Clinical classifications of functional status are created primarily so that physicians can apply a common language to describe the functional impact of the same underlying disease on individual patients. Classifications should facilitate communication between physicians, all those involved in caring for the patient and the funding agencies providing financial support. The design of clinical trials is heavily dependant on an accepted, standardized means of describing the efficacy or otherwise of the treatment being evaluated. Studying the natural history of a disease, both treated and untreated, is dependant on a universally accepted means of describing functional status. Most importantly, a good classification should encapsulate the clinical status of a patient and so make it possible to review the patient's progress with time and their response to treatment.
Classifications of functional status are familiar to cardiologists caring for adult patients. The New York Heart Association (NYHA), the classification most widely used by adult cardiologists since 1964 describes the functional impact of heart failure and places patients with a similar degree of limitation and similar symptoms into one of four functional classes, Class IV being the most severely disabled ().[1
] The Functional Classification of Pulmonary Hypertension in adults is based on the NYHA classification () and was published in 1998 as a consensus document of the WHO Symposium held in Evian in that year.[2
NYHA classification of functional status
WHO classification of pulmonary hypertension in adults
Maintaining the best possible quality of life is crucial in any chronic disease. In adults, The Minnesota Living with Heart Failure (MLHF) questionnaire has been widely used in both hospital and primary care since it was designed in 1984, and has good reliability and validity.[3
] This questionnaire can be useful in assessing patients with pulmonary hypertension,[6
] as is the Short Form Health Survey 36 (SF-36).[8
] The MLHF has been considered a significant predictor of outcome.[10
] More recently, a disease specific questionnaire, the Cambridge Pulmonary Hypertension Outcome Review Utility Index (CAMPHOR) has been developed, primarily for cost-utility analysis but can also be useful in clinical studies.[11
There is no disease specific classification to assess functional status in children with pulmonary hypertension. Nor is there a generally accepted functional classification for children with heart disease. Measures of generic health status have been developed for children, principally the Children and Youth Version of the International Classification of Functioning, Disability and Health published in 2007.[13
] This classification assesses body structure and function, level of activity and social participation. It was designed primarily to assess children with neuromotor disabilities. Disease specific functional classifications have been developed for use in children with other conditions such as cystic fibrosis, rheumatoid arthritis and juvenile idiopathic arthritis.[15
Quality of life is particularly difficult to assess in children. A Short Form Health Survey has been designed for children, SF-10[19
] and can be used in children with pulmonary hypertension, but it is not disease specific. Nor does it help assess children less than 5 five years of age.