BACKGROUND: Normal diagnosis of clubbing is clinical; however use of objective criteria may improve the accuracy of findings OBJECTIVE: To present a simple method of obtaining finger images for the purpose of studying clubbing. METHOD: Shadow images of the index fingers obtained by projection through a transparent glass plate virtually without distortion and displayed on a common sheet of paper yielded the profile (PA) and hyponychial (HA) angles; as well as the ratio between distal phalangean and interphalangean depths (DPD/IPD). Upon physical examination of 306 adult bearers of pulmonary disease, 116 disclosed presence of clubbing (YES); 126 absence (NO); and 64 were doubtful cases (DBT). Also studied were 452 normal adult individuals. Among these 71.0% of the bearers and 33.4% of the controls were smokers. RESULTS: Values found in normal individuals and in patients bearers of clubbing (YES) were, respectively, 172.8±5.9° vs. 183.4±5.9° for PA, 181.5±5.0° vs. 201.4±6.5° for HA, and 0.904±0.029 vs. 1.014±0.062 for DPD/IPD (significant differences, p<0.05). CONCLUSIONS: This is a simple method of obtaining clear index finger images. The hyponychial angle determined on the images was the most useful measurement to discriminate digits clinically with and without clubbing (sensitivity of 76.7%, specificity of 83.2%, predictive positive value of 95.5% and predictive negative value of 96.9%).
Clubbing; profile angle; hyponychial angle; relation DPD/IPD
