The current study brought important information on the relationship between the PASS and disease score in psoriasis. Most patients with mild or moderate psoriasis considered their symptoms acceptable. A dose-response relationship was identified in the association between the PASS status and severity of disease. In addition, female sex and exposed skin involved were risk factors for the acceptable status. Both PASI and BSA showed limited capability in differentiating psoriasis patients in an acceptable symptom state from those not.
The clinician’s and patient’s perspectives could be different in terms of the severity of disease or therapeutic effect, and the discrepancy might not be conducive to the management of disease14,20−22. As a patient-reported measure, acceptable symptom state effectively reflects patient’s perception on disease’s impact on themselves. In our study, most patients with mild or moderate psoriasis considered their symptoms acceptable; this is consistent with the findings of studies in RA and PsA13,14. Mild severity indicates less time needed for skin care and less visibility of lesions. In addition, we examined the possible factors associated with PASS status, and found that females were less likely to report acceptable symptom state, and similar result was reported in patients who underwent ligament reconstruction23. Exposed skin involved also considerably affected patient’s acceptable symptom state in our study. In contrast to musculoskeletal diseases such as RA and AS, psoriasis is a skin disease with evidently negative impact on appearance, and is thus more likely to cause psychological distress24–26. The degree of emphasis on smooth and beautiful skin in female is stronger than that in male. These characteristics might be the reasons why female and exposed skin involved are risk factors for PASS-N. Subgroup analysis also noted that the effect of exposed skin involved on PASS status was stronger as the severity increased. Patients with severe psoriasis may have larger areas of exposed skin lesion compared with moderate or mild psoriasis, as well as higher levels of systematic inflammation and metabolic disruption, resulting in effect modification statistically.
Through the ROC curve analyses, we determined the thresholds of PASI and BSA in differentiating PASS-Y from PASS-N was 3.95 and 2.85%, respectively. The cut-offs were within the moderate severity for PASI and mild for BSA. Previous studies reported the 75th percentile approach was also used to determine the thresholds of disease scores for PASS11,23, but the ROC curve analyses may generate a more precise estimate owing to the thresholds defined by ROC curve analyses are based on the best trade-off for sensitivity and specificity14. Our results indicated that the PASI and BSA had limited capability in differentiating acceptable symptom state in psoriasis, and the sensitivity and specificity for the both scores were lower compared with previous studies in other diseases13,14. This indicates that cutaneous symptoms and disfigurement may contribute to acceptability which is not captured by the objective measure of psoriasis severity. Therefore, acceptability of patient symptoms should be taken into consideration in treatment decision-making processes in addition to the changes of PASI or BSA, patients who reported PASS-N should receive additional interventions to improve health-related outcome.
Other common patient-reported measures that are used in psoriasis include instruments for health-related quality of life, among which DLQI is the most frequently used7,8. However, the tool has weaknesses, such as disordered response thresholds, item bias, and psychometric properties27. The bio-psycho-social medical model is proposed as an integrated way to understand diseases28, and the acceptability of patients is an outcome of multifaceted factors. Further studies on the association of PASS with other patient-reported measures in psoriasis are warranted.
This study has some limitations. First, selection bias might be introduced in a single-center hospital-based study that captures patients with severer disease status and stronger willingness to seek help. Second, patients may have different understanding on the single question that was used to assess the outcome. Third, more intermediate and modifiable factors for PASS should be investigated, such as psychological resilience, perceived stress, symptoms of depression and anxiety, and social support.
In conclusion, this study accentuated the importance of patient-reported measures, which should be taken into consideration in treatment decision-making processes. To our knowledge, this is the first study that described PASS and investigated the association of disease severity and patient characteristics with PASS in psoriasis. We found that patients with mild psoriasis had a high proportion of acceptable status, while female sex and exposed skin involved were factors for less acceptability. Poor discrimination capability of PASI and BSA further indicates the unique value of PASS in the management of psoriasis.