Accuracy and reliability of the Ipswich touch test in identifying loss of protective sensation among diabetic patients

Objective

To evaluate the accuracy of the Ipswich touch test compared to the 10-g monofilament test for identifying of loss of protective sensation in Thai patients with diabetes mellitus.

Methods

A cross-sectional observational study was conducted on Thai patients with diabetes mellitus who attended routine annual foot check-ups in an outpatient diabetes clinic. The loss of protective sensation was assessed by the Ipswich touch test and compared with the Semmes-Weinstein 10-g monofilament test. Sensitivity, specificity, predictive values and likelihood ratios were calculated to measure the accuracy of the Ipswich touch test against 10-g monofilament as a reference standard. The interrater reliability of the Ipswich touch test was assessed by two raters.

Results

In a study of 283 diabetic patients, 10-g monofilament detected a 25 % prevalence of loss protective sensation. The Ipswich touch test demonstrated a good diagnostic accuracy, with a sensitivity of 70.8 %, specificity of 98.6 %, and an area under the curve of 0.85 when compared to 10-g monofilament. Positive and negative predictive values were 94.4 % and 90.8 % respectively. The positive likelihood ratio was 49.82, and the negative likelihood ratio was 0.30. Interrater reliability, assessed with two raters in a subset of 93 participants, yielded a kappa of 0.88, indicating almost perfect agreement.

Conclusions

The Ipswich Touch Test demonstrated good accuracy and interrater reliability compared to the standard 10-g monofilament, thus establishing its effectiveness as a valuable diagnostic tool for identifying loss of protective sensation among diabetic patients. However, its relatively low sensitivity suggests it should be used with caution as a screening tool.