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Dactylitis, a uniform swelling of an entire digit, occurs in up to half of patients with psoriatic arthritis and is sometimes the first manifestation of the condition.
Ultrasound (US) imaging verifies steroid injection for dactylitis is an effective treatment method, resolving extra-articular inflammation in soft tissue oedema (STO) and flexor tenosynovitis (FT), according to an article published in Springer.1
Dactylitis, a uniform swelling of an entire digit, occurs in up to half of patients with psoriatic arthritis (PsA) and is sometimes presented as the first manifestation of the condition.
“The most common first-line therapies for dactylitis are non-steroidal anti-inflammatory drugs (NSAIDs) and local corticosteroid injections,” investigators stated. “Even though infiltrative therapy is commonly used in everyday clinical practice, this therapeutic strategy is largely empirical since no formal studies on local corticosteroid injections in PsA dactylitis have been published.”
The multicenter, longitudinal, observational study enrolled PsA patients with symptomatic hand dactylitis at 3 Italian rheumatology centers. Active dactylitis was determined through a physical examination by a rheumatologist and confirmed using the dactylometer and related Leeds Dactylitis Index basic (LDI-b). Disease Activity for Psoriatic Arthritis (DAPSA) information was collected at baseline.
Infiltrative therapy was offered to all patients, and those who received the steroid injection were placed in the local treatment (LT) cohort. Those who opted out of local therapy received a 4-week treatment of NSAIDS instead and were placed in the systemic treatment (ST) cohort. If patients did not achieve clinical response at 1 month, the type of NSAIDs was changed. Baseline therapies of either conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or oral corticosteroids were continued through the duration of the study. Patients in the LT group received an injection of 20 mg methylprednisolone acetate (Depo-medrol, Pfizer, Italy).
US assessments, in both greyscale (GS) and power Doppler (PD), were performed at baseline (T0), month 1 (T1), and month 3 (T3). Sonographers evaluated the presence of FT, STO, peritendon extensor inflammation (PTI), and synovitis. Images of both affected and non-affected digits were collected.
US response was defined as DACTylitis glObal Sonographic (DACTOS) score of < 3 and remission was defined as a score of 0.
Patient-reported outcomes (PROs) included the visual analogue scale (VAS), the VAS pain (VAS-p), and the VAS functional impairment (VAS-FI) to evaluate dactylitis-affected digits.
All assessors were blinded to treatment information.
A total of 61 PsA patients presented 88 dacylitic fingers throughout the study. The mean age was 47.2 years, 36 patients were male, 25 were female, and all presented PsA minimal disease activity (DAPSA < 14). While no patient had more than one affected finger simultaneously, 15 participants had more than 1 episode. There were 31 patients, with 45 dactylitic fingers, in the LT cohort and 30 patients, with 43 dactylitic fingers, in the ST cohort.
VAS-FI was significantly different between the 2 groups at baseline FI (LT 7.8 ± 1.6 vs. ST 6.6 ± 2.3, p = 0.010). While there were no significant differences for US lesions between the groups, a significant difference was reported at T1 regarding GS FT (p = 0.002), PD FT (p < 0.001), GS STO (p < 0.001), and PD STO (p < 0.001), which continued through T3. At the T3 follow up, some grade 3 lesions were completely cleared in the LT group, while only reduced in the ST group.
The ST cohort had significantly higher rates of GS FT, PD FT, GS STO, PD STO, and metacarpophalangeal (MCP) synovitis (p = 0.001) at T3.
The LT cohort had significantly greater US response at both T1 (50% vs 7%, p < 0.001) and T3 (76% vs 7% p <0.001) when compared with the ST cohort, and remission only occurred in LT patients (31% vs 0%, p < 0.001).
DACTOS < 3 was higher in the LT group when compared with the ST group at both T1 (49% v 5%, p < 0.001) and T3 (76% vs 7%, p < 0.001). VAS-p and VAS-FI were significantly higher for those with DACTOS < 3 when compared with those with DACTOS ≥ 3 at T3 follow-up (1.49 ± 1.72 vs 4.37 ± 2.69, p = 0.001, for VAS-p and 1.43 ± 1.46 vs 4.98 ± 2.81, p < 0.001, for VAS-FI).
Clinical remission was only achieved in the LT cohort with 3 cases at T1 and 10 cases at T3.
Multiple logistic regression analysis reported that treatment with local injection was the only variable impacting US remission (odds ratio T1 13.33 [95% CI 3.52–49.60, p < 0.001], odds ratio T3 41.21 [95% CI 10.62–159.92, p < 0.001]).
The study was limited by the lack of randomization; however, it does reflect common clinical practice. Further, investigators did not utilize a placebo arm. This limitation is mitigated by having US assessors blind to treatment. While the follow-up period was short, > 3 months is an adequate amount of time to make changes to oral therapies. A larger number of cases would help validate results.
“To the best of our knowledge, this is the first study that provides evidence of the value of US in the detection of changes induced by local steroid injection in the flexor tendon sheaths of patients with acute dactylitis. Such changes can be clearly seen even after a short-term follow-up and maintained for at least 3 months with good correlation with the clinical evolution of the dactylitis,” investigators concluded. “US examination of dactylitic fingers may be considered a useful adjunctive tool for assessing articular and extra-articular changes after steroid injection in the flexor tendon sheath of patients with acute dactylitis.”
Girolimetto N, Macchioni P, Tinazzi I, et al. Ultrasound Effectiveness of Steroid Injection for hand Psoriatic Dactylitis: Results from a Longitudinal Observational Study [published online ahead of print, 2021 Oct 15]. Rheumatol Ther. 2021;10.1007/s40744-021-00383-z. doi:10.1007/s40744-021-00383-z