The average age in the HSP group was 13.5 ± 3.9 years (range 7–19.7 years) and was similar to the control group 12.8 ± 4.5 years (range 6–23 years) (p = 0.4), there were 11/19 male (57%) in the HSP group and 16/23 (69%) male in the control group (P = 0.35). BMI was similar in both groups, 22 ± 6.1 in the HSP group and 18.8 ± 3.8 in the control group p = 0.13.