Nagwa Abdallah Ismail XR-46, USA). Bone mineral density of the lumbar spine (L1-L4) and Lt femoral neck were performed at the Medical Services’ Centre, NRC. Absolute values were converted to Z-scores. Bone mineral density was expressed in g/cm2 [8]. Height-for-age Z-score (HAZ) and age were used to adjust the effect of short or tall stature on BMD Z-scores [4]. Statistical analysis Statistical Package for Social Sciences (SPSS) program version 12 was used for analysis of data. Data were described in terms of mean ± SD and percentage. Analysis of two quantitative indepen- dent variables was done by using a non-parametric test (Mann-Whitney U test) and χ2 test was used FEMZ SpinZ Figure 1. Relation between femoral and spinal BMD scores in a subgroup including 60 patients Table II. Characteristics of the patients and controls 1.0 0.5 0.0 –0.5 –1.0 –1.5 –2.0 –2.5 –3.0 –3.5 0 10 20 30 40 50 60 70 for qualitative variables. Spearman correlation was done. Value of p is considered significant if < 0.05. Results We studied 468 patients (266 female and 202 male) with different types of chronic diseases (Table I) whose mean age was 9.69 ±4.46 years, and 36 healthy controls (21 females and 15 males) whose mean age was 10.07 ±4.36 years. Characteristics of patients and controls are sum- marized in Table II. Duration of disease ranged from 1 to 12 years. Dual energy X-ray absorptiometry measurements demonstrate that BMD of the femoral neck and lumbar sites were significantly lower in chronic patients than in the control group (p = 0.005 and p = 0.001 respectively). Prevalence of very low BMD (–2 or less) using femoral neck DXA, lumbar DXA and either of the sites was 3.37%, 1.38%, and 3.95%, respectively, while low BMD (between –1 and –2) using femoral neck DXA, lumbar DXA, and either of the sites was 18.05%, 9.52%, and 22.02% respectively, as shown in Table III. Figure 1 shows the relation between femoral and spinal BMD scores in a subgroup including 60 patients. It also shows that femoral BMD could be reduced while spinal BMD is still within the normal range. Table IV shows the correlations between BMD and anthropometry in the studied group. Fracture rates as high as 13.3% have been reported in the juvenile rheumatoid arthritis (JRA) group. The frequency of low BMD (Z score < –1 SD) at the level of the femoral neck was significantly Femoral Z All cases Spinal Z All cases Both sites Spine alone Femoral alone affected No 17 91 396 504 (%) 3.37 18.05 78.57 100 No 7 48 449 504 (%) 1.38 9.52 89.08 100 No 4 31 323 358 (%) 0.79 6.15 64.08 71.03 Parameters Age Femoral neck BMD Spine BMD Item –2 or less Between –1 and –2 Above –1 Total 702 1 = case, 2 = control Case Control Case Control Case Control N 468 36 468 36 468 36 Mean 9.6980 10.0759 –0.4997 –0.2970 –0.2536 0.0814 Standard deviation 4.46 4.36 0.77 0.53 0.85 0.72 *value of p is statistically significant Table III. Percentage distribution of BMD Z scores in the studied group No 13 60 – 73 Standard error mean 0.22 0.49 0.03 0.06 0.04 0.08 (%) 2.57 11.90 0.0 14.48 Value of p 0.49 0.005* 0.001* No 3 18 52 73 (%) 0.59 3.97 10.31 14.48 Arch Med Sci 4, August / 2011