Body mass index (BMI) and moderate drinking are modifiable risk factors associated with the development of psoriatic arthritis in people who have severe psoriasis, according to a study published in the British Journal of Dermatology.
The investigators of this retrospective cohort study sought to explore the associations of modifiable risks such as obesity, body mass index (BMI), alcohol, and smoking with the development of psoriatic arthritis in people with psoriasis.
The study population included 1409 individuals with incident psoriasis and a subsequent diagnosis of psoriatic arthritis whose data were extracted from the UK Clinical Practice Research Datalink between 1998 and 2014. Adjusting for all significant covariates, logistic regression models were used to compare baseline demographics and modifiable lifestyle factors associated with the risk of developing psoriatic arthritis. In addition, nonlinear and cumulative changes in BMI were determined using distributed lag nonlinear models.
The investigators found significantly increased odds of psoriatic arthritis developing in people with BMIs of 25.0 to 29.9 kg/m2 (odds ratio [OR], 1.79; 95% CI, 1.46-2.19), 30.0 to 34.9 kg/m2 (OR, 2.10; 95% CI, 1.67-2.63), and 35.0 kg/m2 or higher (OR, 2.68; 95% CI, 2.09-3.43) compared with those having BMIs below 25.0. Adjusting for potential confounders and sensitivity analyses revealed similar findings. No significant associations with psoriatic arthritis were observed for past or current smokers (OR, 0.83; 95% CI, 0.69-1.02) and never-smokers (OR 0.94; 95% CI, 0.76-1.16). Compared with nondrinkers, the odds of developing psoriatic arthritis were significant in moderate drinkers (OR, 1.57; 95% CI, 1.16-2.11), but not in heavy drinkers (OR, 1.06; 95% CI, 0.69-1.62) or ex-drinkers (OR, 0.94; 95% CI, 0.56-1.58). Individuals who reported a reduction in BMI during a 10-year period were found to have a reduced risk for psoriatic arthritis vs those who maintained a constant BMI over the same time.
A limitation of the study was the lack of data on secondary care, such as the use of biologic agents, which may have acted as confounders or had an interaction with alcohol or disease severity. Although no association with psoriatic arthritis risk was attributed to smoking status, smoking may have had a protective effect on lower BMI among smokers.
The researchers of the study concluded that the risk for incident psoriatic arthritis was associated with increased BMI in people with severe psoriasis. Psoriatic arthritis risk is further associated with moderate drinking, but not with heavy drinking, ex-drinking, or smoking status. People with psoriasis who reduce their weight over time may reduce their risk of developing psoriatic arthritis.