Receiving treatment with a biologic medication, compared with no biologic treatment, appeared to be associated with a lower risk for developing psoriatic arthritis (PsA) in patients with psoriasis.
Dr. Philip Helliwell
That’s according to the results of a nested case-control study involving electronic medical record data from an Israeli health maintenance organization in Arthritis & Rheumatology. Compared with no biologic treatment, the risk for developing PsA among PsO patients was reduced by 39%.
This study shows “a statistically and clinically significant lower risk for developing PsA among patients receiving biologic medications for psoriasis treatment,” wrote Yael Shalev Rosenthal, MPH, of the Sackler Faculty of Medicine, Tel Aviv University and colleagues. “The results suggest considering treatment with biologic medications in patients [who] present with significant risk factors for PsA at an earlier stage of treatment.”
“It would be nice to believe this story, but I don’t think we can based on the evidence we’ve got so far,” commented Philip Helliwell, PhD, DM, in an interview.
Dr. Helliwell, who is professor of clinical rheumatology at the University of Leeds (England) and an Honorary Consultant Rheumatologist for the Leeds Teaching Hospitals and Bradford Teaching Hospitals NHS Trust, noted that there were several issues with the current evidence.
Aside from their often retrospective or nonrandomized nature, prior analyses, including the current one, were based on EMR data.
“There’s actually no face-to-face patient contact going on here. It’s all done on coding, and coding can be unreliable,” Dr. Helliwell said.
While the study’s findings are “in line with other studies that have looked at this, and suggest that if you get a biologic, you’re less likely to get PsA with your psoriasis, there could be lots of reasons why.”
The big problem here is confounding by indication. “You don’t get on a biologic unless you’ve got bad psoriasis,” Dr. Helliwell explained. The Israeli criteria for starting a biologic are much higher than in the United Kingdom, he added, requiring more than 50% of patients’ body surface area to be affected, or a Psoriasis Area and Severity Index score of more than 50. Moreover, people with bad psoriasis are more likely to get PsA. This, however, makes the results more impressive.
Confounding by indication is an issue with this study, agreed consultant rheumatologist Adewale Adebajo, PhD, in a separate interview. He acknowledged, however, that the study’s authors did try to account for this by limiting the timescale of their analysis to the first 10 years of biologic therapy. They also used the usual methods of propensity score matching and multivariate Cox regression analysis to hopefully iron out any differences between the two groups of patients.
Study details and results
Ms. Rosenthal and coauthors analyzed EMR data on patients with psoriasis but not PsA that were logged in the Maccabi Healthcare Services (MHS) database. The MHS is the second-largest health maintenance organization in Israel, insuring over 2 million members, the researchers said.