Yan Li Guangying Cheng ^* Kaihua Ma ^* Yuqin Wang ^*

• Zibo Central Hospital, Shandong, China

We recently read the article "Association between systemic immunity-inflammation index and 25 psoriasis among outpatient US adults" published in your journal (1). The authors used data from a 26 total of five cycles, 2003-2006 and 2009-2014. The aim was to explore the relationship between the 27 Systemic Immune Inflammatory Index (SII) and psoriasis. A total of 16,831 adults aged 20-59 years 28 were included in the study. The authors used weighted logistic regression models to analyze the 29 association between SII and psoriasis, variance inflation factor (VIF) to detect multicollinearity, and 30 subgroup analyses of variables that might influence the results. The authors suggest that SII may 31 serve as an important biomarker for psoriasis. This study provides new perspectives for our 32 understanding of the inflammatory mechanisms of psoriasis. It is an interesting study. We appreciate 33 the authors' findings and offer constructive comments for further discussion. 34 The authors conducted a careful analysis using weighted logistic regression in this study. However, 36 the sample sizes of unweighted participants in Table 2 were not consistent across the original model, 37Model 1, and Model 2, and the authors did not mention in the Statistical Methods section or Figure 1 38 the process of screening and recruiting participants when different models were used or whether there 39 was missing data in the different models. We believe that variations in sample sizes in different data 40 models may affect the accuracy of the study results and that they affect the representativeness of the 41 results. 42 The authors divided the study into subgroup analyses by age group, drinking status, gender, BMI group, 44 and marital status. This is a commendable work. However, the authors mention in the discussion 45 section that there is a significant positive association between psoriasis and nonalcoholic fatty liver 46 disease (NAFLD) in U.S. adults(2). NAFLD was not included in the subgroup analyses. Fat builds up 47 in the liver, leading to inflammation and liver damage. This suggests that NAFLD may be an important 48 factor affecting psoriasis(3). We recommend adding NAFLD to the subgroup analysis for more 49 accurate results. 50 We appreciate that the authors used the variance inflation factor (VIF) method to check for 52 multicollinearity. However, we did not find detailed specific information about the multicollinearity 53 results or the VIF values. In addition, the article does not state whether multicollinearity exists. We 54 are very interested in how the authors handle multicollinearity. We recommend that the authors 55 increase the article's readability by adding the study's VIF values and explaining how such issues 56 were handled. 57 In conclusion, this study provides an in-depth analysis of the relationship between SII and psoriasis 59 among adults in the United States. The results of the study that were obtained are commendable. It is 60 hoped that the authors will consider these issues we have mentioned, and our recommendations are 61 intended to refine and expand this respectable study. In addition, we eagerly look forward to the 62 authors' continued scholarly contributions in their future work. 63