Twenty-five reports of 23 studies were included (n=868); 2 studies were extensions of other studies. There were 7 double-blind RCTs evaluating prednisone/prednisolone (n=276; sample size ranged from 14 to 103), 2 double-blind RCTs evaluating deflazacort (n=56), 11 open trials or case reports of prednisone (n=278; sample size ranged from 1 to 103), 3 double-blind RCTs comparing prednisone and deflazacort (n=172), and 2 retrospective reports comparing deflazacort and no treatment (reported as historical controls) (n=86).
Seven RCTs demonstrated beneficial effects of prednisone, with 0.75 mg/kg per day being the optimal dose for boys aged 5 to 15 years. The results from the 11 open trials and case reports were consistent with the RCT results.
Muscle strength and function: 4 RCTs reported improvements in muscle strength (average muscle score over 34 muscle groups, or kg weights lifted) with prednisone treatment, with maximum benefits observed after 3 months. The increase in muscle strength was significantly greater with 0.75 mg/kg per day compared with 0.03 mg/kg per day in 2 studies. One of these studies also reported on muscle function and found that the time to climb four stairs, travel 9 metres, or arise from supine to standing significantly improved at 6 months (p<0.005) in boys taking prednisolone (0.75 or 1.5 mg/kg per day) compared with placebo. However, an extension to one of these studies also reported that alternate day prednisolone (1.25 or 2.5 mg/kg) was associated with a decline in previous gains observed for strength and muscle function from daily prednisolone 0.75 or 1.5 mg/kg. The other RCT of alternate day prednisolone (5.0 mg/kg) found less deterioration in ambulation at 36 months compared with placebo (6 out of 7 on corticosteroids continued walking versus 7 out of 7 on placebo who stopped walking).
Other outcomes: one RCT reported that 24-hour urinary creatinine excretion was significantly increased after 6 months in boys taking prednisolone (0.75 or 1.5 mg/kg per day), consistent with an increase in muscle mass, but was significantly decreased in boys taking placebo. One RCT reported that FVC was significantly higher at 6 months in boys taking 0.75 mg/kg per day and also 1.5 mg/kg per day prednisolone compared with placebo.
Side effects: the most common side-effect was weight gain. After 6 and 18 months, the percentage of boys whose weight increased was greater for boys taking 0.3 to 1.5 mg/kg prednisolone than for those given a placebo. Other side-effects included increased appetite, irritability, hirsuitism and cushingoid appearance; the latter two were more common with prednisolone 0.75 mg/kg per day.
Two RCTs reported that 1.0 mg/kg per day of deflazacort for 9 months and alternate day treatment with 2.9 mg/kg for 2 years increased muscle strength and function compared with placebo. Three RCTs, which were considered to be of lower quality, compared deflazacort with prednisolone and reported similar effects for both regimens for slowing progression and improving strength and muscle function.
Side-effects: the side-effects were similar to those with prednisolone and were mainly weight gain and the development of cushingoid features. They were more frequent in longer term studies: 2 retrospective studies of 3 to 5 years' duration assessing 0.9 mg/kg per day deflazacort reported cataracts, obesity or weight gain, and short stature.