Trends in hospital treatment of ventricular arrhythmias among Medicare beneficiaries, 1985 to 1995

Identifying Patients With Advanced Heart Failure Using Administrative Data

Objective

To develop algorithms to identify patients with advanced heart failure (HF) that can be applied to administrative data.

Patients and Methods

In a population-based cohort of all residents of Olmsted County, Minnesota, with greater than or equal to 1 HF billing code 2007-2017 (n=8657), we identified all patients with advanced HF (n=847) by applying the gold standard European Society of Cardiology advanced HF criteria via manual medical review by an HF cardiologist. The advanced HF index date was the date the patient first met all European Society of Cardiology criteria. We subsequently developed candidate algorithms to identify advanced HF using administrative data (billing codes and prescriptions relevant to HF or comorbidities that affect HF outcomes), applied them to the HF cohort, and assessed their ability to identify patients with advanced HF on or after their advanced HF index date.

Results

A single hospitalization for HF or ventricular arrhythmias identified all patients with advanced HF (sensitivity, 100%); however, the positive predictive value (PPV) was low (36.4%). More stringent definitions, including additional hospitalizations and/or other signs of advanced HF (hyponatremia, acute kidney injury, hypotension, or high-dose diuretic use), decreased the sensitivity but improved the specificity and PPV. For example, 2 hospitalizations plus 1 sign of advanced HF had a sensitivity of 72.7%, specificity of 89.8%, and PPV of 60.5%. Negative predictive values were high for all algorithms evaluated.

Conclusion

Algorithms using administrative data can identify patients with advanced HF with reasonable performance.

Ventricular Arrhythmias Among Patients With Advanced Heart Failure: A Population-Based Study

Background The epidemiology of ventricular arrhythmias (VAs) in patients with advanced heart failure (HF) is not well defined. Methods and Results Residents of Olmsted County, Minnesota, with advanced HF from 2007 to 2017 were identified using the 2018 European Society of Cardiology criteria. Billing codes were used to capture VAs; severe VAs requiring emergency care were defined as events associated with emergency department visits or hospitalizations. The cumulative incidence of VAs postadvanced HF was estimated with the Kaplan-Meier method. Multivariable Cox analyses were used to determine the following: (1) Predictors of severe VAs postadvanced HF; and (2) Impact of severe VAs on mortality. Of 936 patients with advanced HF, 261 (27.9%) had a history of VA. The 1-year cumulative incidence of severe VAs postadvanced HF was 5.4%. Prior VAs (hazard ratio [HR] 2.22 [95% CI, 1.26-3.89], P=0.006) and left ventricular ejection fraction <40% (HR, 3.79 [95% CI, 1.72-8.39], P<0.001) were independently associated with increased severe VA risk postadvanced HF. New-onset severe VAs were associated with increased mortality (HR, 4.41 [95% CI, 2.80-6.94]; P<0.001), whereas severe VAs in patients with prior VAs had no significant association with mortality risk (HR, 1.08 [95% CI, 0.65-1.78]; P=0.77). Severe VAs were associated with increased mortality in patients without implantable cardioverter defibrillators (HR, 4.89 [95% CI, 2.89-8.26]; P<0.001), but not in patients with implantable cardioverter defibrillators (HR, 1.42 [95% CI, 0.92-2.19]; P=0.11). Conclusions Patients with left ventricular ejection fraction <40% and prior VAs have increased risk of severe VA postadvanced HF. New-onset severe VAs or severe VAs without implantable cardioverter defibrillators postadvanced HF are associated with increased mortality.

Ventricular Ectopy and Arrhythmia Characteristics for Persons Living with HIV and Uninfected Controls

BACKGROUND

Persons with HIV have elevated risk for cardiovascular disease, but little is known about the risk of ventricular ectopy and ventricular tachycardia (VE/VT) for HIV-infected (HIV+) persons.

METHODS

We evaluated the presence and anatomic origin of VE/VT for HIV+ persons and controls by screening a cohort using International Classification of Diseases codes and adjudicating positive screens by chart review. We sought to evaluate (1) presence of VE/VT and (2) likely anatomic origin of the VE/VT based on electrocardiogram.

RESULTS

There was no significant difference in the prevalence of VE/VT for HIV+ or uninfected persons. Among HIV+ persons, worse HIV control was associated with significantly greater odds of VE/VT. Exploratory analyses suggested that HIV+ persons may have a greater likelihood of VE/VT originating from the left ventricle.

CONCLUSION

Although worse HIV control was associated with higher odds of VE/VT among persons with HIV, odds of VE/VT were not higher for persons with HIV than uninfected persons.

Algorithms used to identify ventricular arrhythmias and sudden cardiac death in retrospective studies: a systematic literature review

Drug-induced QT interval prolongation may increase the risk of sudden cardiac death or ventricular arrhythmias (SCD/VA), and therefore affects the safety profile of medications. Administrative databases can be used to inform pharmacoepidemiologic drug safety studies for such rare events. In order to compare event rates between studies, validated operational definitions of these events are needed. We conducted a systematic literature review in PubMed to identify algorithms for SCD/VA. Twenty-two studies were included in the review. Fifteen (68%) studies evaluated International Classification of Diseases, 9th revision (ICD-9) based medical data, of which six utilized a common, validated operational definition. This algorithm was based on principal hospitalization discharge diagnosis or first-listed emergency department visit diagnosis, with an average positive predictive value (PPV) of 85%. Four studies evaluated ICD-9 based death data, of which three utilized a common algorithm with an average PPV of 88%. Further validation of ICD, 10th revision algorithms are needed. In conclusion, we identified a validated algorithm for SCD/VA in medical data, as well as in death data. As such, to ensure comparability between new research and the existing literature, pharmacoepidemiologic research in this area should utilize common, validated algorithms, such as the ones identified in our review, to operationally define these events.

An audit of in-hospital cardiopulmonary resuscitation in a teaching hospital in Saudi Arabia: A retrospective study

OBJECTIVES

Data reflecting cardiopulmonary resuscitation (CPR) efforts in Saudi Arabia are limited. In this study, we analyzed the characteristics, and estimated the outcome, of in-hospital CPR in a teaching hospital in Saudi Arabia over 4 years.

METHODS

A retrospective, observational study was conducted between January 2009 and December 2012 and included 4361 patients with sudden cardiopulmonary arrest. Resuscitation forms were reviewed. Demographic data, resuscitation characteristics, and survival outcomes were recorded.

RESULTS

The mean ± standard deviation age of arrested patient was 40 ± 31 years. The immediate survival rate was 64%, 43% at 24 h, and 30% at discharge. The death rate was 70%. Respiratory type of arrest, time and place of arrest, short duration of arrest, witnessed arrest, the use of epinephrine and atropine boluses, and shockable arrhythmias were associated with higher 24-h survival rates. A low survival rate was found among patients with cardiac types of arrest, and those with a longer duration of arrest, pulseless electrical activity, and asystole. Comorbidities were present in 3786 patients with cardiac arrest and contributed to a poor survival rate (P < 0.001).

CONCLUSIONS

The study confirms the findings of previously published studies in highly developed countries and provides some reflection on the practice of resuscitation in Saudi Arabia.

Mediators of First- Versus Second-generation Antipsychotic-related Mortality in Older Adults

BACKGROUND

Observational studies of older adults showed higher mortality for first-generation antipsychotics than their second- generation counterparts, which led to US Food and Drug Administration warnings, but the actual mechanisms involved remain unclear.

METHODS

A cohort of 9,060 initiators of first-generation antipsychotics and 17,137 of second-generation antipsychotics enrolled in New Jersey and Pennsylvania Medicare were followed for 180 days. Medical events were assessed using diagnostic and procedure codes on inpatient billing claims. For the individual and joint set of medical events (mediators), we estimated the total, direct, and indirect effects of antipsychotic type (first versus second generation) on mortality on the risk ratio scale and the proportion mediated on the risk difference scale, obtaining 95% confidence intervals through bootstrapping. We performed bias analyses for false-negative mediator misclassification in claims data, with sensitivity ranging from 0.25 to 0.75.

RESULTS

There were 3,199 deaths (outcomes), 862 cardiovascular events, 675 infectious events, and 491 hip fractures (potential mediators). Mortality was higher for first- than second-generation antipsychotic initiators (adjusted risk ratio: 1.14; 95% confidence interval: 1.06, 1.22). In naïve analyses, that ignored potential misclassification, less than 4% of this difference was explained by any particular medical event. In bias analyses, the proportion mediated ranged from 6% to 16% for stroke, 3% to 9% for ventricular arrhythmia, 3% to 11% for myocardial infarction, 0% venous thromboembolism, 3% to 9% for pneumonia, 0% to 1% for other bacterial infection, and 1% to 3% for hip fracture.

CONCLUSIONS

Acute cardiovascular events and pneumonia may explain part of the mortality difference between first- and second-generation antipsychotic initiators in this analysis.

Trends in implantable cardioverter-defibrillator racial disparity

OBJECTIVES

The study was designed to determine whether racial disparity in utilization of the implantable cardioverter-defibrillator (ICD) has improved over time, and whether small-area geographic variation in ICD utilization contributed to national levels of racial disparity.

BACKGROUND

Although racial disparities in cardiac procedures have been well-documented, it is unknown whether there has been improvement over time. Low ICD utilization rates in predominantly black geographic areas may have exacerbated national levels of disparity.

METHODS

Discharge abstracts from elderly black and white Medicare beneficiaries hospitalized with ventricular arrhythmias from 1990 to 2000 were analyzed to determine if ICD implantation occurred within 90 days of initial hospitalization. Multivariate logistic regression models were constructed to assess the relationship between ICD implantation, year of admission, and the percentage of black inhabitants in each patient's county of hospitalization while controlling for clinical, hospital, and demographic characteristics.

RESULTS

There was improvement in ICD implantation racial disparity: In the period 1990 to 1992, black patients had an odds ratio of 0.52 (95% confidence interval [CI] 0.42 to 0.64) for receiving an ICD compared with whites. However, by 1999 to 2000, the odds ratio for blacks had risen to 0.69 (95% CI 0.61 to 0.78) (test-for-trend p=0.01). Approximately 20% of this trend could be explained by reduction in geographic variation in ICD use between areas with larger black and predominantly white populations.

CONCLUSIONS

Rates of ICD implants became more equal among whites and blacks during the 1990s, although persistent disparity remained at the decade's end. Geographic equalization in cardiovascular procedure rates may be an essential mechanism in rectifying disparities in health care.

Utilization of implantable cardioverter-defibrillators in survivors of cardiac arrest in the United States from 1996 to 2001

OBJECTIVES

We analyzed the incidence of implantable cardioverter-defibrillator (ICD) therapy in survivors of cardiac arrest (CA) in the U.S. from 1996 through 2001.

BACKGROUND

Cardiac arrest is a class I indication for ICD therapy. The current patterns of ICD utilization in survivors of CA have not been fully examined.

METHODS

We searched a representative sample of all hospital discharges for patients admitted with the primary diagnosis of CA who survived to hospital discharge. Patients with a concomitant diagnosis of acute myocardial infarction or previous ICD in situ were excluded.

RESULTS

From 1996 to 2001, 113,262 patients were admitted for CA. Of those, 63,745 (56.3%) did not survive to hospital discharge. Of the remaining 49,517 patients, 30.7% received an ICD before discharge, with a gradual increase in implantation rates from 1996 (23.6%) to 2001 (46.3%). Using logistic regression for the years 2000 and 2001, patients who were discharged without an ICD were older (odds ratio [OR] 0.93 for every 10-year increase in age, p < 0.001), more likely to be African American (OR 0.19, p < 0.001), and more likely to be admitted to a smaller hospital (OR 2.24 for each additional 100 beds, p < 0.001). These predictors were independent of other co-morbid illnesses.

CONCLUSIONS

Although they are increasing, the rates of ICD therapy after CA remain very low. There are gross discrepancies by race. At a time when newer indications for ICD implantation are emerging, efforts should be focused on identifying the causes of this underutilization and discrepancies in survivors of CA.

Temporal patterns in long-term survival after resuscitation from out-of-hospital cardiac arrest

BACKGROUND

During the past quarter century, advances in treatment of cardiovascular disease have occurred that might potentially benefit survivors of sudden cardiac arrest (SCA). Little is known, however, about the temporal patterns in long-term survival among persons resuscitated from SCA. We hypothesized that long-term survival would improve over time and that this temporal pattern would be most evident for cardiac causes of death.

METHODS AND RESULTS

The investigation was a retrospective cohort study of survival among persons who were discharged alive from the hospital after resuscitation from out-of-hospital SCA due to heart disease in King County, Wash, between May 1, 1976, and December 31, 2001 (n=2035). Calendar time was divided into four 5-year intervals: 1976 to 1980, 1981 to 1985, 1986 to 1990, and 1991 to 1995, and one 6-year interval, 1996 to 2001. Age-adjusted survival curves were constructed, and Cox proportional-hazards regression was used to compute hazard ratios (HRs) for the association between mortality and time period. During 11 201 person-years of follow-up, 1334 persons died. Compared with the initial time period, the HR for total mortality was 0.86 (95% confidence interval, 0.73 to 1.01) for 1981 to 1985, 0.82 (0.69 to 0.96) for 1986 to 1990, 0.66 (0.55 to 0.79) for 1991 to 1995, and 0.58 (0.47 to 0.71) for 1996 to 2001 (HR for trend=0.87 [0.84 to 0.91] for each successive time period). In analyses that assessed cardiac mortality, an even stronger temporal association was evident (HR for trend=0.79 [0.75 to 0.84]).

CONCLUSIONS

Long-term survival after resuscitation from SCA improved steadily over time in this cohort. To continue this trend, future studies should identify circumstances in which proven treatments are underutilized as well as investigate new therapies that might benefit survivors of SCA.

Effect of risk stratification on cost-effectiveness of the implantable cardioverter defibrillator

BACKGROUND

Implantable cardioverter defibrillators (ICDs) effectively prevent sudden cardiac death, but selection of appropriate patients for implantation is complex. We evaluated whether risk stratification based on risk of sudden cardiac death alone was sufficient to predict the effectiveness and cost-effectiveness of the ICD.

METHODS

We developed a Markov model to evaluate the cost-effectiveness of ICD implantation compared with empiric amiodarone treatment. The model incorporated mortality rates from sudden and nonsudden cardiac death, noncardiac death and costs for each treatment strategy. We based our model inputs on data from randomized clinical trials, registries, and meta-analyses. We assumed that the ICD reduced total mortality rates by 25%, relative to use of amiodarone.

RESULTS

The relationship between cost-effectiveness of the ICD and the total annual cardiac mortality rate is U-shaped; cost-effectiveness becomes unfavorable at both low and high total cardiac mortality rates. If the annual total cardiac mortality rate is 12%, the cost-effectiveness of the ICD varies from $36,000 per quality-adjusted life-year (QALY) gained when the ratio of sudden cardiac death to nonsudden cardiac death is 4 to $116,000 per QALY gained when the ratio is 0.25.

CONCLUSIONS

The cost-effectiveness of ICD use relative to amiodarone depends on total cardiac mortality rates as well as the ratio of sudden to nonsudden cardiac death. Studies of candidate diagnostic tests for risk stratification should distinguish patients who die suddenly from those who die nonsuddenly, not just patients who die suddenly from those who live.