Obesity

Group A (BMI ≥ 25) (N = 440)

Group B (BMI < 25) (N = 161)

Age

64.90 ± 7.70

66.70 ± 8.78

Sex

224 F, 216 M

95 F, 66 M

BMI ± SD

(Range)

30.52 ± 4.66

(25.03–66.17)

22.52 ± 2.15

(14.35–24.97)

%BF ± SD

(Range)

38.51 ± 5.51

(18.88–57.41)

34.70 ± 5.61

(19.55–48.59)

BMI body mass index, %BF body fat percentage, SD standard deviation, F female, M male

Figure 1 and Table 2 show the regression analysis between BMI and BF%.

Fig. 1

Linear equations relating % BF to BMI in Groups A and B. BMI body mass index, % BF body fat percentage

Table 2

Linear equations relating body fat percentage and body mass index

Standardized coefficients beta	r ²	Adjusted r ²	SEE	p value
0.338	0.114	0.113	5,14054	<0.001

SEE standard error of the estimate

The 69 % (N = 303) of Group A and the 48 % (N = 78) of Group B had a rotator cuff tear (Table 3). Patients with RCT had a BMI value higher than subjects with no RCT in both groups (p = 0.031 in Group A; p = 0.02 in Group B).

Table 3

BMI and % BF of the two groups

	Group A (BMI ≥ 25) (N = 440)		Group B (BMI < 25) (N = 161)
	RCT (N = 303)	Control (N = 137)	RCTs (N = 78)	Control (N = 83)
BMI ± SD (Range)	31.18 ± 4.71 (25.16–48.55)	30.23 ± 4.62 (25.03–46.17)	22.23 ± 1.54 (18.02–24.97)	21.86 ± 2.42 (14.35–24.80)
BF% ± SD (Range)	37.64 ± 5.71 (19.55–57.41)	36.70 ± 5.63 (18.88–48.67)	38.09 ± 5.87 (22.60–55.57)	37.68 ± 6.19 (24.65–56.73)

BMI body mass index, %BF body fat percentage, SD standard deviation, RCT rotator cuff tear, N number

Chi-square test demonstrated significant relationship between BMI value and the presence of the RTC (chi-square = 21.17, p < 0.001). In particular, significance was achieved for subjects of Group A (odds ratio = 2.35; 95 % confidence interval = 1.63–3.40; p < 0.001).

Moreover, significance was achieved for both men (odds ratio = 2.10; 95 % confidence interval = 1.27–3.52; p = 0.0036) and women (odds ratio = 1.94; 95 % confidence interval = 1.18–3.18; p = 0.0082) with a BMI between 25.00 and 30.00 kg/m² as well as for both men (odds ratio = 2.49; 95 % confidence interval = 1.41–3.90; p = 0.0037) and women (odds ratio = 2.31; 95 % confidence interval = 1.38–3.62; p = 0.0071) with a BMI of ≥ 30.00 kg/m² (Fig. 2 and Table 4).