Background/Purpose: Psoriatic arthritis (PsA) is a multifaceted disease. Affecting joints, skin, entheses and dactylitis, its impact on health-related quality-of-life (HRQoL) could be substantial. Up to now, the joints have been the main focus of treatment, while other disease facets were expected to improve along with DMARD treatment. Our aim is to describe HRQoL in newly diagnosed PsA patients taking into account swollen joints, tender entheses, dactylitis and the extent of skin involvement.

Methods: Baseline data of incident PsA patients was used from the Dutch south-west Psoriatic Arthritis Registry (DEPAR) study between August 2013 and March 2016. HRQoL was assessed by 8 subscales of the Short-Form 36 (SF-36) questionnaire (0-100, higher score represents a better HRQoL). Patients were classified in arthritis subtypes (i.e. mono-, oligo- or polyarthritis) by their rheumatologist.  Entheses were evaluated using the Leeds Enthesitis Index (LEI) and Maastricht Ankylosing Spondylitis Enthesitis Score (MASES; positive if tender entheses >1). Psoriasis was evaluated using the Psoriasis Area Severity Index (PASI; mild: 0-7; moderate/severe: >7) and dactylitis using the Leeds Dactylitis Index (LDI).

Results: 271 patients completed the SF-36 at baseline. Their average age was 50.4 years (SD 13.7) and 50% were male. 256 patients had arthritis: 62 had monoarthritis (M), 125 oligoarthritis (O) and 69 polyarthritis (P). Psoriasis was mild in 74% and moderate/severe in 13%. At least one digit with dactylitis was present in 12% of the patients. A tender enthesis was present in 47% of patients. Mean scores of the subdomains in the SF-36 were similar across the different arthritis-groups, with slightly worse scores for polyarthritis compared to mono- and oligoarthritis. However, when stratifying these groups for the presence of a tender enthesis, HRQoL decreased substantially for all groups across all subdomains of the SF-36, with a median difference of 14.3 points.  Irrespective of joint involvement, a tender enthesis (n=127) decreased the mean scores of all subdomains significantly compared to the non-tender enthesis group (n=144, p=0.0001). Severity of psoriasis and presence of dactylitis did not lead to significantly different SF-36 values compared to those not affected.

Conclusion: Having tender entheses impacts HRQoL severly in both its physical and mental dimensions in incident untreated PsA.