Table 4.
Relative risks of fracture between groups by fracture site and period
| Groups | Period before surgery (or index date) | Period after surgery (or index date) | |||
|---|---|---|---|---|---|
| Unadjusted RR (95% CI) | Adjusted RR* (95% CI) | Unadjusted RR (95% CI) | Adjusted RR* (95% CI) | ||
| Distal lower limb (knee, foot, ankle, and tibia/fibula) | |||||
| Bariatric group (n=12 676) | 2.15 (1.99 to 2.32) | 1.71 (1.57 to 1.85) | 1.47 (1.26 to 1.72) | 1.15 (0.98 to 1.35) | |
| Obese group (n=38 028) | 1.46 (1.38 to 1.55) | 1.43 (1.35 to 1.52) | 1.30 (1.18 to 1.44) | 1.21 (1.09 to 1.34) | |
| Non-obese group (n=126 760) | Reference | Reference | Reference | Reference | |
| P value† | <0.001 | <0.001 | <0.001 | 0.001 | |
| Clinical spine | |||||
| Bariatric group (n=12 676) | 1.33 (0.97 to 1.82) | 0.81 (0.58 to 1.13) | 2.14 (1.40 to 3.28) | 1.70 (1.06 to 2.73) | |
| Obese group (n=38 028) | 0.96 (0.77 to 1.20) | 0.88 (0.70 to 1.11) | 1.03 (0.70 to 1.52) | 1.00 (0.68 to 1.49) | |
| Non-obese group (n=126 760) | Reference | Reference | Reference | Reference | |
| P value† | 0.25 | 0.31 | 0.03 | 0.15 | |
| Pelvis, hip, and femur | |||||
| Bariatric group (n=12 676) | 1.76 (1.30 to 2.38) | 1.08 (0.78 to 1.49) | 3.12 (2.35 to 4.14) | 1.88 (1.37 to 2.58) | |
| Obese group (n=38 028) | 1.16 (0.94 to 1.44) | 1.05 (0.84 to 1.31) | 1.11 (0.84 to 1.47) | 0.90 (0.67 to 1.21) | |
| Non-obese group (n=126 760) | Reference | Reference | Reference | Reference | |
| P value† | 0.009 | 0.84 | <0.001 | 0.001 | |
| Upper limb (shoulder, humerus, elbow, forearm, and wrist) | |||||
| Bariatric group (n=12 676) | 1.11 (1.00 to 1.23) | 0.89 (0.80 to 1.00) | 2.03 (1.77 to 2.34) | 1.65 (1.42 to 1.91) | |
| Obese group (n=38 028) | 0.96 (0.90 to 1.03) | 0.93 (0.87 to 1.00) | 0.95 (0.84 to 1.08) | 0.90 (0.80 to 1.02) | |
| Non-obese group (n=126 760) | Reference | Reference | Reference | Reference | |
| P value† | 0.07 | 0.04 | <0.001 | <0.001 | |
RR=relative risk.
*Adjusted for duration of follow-up, material and social deprivation, area of residence, history of fracture (period after index date only), and number of comorbidities in previous five years, using multivariate conditional Poisson regression model.
†Type III P value for group variable.