Issues in Cardiovascular NursingValidity and reliability of the NYHA classes for measuring research outcomes in patients with cardiac disease*
Section snippets
Development of the NYHA functional classification system
When the NYHA functional classification system was originally developed in 1928, it represented a major advance in the assessment of CVD that allowed physicians to identify and communicate gross changes in illness severity. The wording that describes the NYHA classes in the current version of the NYHA classification system,13 shown in Table I, uses descriptions of the classes developed by a criteria committee in 1964.The NYHA system was designed for clinical assessment of patients by physicians
Concepts of function in cardiac patients
Measures of function in research studies must be conceptually clear to differentiate the various types of function that may be affected by other variables. Functional capacity is a concept that represents the maximum physiologic function of which a person is capable.16 A related concept, functional performance, represents the amount of function that a person chooses to actually perform (ie, a person may be capable of a high level of functional capacity but may perform at a lower level for a
Essential characteristics of measurement instruments
Validity and reliability are essential characteristics of any measurement instrument. An instrument that is valid is one that precisely measures the concept that it is intended to measure. It should correlate with other instruments that measure the same concept and have low or moderate correlation with measures of related, but different, concepts. To select a valid research measure, it is essential to clarify the outcome concept that appropriately answers the research question and to choose a
Validity of the NYHA functional classification system
Because functional capacity, functional performance, and functional status are related but unique concepts, a moderate correlation would be expected between measures of these concepts. Studies comparing the NYHA functional classifications (functional status) to measures of functional performance and functional capacity have reported low to moderate correlations between measures, supporting the validity of the NYHA classes as a measure of functional status but not of performance or capacity.
In
Reliability of the NYHA functional classification system
If the NYHA functional classification system is used in an intervention study as a measure of change in functional status over time, multiple evaluations of NYHA class by a rater must be reliable. Further, if multiple raters evaluate NYHA class, inter-rater reliability should be assessed and reported. Yet, intra-rater and inter-rater reliability of the NYHA classes have rarely been reported in the research.
Appropriate classification relies on the judgment, observations, and interpretation of
Discussion and recommendations
The NYHA functional classification system is widely used by health care providers as a clinical measure to distinguish cardiac patients who are disabled by cardiac symptoms from those who are less ill. It is not surprising that the NYHA classes have stood the test of time in clinical situations since the classifications are simple to use; provide a rough estimate of the impact of illness; and correlate to some degree with other measures of function, such as VO2max, the SAS, and the 6-minute
Acknowledgements
The authors gratefully acknowledge Thomas A. Gillespie, MD, and Derek Exner, MD, for their reviews of a prior version of this manuscript.
References (30)
- et al.
Comparison of vasopeptidase inhibitor, omapatrilat, and lisinopril on exercise tolerance and morbidity in patients with heart failure: IMPRESS randomised trial
Lancet
(2000) - et al.
The disablement process
Soc Sci Med
(1994) - et al.
Functional capacity of patients with chronic left ventricular failure. Relationship of bicycle exercise performance to clinical and hemodynamic characterization
Am J Med
(1979) - et al.
[Pacemaker therapy of hypertrophic obstructive cardiomyopathy. PIC (Pacing in Cardiomyopathy) Study Group]
Herz
(2000) - et al.
Mitral balloon valvotomy for the treatment of mitral stenosis in octogenarians
J Am Geriatr Soc
(2000) - et al.
Mitral valve surgery in patients with severe left ventricular dysfunction
Eur J Cardiothorac Surg
(2000) - et al.
Progressive decrease of outflow gradient and septum thickness after percutaneous alcoholization of the interventricular septum in hypertrophic obstructive cardiomyopathy
Ital Heart J
(2000) - et al.
Improvement of cardiac neuronal function after carvedilol treatment in dilated cardiomyopathy: a 123I-MIBG scintigraphic study
J Nucl Med
(2000) - et al.
[6 years clinical experience with the TEKNA bivalve heart valve prosthesis]
Zeitschrift fur Kardiologie
(2000) - et al.
Medium-term results after the modified Cox/Maze procedure combined with other cardiac surgery
Eur J Cardiothorac Surg
(2000)
Immunoglobulin adsorption in patients with idiopathic dilated cardiomyopathy
Circulation
[Percutaneous transluminal septal myocardial ablation in hypertrophic obstructive cardiomyopathy. A new therapeutic option]
Ugeskr Laeger
Extracardiac conduit fontan procedure: early and intermediate results
Eur J Cardiothorac Surg
Clinical outcome after isolated tricuspid valve replacement: 20-year experience
Can J Cardiol
Nomenclature and criteria for diagnosis of diseases of the heart and great vessels
Cited by (298)
Beyond Stage C: Considerations in the Management of Patients With Heart Failure Progression and Gaps in Evidence
2023, Journal of Cardiac FailureImpact of beta blockers on resting respiratory rate in older adults: A cross-sectional study
2023, Pulmonary Pharmacology and TherapeuticsQuality of life in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation: tools and evidence
2024, Journal of Cardiovascular MedicineA Predictive Nomogram for Intensive Care-Acquired Weakness after Cardiopulmonary Bypass
2024, Annals of Thoracic and Cardiovascular SurgeryCorrelation between the insertion-deletion variant of the angiotensin-converting enzyme gene and various classes of heart failure
2023, Cellular and Molecular Biology
- *
Reprint requests: Jill A. Bennett, UCSF School of Nursing, San Francisco, CA 94143-0610.