Psoriatic arthritis: improvement in outcomes but persistent sex difference – 5-year follow-up study of a Norwegian outpatient clinic population

Abstract

Objective

This study aimed to explore long-term changes in disease activity and remission rates, and potential sex-related differences in these outcomes, in psoriatic arthritis (PsA) patients treated in an outpatient clinic.

Method

This prospective longitudinal cohort study included 114 patients. The Disease Activity Index for Psoriatic Arthritis (DAPSA), clinical DAPSA (cDAPSA), 28-joint Disease Activity Score (DAS28), Simplified and Clinical Disease Activity Indices (SDAI, CDAI), Boolean remission for PsA, and minimal and very low disease activities (MDA, VLDA) were assessed. For group characteristics, parametric statistics and linear regression were used.

Results

At 5 year follow-up, improvement was noted for multiple measures reflecting disease activity and patient-reported outcomes. Statistically significant increases in remission rates were observed using DAS28 (+21.2%), CDAI (+9.7%), and cDAPSA (+7.6%), but not SDAI, DAPSA, Boolean remission, MDA, or VLDA. During the study period, the proportion of patients treated with biological disease-modifying anti-rheumatic drugs (bDMARDs) increased from 37.7% to 48.3% (p = 0.007). At baseline, women reported higher pain and fatigue, and had higher tender joint counts, DAPSA, cDAPSA, SDAI, CDAI, and DAS28 than men. Despite higher mean baseline C-reactive protein, men more often achieved remission, regardless of the definition applied. A higher proportion of men than women was treated with bDMARDs (baseline: 46.6% vs 28.6%; follow-up: 58.6% vs 33.9%).

Conclusion

This study adds evidence supporting recent improvements in PsA outcomes. Women had higher disease activity and were less likely to achieve remission than men. Despite progress in achieving remission goals, there is still room for improvement in therapeutic approaches for PsA patients.

Acknowledgements

The authors thank the patients for participating in the study, research nurse Hanne Vestaby, and the local rheumatology staff at Division of Rheumatology, Department of Medicine, Kristiansand, Norway, for data collection.

Disclosure statement

GH is a founder of and previous shareholder in the company manufacturing the GoTreatIT Rheuma tool. KŁ, BM, AK, and MK have declared no conflicts of interest.

Ethics

The study was approved by the Norwegian Regional Committees for Medical and Health Research Ethics (Regional komité for Medisinsk og helsefaglig forskningsetikk Midt-Norge 2012/101) and followed the ethical principles of
medical research involving human subjects of the Declaration of Helsinki. Written informed consent was obtained from each patient.

Data availability statement

The data underlying this article will be shared upon reasonable request to the corresponding author.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03009742.2023.2247703.

Additional information

Funding

This work was supported by an unrestricted research grant from Pfizer Norway [grant number 5714134 to GH].