Weight loss may improve disease activity in obese patients with psoriatic arthritis

Weight loss is associated with improvements in disease activity in obese individuals with psoriatic arthritis (PsA), a prospective study from Sweden has shown.

“[Our findings show that] weight loss treatment with a [very low energy diet (VLED)] … was associated with long-term improvement of measures of disease activity … after 24 months,” said the researchers. “These support the hypothesis of obesity as a promotor of disease activity in PsA, showing what could be attained by adding a weight loss programme to routine medical care in patients with PsA and obesity.”

Taking off from the favourable results of their previous study, [Arthritis Res Ther 2019;21:17] the investigators sought to evaluate the longer-term effects of VLED* on disease activity in 46 obese individuals with PsA (median baseline weight 106 kg). Of these, 39 and 35 attended the respective 1- and 2-year follow-up visits. Fifty-two obese but otherwise healthy patients on the same VLED regimen stood as controls. VLED was strictly maintained for 12–16 weeks; following which, food** was re-introduced gradually for 12 weeks. [Arthritis Res Ther 2020;22:254]

At 1 year, median weight loss was 16.0 percent. Seventy-seven percent of participants lost ≥10 percent of their weight. The fraction of participants with minimal disease activity (MDA) increased from 28 percent at baseline to 38 percent (p=0.008).

Year 2 saw a median weight loss of 7.4 percent, with 40 percent having ≥10-percent weight loss. The percentage of patients with MDA also increased to 46 percent (p=0.016).

The weight loss led to marked improvements in most disease activity variables, ie, tender joint count (p=0.001 [1 year] and p<0.001 [2 years]), swollen joint count (p=0.015 and p=0.003, respectively), Leeds Enthesitis Index (p<0.001 and p=0.002, respectively), C-reactive protein (p=0.009 and p=0.011, respectively), DAS28-CRP*** (p<0.001 for both), and DAPSA^# (p<0.001 for both).

“The anti-inflammatory effect of weight loss may rather be explained by a decreased production of pro-inflammatory cytokines and adipokines by the adipose tissue. Lowered mechanical loading by weight loss and less risk of microdamage, enthesitis, and arthritis could also be explanatory factors,” the researchers explained.

The rebound

However, almost all (n=34) participants regained weight at 1 year (median 3.9 kg), while all regained weight by year 2 (median 6.3 kg). “[P]articipants started to gain weight at 6 months … The weight regain, especially between 12 and 24 months … is a marker of [reduced] adherence to the energy intake restriction given during the first year,” explained the researchers. The lack of treatments or follow-ups during year 2 may have also influenced the regain, they noted.

“[These imply that] short-term weight loss can easily be regained, … [and] that prolonged treatment periods for weight maintenance or further weight loss may be needed,” they added. Also, transitioning back from VLED to normal food was reportedly harder despite the easy implementation of VLED at the beginning of the treatment phase.

Keeping the weight off is key

Taken together, the findings underline the importance of preventing weight gain and the development of obesity in this patient setting, the researchers stressed. “[P]atients should be informed about the unfavourable effects of obesity on disease course and CV risk … and that body weight should be routinely measured and discussed during medical follow-ups.”

“[P]atients with overweight should aim for weight maintenance, and patients with obesity should be offered a weight loss programme and be encouraged to participate in health-enhancing physical activity throughout the disease course,” they continued.

However, some limitations must be taken into context, noted the researchers. The lack of an untreated control arm is a major drawback despite the longer follow-up. Also, modifications in background cs/bDMARDs^## in some patients, as well as the concomitant use of antihypertensive, antihyperlipidaemic, and antidiabetic agents, may have impacted the findings. The study population was also relatively small.

Nonetheless, the VLED programme may have instilled some healthy food options and practices among participants which, according to the researchers, may contribute to subsequent weight and disease improvements in the long run.