Survival of patients with Duchenne muscular dystrophy

Abstract

Introduction: Duchenne muscular dystrophy (DMD) leads to a progressive deterioration of the mus cle function and premature death. There are no longitudinal studies on the course of this pathology in Chile.

Objective: To determine survival between the years 1993-2013, divided into two periods (1993-2002 and 2003-2013), and the effect of social determinants in patients with DMD admitted in Teleton Institutes of Chile (TI).

Patients and method: Prospective follow-up study in a clinical series of 462 patients with DMD. The information was obtained by searching for patients with DMD in OLAP cube (Online Analytical Processing). From the clinical records of the TI of Santiago, the variables corresponding to the diagnostic method, stage of DMD described in terms of muscle de terioration and function according to Swinyard classification were recorded; existence and type of tests that conclude the diagnosis and, in the cases reported, the existence of family history. Kaplan Meier survival analysis was applied, where global survival was defined between birth and age of death. The determinant factors analyzed were estimated through the Cox-Snell's proportional risk model.

Results: Survival at 20 years of age from TI entry was 51.7% (CI95%: 45.1-57.8), 48.5% in the period 1993-2002 and 72.8% between 2003-2013. The percentage of survival at the same age according to socioeconomic status (SES) was 82% in high SES, 67% in middle SES, and 42% in low SES, with a statistically significant difference between high and middle SES in relation to extreme poverty. Ac cording to country areas, the survival was close to 75 % at 17 years of age.

Conclusions: The survival information from patients with DMD from childhood to adult life is valuable for predicting the clinical course of the disease with the current medical care. There is evidence of improvement in the probability of survival at the age of 20 and marked inequity according to the socioeconomic variable.