SLR - May 2018 - Najwah S. Hayman

A New Mobile Application for Standardizing Diabetic Foot Images

Yap MH, Chatwin KE, Ng CC, Abbott CA, Bowling FL, Rajbhandari S, Boulton AJM, Reeves ND. A New Mobile Application for Standardizing Diabetic Foot Images. J Diabetes Sci Technol. 2018 Jan; 12(1): 169–173.

Scientific Literature Review

Reviewed By: Najwah S. Hayman, DPM
Residency Program: Cambridge Health Alliance, Cambridge, MA

Podiatric Relevance:
For many podiatrists, the patient living with diabetes comprises the majority of their patient population and is perhaps one of the most challenging to manage. With complications, such as infections, ulcerations and Charcot deformities, these patients are at increased risk for limb loss and decreased quality of life—emphasizing the need for close surveillance on the part of the physician. Recently, there has been a trend toward documenting diabetic foot pathologies with clinical photographs. To date, however, there is no standardized way of capturing these images, leading to inconsistencies in the ability to detect and monitor these disease processes. This study introduces a new mobile iPad application, FootSnap, developed specifically to help standardize pedal images, with intended future use in diabetic foot lesions. The goal was to test intrarater and interrater reliability parameters to enable further research studies and clinical evaluation.  

Methods: For this pilot, case-controlled study, a total of 30 patients were enrolled: 15 patients living with diabetes (Group A) and 15 controls (Group B). To meet inclusion criteria, patients living with diabetes needed a history of plantar ulcerations with the presence of peripheral neuropathy. They were excluded if they had active foot ulcers, peripheral vascular disease or amputation of more than one digit. Control patients did not have diabetes or any notable foot pathology. From these 30 patients, four plantar images were acquired with FootSnap from each foot: two by operator 1 and two by operator 2. The dataset thus consisted of 240 separate foot images. This approach enabled assessment of intra- and interrater reliability. Reproducibility of foot images was then calculated using the Jaacard Similarity Index (JSI).

Results: A JSI value of 1 indicates that both groups are in perfect agreement. For Group A, the mean JSI for intrarater reliability for operator 1 was 0.89 and 0.91 for operator 2, with interrater score of 0.89. Group B had slightly higher values with mean JSI for intrarater reliability for operator 1 at 0.94 and 0.93 for operator 2, with interrater score of 0.93.

Given the high JSI values for intrarater and interrater reliability between Groups A and B, the authors concluded that FootSnap is indeed fit-for-purpose in imaging diabetic feet. However, several limitations exist in this report that decrease the validity of the results: small sample size, use of trained operators rather than naïve photographers and recruitment of unmatched control participants. Additionally, they did not reveal how study subjects were selected nor did they provide any clinical or demographic information to explain the extent of deformities and disease processes that were captured. Moreover, only plantar feet were imaged. It is thus unclear whether or not this application can be translated to other anatomic regions, such as dorsal or interdigital foot surfaces—a crucial factor for many podiatrists. Nevertheless, as this technology is still in the developmental phase, the current data supports proof of concept and hopefully represents a step toward future prevention and management of diabetic foot pathologies.

Educational Opportunities