Background/Purpose:

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis associated with progressive joint damage and disability. In the last 15 years, tumour necrosis factor inhibitors (TNFi) have emerged as an effective treatment in reducing the incidence of joint damage.

It has been reported that TNFi are associated with weight gain in both psoriasis and PsA. If true, such an adverse effect could contribute to the increased prevalence of cardiovascular disease in PsA and its associated risk factors. In the general population, however, weight increases with age. Studies that have reported weight gain with TNFi in PsA have not accounted for this natural tendency.

In this study, the aim was to investigate whether therapy with TNFi  is associated with weight gain in patients attending a large PsA clinic.

Methods:

Patients were selected for inclusion in this study if they had at least 2 weight measurements prior to, and after, commencing TNFi. The relevant data were obtained from the clinic database where clinical, radiologic and laboratory data are collected prospectively on all patients satisfying the CASPAR classification criteria for PsA. Change point modelling, to model weight using a random effects analysis, was used to assess differences in weight over time using the mean of the slope before and after starting TNFi. The ‘pre’ and ‘post’ slopes were compared using a t-test. All 4 TNFi licensed for use in PsA were analysed as a single entity.

Results:

One hundred seventy two patients were eligible for inclusion, of which 60% were male. At the first clinic visit, mean age was 41.7 ± 12.8 years, while mean disease duration was 6.6 ± 8.0 years. At the visit prior to initiation of TNFi, mean number of tender and/or swollen joints was 10.2 ± 10.9, while 115 patients had clinical evidence of joint damage (mean number of damaged joints: 12.9 ± 12.9). Of those taking disease modifying therapy at the time of TNFi initiation, 51% (n=87) were prescribed methotrexate, 9% (n=16) sulphasalazine and 13% (n=22) leflunomide. Mean weight for visits prior to TNF use (adjusting for repeated visits) is 83.5 ± 17.0 kg, while the mean weight after TNFi use was 84.9 ± 17.7 kg (p=0.006).

The means of the pre- and post-TNFi slopes were 0.26 ± 0.17 and 0.13 ± 0.13, respectively, which were not significantly different (p=0.55). This implies that there was no weight gain after commencement of TNFi therapy in this patient population.

Conclusion:

TNF inhibitors do not cause an increase in weight in PsA, contradicting previous reports pertaining to weight gain. The statistical methods employed along with consideration of adults’ natural propensity for weight gain with age may account for our findings.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/changes-in-weight-associated-with-tumour-necrosis-factor-inhibition-in-psoriatic-arthritis/