Body mass index and severity of psoriasis: a cross-sectional study

Background: The relationship between body mass index (BMI) and the severity of psoriasis is of debate. We investigated the relationship between BMI and psoriasis area and severity index (PASI) in Northern Iran. Method: In this prospective, observational descriptive study, 190 patients with chronic plaque-type psoriasis were included from January 2015 to 2017. None of the patients used systemic therapy for psoriasis during the last month. Results: There was a slight female predominance in our study (n = 116; 61.1%). The mean age of our patients was 28.88 ± 18.17 (mean ± standard deviation) years. We found a positive correlation between BMI and PASI in the groups of psoriatic patients who had normal weight or were overweight (r = 0.369, P = 0.006 and r = 0.287, P = 0.019, respectively). In the final logistic regression model, it was shown that in cases with BMI < 18.5, the mean PASI score was lower in comparison with those with normal BMI (OR = 0.074, CI: 0.009, 0.636). Conclusion: A relationship between BMI and PASI was only seen in psoriatic patients who had normal weight or were overweight. To reduce the effect of factors such as systemic treatments, it is suggested to evaluate the relationship between BMI and PASI score as soon as the diagnosis of psoriasis is confirmed.