AJTCCM VOL. 30 NO. 3 2024 85
EDITORIAL
e idiopathic inammatory myopathies (IIMs) are a group of rare,
chronic, autoimmune diseases characterised by inammation and
progressive weakness of the skeletal muscles. e primary forms
of IIM are dermatomyositis (DM), polymyositis, inclusion body
myositis, the antisynthetase syndrome, overlap syndromes, and
clinically amyopathic dermatomyositis.[1] e IIMs are of relevance
to the pulmonologist because of their frequent association with
pulmonary complications, in particular interstitial lung disease
(ILD), which contributes signicantly to the morbidity and mortality
of aected individuals.
In this issue of AJTCCM, Hes etal.[2] retrospectively describe the
spectrum and prevalence of these pulmonary manifestations in a local
patient population, oering crucial insights in a region-specic context.
ey studied a cohort of 77 patients diagnosed with IIM, all presenting
with respiratory complaints at a tertiary care facility in Johannesburg.
Most patients (almost two-thirds) had DM. Pulmonary complications
were documented in 85% of patients, with a higher incidence in the
DM subgroup compared with other IIMs. As expected, ILD was
the most prevalent pulmonary complication,[3] present in ~70% of
patients, with nonspecic interstitial pneumonitis (NSIP) being the
predominant pattern of ILD, present in just over one-third of patients.
is nding is consistent with the global understanding of ILD in
IIM, where NSIP is frequently observed.[4] Infection and pulmonary
hypertension also contributed to the burden of disease. Relevant to
the South African (SA) context is that ~10% of patients presented with
pulmonary tuberculosis (TB) as an immunosuppression-associated
infection, underscoring the importance of vigilant screening and
management of TB in this population. In addition to ILD, alveolar
hypoventilation secondary to diaphragmatic and chest wall muscle
weakness is another cause of respiratory insuciency in IIMs, but this
complication was not reported by Hes etal.[2]
A few points are worthy of note. Firstly, the study conrmed the
importance of clinical assessment of patients with IIMs, with dyspnoea
and cough, and the presence of bibasal crackles on auscultation,
independently associated with physiological restriction and reduced
diffusing capacity. Other clinical features associated with poor
outcome in ILD in IIMs reported in the literature include progressive
pulmonary restriction aer 3 months, heliotrope erythema, delay in
diagnosis, and Raynaud’s phenomenon.[5] Secondly, the authors found
that in approximately one-h of patients, respiratory symptoms
predated the onset of clinical myopathy, in contrast to studies from
other settings that suggest that they occur contemporaneously.[6]
irdly, the authors replicated the strong association between anti-
Jo1 antibody (histidyl-tRNA synthetase)-positive status and elevated
acute inammatory markers and muscle enzymes, indicating a more
aggressive disease phenotype.[7] The presence of this serological
marker underscores the need for tailored therapeutic strategies to
mitigate the inammatory cascade and preserve pulmonary function
in these patients. And lastly, the study emphasises the increased
susceptibility of patients on chronic immunosuppressive drugs to
TB, where SA presents a particularly high-risk environment. No data
are given on the prescription of TB prophylaxis in this cohort, but
the rationale for its use may be extrapolated from other studies of
vulnerable populations, such as patients on chronic haemodialysis or
the recipients of solid organ transplants, where it may mitigate the risk
of latent TB reactivation and new TB infections.[8-10]
In conclusion, and notwithstanding the limitations of the retrospective
design, this study provides important insights into the pulmonary
complications in SA patients with IIM. e high prevalence of ILD,
coupled with signicant rates of pulmonary infections and pulmonary
hypertension, underscores the multifaceted nature of pulmonary
involvement in IIM. e ndings advocate for heightened awareness,
early diagnostic evaluations, and prompt therapeutic interventions to
mitigate the pulmonary morbidity in this patient population. Aswe
deepen our understanding of the regional manifestations of IIM,
tailored strategies can be developed to improve patient outcomes and
quality of life.
Gregory L Calligaro, BSc Hons, MB ChB, Dip PEC (SA), MMed
(Med), FCP (SA), Cert Pulmonology (SA) Phys
Centre for Lung Infection and Immunity, Division of Pulmonology, Department
of Medicine, Groote Schuur Hospital and UCT Lung Institute, University of
Cape Town, South Africa
greg.calligaro@uct.ac.za
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Chest Med 2019;40(3):561-572. https://doi.org/10.1016/j.ccm.2019.05.004
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https://doi.org/10.1086/599035
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Afr J Thoracic Crit Care Med 2024;30(3):e2682. https://doi.
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Unveiling the pulmonary burden of idiopathic inammatory
myopathies in South Africa
