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#apaperaday: Respiratory comorbidities and treatments in Duchenne muscular dystrophy: impact on life expectancy and causes of death

In today’s #apaperaday, Prof. Aartsma-Rus reads and comments on the paper titled: Respiratory comorbidities and treatments in Duchenne muscular dystrophy: impact on life expectancy and causes of death

Today’s pick is a confetti favorite for Yuzu, from Journal of Neurology by Wahlgren et al on respiratory comorbidities in Duchenne patients and their impact on life expectancy in a historical cohort of patients in Sweden. DOI: 10.1007/s00415-024-12372-7

Duchenne muscular dystrophy affects skeletal muscle and heart (and brain and smooth muscle). Most patients die due to heart or respiratory failure. The latter is due to weakness of respiratory muscles and less ability to cough and clear airways.

Introduction of respiratory care has increased life expectancy from teens to thirties. Care includes monitoring of function and intervention with assisted ventilation and cough assist. Scoliosis surgery is needed less with the introduction of steroids, but sometimes still needed.

Here authors studied the impact of respiratory problems and comorbidities on death in a cohort of Swedish Duchenne patients born between 1970 and 2019. 129 patients who died were identified, 35% had a genetic diagnosis. Average age of death was 24.3 years (19-29 years).

Cardiac problems were the leading cause of death (42%) followed by respiratory failure (38%). Of the latter, 63% had acute respiratory failure. Age of death was the same for those dying from respiratory problems and other causes.

70% of patients had at least 1 episode of pneumonia and 60% had 2 or more episodes. There was a strong correlation between age of 1st pneumonia and age of hypoventilation and a moderate correlation between age of hypoventilation and loss of ambulation.

60% used steroids and 47% of those stopped before they died. Of the patients with scoliosis, 71% had surgery. 18% of patients had a tracheostomy, 2/3 after an acute respiratory event. Having severe scoliosis and NOT a surgery was associated with an increased risk of death.

Assisted ventilation increased the age of death from 18 to 26 in this cohort and a tracheostomy increased it to 30. Authors discuss that poor airway clearance means upper respiratory tract infections can become pneumonias. Later, also the lungs are colonized by many pathogens.

Authors discuss that they did not take dysphagia into account – poor swallowing (due to weakness of swallowing muscles) can also result in respiratory tract infections. Authors discuss that their cohort is relatively large and unique given good administration in Sweden.

However, like all retrospective studies it does suffer from missing data and the fact that those born most recently (fortunately) have not yet died, so the impact of recently improved care is not yet reflected in this cohort as it only includes patients who died.

Authors do not discuss that a genetic diagnosis was present in only 35% of patients. This means that some of the patients studied may not have been Duchenne, but instead e.g. Limb Girdle patients. This is more rare, so likely not a major component, but still something to discuss.

Nevertheless all in all it is a good study and it brings home that many complications patients face – this is just one example from one discipline. However it also highlights the impact of good care on life expectancy.