Evaluation of a simple bedside tool developed to measure different parameters of clubbing.

Sir,

Clubbing is the selective bulbous enlargement of the distal segments of the fingers and toes due to proliferation of connective tissue. The diagnosis of clubbing is subjective and suffices in cases associated with higher grades of clubbing. However, for the lower grades of clubbing, the method becomes unreliable. Determination of the amount of soft tissue growth in the subungal region is used as an objective method of assessment of finger clubbing.[1] A recent method involving the use of shadowgrams has been developed by Moreira. We developed a simple, low cost, portable apparatus for the measurement of clubbing, which in principle is similar to that developed by Moreira.[2]

The apparatus consists of two vertical wooden stands fixed on a horizontal wooden base. On the top of the first stand, is fixed a battery operated torch. The second vertical stand is so kept that the index finger while resting on the top of the second stand touches a glass pane attached to it. A sharp projection of the shadow of the index finger fell on a piece of paper placed over the glass pane. Just beneath the glass pane and at right angles to it, a block of wood is attached horizontally, so that a digital camera can be placed on it [Figure 1]. Digital photographs of the shadow were taken without a flash, transferred to a computer, and edited on Microsoft Word. Printouts of the shadowgrams were marked to measure the profile angle (PA), hyponychial angle (HA) and the distal phalangeal depth (DPD) and inter phalangeal depth (IPD) [Figure 2].

Figure 1

The instrument with the shadow of the finger projected on the glass screen. The digital camera is to be kept on the horizontal block of wood at right angles to the glass pane

Figure 2

Computer print after minimal editing of the shadowgram of the index finger with the PA, HA, DPD and IPD

Observations on relatives of patients accompanying them to the outpatient department of a primary care hospital reveal that the clubbing parameters were similar to those seen in subjects from previous studies [Table 1]. All parameters in smokers were higher than in nonsmokers [Table 2], the reasons for which need a more detailed evaluation. Further studies utilizing HRCT thorax or spirometry to detect small airway disease is essential to confirm whether detection of early or subclinical clubbing with our instrument can be a surrogate marker of small airway disease in smokers.

Table 1

Parameters of clubbing in normal subjects as calculated by other workers

Table 2

Comparison of different clubbing parameters in non smokers and smokers