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Congestive heart failure in the United States: is there more than meets the I(CD code)? The Corpus Christi Heart
D C Goff1, D K Pandey, F A Chan
1Department of Public Health Science, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1063, USA. dgoff@rc.phs.wfubmc.edu
Insights
International Classification of Diseases (ICD) codes underestimate hospitalizations for congestive heart failure (CHF). This underenumeration suggests CHF may be a greater public health concern than currently recognized, requiring reevaluation of resource allocation.
Area of Science:
- Cardiology
- Public Health Surveillance
- Health Informatics
Background:
- Congestive heart failure (CHF) presents a growing public health challenge in the U.S.
- Accurate quantification of CHF prevalence is hindered by limitations in identifying valid cases.
- Existing data lacks comprehensive validation for CHF identification methods.
Purpose of the Study:
- To evaluate the accuracy of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD) codes for identifying hospitalizations with acute CHF.
- To assess the validity of ICD codes within the Corpus Christi Heart Project, a population-based surveillance program.
- To compare ICD code-based algorithms against clinical evidence for CHF detection.
Main Methods:
- A composite validation standard was established, including physician-diagnosed acute CHF or radiographic pulmonary edema.
- Medical records of 5083 patients hospitalized for cardiac procedures were reviewed.
- Three computer algorithms were applied to discharge diagnoses to assess ICD code assignment accuracy.
Main Results:
- Clinically confirmed CHF prevalence was 27.1%.
- ICD code 428 (CHF) demonstrated 62.8% sensitivity and 95.4% specificity, with a 24.8% underenumeration.
- An algorithm using multiple ICD codes showed 67.1% sensitivity and 92.6% specificity, with a 13.0% underenumeration.
Conclusions:
- Relying solely on ICD codes excludes a significant portion (one-third) of patients with clinical CHF.
- Underenumeration is exacerbated by prioritizing the primary listed diagnosis.
- Congestive heart failure may be a more substantial public health issue than currently understood, necessitating resource reallocation for surveillance, research, and care.
Background:
Congestive heart failure (CHF) is increasing as a public health problem in the United States. The ability to quantify this problem has been limited by a lack of data regarding the validity of CHF identification.
Objective:
To assess the validity of the use of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD) codes to identify hospitalizations with clinical evidence of an episode of acute CHF in data of The Corpus Christi Heart Project, a population-based surveillance program for hospitalized coronary heart disease.
Methods:
The validation standard was a composite variable including the presence of physician diagnosed acute CHF or radiographic evidence of pulmonary edema. Data were abstracted from the medical records of 5083 patients identified as hospitalized for possible acute myocardial infarction, aortocoronary bypass surgery, percutaneous transluminal coronary angioplasty, and related revascularization procedures in the Corpus Christi Heart Project. Discharge diagnoses, a secondary source of data, were used to apply 3 computer algorithms to assess the assignment of ICD codes.
Results:
The prevalence of clinically documented CHF was 27.1% (1376/5083). The ICD code 428 (CHF), assigned as the primary or a secondary discharge diagnosis, was associated with 62.8% sensitivity, 95.4% specificity, 83.5% positive predictive value, 87.4% negative predictive value, and a 24.8% underenumeration of CHF-related hospitalizations. An algorithm based on a series of ICD codes was associated with 67.1% sensitivity, 92.6% specificity, 77.1% positive predictive value, 88.3% negative predictive value, and a 13.0% underenumeration of CHF-related hospitalizations.
Conclusions:
Reliance on ICD codes results in the exclusion of one third of the patients with clinical evidence of acute CHF. This underenumeration is compounded by the typical reliance on the first listed diagnosis. Congestive heart failure may be a greater public health problem than currently recognized. The allocation of resources for relevant surveillance, research, medical care, and preventive efforts should be reevaluated.