Evaluating Common Conditions That Precede Psoriatic Arthritis Diagnosis

Musculoskeletal symptoms and incidence of psoriasis may serve as predictors of psoriatic arthritis (PsA) diagnosis, according to study findings published in Arthritis Research & Therapy.

As a chronic inflammatory disease marked by a myriad of skin and musculoskeletal manifestations, there are 6 clinical domains of PsA, which include axial disorders, nail disease, skin disease, peripheral disease, enthesitis, and dactylitis, either alone or in combination.

Although timely diagnosis of PsA is vital to patient outcomes, researchers note that diagnostic delay is common for the condition, with a prior cross-sectional study finding that one-third of evaluated patients had to wait for more than 5 years to receive their diagnosis despite having consulted with numerous health care providers.

“A 6-month delay from PsA symptom onset to initial rheumatology consult may lead to joint erosion and damage,” cautioned the study authors. “ An increased awareness of the heterogeneity of PsA symptoms and diagnostic barriers may lead to a timely diagnosis.”

Seeking to better understand patient experiences and health events in the period prior to PsA diagnosis as a way to uncover potential predictors of PsA pathophysiology, they conducted a retrospective cohort study of diagnostic codes and provider type data derived from MarketScan claims data between January 2006 and April 2019.

In the analysis, adult patients who were enrolled in the database for 6 or more years before PsA diagnosis and who had greater than 2 PsA diagnoses 30 or more days apart were included (n = 13,661; mean [SD] age, 55.8 [12.6] years; 60.2% women). Matched controls (n = 26,729) were compared at a 2:1 ratio with patients with PsA, with health events (diagnoses and provider types) analyzed before PsA diagnosis and also stratified by presence of psoriasis.

Compared with controls, patients with PsA were indicated to receive more diagnosis codes for arthritis and dermatologic issues, including for osteoarthritis (OA; 47.8% vs 21.7%), rheumatoid arthritis (RA; 18.1% vs 2.3%), inflammatory polyarthropathy (IA; 17.6% vs 1.0%), and psoriasis (61.3% vs 1.9%).

Moreover, patients with PsA who did not have a prior psoriasis diagnosis were found to receive more diagnosis codes than controls for OA (52.5% vs 44.8%), RA (26.8% vs 12.6%), and IA (25.6% vs 12.5%).

Researchers noted that patients received a variety of diagnosis codes for their condition prior to the first PsA diagnosis code, suggesting potential misdiagnosis.

In the 6 years prior to PsA diagnosis, more than 10% of patients had coding for axial manifestations, nonspecific musculoskeletal manifestations, psoriasis, and/or skin manifestations. And when PsA was finally diagnosed, codes of nonspecific musculoskeletal manifestations, skin manifestations, axial manifestations, psoriasis, OA, and/or tendonitis/enthesitis were reported in more than 20% of patients.

“A sharp rise in psoriasis diagnoses was observed 6 months before PsA diagnosis,” added the study authors.

When evaluating types of providers in patients’ pathways to diagnosis, rheumatology consults were found to be more common in the final 6-month period immediately before the diagnosis of PsA (22.9 to 34.9%). Notably, diagnoses made prior to PsA diagnosis differed by the type of provider that patients saw:

• Dermatologists were less likely than other providers to enter codes for arthritis and musculoskeletal issues (<1%).
• Rheumatologists were unlikely to code for psoriasis (15.5%).
• General practitioners focused more on axial symptoms (18.5%) and nonspecific musculoskeletal manifestations (18.0%) than arthritis diagnoses.
• PsA was most commonly diagnosed by rheumatologists (39.8%), general practitioners (22.3%), and dermatologists (7.3%).

“The clinical and economic burden associated with PsA will most likely impact disease management and medical and pharmacy policy formulation,” concluded the study authors. “Increased awareness and understanding of diagnostic barriers may lead to timelier diagnosis, cost savings, and appropriate intervention to improve outcomes.”

Reference

Ogdie A, Rozycki M, Arndt T, Shi C, Kim N, Hur P. Longitudinal analysis of the patient pathways to diagnosis of psoriatic arthritis. Arthritis Res Ther. Published online October 1, 2021. doi:10.1186/s13075-021-02628-2