Demora para diagnóstico da distrofia muscular de Duchenne: estudo epidemiológico

USA - aqui no Brasil há uma demora para se diagnosticar as distrofias musculares. Nos países mais avançados o problema se repete. Neste estudo epidemiológico os autores constataram que o diagnóstico de Duchenne é feito em média 2,5 anos após o início dos sintomas. Este tempo é precioso para que medidas possam ser utilizadas como a fisioterapia e os corticóides. Em um editorial publicado na revista se discute o problema ressaltando a necessidade de treinamento dos pediatras e médicos generalistas para o diagnóstico da doença e a possibilidade de realização de triagem precoce com a dosagem da enzima CPK que é um procedimento simples e barato.

O resumo da pesquisa e a íntegra do editorial, em inglês, podem ser lidos abaixo:

(J Pediatr 2009;155:380-5) Delayed Diagnosis in Duchenne Muscular Dystrophy: Data from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet)

Emma Ciafaloni, Deborah J. Fox, Shree Pandya, Christina P. Westfield, RN, Soman Puzhankara, Paul A. Romitti, Katherine D. Mathews, Timothy M. Miller, Dennis J. Matthews, Lisa A. Miller, Christopher Cunniff, Charlotte M. Druschel, and Richard T. Moxley - USA

Objective: To identify key factors for the delay in diagnosis of Duchennemuscular dystrophy (DMD) without known family history.
Study design: The cohort comes from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet), a multistate, multiple-source, population-based surveillance system that identifies and gathers in- formation on all cases of Duchenne and Becker muscular dystrophy born since 1982.We analyzed medical records of 453 Duchenne and Becker muscular dystrophy boys to document the time course and steps taken to reach a de- finitive diagnosis.
Results: Among 156 boys without known family history of DMD prior to birth, first signs or symptoms were noted at a mean age of 2.5 years. Concerns resulted in primary care provider evaluation of the child at a mean age of 3.6 years. Mean age at time of initial creatine kinase was 4.7 years. Mean age at definitive diagnosis of DMD was 4.9 years.
Conclusions: There is a delay of about 2.5 years between onset of DMD symptoms and the time of definitive diagnosis, unchanged over the previous 2 decades. This delay results in lost opportunities for timely genetic counseling and initiation of corticosteroid treatment. We recommend checking creatine kinase early in the evaluation of boys with unexplained developmental delay.

EDITORIAL: Missed Opportunities for Duchenne Muscular Dystrophy

Petra Kaufmann, MD, MSc, Columbia University, Department

Duchenne Muscular Dystrophy (DMD) continues to challenge affected boys and their families because it causes progressive weakness in children who were seemingly normal as infants and toddlers. The discovery of mutations in the dystrophin gene more than 2 decades ago1 raised hopes for improved diagnosis and treatment, some of which have been ful-filled. For almost all patients, the diagnosis can be confirmed by genetic testing, largely obviating the need for muscle biopsy. The survival rate has shown significant improvement, with now more than half of the patients surviving past age 25 years,2 largely as a result of proactive pulmonary and cardiac management. There is clear evidence for prednisone delaying the loss of motor function3 and reducing mortality rates.4 Animal models are available,5 and clinical trials are underway.6 Despite these advances, there has been no significant change over the past 20 years in the time from symptomonset to diagnosis. Ciafaloni et al7 report that 2.5 years go by on average until patients without known family history are given a definite diagnosis. It is not only surprising that it takes 2.5 years until adefinite diagnosis is reached, but it is even more surprising that the interval has not decreased over the past 2 decades. The report by Ciafaloni et al7 suggests that there is room for improvement in appropriate training and ongoingmedical education that would allow practitioners to make the diagnosis in a timelier manner. The initial screen, a blood test for creatine kinase, is widely available and inexpensive. In the past, one might have argued that little is gained by making an earlier diagnosis of an ‘‘incurable’’ disease. Today, effective treatments are available that can temporarily preserve motor function and prolong survival. There is therefore newfound urgency in making a correct diagnosis that will become more pressing as novel treatments enter clinical trials. It is reasonable that practitioners do not include screening for a relatively rare and serious diagnosis such as DMD in the very first work-up for developmental delay in young boys when there is no calf hypertrophy, toe-walking or weakness. However, persistent delay should prompt screening earlier in the work-up so that a diagnosis can be made in less than 2.5 years from symptom onset. The report by Ciafaloni et al7 suggests that neurologists are more likely to order a creatine kinase test than primary care clinicians. Therefore educational initiatives aimed at primary care clinicians are a first approach to shorten the time to a correct diagnosis. Ciafaloni et al7 also report that about 15 additional affected maternal relatives were born in the interval from symptom onset to a definite diagnosis. These families did not have the genetic counseling opportunities thatwould have permitted an informed decision. It is imperative that we improve translating scientific advances into medical practice for boys with DMD and their families by educating medical students, pediatricians, and other primary care practitioners that DMD is a readily diagnosable and treatable condition. Although thought of as a muscle disease, a dystrophinopathy often affects language development early on in the course. Therefore checking for subtle signs of muscle weakness or calf hypertrophy and sending off a blood test for creatine kinase should be considered early on in the evaluation of any boy with not only motor, but also language delay. This simple message should be clearly incorporated in medical training and practice guidelines. Most experts support the implementation of newborn screening. However, until newborn screening is universally implemented, families depend on well-trained clinicians to afford them early access to a correct diagnosis and thus genetics counseling and treatment.

Fonte: http://distrofiamuscular.net/noticias.htm