Table 4

Calculation modalities of the PsAID scores

CalculationDealing with missing data
PsAID-9PsAID final value=(PsAID1 (pain) NRS value (range 0–10)×0.174)+(PsAID2 (fatigue) NRS value (range 0–10)×0.131)+(PsAID3 (skin) NRS value (range 0–10)×0.121)+(PsAID4 (work and/or leisure activities) NRS value (range 0–10)×0.110)+(PsAID5 (function) NRS value (range 0–10)×0.107)+(PsAID6 (discomfort) NRS value (range 0–10)×0.098)+(PsAID7 (sleep) NRS value (range 0–10)×0.089)+(PsAID8 (coping) NRS value (range 0–10)×0.087)+(PsAID9 (anxiety) NRS value (range 0–10)×0.085)If one of the 9 NRS values composing the PsAID is missing, the imputation is as follows:
A. Calculate the mean value of the 8 other (non-missing) NRS values (range, 0–10)
B. Impute this value for the missing NRS value
C. Then, calculate the PsAID as explained above
If 2 or more of the NRS values are missing, the PsAID is considered a missing value (no imputation)
PsAID-12PsAID final value=(PsAID1 (pain) NRS value (range 0–10)×3)+(PsAID2 (fatigue) NRS value (range 0–10)×2)+(PsAID3 (skin) NRS value (range 0–10)×2)+(PsAID4 (Work and/or leisure activities) NRS value (range 0–10)×2)+(PsAID5 (function) NRS value (range 0–10)×2)+(PsAID6 (discomfort) NRS value (range 0–10)×2)+(PsAID7 (sleep) NRS value (range 0–10)×2)+(PsAID8 (coping) NRS value (range 0–10)×1)+(PsAID9 (anxiety) NRS value (range 0–10)×1)+(PsAID10 (embarrassment) NRS value (range 0–10)×1)+(PsAID11 (social life) NRS value (range 0–10)×1)+(PsAID12 (depression) NRS value (range 0–10)×1). The total is divided by 20.If one of the 12 NRS values composing the PsAID score is missing, the imputation is as follows:
A. Calculate the mean value of the 11 other (non-missing) NRS values (range, 0–10)
B. Impute this value for the missing NRS value
C. Then, calculate the PsAID score as explained above
If 2 or more of the NRS values are missing, the PsAID score is considered a missing value (no imputation)
• The PsAID calculation is based on NRS questions. Each NRS is assessed as a number between 0 and 10. The range of the final PsAID value is 0–10 where higher numbers indicate worse status. Calculators and translations are available at http://www.eular.org/index.cfm?framePage=/st_com_clinical_tools.cfm.

• NRS, numeric rating scale; PsAID, Psoriatic Arthritis Impact of Disease.