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  • Writer's pictureIvan Bristow

Assessing Progress in Onychomycosis

Onychomycosis is a common clinical problem we see on a regular basis. There are many ways to treat it - topically, systemically or a combination of both. Most studies measure success by assessing the presence or absence of fungus before and after treatment within the nail (termed “mycological cure”). This is typically assessed by taking a clipping of the nail and testing it.

A patient who has a ‘mycological cure’ following a treatment may have expectations that are somewhat different from the podiatrist treating them, as their previously fungal nail may look much the same to them as it did at the start. This phenomenon has long been recognised in studies and subsequently a secondary term has evolved – the ‘clinical cure’. This essentially measures if there is an aesthetic improvement in the nail, in addition to a mycological cure. I covered this in an article I published a few years back (1) (click here to read it in full here) .

It is tempting to think that patients and practitioners should be capable of assessing nail changes in the face of onychomycosis, but this is not entirely the case. Research has shown that patients tend to underestimate the extent of fungal infection in their nails, particularly if it affects just their toenails (2). Moreover, agreement between experienced dermatologists for signs of onychomycosis has been shown to be poor in some areas (3).

Improvement visually can be calculated by measuring and scoring the amount of clear nail apparent at each appointment. The onychomycosis severity index [OSI] (4) is system developed originally for research purposes but can also be used day to day in the clinic to assess progress in a fungal nail treatment. Below is a short video explaining what it is and how to use it.

Of course, this is a formal approach but with the availability of mobile phone cameras in clinic, this maybe a little excessive but nevertheless it’s another useful clinical tool which has been validated. Also, as they say in the media - "other alternatives are also available”. The Scoring Clinical Index for Onychomycosis (SCIO index) is another tool which is able to quantify the extent of fungal nails disease but rather working solely on the basis of proportions of the nail affected, it is scored based on the type of onychomycosis (i.e., Distal Lateral Sub-ungual Onychomycosis v Proximal Subungual Onychomycosis), nail thickness, patient age and which nails are affected (5). The higher the score obtained, the longer the treatment is required to shift the infection.


1. Bristow IR. Be sure of the cure when treating onychomycosis. Podiatry Now. 2017;20(1):14-6.

2. Cham PMH, Chen SC, Grill JP, Warshaw EM. Validity of self-reported nail counts in patients with onychomycosis: A retrospective pilot analysis. J Am Acad Dermatol. 2008;58(1):136-41.

3. Ginarte M, Garcia-Doval I, Monteagudo B, Cabanillas M, Labandeira J, Florez A, et al. Observer agreement in toenail disorders: implications for diagnosis and clinical research. Brit J Dermatol. 2009;160(6):1315-7.

4. Carney C, Tosti A, Daniel R, et al. A new classification system for grading the severity of onychomycosis: Onychomycosis severity index. Arch Dermatol. 2011;147(11):1277-82.

5. Sergeev AY, Gupta AK, Sergeev YV. The Scoring Clinical Index for Onychomycosis (SCIO index). Skin Therapy Lett. 2002;7 Suppl 1:6-7.


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