Assessment of digital clubbing in medical inpatients by digital photography and computerized analysis.

Background: Digital clubbing has been associated with a large number of disorders. To overcome the limitation of subjective clinical assessment, several objective measurements have been developed among which the hyponychial angle was considered most accurate for quantification of finger clubbing.

Methods And Results: Here we investigated hyponychial angles in 123 healthy subjects and 515 medical inpatients from a tertiary hospital. Healthy subjects had a mean angle of 178.87 +/- 4.70 degrees (range: 164.78-192.10 degrees ), a finding that is well in accordance with previous results obtained using other techniques, underlining the accuracy of the chosen method of assessment. The mean angle of patients was 181.65 +/- 7.18 degrees (range: 162.22-209.19; p <0.0001 compared to healthy controls). When the upper limit of normality, i.e. 192.10 degrees, was used to define digital clubbing, the prevalence of digital clubbing in our patients was 8.9%; the percentage of clubbed fingers varied substantially among the various disease states (up to 80% in patients with cystic fibrosis).

Conclusion: The use of digital photography with computerised analysis was found to be an easy, fast and inexpensive method for the quantification of hyponychial angles with excellent intra and inter observer reliability whilst causing no discomfort to patients. This tool may therefore be useful in further longitudinal and cross-sectional studies of finger morphology and may become an accepted standard in the diagnosis of digital clubbing.