Psoriasis Disability Index PDI

Instructions for Use and Scoring

The Psoriasis Disability Index questionnaire is designed for use in adults, i.e. patients over the age of 16. It is self explanatory and can be handed to the patient who is asked to fill it in without the need for a detailed explanation. It is usually completed in three or four minutes.

Scoring (Visual Analogue Scale)

The scoring of each question is answered on a graded scale from 0 - 6. If a question is left unanswered the score taken is 0. The PDI is calculated by summing the score of each of the fifteen questions resulting in a maximum of 90 and a minimum of 0. The higher the score, the more quality of life is impaired. The PDI can also be expressed as a percentage of the maximum possible score of 90.

Scoring (Tick-box method)

The scoring of each question is answered on a series of 4 answers; not at all (scores 0), a little (scores 1), a lot (scores 2), very much (scores 3). If a question is left unanswered the score taken is 0. The PDI is calculated by summing the score of each of the 15 questions resulting in a maximum of 45 and a minimum of 0. The higher the score, the more quality of life is impaired. The PDI can also be expressed as a percentage of the maximum possible score of 45.

Detailed analysis of the PDI (second version)

The PDI can be analysed under five headings as follows:

VAS

Tick-Box
Daily Activities Questions 1, 2, 3, 4 and 5 Score maximum 30

15
Work or School or alternative questions Question 6, 7 and 8 Score maximum 18

9

Personal relationships Questions 9 and 10 Score maximum 12

6

Leisure Questions 11, 12, 13 and 14 Score maximum 24

12
Treatment Question 15 Score maximum 6

3

The scores for each of these sections can also be expressed as a percentage of the maximum score for each section.

References

  1. Finlay AY, Kelly SE. Psoriasis: an index of disability. Clin Exper Derm, 1987; 12: 8-11. (Gives text of original version)
  2. Finlay AY, Khan GK, Luscombe DK, Salek MS. A validation of Sickness Impact Profile and Psoriasis Disability Index in Psoriasis. Brit J Dermatol, 1990; 123: 751-756. (Second version)
  3. Finlay AY, Coles EC. The effect of severe psoriasis on the quality of life of 369 patients. Brit J Dermatol, 1995; 132: 236-244. (Gives text of current (second) version)
  4. Lewis VJ, Finlay AY. Two Decades Experience of the Psoriasis Disability Index. Dermatology, 2005, 210:261-268.

COPYRIGHT

Please note that the Psoriasis Disability Index (PDI) is protected under copyright. However, permission is usually given for the PDI to be used. Please contact:

Professor A.Y. Finlay, FRCP.
Department of Dermatology
Wales College of Medicine, Cardiff University
Heath Park
Cardiff CF14 4XN United Kingdom.

Tel: +44 (0)29 2074 2615
Fax: +44 (0)29 2074 4312
E-mail: FinlayAY@cf.ac.uk