Comparison of survival analysis between surgical and non-surgical treatments in Duchenne muscular dystrophy scoliosis

Abstract

Background context: There are still controversies about the effects of spinal surgeries for Duchenne muscular dystrophy (DMD) scoliosis on functional outcome, respiratory function, and the survival rate.

Purpose: The purpose of this retrospective investigation was to compare the clinical course over time between the patients who were treated surgically and those who were treated nonsurgically. Through this comparison, we tried to determine how surgical treatment could affect the functional status, pulmonary function, and survival rate in patients with DMD scoliosis.

Study design/setting: Single-center retrospective cohort study.

Patient sample: We reviewed the clinical data of 199 male patients with DMD scoliosis who were followed up at our center for an average of 6.4 years between 2003 and 2017.

Outcome measures: The basic radiologic parameters evaluated include the Cobb angle and pelvic obliquity on a whole spine X-ray. Further, the Swinyard scale for functional status, forced vital capacity (FVC) for respiratory function, and mortality were compared between the surgical group and nonsurgical group.

Methods: The radiologic parameters and Swinyard scale stage were compared between the surgical group and nonsurgical group at baseline and 2, 5, and 10 years. For the FVC, serial changes every year were investigated in both groups. Mortality was surveyed between the surgical group and nonsurgical group.

Results: Of the 199 patients, 99 patients underwent the instrumented spinal fusion surgery and 100 patients in the nonsurgical group opted for conservative management. Radiologic results of the two groups were not different at baseline, but during the follow-up periods, the surgical group demonstrated better Cobb angles and pelvic obliquities. The surgical group showed a better functional status than did the nonsurgical group (6.7±0.9 versus [vs.] 7.2±0.7, p<.001). These functional differences between the groups were continuously observed during the follow-up period. Similarly, the FVC at baseline was higher in the surgical group than in the nonsurgical group (1005.7±421.4 mL vs. 787.3±574.1 mL, p=.005). Although FVC in the nonsurgical group consistently decreased during the follow-up (4.8% decrease/year), FVC in the surgical group increased up to the 2-year follow-up period compared with the baseline value and decreased during the follow-up period (2.8% decrease/year). Mortality was higher in the nonsurgical group than in the surgical group (n=22/100, 22.0% vs. n=8/99, 8.1%; p<.001) during an average follow-up duration of 6.4 years. Mean survival was longer in the surgical group than in the nonsurgical group (12.2 years vs. 8.3 years, hazard ratio=2.43, p=.02).

Conclusions: Spinal surgery for DMD scoliosis improved the FVC for approximately 2 years postoperatively compared to non-surgical treatment. The surgical group had a better functional status and FVC at baseline than the non-surgical group. The positive effect of surgical treatment on the FVC is owing to scoliosis correction, which delayed the decrease of FVC and consequently extended the survival rate of the patients with DMD scoliosis.