Assessing the validity and interpretability of the Simplified Psoriasis Index in Tunisian patients.

INTRODUCTION

Multiple scores have been developed to assess the severity of psoriasis, but these scores have many limitations. The Simplified Psoriasis Index (SPI) is a summary score with separate components for current severity (SPI-s), psychosocial impact (SPI-p), and past history and interventions (SPI-i). It is available in two similar versions: proSPI and saSPI.

AIM: To assess the validity of the SPI by studying its correlation to the benchmark scores in Tunisian patients.

METHODS

It was a prospective bicentric study including 80 patients with plaque psoriasis.

RESULTS

The median PASI was 7.6 and the median DLQI was 9. The median proSPI-s was 6 and the median saSPI-s was 8. The median SPI-p was 7. The median SPI-i was 2. There was a strong correlation between the proSPI-s and PASI (r=0.87) and between the proSPI-s and saSPI-s (r=0.82). There was a medium correlation between saSPI-s and PASI (r=0.70) and between SPI-p and DLQI (r=0.67). The threshold value for proSPI-s and saSPI-s was 7.25. The threshold value for SPI-p was 6.5.

CONCLUSION

The SPI aims to provide a concise but global measure of the severity and impact of psoriasis on quality of life. The use of SPI has several advantages: the simplicity of use, the additional weight given to critical locations of psoriasis, the possibility for the patient to self-assess his own disease, and the possibility of evaluating all the dimensions of psoriasis at the same time.