Lifestyle Changes Can Make a Difference in Psoriasis
The British Journal of Dermatology. 2015;172(2):317-318.
In this issue of the BJD, Kinahan et al. have investigated the effect of smoking on the response to systemic antipsoriatic treatment in a retrospective case–control study.
The hypothesis of the authors was that patients with psoriasis who smoke respond less well to systemic medication. The primary outcome measure was the Physician's Global Assessment (PGA) score. The source population was relatively large (n = 1520); however, only 7% met the inclusion criteria and only 4% had complete data in order to be included in the analysis. The authors found that post-treatment PGA was not significantly different in smokers (n = 20) compared with nonsmokers (n = 46). Baseline PGA was significantly higher in smokers, supporting the fact that smokers have more severe psoriasis or that more severe psoriasis leads to more smoking.
The authors did discover a borderline significant trend with a higher percentage of patients smoking < 10 cigarettes per day achieving better PGA scores than patients smoking > 10 cigarettes per day.
It is known that lifestyle factors such as smoking and obesity may affect psoriasis severity. Furthermore, addressing risk factors might also contribute to better treatment responses to systemic medication. In a recent trial, overweight patients with psoriasis randomized to a hypocaloric diet achieved significant weight loss after 16 weeks and a higher mean Psoriasis Area and Severity Index change compared with the group with a normal diet.
The data from the Psocare study in Italy showed that patients with psoriasis with lower body mass index responded better to systemic therapy than obese patients. These results suggest that lifestyle changes could lead to a better control of psoriasis and also a better response to systemic antipsoriatic therapy.
The topic of the present study is relevant as smoking can intervene with drug mechanisms of action, leading to a lower effect of the drug, such as is the case for example with hydroxychloroquine in the treatment of lupus erythematosus.
However, in this study the number of subjects was too low to conduct subgroup analyses for specific antipsoriatic therapies. The authors may have found a trend in light smokers achieving better therapeutic effects compared with heavy smokers; however, smoking could also be a confounder and the differences may be explained by smoking being associated with an unhealthier lifestyle, leading to a lower response to systemic therapy.
Studies have also shown that adherence to treatment is lower in smokers. A recent cohort study based on the Danish nationwide registry showed that in patients with psoriatic arthritis, current smoking was associated with poorer treatment adherence and smokers had poorer response to tumour necrosis factor-α inhibitors compared with nonsmokers.
Based on the results obtained in the study by Kinahan et al., it would be of value to perform a prospective study, with a preliminary sample size calculation and primary outcome measures, including more than one measure of disease severity, data on all potential confounders and possibly also patient-reported outcome measures. The goal of this study would be to determine the influence of smoking on the response to specific systemic treatments, adjusting for known risk factors involved in psoriasis and to investigate whether there is a dose–response relationship with the degree of smoking and response to systemic treatment.
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