Osteoporotic Fractures and Subsequent Fractures: Imminent Fracture Risk from an Analysis of German Real-World Data

Introduction:

Objectives were to analyze the incidence of subsequent fractures within one year after a first osteoporotic fracture at vertebra, forearm or femur using German claims data.

Methods:

Patients of age ≥50 years with a first osteoporotic fracture (index) between Jan 1st, 2010, and Dec 31st, 2014 and a diagnosis of osteoporosis or first osteoporosis medication were included in the analysis. Main outcome variable was the incidence of subsequent fractures during a follow-up time of four quarters. Odds ratios (OR), confidence intervals (CI) and p-values are reported vs. incidence after femoral index fracture, calculated using a chi-squared test, without adjustment to age.

Results:

18,354 patients with an average age of 77.53 years (female: 77.98; male: 73.40) experienced an index fracture, of which 16,293 were at vertebra, forearm or femur (female: 7,968 vertebral, 4,191 forearm and 2,476 femoral fractures; male: 1,165 vertebral, 264 forearm and 229 femoral fractures). In female patients, the incidence of any subsequent fracture (vertebral, forearm or femoral) was significantly higher within one year after a vertebral (18.9% [p < 0.001]) or forearm (14.2% [p = 0.007]) compared to a femoral (11.8%) index fracture. For male patients, the subsequent fracture incidence was 15.7% after vertebral, 9.5% after forearm and 10.9% after femoral index fractures. Subsequent vertebral fractures occurred significantly more frequently after vertebral than femoral index fractures (female: 13.6% vs. 6.7% [p < 0.001]; male: 12.4% vs. 7.4% [p = 0.03]), and least frequently following forearm fractures (female: 5%, male: 3.8%). The highest risk of a subsequent forearm fracture was seen in female patients with forearm index fractures, with an incidence of 7.2% [p < 0.001] compared to 2.6% after vertebral and 2.5% after femoral index fractures. The incidence of subsequent forearm fractures in male patients was 3.8% after forearm, 1.1% after vertebral, and 2.2% after femoral index fractures. The risk for a subsequent fracture at femur was 2.8%, 2.0% and 2.6% for female and 2.1%, 1.9% and 1.3% for male patients after a vertebral, forearm and femoral index fracture, respectively.

Discussion:

Limitations to be mentioned here are that the number of forearm index fractures might be underestimated, because these fractures compared to vertebral or femoral fractures are often not identified as osteoporotic fractures with a following osteoporosis diagnosis or medication. Besides, adjustment for age will modify the magnitude of imminent risk but likely will have a limited impact on the ranking of the frequency of subsequent fracture across different fracture types. In conclusion, our results indicate a high imminent risk for a subsequent fracture within one year after a first fracture among German osteoporosis patients, showing that up to one-fifth experienced a subsequent fracture.

Fig. 1