Onychomycosis Severity Index (OSI) Medical Algorithm

Description

Carney et al developed the Onychomycosis Severity Index (OSI) for grading the severity of onychomycosis that is involving a nail.. The authors are from the University of Alabama at Birmingham, Columbia University, University of North Carolina at Chapel Hill, Oregon Health and Science University, University of Miami, University of Mississippi and the University of Alabama at Tuscaloosa.

Parameters:

(1) area of nail involved

(2) percent of nail length involved, measured from distal edge

(3) dermatophytoma or significant subungual hyperkeratosis

percent of nail length involved =

= (length of nail involvement measured from distal end) / (nail length) * 1005

Parameter	Finding	Points
area of nail involved	none	0
	1 to 10%	1
	11 to 25%	2
	26 to 50%	3
	51 to 75%	4
	76 to 100%	5
percent of nail length involved	< 25%	1
	25 to 50%	2
	51 to 75%	3
	> 75%	4
	matrix involved	5
high risk features	dermatophytoma OR subungual hyperkeratosis > 2 mm	10
	neither present	0

where:

• The area of nail involved and percent of nail length are linked since the area involves the length of the nail involved.

• Involvement of the lunula and/or proximal nail fold indicates matrix involvement.

total score =

= ((points for area involved) * (points for percent of nail length)) + (high risk features)

Interpretation:

• minimum score: 0

• maximum score: 35

• The higher the score the more severe the disease.

Total Score	Onychomycosis
0	cured
1 to 5	mild
6 to 15	moderate
16 to 35	severe

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Description

Specialty

Objective

ICD-10

Onychomycosis Severity Index (OSI) of Carney et al for Grading the Severity of Onychomycosis

Purpose: To grade the severity of onychomycosis using the Onychomycosis Severity Index (OSI) of Carney et al.

Description

Specialty

Objective

ICD-10