Background/Purpose: To describe selected epidemiologic, demographic and outcome data in a cohort of Afro-Caribbean patients diagnosed clinically with dermatomyositis. To demonstrate clinical features of the disease typically seen in these patients

Methods: This is a retrospective, observational study of patients diagnosed clinically with dermatomyositis over a 24-year period from January 1998 to December 2021. Cases were ascertained from the neurology, rheumatology and dermatology clinic databases of our only public hospital and private neurology, rheumatology, and dermatology centers. The charts were reviewed and demographic, clinical and outcome data abstracted. Images of cutaneous lesions included. Detailed investigations such as electromyography, MRI of muscle, histologic data and myositis-specific antibodies were not accessible by most patients

Results: Between 1998 and 2021, 37 adults were diagnosed clinically with dermatomyositis. There were 31 females (84%) and 6 males, all of whom were of Afro-Caribbean origin with the median age being 47 years. Almost half of the patients could recall the month and year of symptom onset and in those cases the diagnostic latency was less than 3 months and less than 6 months in 56% and 78% respectively. The most frequently reported initial feature of the disease was a rash. The most common cutaneous features of the disease were abnormal nailfolds and Gottron’s papules with the least common being acquired ichthyosis and calcinosis. Proximal muscle weakness with creatine kinase elevation occurred in 68% of patients, the median value being 3066 iu/L- higher levels did not corelate with a worse outcome. Only 8% of patients with muscle weakness had severe involvement with dysphagia. 8/37 (21.6%) patients had interstitial lung disease which remained chronic and symptomatic in 3 patients. 5/37 (13.5%) patients had polyarthritis at time of diagnosis. Prednisolone was prescribed in all but 1 patient. The most common disease-modifying agent prescribed in patients without lung disease was Methotrexate (72% of patients). For those with lung disease Mycophenolate Mofetil was prescribed in 88% of cases. The outcome in 67.5% of patients was resolution off medication or quiescence on medication. The incidence of dermatomyositis almost tripled in the last 8 years compared with the first 8-year period.

Conclusion: Dermatomyositis in an Afro-Caribbean population demonstrated an increased incidence and was typically a disease of middle-aged women which started with a rash and evolved over a period of months to involve muscle weakness with CK elevation. A minority of patients had interstitial lung disease. At least two-thirds of patients had a good outcome. Management was not compromised by unavailability of detailed investigations to support the clinical diagnosis of the disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/lessons-learned-from-a-cohort-of-adult-afro-caribbean-patients-diagnosed-clinically-with-dermatomyositis/