Identification of Acute Decompensated Heart Failure Hospitalizations Using Administrative Data

Clinical Impact of Routine Assessment of Patient-Reported Health Status in Heart Failure Clinic: The PRO-HF Trial

BACKGROUND

The impact of routine clinic use of patient-reported outcome (PRO) measures on clinical outcomes in patients with heart failure (HF) has not been well-characterized. We tested if clinic-based use of a disease-specific PRO improves patient-reported quality of life at 1 year.

METHODS

The PRO-HF trial (Patient-Reported Outcome Measurement in Heart Failure Clinic) was an open-label, parallel, patient-level randomized clinical trial of routine PRO assessment or usual care at an academic HF clinic between August 30, 2021, and June 30, 2022, with 1 year of follow-up. In the PRO assessment arm, participants completed the Kansas City Cardiomyopathy Questionnaire-12 (KCCQ-12) at each HF clinic visit, and results were shared with their treating clinician. The usual care arm completed the KCCQ-12 at randomization and 1 year later, which was not shared with the treating clinician. The primary outcome was the KCCQ-12 overall summary score (OSS) between 12 and 15 months after randomization. Secondary outcomes included domains of the KCCQ-12, hospitalization and emergency department visit rates, HF medication therapy, clinic visit frequency, and testing rates.

RESULTS

Across 17 clinicians, 1248 participants were enrolled and randomized to PRO assessment (n=624) or usual care (n=624). The median age was 63.9 years (interquartile range [IQR], 51.8-72.8), 38.9% were women, and the median baseline KCCQ-12 OSS was 82.3 (IQR, 58.3-94.8). Final KCCQ-12 (available in 87.9% of the PRO arm and 85.1% in usual care; P=0.16) median OSS were 87.5 (IQR, 68.8-96.9) in the PRO arm and 87.6 (IQR, 69.7-96.9) in the usual care arm with a baseline-adjusted mean difference of 0.2 ([95% CI, -1.7 to 2.0]; P=0.85). The results were consistent across prespecified subgroups. A post hoc analysis demonstrated a significant interaction with greater benefit among participants with a baseline KCCQ-12 OSS of 60 to 80 but not in less or more symptomatic participants. No significant differences were found in 1-year mortality, hospitalizations, emergency department visits, medication therapy, clinic follow-up, or testing rates between arms.

CONCLUSIONS

Routine PRO assessment in HF clinic visits did not impact patient-reported quality of life or other clinical outcomes. Alternate strategies and settings for embedding PROs into routine clinical care should be tested.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04164004.

Chlorthalidone vs Hydrochlorothiazide for Hypertension Treatment After Myocardial Infarction or Stroke: A Secondary Analysis of a Randomized Clinical Trial

Importance

Patients with prior myocardial infarction (MI) or stroke have a greater risk of recurrent cardiovascular (CV) events.

Objective

To evaluate the association of chlorthalidone (CTD) vs hydrochlorothiazide (HCTZ) with CV outcomes and noncancer deaths in participants with and without prior MI or stroke.

Design, Setting, and Participants

This was a prespecified secondary analysis of the Diuretic Comparison Project (DCP), a pragmatic randomized clinical trial conducted within 72 participating Veterans Affairs health care systems from June 2016 to June 2021, in which patients aged 65 years or older with hypertension taking HCTZ at baseline were randomized to continue HCTZ or switch to CTD at pharmacologically comparable doses. This secondary analysis was performed from January 3, 2023, to February 29, 2024.

Exposures

Pharmacologically comparable daily dose of HCTZ or CTD and history of MI or stroke.

Main Outcomes and Measures

Outcome ascertainment was performed from randomization to the end of the study. The primary outcome consisted of a composite of stroke, MI, urgent coronary revascularization because of unstable angina, acute heart failure hospitalization, or noncancer death. Additional outcomes included achieved blood pressure and hypokalemia (potassium level <3.1 mEq/L; to convert to mmol/L, multiply by 1.0).

Results

The DCP randomized 13 523 participants to CTD or HCTZ, with a mean (SD) study duration of 2.4 (1.4) years. At baseline, median age was 72 years (IQR, 69-75 years), and 96.8% were male. Treatment effect was evaluated in subgroups of participants with (n = 1455) and without (n = 12 068) prior MI or stroke at baseline. There was a significant adjusted interaction between treatment group and history of MI or stroke. Participants with prior MI or stroke randomized to CTD had a lower risk of the primary outcome than those receiving HCTZ (105 of 733 [14.3%] vs 140 of 722 [19.4%]; hazard ratio [HR], 0.73; 95% CI, 0.57-0.94; P = .01) compared with participants without prior MI or stroke, among whom incidence of the primary outcome was slightly higher in the CTD arm compared with the HCTZ arm (597 of 6023 [9.9%] vs 535 of 6045 [8.9%]; HR, 1.12; 95% CI, 1.00-1.26; P = .054) (P = .01 for interaction). The incidence of a nadir potassium level less than 3.1 mEq/L and hospitalization for hypokalemia differed among those with and without prior MI or stroke when comparing those randomized to CTD vs HCTZ, with a difference only among those without prior MI or stroke (potassium level <3.1 mEq/L: prior MI or stroke, 43 of 733 [5.9%] vs 37 of 722 [5.1%] [P = .57]; no prior MI or stroke, 292 of 6023 [4.9%] vs 206 of 6045 [3.4%] [P < .001]; hospitalization for hypokalemia: prior MI or stroke, 14 of 733 [1.9%] vs 16 of 722 [2.2%] [P = .72]; no prior MI or stroke: 84 of 6023 [1.4%] vs 57 of 6045 [0.9%] [P = .02]).

Conclusions and Relevance

Results of this secondary analysis of the DCP trial suggest that CTD may be associated with reduced major adverse CV events and noncancer deaths in patients with prior MI or stroke compared with HCTZ.

Trial Registration

ClinicalTrials.gov Identifier: NCT02185417.

Centralized Interactive Phenomics Resource: an integrated online phenomics knowledgebase for health data users

OBJECTIVE

Development of clinical phenotypes from electronic health records (EHRs) can be resource intensive. Several phenotype libraries have been created to facilitate reuse of definitions. However, these platforms vary in target audience and utility. We describe the development of the Centralized Interactive Phenomics Resource (CIPHER) knowledgebase, a comprehensive public-facing phenotype library, which aims to facilitate clinical and health services research.

MATERIALS AND METHODS

The platform was designed to collect and catalog EHR-based computable phenotype algorithms from any healthcare system, scale metadata management, facilitate phenotype discovery, and allow for integration of tools and user workflows. Phenomics experts were engaged in the development and testing of the site.

RESULTS

The knowledgebase stores phenotype metadata using the CIPHER standard, and definitions are accessible through complex searching. Phenotypes are contributed to the knowledgebase via webform, allowing metadata validation. Data visualization tools linking to the knowledgebase enhance user interaction with content and accelerate phenotype development.

DISCUSSION

The CIPHER knowledgebase was developed in the largest healthcare system in the United States and piloted with external partners. The design of the CIPHER website supports a variety of front-end tools and features to facilitate phenotype development and reuse. Health data users are encouraged to contribute their algorithms to the knowledgebase for wider dissemination to the research community, and to use the platform as a springboard for phenotyping.

CONCLUSION

CIPHER is a public resource for all health data users available at https://phenomics.va.ornl.gov/ which facilitates phenotype reuse, development, and dissemination of phenotyping knowledge.

Accuracy of heart failure ascertainment using routinely collected healthcare data: a systematic review and meta-analysis

BACKGROUND

Ascertainment of heart failure (HF) hospitalizations in cardiovascular trials is costly and complex, involving processes that could be streamlined by using routinely collected healthcare data (RCD). The utility of coded RCD for HF outcome ascertainment in randomized trials requires assessment. We systematically reviewed studies assessing RCD-based HF outcome ascertainment against "gold standard" (GS) methods to study the feasibility of using such methods in clinical trials.

METHODS

Studies assessing International Classification of Disease (ICD) coded RCD-based HF outcome ascertainment against GS methods and reporting at least one agreement statistic were identified by searching MEDLINE and Embase from inception to May 2021. Data on study characteristics, details of RCD and GS data sources and definitions, and test statistics were reviewed. Summary sensitivities and specificities for studies ascertaining acute and prevalent HF were estimated using a bivariate random effects meta-analysis. Heterogeneity was evaluated using I2 statistics and hierarchical summary receiver operating characteristic (HSROC) curves.

RESULTS

A total of 58 studies of 48,643 GS-adjudicated HF events were included in this review. Strategies used to improve case identification included the use of broader coding definitions, combining multiple data sources, and using machine learning algorithms to search free text data, but these methods were not always successful and at times reduced specificity in individual studies. Meta-analysis of 17 acute HF studies showed that RCD algorithms have high specificity (96.2%, 95% confidence interval [CI] 91.5-98.3), but lacked sensitivity (63.5%, 95% CI 51.3-74.1) with similar results for 21 prevalent HF studies. There was considerable heterogeneity between studies.

CONCLUSIONS

RCD can correctly identify HF outcomes but may miss approximately one-third of events. Methods used to improve case identification should also focus on minimizing false positives.

Strategies for secondary use of real-world clinical and administrative data for outcome ascertainment in pragmatic clinical trials

BACKGROUND

Pragmatic trials are gaining popularity as a cost-effective way to examine treatment effectiveness and generate timely comparative evidence. Incorporating supplementary real-world data is recommended for robust outcome monitoring. However, detailed operational guidelines are needed to inform effective use and integration of heterogeneous databases.

OBJECTIVE

Lessons learned from the Veterans Affairs (VA) Diuretic Comparison Project (DCP) are reviewed, providing adaptable recommendations to capture clinical outcomes from real-world data.

METHODS

Non-cancer deaths and major cardiovascular (CV) outcomes were determined using VA, Medicare, and National Death Index (NDI) data. Multiple ascertainment strategies were applied, including claims-based algorithms, natural language processing, and systematic chart review.

RESULTS

During a mean follow-up of 2.4 (SD = 1.4) years, 907 CV events were identified within the VA healthcare system. Slight delays (∼1 year) were expected in obtaining Medicare data. An additional 298 patients were found having a CV event outside of the VA in 2016 - 2021, increasing the CV event rate from 3.5 % to 5.7 % (770 of 13,523 randomized). NDI data required ∼2 years waiting period. Such inclusion did not increase the number of deaths identified (all 894 deaths were captured by VA data) but enhanced the accuracy in determining cause of death.

CONCLUSION

Our experience supports the recommendation of integrating multiple data sources to improve clinical outcome ascertainment. While this approach is promising, hierarchical data aggregation is required when facing different acquisition timelines, information availability/completeness, coding practice, and system configurations. It may not be feasible to implement comparable applications and solutions to studies conducted under different constraints and practice. The recommendations provide guidance and possible action plans for researchers who are interested in applying cross-source data to ascertain all study outcomes.

Association Between End-Stage Liver Disease and Incident Heart Failure in an Integrated Health System

BACKGROUND

End-stage liver disease (ESLD) and heart failure (HF) often coexist and are associated with significant morbidity and mortality. However, the true incidence of HF among patients with ESLD remains understudied.

OBJECTIVE

This study aims to evaluate the association between ESLD and incident HF in a real-world clinical cohort.

DESIGN AND PARTICIPANTS

A retrospective electronic health records database analysis of individuals with ESLD and frequency-matched controls without ESLD in a large integrated health system.

MAIN MEASURES

The primary outcome was incident HF, which was defined by the International Classification of Disease codes and manually adjudicated by physician reviewers. The Kaplan-Meier method was used to estimate the cumulative incidence of HF. Multivariate proportional hazards models adjusted for shared metabolic factors (diabetes, hypertension, chronic kidney disease, coronary heart disease, body mass index) were used to compare the risk of HF in patients with and without ESLD.

KEY RESULTS

Of 5004 patients (2502 with ESLD and 2502 without ESLD), the median (Q1-Q3) age was 57.0 (55.0-65.0) years, 59% were male, and 18% had diabetes. Over a median (Q1-Q3) follow-up of 2.3 (0.6-6.0) years, 121 incident HF cases occurred. Risk for incident HF was significantly higher for patients with ESLD compared with the non-ESLD group (adjusted HR: 4.67; 95% CI: 2.82-7.75; p < 0.001), with the majority of the ESLD group (70.7%) having HF with preserved ejection fraction (ejection fraction ≥ 50%).

CONCLUSION

ESLD was significantly associated with a higher risk of incident HF, independent of shared metabolic risk factors, with the predominant phenotype being HF with preserved ejection fraction.

Practical issues in pragmatic trials: the implementation of the Diuretic Comparison Project

BACKGROUND/AIMS

The US Department of Veterans Affairs Point of Care Clinical Trial Program conducts studies that utilize informatics infrastructure to integrate clinical trial protocols into routine care delivery. The Diuretic Comparison Project compared hydrochlorothiazide to chlorthalidone in reduction of major cardiovascular events in subjects with hypertension. Here we describe the cultural, technical, regulatory, and logistical challenges and solutions that enabled successful implementation of this large pragmatic comparative effectiveness Point of Care clinical trial.

METHODS

Patients were recruited from 72 Veterans Affairs Healthcare Systems using centralized processes for subject identification, obtaining informed consent, data collection, safety monitoring, site communication, and endpoint identification with minimal perturbation of the local clinical care ecosystem. Patients continued to be managed exclusively by their clinical care providers without protocol specified study visits, treatment recommendations, or data collection extraneous to routine care. Centralized study processes were operationalized through the application layer of the electronic health record via a data coordinating center staffed by clinical nurses, data scientists, and statisticians without site-based research coordinators. Study data was collected from the Veterans Affairs electronic health record supplemented by Medicare and National Death Index data.

RESULTS

The study exceeded its enrolled goal (13,523 subjects) and followed subjects for the 5-year study duration. The key determinant of program success was collaboration between researchers, regulators, clinicians, and administrative staff at the site level to customize study procedures to align with local clinical practice. This flexibility was enabled by designation of the study as minimal risk and determination that clinical care providers were not engaged in research by the Veterans Affairs Central Institutional Review Board. Cultural, regulatory, technical, and logistical problems were identified and solved through iterative collaboration between clinical and research entities. Paramount among these problems was customization of the Veterans Affairs electronic health record and data systems to accommodate study procedures.

CONCLUSIONS

Leveraging clinical care for large-scale clinical trials is feasible but requires a rethinking of traditional clinical trial design (and regulation) to better meet requirements of clinical care ecosystems. Study designs must accommodate site-specific practice variation to reduce the impact on clinical care. A tradeoff thus exists between designing trial processes tailored to expedite local study implementation versus those to produce a more refined response to the research question. The availability of a uniform and flexible electronic health record in the Department of Veterans Affairs played a major role in the success of the trial. Conducting Point of Care research in other healthcare systems without such research-friendly infrastructure presents a more formidable challenge.

A multicenter program for electronic health record screening for patients with heart failure with preserved ejection fraction: Lessons from the DELIVER-EHR initiative

Efficiency in clinical trial recruitment and enrollment remains a major challenge in many areas of clinical medicine. In particular, despite the prevalence of heart failure with preserved ejection fraction (HFpEF), identifying patients with HFpEF for clinical trials has proven to be especially challenging. In this manuscript, we review strategies for contemporary clinical trial recruitment and present insights from the results of the DELIVER Electronic Health Record (EHR) Screening Initiative. The DELIVER trial was designed to evaluate the effects of dapagliflozin on clinical outcomes in patients with HFpEF. Within this trial, the multicenter DELIVER EHR Screening Initiative utilized EHR-based techniques in order to improve recruitment at selected sites in the United States. For this initiative, we developed and deployed a computable phenotype from the trial's eligibility criteria along with additional EHR tools at interested sites. Sites were then surveyed at the end of the program regarding lessons learned. Six sites were recruited, trained, and supported to utilize the EHR methodology and computable phenotype. Sites found the initiative to be helpful in identifying eligible patients and cited the individualized expert technical support as a critical factor in utilizing the program effectively. We found that the major challenge of implementation was the process of converting traditional inclusion/exclusion criteria into a computable phenotype within an established and ongoing trial. Other significant challenges noted by sites were the following: impact of the COVID-19 pandemic, engagement/support by local institutions, and limited availability of internal EHR experts/resources to execute programming. The study represents a proof-of-concept in the ability to utilize EHR-based tools in clinical trial recruitment for patients with HFpEF and provides important lessons for future initiatives. ClinicalTrials.gov Identifier: NCT03619213.

Design of a pragmatic clinical trial embedded in the Electronic Health Record: The VA's Diuretic Comparison Project

BACKGROUND

Recent US guidelines recommend chlorthalidone over other thiazide-type diuretics for the treatment of hypertension based on its long half-life and proven ability to reduce CVD events. Despite recommendations most clinicians prescribe hydrochlorothiazide (HCTZ) over chlorthalidone (CTD). No randomized controlled data exist comparing these two diuretics on cardiovascular outcomes.

METHODS

The Diuretic Comparison Project (DCP) is a multicenter, two-arm, parallel, Prospective Randomized Open, Blinded End-point (PROBE) trial testing the primary hypothesis that CTD is superior to HCTZ in the prevention of non-fatal CVD events and non-cancer death. Patients with hypertension taking HCTZ 25 or 50 mg were randomly assigned to either continue their current HCTZ or switch to an equipotent dose of CTD. The primary outcome is time to the first occurrence of a composite outcome consisting of a non-fatal CVD event (stroke, myocardial infarction, urgent coronary revascularization because of unstable angina, or hospitalization for acute heart failure) or non-cancer death. The trial randomized 13,523 patients at 72 VA medical centers. The study is conducted by a centralized research team with site procedures embedded in the electronic health record and all data collected through administrative claims data, with no study related visits for participants. The trial will have 90% power to detect an absolute reduction in the composite event rate of 2.4%.

RESULTS

Enrollment ended in November 2021. There are 4128 participting primary care providers and 16,595 patients individually consented to participate, 13,523 of whom were randomized.

CONCLUSIONS

DCP should provide much needed evidence as to whether CTD is superior to HCTZ in preventing cardiovascular events in hypertensive patients.

CLINICAL TRIAL REGISTRATION

NCT02185417 [https://clinicaltrials.gov/ct2/show/NCT02185417].

Long-Term Trajectories of Left Ventricular Ejection Fraction in Patients With Chronic Inflammatory Diseases and Heart Failure: An Analysis of Electronic Health Records

BACKGROUND

Immune regulation and inflammation play a role in the pathogenesis and progression of acute and chronic heart failure (HF). Although the clinical course of acute, severe inflammatory cardiomyopathy is well described, the effects of chronic systemic inflammation on cardiovascular function over time are less clear. To investigate this question, we compared trajectories over time in left ventricular ejection fraction for patients with HF with different chronic inflammatory diseases (CIDs): HIV, systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis, inflammatory bowel disease, and/or psoriasis.

METHODS

Using a database of patients receiving care in a large metropolitan health care system since January 1, 2000, we analyzed serial, clinically indicated echocardiograms from patients with HF with CIDs and frequency-matched patients with HF without CIDs. We included patients with ≥3 serial echocardiograms (N=974; median 6.1 years between first and most recent echo). We assessed left ventricular ejection fraction trajectories over time using latent trajectory models, then investigated differences in left ventricular ejection fraction trajectories for specific CID subtypes compared with controls.

RESULTS

Overall, the majority of patients studied (N=687; 70.5%) had left ventricular ejection fraction trajectories consistent with HF with preserved or midrange EF, whereas 255 (26.2%) had HF with reduced EF and 32 (3.3%) had HF with recovered EF. Compared with non-CID controls with HF, patients with rheumatoid arthritis, inflammatory bowel disease, and systemic lupus erythematosus were significantly more likely than controls to have HF with preserved or midrange EF whereas patients with HIV were significantly more likely to have HF with reduced EF.

CONCLUSIONS

Among patients with HF with CIDs, distinct left ventricular ejection fraction trajectory patterns associate with different specific individual CIDs. This highlights the heterogeneity of HF subtypes and changes over time across different CIDs.

Investigating changes in disease activity as a mediator of cardiovascular risk reduction with methotrexate use in rheumatoid arthritis

OBJECTIVE

Examine the association of methotrexate (MTX) use with cardiovascular disease (CVD) in rheumatoid arthritis (RA) using marginal structural models (MSM) and determine if CVD risk is mediated through modification of disease activity.

METHODS

We identified incident CVD events (coronary artery disease (CAD), stroke, heart failure (HF) hospitalisation, CVD death) within a multicentre, prospective cohort of US Veterans with RA. A 28-joint Disease Activity Score with C-reactive protein (DAS28-CRP) was collected at regular visits and medication exposures were determined by linking to pharmacy dispensing data. MSMs were used to estimate the treatment effect of MTX on risk of incident CVD, accounting for time-varying confounders between receiving MTX and CVD events. A mediation analysis was performed to estimate the indirect effects of methotrexate on CVD risk through modification of RA disease activity.

RESULTS

Among 2044 RA patients (90% male, mean age 63.9 years, baseline DAS28-CRP 3.6), there were 378 incident CVD events. Using MSM, MTX use was associated with a 24% reduced risk of composite CVD events (HR 0.76, 95% CI 0.58 to 0.99) including a 57% reduction in HF hospitalisations (HR 0.43, 95% CI 0.24 to 0.77). Individual associations with CAD, stroke and CVD death were not statistically significant. In mediation analyses, there was no evidence of indirect effects of MTX on CVD risk through disease activity modification (HR 1.03, 95% CI 0.80 to 1.32).

CONCLUSIONS

MTX use in RA was associated with a reduced risk of CVD events, particularly HF-related hospitalisations. These associations were not mediated through reductions in RA disease activity, suggesting alternative MTX-related mechanisms may modify CVD risk in this population.

Identification of Patients with Heart Failure in Large Datasets

Large registries, administrative data, and the electronic health record (EHR) offer opportunities to identify patients with heart failure, which can be used for research purposes, process improvement, and optimal care delivery. Identification of cases is challenging because of the heterogeneous nature of the disease, which encompasses various phenotypes that may respond differently to treatment. The increasing availability of both structured and unstructured data in the EHR has expanded opportunities for cohort construction. This article reviews the current literature on approaches to identification of heart failure, and looks toward the future of machine learning, big data, and phenomapping.

Differential Associations of Chronic Inflammatory Diseases With Incident Heart Failure

OBJECTIVES

The purpose of this study was to compare the risks of incident heart failure (HF) among a variety of chronic inflammatory diseases (CIDs) and to determine whether risks varied by severity of inflammation within each CID.

BACKGROUND

Individuals with CIDs are at elevated risk for cardiovascular diseases, but data are limited regarding risk for HF.

METHODS

An electronic health records database from a large urban medical system was examined, comparing individuals with CIDs with frequency-matched controls without CIDs, all of whom were receiving regular outpatient care. Rates of incident HF were determined by using the Kaplan-Meier method and subsequently used multivariate-adjusted proportional hazards models to compare HF risks for each CID. Exploratory analyses determined HF risks by proxy measurement of CID severity.

RESULTS

Of 37,636 patients (n = 18,278 patients with CIDs; and n = 19,358 controls without CIDs) there were 960 incident HF cases over a median of 3.6 years. Risks for incident HF were significantly or borderline significantly elevated for patients with systemic sclerosis (hazard ratio [HR]: 7.26; 95% confidence interval [CI]: 5.72 to 9.21; p < 0.01), systemic lupus erythematosus (HR: 3.15; 95% CI: 2.41 to 4.11; p < 0.01), rheumatoid arthritis (HR: 1.39; 95% CI: 1.13 to 1.71; p < 0.01), and human immunodeficiency virus (HR: 1.28; 95% CI: 0.99 to 1.66; p = 0.06). There was no association between psoriasis or inflammatory bowel disease and incident HF, although patients with those CIDs with higher levels of C-reactive protein had higher risks for HF than controls.

CONCLUSIONS

Systemic sclerosis and systemic lupus erythematosus were associated with the highest risks of HF, followed by rheumatoid arthritis and HIV. Measurements of inflammation were associated with HF risk across different CIDs.

Which ICD-9-CM codes should be used for bronchiolitis research?

Background

Bronchiolitis is a common respiratory disorder in children. Although there are specific ICD-9-CM diagnosis codes for bronchiolitis, the illness is often coded using broader diagnosis codes. This creates the potential for subject misclassification if researchers rely on specific diagnosis codes when assembling retrospective cohorts. Here we challenge the common research practice of relying on specific diagnosis codes for bronchiolitis.

Methods

We examined the use of diagnosis codes for the first episode of bronchiolitis, bronchitis, acute asthma, and bronchospasm and wheezing, in children younger than six and 24 months in the State of California Medic-Aid database. We categorized codes as narrow or broad diagnosis codes. We compared patient, geographic, and temporal characteristics of the different diagnoses codes.

Results

We identified visits from 48,732 children for first episode of wheezing illness. We retained 48,269 who had the diagnosis codes and data of interest. Diagnosis codes for acute asthma were widely used, even in children younger than six months in whom a diagnosis code for bronchiolitis would have been anticipated. The temporal pattern was similar across all diagnoses. Antipyretics were prescribed more often in those with diagnosis codes for bronchiolitis and bronchitis. Other statistically significant differences were too small to usefully distinguish the groups. There was substantial geographic variability in the diagnosis codes selected.

Conclusion

Users of Medic-Aid administrative data should generally favor broad rather than narrow definitions of bronchiolitis and should perform sensitivity analysis comparing broad and narrow definitions.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0589-4) contains supplementary material, which is available to authorized users.

Concordance between administrative data and clinical review for mortality in the randomized on/off bypass follow-up study (ROOBY-FS)

BACKGROUND

The optimal methodology to identify cardiac versus non-cardiac cause of death following cardiac surgery has not been determined.

METHODS

The Randomized On/Off Bypass Trial was a multicenter, randomized, controlled clinical trial of 2203 patients (February 2002-May 2008) comparing 1-year cardiac outcomes between off-pump and on-pump bypass surgery. In 2013, the Veterans Affairs (VA) Cooperative Studies Program funded a follow-up study to assess 5-year outcomes including mortality. Deaths were identified and confirmed using the National Death Index (NDI), VA Vital Status file, and medical records. An Endpoints Committee (EC) reviewed patient medical records and classified each cause of death as cardiac, non-cardiac, or unknown. Using pre-determined ICD-10 codes, NDI death certificates were independently used to classify deaths as cardiac or non-cardiac. Cause of death was compared between the NDI and EC classifications and concordance measured, using Kappa statistics.

RESULTS

Of the 297 5-year deaths identified by the NDI and/or VA vital status file and confirmed by the EC, 219 had adequate patient records for EC cause of death determination. The EC adjudicated 141 of these deaths as non-cardiac and 78 as cardiac, while the NDI classified 150 as non-cardiac and 69 as cardiac; agreement was 77.6% (kappa 0.500; P < 0.001).

CONCLUSIONS

Since concordance between EC and NDI cause of death classifications was only moderate, caution should be exercised in relying exclusively on NDI data to determine cause of death. A hybrid approach, integrating multiple information sources, may provide the most accurate approach to classifying cause of death.