[A longitudinal cause-of-death analysis of patients with Duchenne muscular dystrophy]

Mechanical ventilation (MV) and cardiac protective therapy have improved the prognosis and quality of life of patients with Duchenne muscular dystrophy (DMD). To understand how these therapies have changed prognosis, we performed a cause-of-death analysis in DMD patients. Mean age at death before initiation of MV (January 1977-July 1984) was 18.9±4.1 years. After the introduction of MV, from August 1984 to December 1993 (1(st) term), it was 20.0±4.5 years, from January 1994 to December 2003 (2(nd) term), it was 25.2±4.6 years, and from January 2004 to December 2010 (3(rd) term), it was 31.1±5.4 years. Almost half of all deaths before MV were due to respiratory failure (RF). Because MV was performed by a tracheostomy in the initial stage, some patients were reluctant to use it, and as a result, RF accounted for 43% of deaths in the 1(st) term. Over time, patients started to accept non-invasive ventilation and home mechanical ventilation, which became available in the 1990s. Consequently, no DMD patients have died from RF since 2000. Respiratory physiotherapy and risk management became important tools, because many patients undergo decades of respiratory managements at home. Cardiac treatments for patients with DMD consisted mainly of diuretics and digitalis in the 1(st) term, angiotensin-converting enzyme inhibitors (ACEI) in the 2(nd) term, and a combination of ACEIs and beta blockers in the 3(rd) term. Compared to the 2(nd) term, the ratios of severe cardiac dysfunction (fractional shortening <10%, left ventricle diastolic dimension >75mm, plasma brain natriuretic peptide >1,000pg/ml) were reduced in the 3(rd) term. In the 3(rd) term, 14% of patients died from renal failure nevertheless their cardiac indices remained mildly abnormal or normal. We should pay enough attention for cardio-renal association.