the results of a retrospective cohort study suggest.
A family history of psoriasis was associated with younger onset of psoriatic disease and the presence of enthesitis, while by contrast, a family history of psoriatic arthritis (PsA) was associated with lower risk of plaque psoriasis and higher risk of deformities, according to Dilek Solmaz, MD, of the University of Ottawa and her coauthors, who reported their findings in Arthritis Care & Research.
“The link between family history of psoriasis/psoriatic arthritis and pustular/plaque phenotypes may point to a different genetic background and pathogenic mechanisms in these subsets,” the investigators wrote.
Most, if not all, previous studies evaluating family history have grouped psoriasis and PsA together, according to Dr. Solmaz and her colleagues, rather than looking at the individual effects of psoriasis or PsA family history that may lead to unique disease phenotypes, as was done in the present study.
The investigators based their retrospective analysis on patients recruited in a longitudinal, multicenter database in Turkey and Canada. The mean age of patients in the study was 48 years; nearly 65% were female.
Out of 1,393 patients in the database, 444 had a family history of psoriasis or PsA. That included 335 patients with a psoriasis-only family history and 74 with a family history of PsA; another 35 patients weren’t sure about having a family history of PsA or psoriasis and were left out of the analysis.
Plaque psoriasis was more common in individuals with a family history of only psoriasis, while pustular psoriasis was more common in those with a PsA family history, the investigators reported.
In multivariate analyses, having a family member with psoriasis was a risk factor for younger age of psoriasis onset (odds ratio, 0.976; 95% confidence interval, 0.964-0.989; P less than .001) as well as a higher risk for enthesitis (OR, 1.931; 95% CI, 1.276-2.922; P = .002) when compared against patients without a family history of psoriasis.
Patients with a family history of PsA were more likely to have deformities (OR, 2.557; 95% CI, 1.250-5.234; P less than .010) and lower risk of plaque-type psoriasis (OR, 0.417; 95% CI, 0.213-0.816; P less than .011) than patients without a family history of PsA.
Disease onset was earlier among patients with a family history of psoriasis at a mean of 28.1 years versus 31.9 years for those with a family history of PsA (P less than .001).
Dr. Solmaz and her colleagues reported no conflicts of interest related to the research, which was supported in part by the Turkish Society for Rheumatology, the Scientific and Technological Research Council of Turkey, and Union Chimique Belge.
SOURCE: Solmaz D et al. Arthritis Care Res (Hoboken). 2019 Jan 25. doi: 10.1002/acr.23836.