tw-DRG scheme and are classified as the Tw-DRG group; and the other eight departments are classified as the non-Tw-DRG group. Since the introduction of the scheme, the physicians in both groups have been paid under the PCP. Overall, the results show that the case hospital’s performance deteriorated after the scheme was implemented. The findings imply that conflicts arise in hospitals where some departments have implemented the Tw-DRG scheme that encourages hospitals to reduce the utilization of medical resources, while physicians in those departments are still paid under the PCP and are, therefore, motivated to expand medical services without trying to reduce costs. As a result, the Tw-DRG scheme may fail or only have a limited effect. This study also provides evidence that physicians’ behavior affects their clinical performance, especially under a strict cost containment payment policy. Taiwan’s experience provides a good opportunity to evaluate, simultaneously, the effects of cost containment mechanisms and physicians’ incentive plans within a staff-model context.

A contemporary appraisal of the heart failure epidemic in Olmsted County, Minnesota, 2000 to 2010

IMPORTANCE

Heart failure (HF) is commonly referred to as an epidemic, posing major clinical and public health challenges. Yet, contemporary data on its magnitude and implications are scarce.

OBJECTIVE

To evaluate recent trends in HF incidence and outcomes overall and by preserved ejection fraction (HFpEF) or reduced ejection fraction (HFrEF).

DESIGN, SETTING, AND PARTICIPANTS

Incidence rates of HF in Olmsted County, Minnesota (population, approximately 144,248), between January 1, 2000, and December 31, 2010, were assessed.

MAIN OUTCOMES AND MEASURES

Patients identified with incident HF (n = 2762) (mean age, 76.4 years; 43.1% male) were followed up for all-cause and cause-specific hospitalizations (through December 2012) and death (through March 2014).

RESULTS

The age- and sex-adjusted incidence of HF declined substantially from 315.8 per 100,000 in 2000 to 219.3 per 100,000 in 2010 (annual percentage change, -4.6), equating to a rate reduction of 37.5% (95% CI, -29.6% to -44.4%) over the last decade. The incidence declined for both HF types but was greater (interaction P = .08) for HFrEF (-45.1%; 95% CI, -33.0% to -55.0%) than for HFpEF (-27.9%; 95% CI, -12.9% to -40.3%). Mortality was high (24.4% for age 60 years and 54.4% for age 80 years at 5 years of follow-up), frequently ascribed to noncardiovascular causes (54.3%), and did not decline over time. The risk of cardiovascular death was lower for HFpEF than for HFrEF (multivariable-adjusted hazard ratio, 0.79; 95% CI, 0.67-0.93), whereas the risk of noncardiovascular death was similar (1.07; 95% CI, 0.89-1.29). Hospitalizations were common (mean, 1.34; 95% CI, 1.25-1.44 per person-year), particularly among men, and did not differ between HFpEF and HFrEF. Most hospitalizations (63.0%) were due to noncardiovascular causes. Hospitalization rates for cardiovascular causes did not change over time, whereas those for noncardiovascular causes increased.

CONCLUSIONS AND RELEVANCE

Over the last decade, the incidence of HF declined substantially, particularly for HFrEF, contrasting with no apparent change in mortality. Noncardiovascular conditions have an increasing role in hospitalizations and remain the most frequent cause of death. These results underscore the need to augment disease-centric management approaches with holistic strategies to reduce the population burden of HF.

Cardiovascular events in patients with atherothrombotic disease: a population-based longitudinal study in Taiwan

Background

Atherothrombotic diseases including cerebrovascular disease (CVD), coronary artery disease (CAD), and peripheral arterial disease (PAD), contribute to the major causes of death in the world. Although several studies showed the association between polyvascular disease and poor cardiovascular (CV) outcomes in Asian population, there was no large-scale study to validate this relationship in this population.

Methods and Results

This retrospective cohort study included patients with a diagnosis of CVD, CAD, or PAD from the database contained in the Taiwan National Health Insurance Bureau during 2001–2004. A total of 19954 patients were enrolled in this study. The atherothrombotic disease score was defined according to the number of atherothrombotic disease. The study endpoints included acute coronary syndrome (ACS), all strokes, vascular procedures, in hospital mortality, and so on. The event rate of ischemic stroke (18.2%) was higher than that of acute myocardial infarction (5.7%) in our patients (P = 0.0006). In the multivariate Cox regression analyses, the adjusted hazard ratios (HRs) of each increment of atherothrombotic disease score in predicting ACS, all strokes, vascular procedures, and in hospital mortality were 1.41, 1.66, 1.30, and 1.14, respectively (P≦0.0169).

Conclusions

This large population-based longitudinal study in patients with atherothrombotic disease demonstrated the risk of subsequent ischemic stroke was higher than that of subsequent AMI. In addition, the subsequent adverse CV events including ACS, all stroke, vascular procedures, and in hospital mortality were progressively increased as the increase of atherothrombotic disease score.

A plasma long-chain acylcarnitine predicts cardiovascular mortality in incident dialysis patients

Background

The marked excess in cardiovascular mortality that results from uremia remains poorly understood.

Methods and Results

In 2 independent, nested case‐control studies, we applied liquid chromatography‐mass spectrometry‐based metabolite profiling to plasma obtained from participants of a large cohort of incident hemodialysis patients. First, 100 individuals who died of a cardiovascular cause within 1 year of initiating hemodialysis (cases) were randomly selected along with 100 individuals who survived for at least 1 year (controls), matched for age, sex, and race. Four highly intercorrelated long‐chain acylcarnitines achieved the significance threshold adjusted for multiple testing (P<0.0003). Oleoylcarnitine, the long‐chain acylcarnitine with the strongest association with cardiovascular mortality in unadjusted analysis, remained associated with 1‐year cardiovascular death after multivariable adjustment (odds ratio per SD 2.3 [95% confidence interval, 1.4 to 3.8]; P=0.001). The association between oleoylcarnitine and 1‐year cardiovascular death was then replicated in an independent sample (n=300, odds ratio per SD 1.4 [95% confidence interval, 1.1 to 1.9]; P=0.008). Addition of oleoylcarnitine to clinical variables improved cardiovascular risk prediction using net reclassification (NRI, 0.38 [95% confidence interval, 0.20 to 0.56]; P<0.0001). In physiologic profiling studies, we demonstrate that the fold change in plasma acylcarnitine levels from the aorta to renal vein and from pre‐ to post hemodialysis samples exclude renal or dialytic clearance of long‐chain acylcarnitines as confounders in our analysis.

Conclusions

Our data highlight clinically meaningful alterations in acylcarnitine homeostasis at the time of dialysis initiation, which may represent an early marker, effector, or both of uremic cardiovascular risk.

Epidemiology of heart failure

Heart failure (HF) has been singled out as an epidemic and is a staggering clinical and public health problem, associated with significant mortality, morbidity, and healthcare expenditures, particularly among those aged ≥ 65 years. The case mix of HF is changing over time with a growing proportion of cases presenting with preserved ejection fraction for which there is no specific treatment. Despite progress in reducing HF-related mortality, hospitalizations for HF remain frequent and rates of readmissions continue to rise. To prevent hospitalizations, a comprehensive characterization of predictors of readmission in patients with HF is imperative and must integrate the impact of multimorbidity related to coexisting conditions. New models of patient-centered care that draw on community-based resources to support HF patients with complex coexisting conditions are needed to decrease hospitalizations.

Age, male gender, and atrial fibrillation predict lower extremity amputation or revascularization in patients with peripheral artery diseases: a population-based investigation

By using the National Health Insurance (NHI) claim data of Taiwan, we sought to determine the predictors for nontraumatic lower extremity amputation (LEA) or peripheral revascularization procedures (PRP) in patients with peripheral artery disease (PAD). From the NHI claim data, we identified 12,206 patients with newly diagnosed PAD between 1998 and 2008, and followed them up to 2008. We explored the age, gender, and whether the patients had concomitant comorbid conditions, such as diabetes mellitus (DM), hypertension (HTN), atrial fibrillation (AF), stroke, hospitalization for coronary artery disease (CAD), myocardial infarction (MI), or heart failure (HF), and whether they were taking cilostazol at the time of recruitment. We searched for clinical parameters that might be important determinants for LEA or PRP in the study population. Of the 12,206 patients, 150 (1.2%) were found to undergo either LEA or PRP or both (LEA 81, PRP 53, both PRP and LEA 16). Old age, male gender, and history of hospitalization for CAD or MI and AF were found to be risk predictors for both procedures. Patients with DM were at lower risk for PRP (odds ratio 0.418, p = 0.001). Patients who were taking cilostazol had higher risk for LEA or PRP. HTN was not a risk predictor for LEA or PRP. From this nationwide study, we found that among PAD patients in Taiwan, age, male gender, AF, and hospitalization for CAD or MI are risk predictors for future LEA or PRP. DM is a negative predictor for PRP while both DM and HTN are not risk predictors for LEA.

Cilostazol for primary prevention of stroke in peripheral artery disease: a population-based longitudinal study in Taiwan

BACKGROUND

Clopidogrel, cilostazol, and aspirin were compared in terms of efficacy and safety for primary prevention of stroke in peripheral artery disease (PAD) patients.

METHODS

This retrospective cohort study analyzed data contained in the Taiwan National Health Insurance Bureau database for patients treated for PAD but not for stroke during 2002-2008. Patients were stratified according to treatment with aspirin, clopidogrel, cilostazol, or combined therapy. The primary efficacy and safety endpoints were stroke and hemorrhage.

RESULTS

Of the 931 patients enrolled in this study, 479 had received aspirin, 39 had received clopidogrel, 294 had received cilostazol alone, and 33 had received a cilostazol-based combined therapy. Compared to patients treated with aspirin, the patients treated with cilostazol had significantly lower all-stroke risk not only in the overall group (HR=0.66, 95% CI=0.48-0.90, p=0.0086), but also in the subgroup of patients with diabetes (HR=0.64, 95% CI=0.42-0.98, p=0.0394) and in the subgroup of patients with high cardiovascular risk (HR=0.66, 95% CI=0.46-0.95, p=0.0254). Additionally, compared to patients treated with aspirin, those treated with cilostazol did not have significantly more hemorrhagic events in the overall group, in the diabetes subgroup, or in the high cardiovascular risk subgroup. Clopidogrel, cilostazol-based combined therapy and aspirin did not significantly differ in terms of efficacy and hemorrhagic events.

CONCLUSION

Although this database study indicated that cilostazol therapy is an effective alternative treatment for primary prevention of stroke in PAD, further confirmation is needed in large, prospective, and randomized trials.

Derivation and validation of a simple model to identify venous thromboembolism risk in medical patients

BACKGROUND

Fewer than half of eligible hospitalized medical patients receive appropriate venous thromboembolism (VTE) prophylaxis. One reason for this low rate is the complexity of existing risk assessment models. A simple set of easily identifiable risk factors that are highly predictive of VTE among hospitalized medical patients may enhance appropriate thromboprophylaxis.

METHODS

Electronic medical record interrogation was performed to identify medical admissions from January 1, 2000-December 31, 2007 (n=143,000), and those patients with objectively confirmed VTE during hospitalization or within 90 days following discharge. Putative risk factors most predictive of VTE were identified, and a risk assessment model (RAM) was derived; 46,000 medicine admissions from January 1, 2008-December 31, 2009 served as a validation cohort to test the predictive ability of the RAM. The newly derived RAM was compared with a published VTE assessment tool (Kucher Score).

RESULTS

Four risk factors: previous VTE; an order for bed rest; peripherally inserted central venous catheterization line; and a cancer diagnosis, were the minimal set most predictive of hospital-associated VTE (area under the receiver operating characteristic curve [AUC]=0.874; 95% confidence interval [CI], 0.869-0.880). These risk factors upon validation in a separate population (validation cohort) retained an AUC=0.843; 95% CI, 0.833-0.852. The ability of the 4-element RAM to identify patients at risk of developing VTE within 90 days was superior to the Kucher Score.

CONCLUSIONS

The 4-element RAM identified in this study may be used to identify patients at risk for VTE and improve rates of thromboprophylaxis. This simple and accurate RAM is an alternative to more complicated published VTE risk assessment tools that currently exist.

Time trends in pulmonary embolism in the United States: evidence of overdiagnosis

BACKGROUND

Computed tomographic pulmonary angiography (CTPA) may improve detection of life-threatening pulmonary embolism (PE), but this sensitive test may have a downside: overdiagnosis and overtreatment (finding clinically unimportant emboli and exposing patients to harms from unnecessary treatment).

METHODS

To assess the impact of CTPA on national PE incidence, mortality, and treatment complications, we conducted a time trend analysis using the Nationwide Inpatient Sample and Multiple Cause-of-Death databases. We compared age-adjusted incidence, mortality, and treatment complications (in-hospital gastrointestinal tract or intracranial hemorrhage or secondary thrombocytopenia) of PE among US adults before (1993-1998) and after (1998-2006) CTPA was introduced.

RESULTS

Pulmonary embolism incidence was unchanged before CTPA (P = .64) but increased substantially after CTPA (81% increase, from 62.1 to 112.3 per 100,000; P < .001). Pulmonary embolism mortality decreased during both periods: more so before CTPA (8% reduction, from 13.4 to 12.3 per 100,000; P < .001) than after (3% reduction, from 12.3 to 11.9 per 100,000; P = .02). Case fatality improved slightly before (8% decrease, from 13.2% to 12.1%; P = .02) and substantially after CTPA (36% decrease, from 12.1% to 7.8%; P < .001). Meanwhile, CTPA was associated with an increase in presumed complications of anticoagulation for PE: before CTPA, the complication rate was stable (P = .24), but after it increased by 71% (from 3.1 to 5.3 per 100,000; P < .001).

CONCLUSIONS

The introduction of CTPA was associated with changes consistent with overdiagnosis: rising incidence, minimal change in mortality, and lower case fatality. Better technology allows us to diagnose more emboli, but to minimize harms of overdiagnosis we must learn which ones matter.

Determinants of lower extremity amputation or revascularization procedure in patients with peripheral artery diseases: a population-based investigation

We used the National Health Insurance Claim data in Taiwan to evaluate determinants for nontraumatic lower extremity amputation (LEA) or peripheral revascularization procedures (PRP) in patients with peripheral artery diseases (PAD). We identified 14 241 patients. Sex-specific odds ratios of age, diabetes mellitus (DM), hypertension (HTN), coronary artery disease (CAD), cerebral vascular accident (CVA), or using cilostazol for LEA or PRP were explored. In patients with PAD, 14.3% of male and 7.4% of female had LEA; whereas 7.1% of male and 4.6% of female had PRP. Among male patients, HTN and CAD were significant risk factors for LEA, whereas DM and using cilostazol had protective roles. Findings in female patients were similar. For PRP, elderly patients had less such procedures. The risk/protective factors were similar. In conclusion, PAD patients having DM and using cilostazol had less LEA or PRP, whereas those having HTN and CAD had more LEA or PRP.

Burden of anemia in patients with osteoarthritis and rheumatoid arthritis in French secondary care

BACKGROUND

Arthritic disorders can be the cause of hospitalizations, especially among individuals 60 years and older. The objective of this study is to investigate associations between health care resource utilization in arthritis patients with and without concomitant anemia in a secondary care setting in France.

METHODS

This retrospective cohort study utilized data on secondary care activity in 2001 from the Programme de Médicalisation des Systèmes d'Information database. Two cohorts were defined using ICD-10 codes: patients with an arthritis diagnosis with a concomitant diagnosis of anemia; and arthritis patients without anemia. Health care resource utilization for both populations was analyzed separately in public and private hospitals. Study outcomes were compared between the cohorts using standard bivariate and multivariable methods.

RESULTS

There were 300,865 hospitalizations for patients with arthritis only, and 2,744 for those with concomitant anemia. Over 70% of patients with concomitant anemia were in public hospitals, compared with 53.5% of arthritis-only patients. Arthritis patients without anemia were younger than those with concomitant anemia (mean age 66.7 vs 74.6, public hospitals; 67.1 vs 72.2, private hospitals). Patients with concomitant anemia/arthritis only had a mean length of stay of 11.91 (SD 14.07)/8.04 (SD 9.93) days in public hospitals, and 10.68 (SD 10.16)/9.83 (SD 7.76) days in private hospitals. After adjusting for confounders, the mean (95% CI) additional length of stay for arthritis patients with concomitant anemia, compared with those with arthritis only, was 1.56 (1.14-1.98) days in public and 0.69 (0.22-1.16) days in private hospitals. Costs per hospitalization were €;480 (227-734) greater for arthritis patients with anemia in public hospitals, and €;30 (-113-52) less in private hospitals, than for arthritis-only patients.

CONCLUSIONS

Arthritis patients with concomitant anemia have a longer length of stay, undergo more procedures, and have higher hospitalization costs than nonanemic arthritis patients in public hospitals in France. In private hospitals, concomitant anemia was associated with modest increases in length of stay and number of procedures; however, this did not translate into higher costs. Such evidence of anemia-related health care utilization and costs can be considered as a proxy for the clinical significance of anemia.

The heart failure epidemic

Heart failure has been singled out as an emerging epidemic, which could be the result of increased incidence and/or increased survival leading to increased prevalence. Knowledge of the responsibility of each factor in the genesis of the epidemic is crucial for prevention. Population-based studies have shown that, over time, the incidence of heart failure remained overall stable, while survival improved. Therefore, the heart failure epidemic is chiefly one of hospitalizations. Data on temporal trends in the incidence and prevalence of heart failure according to ejection fraction and how it may have changed over time are needed while interventions should focus on reducing the burden of hospitalizations in hear failure.

Sex differences in the incidence of hemorrhagic and ischemic stroke among diabetics in Taiwan

BACKGROUND

Diabetes mellitus is an important risk factor for stroke, but whether there is differential gender-specific risk has not been fully elucidated. We aimed to explore the impact of gender on incidence and relative risks of hemorrhagic and ischemic stroke among the diabetic population in Taiwan.

METHODS

In this study, 500,868 diabetic patients and 500,248 age matched and-sex-matched nondiabetic individuals were linked to inpatient claims (1997-2002) to identify hospitalizations for nontraumatic hemorrhagic and ischemic stroke. Incidence density was calculated with the Poisson assumption, and Kaplan-Meier analysis was used to assess the cumulative incidence over a 6-year follow-up period. We also evaluated the relative hazards of stroke in relation to diabetes with the Cox proportional hazard model, adjusted with demographics and geographic regions.

RESULTS

The incidence of hemorrhagic stroke in diabetic women was less than that in diabetic men except in those aged > or =85, but the difference between male and female diabetic patients was less pronounced with ischemic stroke. The hazard ratios (HRs) of hemorrhagic and ischemic stroke among diabetic women were increased by a magnitude of 1.2 and 1.32, respectively, which were significantly higher than those of diabetic men. Further age-stratified analysis indicated that young and middle-aged diabetic women tended to have higher HRs and that diabetic women aged <35 suffered from particularly high HRs (HR 7.69, 95% confidence interval [CI] 1.81-32.75 for hemorrhagic stroke, and HR = 8.46, 95% CI 4.28-16.75 for ischemic stroke).

CONCLUSIONS

There was a significant gender-diabetes interactive effect on the incidence of hemorrhagic and ischemic stroke. Additionally, young Taiwanese diabetic patients were most vulnerable to an increased relative risk of hemorrhagic and ischemic stroke. Comprehensive diabetic care with stroke prevention measures should be emphasized in young diabetic people in order to prevent premature disability.

Long-term trends in myocardial infarction incidence and case fatality in the National Heart, Lung, and Blood Institute's Framingham Heart study

BACKGROUND

Whereas the prevalence of coronary heart disease risk factors has declined over the past decades in the United States, acute myocardial infarction (AMI) rates have been steady. We hypothesized that this paradox is due partly to the advent of increasingly sensitive biomarkers for AMI diagnosis.

METHODS AND RESULTS

In Framingham Heart Study participants over 4 decades, we compared the incidence and survival rates of initial AMI diagnosis by ECG (AMI-ECG) regardless of biomarkers with those based exclusively on infarction biomarkers (AMI-marker). We used Poisson regression to calculate annual incidence rates of first AMI over 4 decades (1960 to 1969, 1970 to 1979, 1980 to 1989, and 1990 to 1999) and compared rates of AMI-ECG with rates of AMI-marker. Cox proportional-hazards analysis was used to compare AMI case fatality over 4 decades. In 9824 persons (54% women; follow-up, 212 539 person-years; age, 40 to 89 years), 941 AMIs occurred, including 639 AMI-ECG and 302 AMI-marker events. From 1960 to 1999, rates of AMI-ECG declined by approximately 50% and rates of AMI-marker increased approximately 2-fold. Crude 30-day, 1-year, and 5-year case fatality rates in 1960 to 1969 and 1990 to 1999 were 0.20 and 0.14, 0.24 and 0.21, and 0.45 and 0.41, respectively. Age- and sex-adjusted 30-day, 1-year, and 5-year AMI case fatality declined by 60% in 1960 to 1999 (P for trend <0.001), with parallel declines noted after AMI-ECG and AMI-marker.

CONCLUSIONS

Over the past 40 years, rates of AMI-ECG have declined by 50%, whereas rates of AMI-marker have doubled. Our findings offer an explanation for the apparently steady national AMI rates in the face of improvements in primary prevention.

Epidemiology of myocardial infarction

Myocardial infarction is a key component of the burden of cardiovascular disease. The assessment of the incidence and case fatality of myocardial infarction are important determinants of the decline in coronary disease mortality. The change in biomarkers used to diagnose myocardial infarction raises several methodologic, clinical, and public health challenges, which are discussed herein.

Age and sex may significantly interact with diabetes on the risks of lower-extremity amputation and peripheral revascularization procedures: evidence from a cohort of a half-million diabetic patients

OBJECTIVE

Using the National Health Insurance claim data, we prospectively investigated the age- and sex-specific incidence density and relative hazards of nontraumatic lower-extremity amputation (LEA) and peripheral revascularization procedure (PRP) of the diabetic population in Taiwan.

RESEARCH DESIGN AND METHODS

A total of 500,868 diabetic patients and 500,248 age- and sex-matched control subjects, selected from the ambulatory care claim (1997) and the registry for beneficiaries, respectively, were linked to inpatient claims (1997-2002) to identify hospitalizations due to nontraumatic LEA and PRP. Incidence density was calculated under the Poisson assumption, and the Kaplan-Meier analysis was used to assess the cumulative event rates over a 6-year follow-up period. We also evaluated the age- and sex-specific relative hazards of nontraumatic LEA and PRP in relation to diabetes with Cox proportional hazard regression model adjusted for demographics and regional areas.

RESULTS

The estimated incidence density of nontraumatic LEA and PRP for diabetic men was 410.3 and 317.0 per 100,000 patient-years, respectively. The corresponding data for diabetic women were relatively low at 115.2 and 86.0 per 100,000 patient-years. Compared with control subjects with the same age and sex, diabetic patients consistently suffered from significantly elevated relative hazards of nontraumatic LEA. Young and female patients were especially vulnerable to experience increased risks of nontraumatic LEA, but such effect modification by age and sex was less apparent for PRP.

CONCLUSIONS

Multidisciplinary diabetes foot care systems, including the provision of revascularization procedures, should be further enforced to reduce subsequent risks of nontraumatic LEA, especially in young and female diabetic patients.

Acute coronary syndrome national statistics: challenges in definitions

BACKGROUND

Increasing convergence in the management of acute myocardial infarction (AMI) and unstable angina (UA) has led some to consider whether these 2 diagnoses should be consolidated into acute coronary syndrome (ACS) for the purpose of coronary heart disease surveillance.

METHODS

We used the 1988-2001 Nationwide Inpatient Sample, which has demographic and diagnosis data on 6 to 7 million discharges per year from a sample of US nonfederal hospitals. We identified discharges with a first- or all-listed diagnosis of AMI ( International Classification of Diseases, Ninth Revision, Clinical Modification 410) or UA (International Classification of Diseases, Ninth Revision, Clinical Modification 411) and defined ACS-first as a primary diagnosis of either condition and all-listed ACS as codes 410 or 411 among any diagnoses. Sampling weights were applied to produce yearly national discharge estimates; annual population estimates were used to calculate yearly hospital discharge rates; rates were then adjusted to the 2000 standard population.

RESULTS

Rates of first- and all-listed AMIs changed little. Rates of first-listed UA fell 87% from 29.7/10,000 in 1988 to 3.9/10,000 in 2001. This sharp decline was seen among all age and sex groups. Consequently, rates of ACS as a primary diagnosis declined 44%. In contrast, discharge rates for all-listed UA and ACS declined only modestly.

CONCLUSIONS

As a primary diagnosis, UA is disappearing. Rates of first-listed ACS are quite sensitive to the decline in UA. Although discharge data based on first-listed diagnoses have been used to estimate the national incidence of AMI, they may not provide accurate data regarding current trends for ACS.

Association of hospital ownership with patient transfers to outpatient care under a prospective payment system in Taiwan

Case payment, a prospective payment system akin to diagnosis-related groups (DRGs) has in-built incentives for hospitals to transfer inpatients to their own ambulatory care units following early discharge. This study used nation-wide inpatient claims data on a total of 100,730 patients treated in 2000 in (Taiwan): cesarean section (59,364 cases), femoral/inguinal hernia operation (18,675 cases), and hemorrhoidectomy (22,691 cases), all reimbursed by case payment, to explore the relationship between hospital ownership and patient transfers to outpatient treatment. For all three diagnoses, for-profit (FP) hospitals not only had lower lengths of stay (LOS) compared to public hospitals, but also showed very high odds of patient transfer to their own outpatient units, after controlling for institutional variables, (hospital level, teaching status, and geographic location), hospital competitive environment (the Herfindal-Hirschman index), and patient variables (gender, age, length of stay, and number of secondary diagnoses, a proxy for severity of illness). Similar, though slightly lower odds were observed with not-for-profit (NFP) hospitals relative to public hospitals. The findings support the property rights theory, suggesting that in Taiwan, institutional profit maximization motives may be driving patient transfers under the case payment diagnoses, rather than medical care needs. In NFP hospitals, their physician compensation mechanism, driven largely by care volumes provided by each physician, appears to be driving the disproportionately greater likelihood of patient transfer to outpatient care.

The effect of insurance status, race, and gender on ED disposition of persons with traumatic brain injury

The objective of this study was to assess the effect of insurance status and demographic characteristics on ED disposition among patients with traumatic brain injury (TBI). Statewide hospital discharge and ED datasets in South Carolina, 1996-2001, were analyzed by primary or secondary diagnosis of TBI in a multivariable logistic regression model. Of 70,671 unduplicated patients with TBI evaluated in the ED, 76% were treated and released; 26% had no insurance. The strongest predictors of hospital admission were TBI severity and preexisting health conditions. However, the uninsured and black females were less likely to be hospitalized after adjusting for demographic, clinical, and hospital characteristics (odds ratio [OR], 0.52; 95% confidence interval [CI], 0.48-0.55 and OR, 0.79; CI, 0.72-0.87, respectively). Although this study does not infer causality, insurance status, race, and gender were significant predictors of hospital admission. These results suggest that inpatient resources are not equitably used.

Prognostic value of coronary artery calcium screening in subjects with and without diabetes

OBJECTIVES

The study was done to determine the interaction of coronary artery calcium and diabetes mellitus for prediction of all-cause death.

BACKGROUND

Diabetes is a strong risk factor for coronary artery disease (CAD) and is associated with an elevated overall mortality. Electron beam tomography (EBT) provides information on the presence of subclinical atherosclerosis and may be useful for risk stratification.

METHODS

We followed 10,377 asymptomatic individuals (903 diabetic patients) referred for EBT imaging. Primary end point was all-cause mortality, and the average follow-up was 5.0 +/- 3.5 years. Cox proportional hazard models, with and without adjustment for other risk factors, were developed to predict all-cause mortality.

RESULTS

Patients with diabetes had a higher prevalence of hypertension and smoking (p < 0.001) and were older. The average coronary calcium score (CCS) for subjects with and for those without diabetes was 281 +/- 567 and 119 +/- 341, respectively (p < 0.0001). Overall, the death rate was 3.5% and 2.0% for subjects with and without diabetes (p < 0.0001). In a risk-factor-adjusted model, there was a significant interaction of CCS with diabetes (p < 0.00001), indicating that, for every increase in CCS, there was a greater increase in mortality for diabetic than for nondiabetic subjects. However, patients suffering from diabetes with no coronary artery calcium demonstrated a survival similar to that of individuals without diabetes and no detectable calcium (98.8% and 99.4%, respectively, p = 0.5).

CONCLUSIONS

Mortality from all causes is increased in asymptomatic patients with diabetes in proportion to the screening CCS. Nonetheless, subjects without coronary artery calcium have a low short-term risk of death even in the presence of diabetes mellitus.

Who has diabetes? Best estimates of diabetes prevalence in the Department of Veterans Affairs based on computerized patient data

OBJECTIVE

To optimize methods for identifying patients with diabetes based on computerized records and to obtain best estimates of diabetes prevalence in Department of Veterans Affairs (VA) patients.

RESEARCH DESIGN AND METHODS

The VA Diabetes Epidemiology Cohort (DEpiC) is a linked national database of all VA patients since 1998 with data from VA medical visits, Medicare claims, pharmacy and laboratory records, and patient surveys. Using DEpiC, we examined concordance of diabetes indicators, including ICD-9-CM codes (250.xx), prescription drug treatment, HbA(1c) tests, and patient self-report. We determined the optimal criterion for identifying diabetes and used it in estimating diabetes prevalence in the VA.

RESULTS

The best criterion was a prescription for a diabetes medication in the current year and/or 2+ diabetes codes from inpatient and/or outpatient visits (VA and Medicare) over a 24-month period. This definition had high sensitivity (93%) and specificity (98%) against patient self-report, and reasonable rates of HbA(1c) testing (75%). HbA(1c) testing alone added few additional cases, and a single diagnostic code added many patients, but without confirmation (reduced specificity). However, including codes from Medicare was critical. Applying this definition for 1998-2000, we identified an average of 500,000 VA patients with diabetes per year. We also estimated high and increasing diabetes prevalence rates of 16.7% in FY1998, 18.6% in FY1999, and 19.6% in FY2000 and an incidence estimated to be approximately 2% per year.

CONCLUSIONS

Development and evaluation of methodology for analyzing computerized patient data can improve the identification of patients with diabetes. The increasing high prevalence of diabetes in VA patients will present challenges for clinicians and health system management.

Impact of fractures on health care in a major university hospital in Rome

BACKGROUND AND AIMS

The aim of the study was to investigate the impact of fractures (i.e., hip, Colles, humeral and vertebral fractures), compared with that of other common diseases requiring hospitalization, on health care in the main hospital in Rome (Italy).

METHODS

Hospital discharge forms, filled in according to the 9th International Classification of Diseases, were examined from 1996 to 1999. Data on fractures were compared with those related to other diseases which occupy a considerable proportion of hospital operating time in Italy: coronary heart disease (CHD), cerebrovascular disorders (CVD), diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD) and breast cancer (BC).

RESULTS

In all groups of patients, the mean age of females was significantly higher (p<0.0001) than that of males. Male patients with hip fractures had hospital stays significantly longer than females (p<0.0001), whereas women with Colles fractures had significantly (p<0.02) longer stays. When patients were divided according to age (i.e., over or under 60 years), mean hospital stays did not differ between younger and older patients in all groups except Colles fractures (p<0.001). Hip fractures in older patients showed striking in-hospital mortality. Throughout the study period, hip fractures accounted for the highest overall and per-patient costs. The number of female patients with fractures (and, obviously, breast cancer) was higher, while the opposite applied to the other disorders. Male patients with fractures, CHD and CVD were significantly younger than females (p<0.0001). When the percentage of deaths was added to that of patients discharged to other institutions, fractures showed the poorest outcome of any hospitalization event. Per-patient costs were remarkably higher for CHD, followed by fractures.

CONCLUSIONS

Fractures represent a growing but often underestimated burden for hospital care in Italy; further studies are needed on this issue.

Survival of patients undergoing hemodialysis with paricalcitol or calcitriol therapy

BACKGROUND

Elevated calcium and phosphorus levels after therapy with injectable vitamin D for secondary hyperparathyroidism may accelerate vascular disease and hasten death in patients undergoing long-term hemodialysis. Paricalcitol, a new vitamin D analogue, appears to lessen the elevations in serum calcium and phosphorus levels, as compared with calcitriol, the standard form of injectable vitamin D.

METHODS

We conducted a historical cohort study to compare the 36-month survival rate among patients undergoing long-term hemodialysis who started to receive treatment with paricalcitol (29,021 patients) or calcitriol (38,378 patients) between 1999 and 2001. Crude and adjusted survival rates were calculated and stratified analyses were performed. A subgroup of 16,483 patients who switched regimens was also evaluated.

RESULTS

The mortality rate among patients receiving paricalcitol was 3417 per 19,031 person-years (0.180 per person-year), as compared with 6805 per 30,471 person-years (0.223 per person-year) among those receiving calcitriol (P<0.001). The difference in survival was significant at 12 months and increased with time (P<0.001). In the adjusted analysis, the mortality rate was 16 percent lower (95 percent confidence interval, 10 to 21 percent) among paricalcitol-treated patients than among calcitriol-treated patients. A significant survival benefit was evident in 28 of 42 strata examined, and in no stratum was calcitriol favored. At 12 months, calcium and phosphorus levels had increased by 6.7 and 11.9 percent, respectively, in the paricalcitol group, as compared with 8.2 and 13.9 percent, respectively, in the calcitriol group (P<0.001). The two-year survival rate among patients who switched from calcitriol to paricalcitol was 73 percent, as compared with 64 percent among those who switched from paricalcitol to calcitriol (P=0.04).

CONCLUSIONS

Patients who receive paricalcitol while undergoing long-term hemodialysis appear to have a significant survival advantage over those who receive calcitriol. A prospective, randomized study is critical to confirm these findings.

Early indicators of prolonged intensive care unit stay: impact of illness severity, physician staffing, and pre-intensive care unit length of stay

OBJECTIVE

Scoring systems that predict mortality do not necessarily predict prolonged length of stay or costs in the intensive care unit (ICU). Knowledge of characteristics predicting prolonged ICU stay would be helpful, particularly if some factors could be modified. Such factors might include process of care, including active involvement of full-time ICU physicians and length of hospital stay before ICU admission.

DESIGN

Demographic data, clinical diagnosis at ICU admission, Simplified Acute Physiology Score, and organizational characteristics were examined by logistic regression for their effect on ICU and hospital length of stay and weighted hospital days (WHD), a proxy for high cost of care.

SETTING

A total of 34 ICUs at 27 hospitals participating in Project IMPACT during 1998.

PATIENTS

A total of 10,900 critically ill medical, surgical, and trauma patients qualifying for Simplified Acute Physiology Score assessment.

INTERVENTIONS

None.

RESULTS

Overall, 9.8% of patients had excess WHD, but the percentage varied by diagnosis. Factors predicting high WHD include Simplified Acute Physiology Score survival probability, age of 40 to 80 yrs, presence of infection or mechanical ventilation 24 hrs after admission, male sex, emergency surgery, trauma, presence of critical care fellows, and prolonged pre-ICU hospital stay. Mechanical ventilation at 24 hrs predicts high WHD across diagnostic categories, with a relative risk of between 2.4 and 12.9. Factors protecting against high WHD include do-not-resuscitate order at admission, presence of coma 24 hrs after admission, and active involvement of full-time ICU physicians.

CONCLUSIONS

Patients with high WHD, and thus high costs, can be identified early. Severity of illness only partially explains high WHD. Age is less important as a predictor of high WHD than presence of infection or ventilator dependency at 24 hrs. Both long ward stays before ICU admission and lack of full-time ICU physician involvement in care increase the probability of long ICU stays. These latter two factors are potentially modifiable and deserve prospective study.

Hospitalized avascular necrosis after renal transplantation in the United States

BACKGROUND

The national incidence of and risk factors for hospitalized avascular necrosis (AVN) in renal transplant recipients has not been reported.

METHODS

This historical cohort study consisted of 42,096 renal transplant recipients enrolled in the United States Renal Data System (USRDS) between 1 July 1994 and 30 June 1998. The data source was USRDS files through May 2000. Associations with hospitalizations for a primary diagnosis of AVN (ICD-9 codes 733.4x) within three years after renal transplant were assessed in an intention-to-treat design by Cox regression analysis.

RESULTS

Recipients had a cumulative incidence of 7.1 episodes/1000 person-years from 1994 to 1998. The two-year incidence of AVN did not change significantly over time. Eighty-nine percent of the cases of AVN were due to AVN of the hip (733.42) and 60.2% of patients with AVN underwent total hip arthroplasty (THA); these percentages did not change significantly over time. In the Cox regression analysis, an earlier year of transplant, African American race [adjusted hazard ratio (AHR), 1.65, 95% confidence interval (CI) 1.33 to 2.03], allograft rejection (AHR 1.67, 95% CI 1.35 to 2.07), peritoneal dialysis (vs. hemodialysis; AHR 1.44, 95% CI 1.15 to 1.81), and diabetes (AHR 0.41, 95% CI 0.27 to 0.64) were the only factors independently associated with hospitalizations for AVN.

CONCLUSIONS

The incidence of AVN did not decline significantly over time in the renal transplant population. Patients with allograft rejection, African American race, peritoneal dialysis and earlier date of transplant were at the highest risk of AVN, while diabetic recipients were at a decreased risk.

Hospitalizations for total hip arthroplasty after renal transplantation in the United States

The national incidence of and factors associated with total hip arthroplasty in renal transplant recipients has not been reported. We conducted an historical cohort study of 42096 renal transplant recipients in the United States between 1 July 1994 and 30 June 1998. Primary outcomes were associations with hospitalizations for a primary discharge code of total hip arthroplasty (ICD9 procedure code 81.51x) within 3 years after renal transplant using Cox regression. Renal transplant recipients had a cumulative incidence of total hip arthroplasty of 5.1 episodes/1000 person-years, which is 5-8 times higher than reported in the general population. Avascular necrosis of the hip was the most frequent primary diagnosis associated with total hip arthroplasty in this population (72% of cases). Repeat surgeries were performed in 27% of patients with avascular necrosis, vs. 15% with other diagnoses. Total hip arthroplasty was more frequent in transplant recipients who were older, African American, or who experienced allograft rejection. Mortality after total hip arthroplasty was 0.21% at 30 days and 15% at 3 years, similar to the mortality of all transplant recipients. The most common indication for total hip arthroplasty after renal transplant is avascular necrosis of the hip, in contrast to the general population. Although repeat surgeries are common, total hip arthroplasty is well tolerated and is not associated with increased mortality in this population.

Significant decline in case fatality after acute myocardial infarction in Denmark--a population-based study from 1994 to 2001

OBJECTIVE

We evaluated trends in in-hospital case fatality after acute myocardial infarction (AMI) in Denmark and analysed changes in the hospitalization rate for AMI.

DESIGN

National population-based registries were used to identify patients (> or =30 years) who were admitted for their first AMI from 1994 to 2001.

RESULTS

The annual relative decline in case-fatality rate was constant at 10.5% (95% confidence interval (CI) 9.5-11.5%). The decline was similar for both genders at all ages. The hospitalization rate decreased from 1994 to 1999 at an annual average of 4.3% (95% CI 3.4-5.1%). In 2000 and 2001 the average annual increase was 7-8%.

CONCLUSION

The case-fatality rate after AMI declined significantly in Denmark, similar to other Western countries, but the level is still higher than that of the USA. The increasing hospitalization rate coincided with changes in risk factors in the general population. However, the influence of introducing troponins in the diagnosis of AMI and diagnosis-related grouping may in particular account for the increased hospitalization rate.

Heart failure after myocardial infarction: a review

PURPOSE

The effects of survival after myocardial infarction on the prevalence of chronic heart failure have not been well characterized. We reviewed studies of the incidence, mortality, and predictors of heart failure after myocardial infarction, and suggest directions for further research.

METHODS AND RESULTS

We conducted a review of the literature from 1978 to 2000. Of 33 identified articles, 18 (55%) included heart failure as a primary endpoint. The mean in-hospital incidence of heart failure after myocardial infarction differed significantly by study design; it was highest in population-based studies and lowest in clinical trials (37% vs. 18%, P <0.01). Only 10 studies reported the incidence of subsequent heart failure. One-year mortality ranged from 16% to 39% and showed no improvement with time. Patients with in-hospital heart failure after myocardial infarction had a two- to sixfold greater in-hospital mortality and up to a fivefold increased 1-year mortality compared with patients without heart failure. The most consistent risk factors for the development of heart failure after myocardial infarction were advanced age, female sex, diabetes, and an increased heart rate at the time of admission.

CONCLUSIONS

The reported incidence of, and mortality from, heart failure after myocardial infarction varies by study design. Additional research on the etiology and prognosis of late heart failure after myocardial infarction is needed.

Hospitalizations for valvular heart disease in chronic dialysis patients in the United States

BACKGROUND

Valvular heart disease has not been studied in a national population of end stage renal disease patients.

METHODS

327,993 dialysis patients in the United States Renal Data System initiated from 1 January 1992 to 30 June 1997 were analyzed in a historical cohort study of patients hospitalized for valvular heart disease (ICD9 Code 424.x, excluding endocarditis, and 394.x-397.x).

RESULTS

2,778 dialysis patients were hospitalized for VHD (incidence rate, 3.57 per 1,000 person years), and dialysis patients had an age-adjusted incidence ratio for valvular heart disease of 5.06 (95% confidence interval, 4.00-6.42) compared to the general population in 1996. In Cox regression analysis, time to hospitalization for valvular heart disease was associated with earlier year of first dialysis, increased age, congestive heart failure and use of erythropoietin prior to dialysis, while African-American race (AHR 0.62, 0.52-0.74) was associated with decreased risk of hospitalization for valvular heart disease. Patients hospitalized for valvular heart disease had increased mortality compared to all other dialysis patients (adjusted hazard ratio by Cox regression 1.35, 95% CI, 1.25-1.46).

CONCLUSIONS

Dialysis patients were at increased risk for hospitalizations for valvular heart disease compared to the general population, which substantially decreased patient survival. The reasons for the decreased risk of African-Americans on chronic dialysis for this complication should be the subject of future trials.

Effect of statin (HMG-Co-A-Reductase Inhibitor) use on 1-year mortality and hospitalization rates in older patients with cardiovascular disease living in nursing homes

OBJECTIVES

To quantify the effect of statins on 1-year mortality, hospitalizations, and decline in physical function among patients with cardiovascular disease (CVD) aged 65 and older living in nursing homes.

DESIGN

Retrospective cohort study.

SETTING

All Medicare/Medicaid certified nursing homes (N = 1,492) in Maine, New York, Mississippi, and South Dakota.

PARTICIPANTS

We identified 51,559 older patients with CVD from a population database that merged sociodemographic data and functional, clinical, and drug treatments from more than 300,000 newly admitted nursing home residents from 1992 to 1997. Statin users (n = 1,313) were matched with nonusers (n = 1,313) in the same facilities.

MEASUREMENTS

All-cause mortality, hospitalization, combined endpoint of mortality or hospitalization, and decline in physical function were determined at 1 year, and survival analysis was performed.

RESULTS

Prevalence of statin use in this frail older cohort with CVD was 2.6%. Statin use varied by age, gender, comorbid condition, medication use, and cognitive and physical function. One-year mortality was 229/1,000 person-years in the statin group and 404/1,000 person-years in the nonusers, with an adjusted hazard rate ratio (HRR) of 0.69, 95% confidence interval (CI) = 0.58-0.81. The estimated number needed to treat was seven (95% CI = 5-13). This association with improved all-cause mortality was evident for women and men and for age groups 75 to 84, and 85 and older.

CONCLUSION

Statin therapy is associated with improved clinical outcomes, including reduction in 1-year all-cause mortality, and the combined endpoint of death or hospitalization in a frail older population with CVD. Some caution should be taken in interpreting these results because potential bias from residual confounding could affect these results.

Predictors of subsequent coronary events, stroke, and death among survivors of first hospitalized myocardial infarction

We identified predictors of prognosis among n = 2,677 health maintenance organization enrollees 30 to 79 years old who survived a first hospitalized myocardial infarction (MI) during 1986-1996 (mean follow-up 3.4 years). Independent risk factors for reinfarction/fatal coronary heart disease (CHD) (incidence = 49.0/1,000 person-years, 445 events) were age, diabetes, chronic congestive heart failure (CHF), angina, high body mass index (BMI), low diastolic blood pressure (DBP), high serum creatinine, and low/high-density lipoprotein (HDL) cholesterol. Independent risk factors for stroke (incidence = 13.0/1,000 person-years, 124 events) were age, diabetes, CHF, high DBP, and high creatinine. Independent predictors of death (incidence = 44.2/1,000 person-years, 431 events) were age, diabetes, CHF, continued smoking after MI, low DBP, high pulse rate, high creatinine, and low HDL cholesterol, while BMI had a significant U-shaped association with death (elevated risk at low and high BMI). The occurrence of study end points did not differ significantly between men and women after adjustment for other risk factors and use of preventive medical therapies, although men tended to have higher rates of reinfarction/CHD than women among older subjects. In summary, we demonstrated that the major cardiovascular risk factors age, diabetes, CHF, smoking, and dyslipidemia are important prognostic factors in the years after nonfatal MI. Elevated BMI was associated with increased risk of reinfarction/CHD and death and elevated DBP with increased risk of stroke, but we also observed high mortality among those with low BMI and high risk of recurrent coronary disease and death among those with low DBP. Finally, high creatinine was a strong, independent predictor of a variety of adverse outcomes after first MI.

Hospitalizations for bacterial endocarditis after initiation of chronic dialysis in the United States

AIMS

Bacterial endocarditis is a significant cause of morbidity and mortality but has not been studied in a national population of end-stage renal disease patients.

METHODS

327,993 dialysis patients in the United States Renal Data System initiated from 1 January 1992 to 30 June 1997 were analyzed in a historical cohort study of hospitalized bacterial endocarditis (ENDO, ICD9 Code 421.x). Renal transplant recipients were excluded.

RESULTS

Hemodialysis patients had an age-adjusted incidence ratio for ENDO of 17.86 (95% confidence interval, 6.62-48.90) and peritoneal dialysis patients 10.54 (95% CI, 0.71- 158.13, not statistically significant) compared to the general population in 1996 (the National Hospital Discharge Survey). 6.1% of patients with ENDO underwent valve replacement surgery. In multivariate analysis, hemodialysis (vs. peritoneal dialysis), earlier year of dialysis, cardiac disease, and lower serum creatinine and albumin were associated with increased risk of ENDO. In Cox regression analysis, patients with ENDO had increased mortality, relative risk 1.48 (95% CI 1.45-1.73).

CONCLUSIONS

Patients on chronic dialysis were at increased risk for ENDO compared to the general population. The risk for peritoneal dialysis patients was not statistically significant, possibly due to the smaller numbers of patients on this modality. Hemodialysis (vs. peritoneal dialysis) and comorbidities were the strongest risk factors for ENDO identified.

Coronary disease surveillance in Olmsted County objectives and methodology

The community surveillance study of coronary heart disease (CHD) in Olmsted County, MN, is designed to estimate trends in myocardial infarction (MI) incidence, case fatality rate, and CHD mortality, while including all ages. A distinctive feature of this study is its ability to capture longitudinal data before and after index events via the medical record linkage system of the Rochester Epidemiology Project. The goal of this report is to describe the methods implemented to measure CHD trends, the implications of including elderly individuals on MI ascertainment and trends in prior CHD among persons with incident MI. The methods are based on standardized criteria involving the review of death certificate information and hospital records to identify CHD deaths, and incident MIs in Olmsted County. The medical record linkage system in place under the auspices of the Rochester Epidemiology Project was used to ascertain antecedent CHD and outcomes. Hospitalized MIs were screened from sampled events coded ICD9 codes 410-414 and classified using enzyme values, cardiac pain, and ECG coding. After screening 5,042 records, a cohort of 1,658 validated incident MIs was assembled 35% (575) among persons aged 75 years or greater. The proportion of MIs validated with cardiac pain and enzymes without Minnesota ECG coding was lower among the elderly than among persons less than 75 years of age (35 vs. 29%, respectively; P <.001). The proportion of events validated without requiring ECG coding decreased over time in both age strata (P for trend.001). Reliability analyses indicated excellent agreement in event classification. More than half of the incident MIs did not have antecedent CHD, and this proportion increased overtime. These data indicate that the elderly contribute approximately one-third of the cases of incident MI, underscoring the importance of including all ages to fully characterize the burden of CHD. Cases among elderly persons more frequently require ECG coding for validation, but standardized ascertainment procedures are feasible and reliable in all age groups. More than half of the incident MIs occurred among persons with no prior CHD, and this proportion increased over time. The combination of standardized methodology and of the longitudinal data via the record linkage system of the Rochester Epidemiology Project will allow reliable measures of CHD trends and help define preventive strategies.

Trends in utilization of coronary artery bypass surgery and associated outcomes: Alberta, Manitoba, and Nova Scotia

The primary objective of this study was to examine trends in rates and outcomes of coronary artery bypass graft (CABG) surgery across the 3 Canadian provinces of Alberta, Manitoba, and Nova Scotia, during fiscal years 1991-1995. Annual age-standardized CABG surgery rates were calculated by sex for each province. Province-specific average length of stay (ALOS) and postsurgical complication rates were calculated using ICD-9 codes. Rates of CABG were higher among men compared with women in all 3 provinces. Whereas ALOS, complications rates, and mortality rates decreased in all provinces over the study period, there was considerable variation in province-specific rates.

Acute coronary syndromes after renal transplantation in patients with end-stage renal disease resulting from diabetes

Coronary heart disease is the leading cause of death in both diabetes mellitus and end-stage renal disease. Although renal transplantation is known to reduce mortality in end-stage renal disease, its effect on the incidence of acute coronary syndromes is unknown. Using data from the United States Renal Data System, we studied 11,369 patients with end-stage renal disease due to diabetes enrolled on the renal and renal-pancreas transplant waiting list from 1 July 1994 to 30 June 1997. Cox nonproportional hazards regression models were used to calculate the adjusted, time-dependent relative risk for the most recent hospitalization for acute coronary syndromes (including acute myocardial infarction, unstable angina, or other acute coronary syndromes, ICD9 Code 410.x or 411.x) for a given patient in the study period. Demographics and comorbidities were controlled by using data from the medical evidence form (HCFA 2728). After renal transplantation, patients had an incidence of acute coronary syndromes of 0.79% per patient year, compared to 1.67% per patient year prior to transplantation. In comparison to maintenance dialysis, renal transplantation was independently associated with a lower risk for acute coronary syndromes (hazard ratio 0.38, 95% confidence interval, 0.30-0.49). Patients with end-stage renal disease due to diabetes on the renal transplant waiting list were much less likely to be hospitalized for acute coronary syndromes after renal transplantation. The reasons for this decreased risk should be the subject of further study.

Hospitalized congestive heart failure after renal transplantation in the United States

PURPOSE

African Americans have increased risk for congestive heart failure (CHF) compared to Caucasians in the general population, but the risk of CHF in African American renal transplant recipients has not been studied in a national renal transplant population.

METHODS

Therefore, 33,479 renal transplant recipients in the United States Renal Data System (USRDS) from 1 July, 1994 to 30 June, 1997 were analyzed in an historical cohort study of the incidence, associated factors, and mortality of hospitalizations with a primary discharge diagnosis of CHF [International Classification of Diseases-9 (ICD9) Code 428.x].

RESULTS

African American renal transplant recipients had increased age-adjusted risk of hospitalizations for congestive heart failure compared to African Americans in the general population [rate ratio 4.60, 95% confidence interval (CI) 4.59-4.62]. In logistic regression analysis, African American recipients had increased risk of congestive heart failure after renal transplantation, independent of other factors. Among other significant factors associated with congestive heart failure, the strongest were graft loss and allograft rejection. No maintenance immunosuppressive medications were associated with CHF. In Cox regression analysis patients hospitalized for CHF had increased all-cause mortality compared with all other recipients (hazard ratio 3.69, 95% CI, 2.23-6.10), but African American recipients with CHF were not at significantly increased risk of mortality compared to Caucasian recipients with CHF.

CONCLUSIONS

African Americans recipients were at high risk for CHF after transplant independent of other factors. The reasons for this increased risk should be the subject of further study. All potential transplant recipients should receive particular attention for the diagnosis and prevention of CHF in the transplant evaluation process, which includes preservation of allograft function.