ACR 2018: Reduced BMI May Lower Risk of Psoriatic Arthritis

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Patients with psoriasis may be able to lower their risk of developing psoriatic arthritis (PsA) by reducing their body mass index (BMI) over time, according to research presented at the 2018 American College of Rheumatology (ACR)/Association of Rheumatology Health Professionals (ARHP) Annual Meeting in Chicago, Illinois, on October 23 by Neil McHugh of the Royal National Hospital for Rheumatic Diseases in Bath, United Kingdom. McHugh and fellow researchers looked at the effect of modifiable risk factors on the development of PsA.

The study
Utilizing the UK Clinical Practice Research Datalink, this study identified 90,189 incident cases of psoriasis, diagnosed between 1998 and 2014. The population was 42% male and had a mean age of 51.

After adjusting for potential confounders, researchers assessed the association between baseline psoriasis severity, smoking, alcohol consumption, and BMI, and the development of PsA using generalized additive models. In addition, possible non-linear and cumulative or lagged risks associated with change in BMI were investigated using distributed lag non-linear models during follow up.

The findings
Of the base population, 1409 patients went on to develop PsA after receiving a diagnosis of psoriasis. Patients with severe psoriasis were found to have an increased risk of developing PsA. For alcohol consumption, ex-drinkers, current drinkers, and heavy drinkers were all at greater risk for PsA compared with non-drinkers. Associations with smoking were not found to be significant.

Significant increases in the risk of developing PsA were observed for BMIs of 25.0 to 29.9, 30.0 to 34.9, and greater than 35 as compared with less than 25.0. By using measurements of BMI over time, researchers were able to quantify the burden of continuing weight gain on the risk of PsA.

For the first time, the researchers were able to show that reducing BMI over time results in a reduction in the risk of PsA. These results add to the growing evidence that severity of psoriasis, alcohol use, and increased BMI are associated with an increased risk of developing PsA for people already living with psoriasis.

Implications for physicians
This study produced a BMI risk calculator to demonstrate the effects of reductions in BMI on cumulative risk of developing PsA. “Reducing BMI over a 10-year period (linearly) was associated with a reduction in the risk of developing PsA when compared to BMI remining constant over the same period,” the researchers offered as an example.

As PsA affects about 20% of people with psoriasis, the results of this study may assist physicians in discussing the benefits of BMI reduction. For obese patients with psoriasis in particular, weight reduction may have the potential to greatly lower their risk of developing PsA, in addition to providing other health benefits.

References:

Green A, Shaddick G, Charlton R, et al. Modifiable Risk Factors and the Development of Psoriatic Arthritis in People with Psoriasis [Abstract 2134]. Arthritis Rheumatol. 2018;70(suppl 10). Accessed October 23, 2018.