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Nail Psoriasis Severity Index (NAPSI)

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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Nail involvement is associated with significant physical and psychological consequences for a substantial number of psoriasis patients

  • prevalence data for nail involvement in psoriasis vary between 10% and 55% (1)
    • prevalence rises to 70%-80% in cases where joint involvement is also present
    • clinical spectrum is very heterogeneous depending on involvement of the nail bed, matrix, or folds, and includes pitting, grooving, and stippling, as well as discoloration, leukonychia, and onychodystrophy ranging to onycholysis
    • combined nail matrix and nail bed psoriasis can develop in cases of very severe inflammation, a possible consequence of which is the formation of only parakeratotic, crumbly material by the matrix and bed, a condition referred to as 'psoriatic crumbly nail '
      • this finding constitutes a risk factor for secondary mycotic infections, which can occur in up to 27% of psoriasis patients
  • nail psoriasis is associated with a prolonged duration of psoriasis itself and greater severity of skin and joint involvement, and may also be an indicator for the activity of psoriatic arthritis
  • click here for images of nail psoriasis

NICE have suggested to use the Nail Psoriasis Severity Index to assess nail disease in specialist settings (2):

  • if there is a major functional or cosmetic impact or
  • before and after treatment is initiated specifically for nail disease.

Nail Psoriasis Severity Index (NAPSI) is a numeric, reproducible, objective, simple tool for evaluation of nail psoriasis. This scale is used to evaluate the severity of nail bed psoriasis and nail matrix psoriasis by area of involvement in the nail unit

  • NAPSI is used to assign a score to each nail for nail bed and nail matrix psoriasis (3):
  • nail plate is divided into quadrants by imaginary longitudinal and horizontal lines
    • nail plate is assessed for nail matrix psoriasis by the presence of any feature of nail matrix psoriasis, including nail pitting, leukonychia, red spots in the lunula, and crumbling in each quadrant of the nail
    • nail bed psoriasis is assessed by the presence of any features of nail bed psoriasis, including onycholysis, oil drop (salmon patch) dyschromia, splinter hemorrhages, and nail bed hyperkeratosis in each quadrant of the nail
    • score is 0 if the findings are not present, 1 if they are present in 1 quadrant of the nail, 2 if present in 2 quadrants of a nail, 3 if present in 3 quadrants of a nail, and 4 if present in 4 quadrants of a nail
      • thus each nail has a matrix score (0-4) and a nail bed score (0-4), and the total nail score is the sum of those 2 individual scores (0-8)
      • sum of the total score of all involved fingernails is the total NAPSI score for that patient at that time
      • if a more sensitive scale is needed, the nail can be given a separate score for all 8 features in each quadrant. The resulting is a 0 to 32 scale for the nail
  • a modified version (mNAPSI) was developed to enhance the face validity and feasibility of this tool (4)


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