New Scoring System for Predicting Survival in Myotonic Dystrophy Type 1

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Simplified score points were attributed to each of the predictors of death, with the summation generating scores between 0 and 20.
Simplified score points were attributed to each of the predictors of death, with the summation generating scores between 0 and 20.

The myotonic dystrophy type 1 (DM1) prognostic score is reliable as a predictor of the probability of long-term (10-year) survival among patients with DM1, according to the results of a longitudinal French cohort study published in JAMA Neurology.

The current study, conducted between January 2000 and November 2014, enrolled a total of 1296 adult patients with genetically proven DM1. Of the total, 1066 were in the derivation cohort and 230 were in the validation cohort. Data derived from the study were analyzed from December 2016 to March 2017. The investigators sought to develop and validate a prognostic score that would predict long-term survival among patients with DM1. Overall, 51.7% (670 of 1296) of the participants were women; mean patient age was 39.8±13.7 years.

Among the 1066 patients in the derivation cohort, 22.6% (241 of 1066) died over a median follow-up of 11.7 years. Age, diabetes, need for support when walking, heart rate, systolic blood pressure, first-degree atrioventricular block, bundle-branch block, and vital lung capacity were all linked with death. Simplified score points were attributed to each of the predictors of death, with the summation of these points generating scores between 0 and 20, with 0 indicative of the lowest risk for death and 20 indicative of the highest risk for death.

When the score was applied, the 10-year survival rate was 96.6% (95% CI, 94.4-98.9) in the group with scores of 0 to 4 points; 92.2% (95% CI, 88.8-95.6) in the group with 5 to 7 points; 80.7% (95% CI, 75.4-86.1) in the group with 8 to 10 points; 57.9% (95% CI, 49.2066.6) in the group with 11 to 13 points; and 19.4% (95% CI, 8.6-30.1) in the group with 14 to 20 points.

In contrast, among the 230 participants in the validation cohort, the 10-year survival rate was 99.3% (95% CI, 95.0-100) in those with scores of 0 to 4 points; 80.6% (95% CI, 67.1-96.7) in the group with 5 to 7 points; 79.3% (95% CI, 66.2-95.1) in the group with 8 to 10 points; 43.2% (95% CI, 28.2-66.1) in the group with 11 to 13 points; and 21.6% (95% CI,10.0-46.8) in the group with 14 to 20 points.

The investigators concluded that the DM1 prognostic score is a reliable and practical tool for the prediction of long-term survival among patients with DM1, based on a set of key patient features.

Reference

Wahbi K, Porcher R, Laforêt P, et al. Development and validation of a new scoring system to predict survival in patients with myotonic dystrophy type 1 [published online February 5, 2018]. JAMA Neurol. doi:10.1001/jamaneurol.2017.4778

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