PURPOSE: We previously described an unexpectedly high incidence of nephrolithiasis among patients (pts) with Duchenne muscular dystrophy (DMD) who achieved prolonged survival through use of noninvasive ventilation (NIV). This study assesses whether DMD was an independent risk factor for nephrolithiasis.
METHODS: Retrospective chart review of DMD pts over 20 years old who achieved prolonged survival through NIV. These pts were compared to a randomly selected control group of immobile pts with spinal cord injury (SCI) or cerebral palsy (CP), of similar age and duration of immobility. All DMD pts were males; controls were matched for race and gender. Nephrolithiasis was diagnosed by persistent gross hematuria and flank pain, with radiographs in 6 of 7 cases. Pts taking medications causing nephrolithiasis (e.g., steroids) were excluded. Incidence of nephrolithiasis in the groups was compared by stratified analysis (SAS software). Exact rate ratio estimate was made comparing rate of stone acquisition per 10,000 patient-years of immobilization in DMD and controls. Study was IRB approved.
RESULTS: 29 pts were in the DMD group and 68 in control group (44 pts with SCI, 24 with CP). Mean age of DMD pts: 25.93 ± 4.86 yrs; mean age of controls: 32.36 ± 7.64 yrs. Mean duration of immobility for DMD pts: 14.06 ± 5.18 yrs; for controls: 18.50 ± 5.00 yrs. Six of the 29 DMD pts had nephrolithiasis (20.7 %). One of the 68 controls had nephrolithiasis (1.5 %). Controlling for duration of immobilization with stratified analysis, risk ratio for stones among DMD pts compared with controls was 9.94 (95% CI: 1.41-70.23). Using rate-based estimates of renal stone acquisition per 10,000 patient-years, ratio of renal stone acquisition among DMD pts compared with controls was 18.5 (95% CI: 2.23-153.6).
CONCLUSION: DMD was an independent risk factor for nephrolithiasis among pts achieving prolonged survival with NIV.
CLINICAL IMPLICATIONS: Pts with DMD who experience prolonged survival may have a high risk of nephrolithiasis, with implications for prognosis, medical management, burden of disease, burden of care, and quality of life.
DISCLOSURE: Yana Shumyatcher, No Financial Disclosure Information; No Product/Research Disclosure Information