How valid is the clubbing in cases of cardiovascular examination?
Clubbing is defined as the bulbous swelling of the distal ends of fingers or toes that results in loss of angle between the skinfold and the nail plate. It is characterized by connective tissue proliferation and edema as a result of which the nails become boggy. To assess the clubbing of fingers Schamroth's window sign is commonly used but it is not considered as the gold standard. Sign is checked by placing the nails of both the fingers against each other to look for any gap in between. Clubbing of the fingers is a commonly checked sign in cardiovascular examination however, it's validity and reliability still need to be ascertained. This test is easy to perform but it's accuracy is still questioned in many studies. A study was done to find the reliability of this sign between two observers and substantial results ( κ = 0.64) was obtained but it was less when compared with phalangeal depth ratio (κ = 0.98).
