Surveillance of atypical femoral fractures in a nationwide fracture register

Abstract

Background and purpose — To continuously assess the incidence of atypical femoral fractures (AFFs) in the population is important, to allow the evaluation of the risks and benefits associated with osteoporosis treatment. Therefore, we investigated the possibility to use the Swedish Fracture Register (SFR) as a surveillance tool for AFFs in the population and to explore means of improvement. Patients and methods — All AFF registrations in the SFR from January 1, 2015 to December 31, 2018 were enrolled in the study. For these patients, radiographs were obtained and combined with radiographs from 176 patients with normal femoral fractures, to form the study cohort. All images were reviewed and classified into AFFs or normal femur fractures by 2 experts in the field (gold-standard classification) and 1 orthopedic resident educated on the specific radiographic features of AFF (educated-user classification). Furthermore, we estimated the incidence rate of AFFs in the population captured by the register through comparison with a previous cohort and calculated the positive predictive value (PPV) and, where possible, the inter-observer agreement (Cohen’s kappa) between the different classifications. Results — Of the 178 available patients with AFF in the SFR, 104 patients were classified as AFF using the goldstandard classification, and 89 using the educated-user classification. The PPV increased from 0.58 in the SFR classification to 0.93 in the educated-user classification. The interobserver agreement between the gold-standard classification and the educated-user classification was 0.81. Interpretation — With a positive predictive value of 0.58 the Swedish Fracture Register outperforms radiology reports and reports to the Swedish Medical Products Agency on adverse drug reactions as a diagnostic tool to identify atypical femoral fractures.

The role of the fracture liaison service in the prevention of atypical femoral fractures

“…AFF is a stress fracture involving the tensile side of the femur from the subtrochanteric to the supracondylar flare, with a mean incidence of 2.2 per 100,000 per year. 39 , 41 , 45 The diagnosis of AFF is based on the ASBMR criteria emended in 2014 (see Table 1 ). 39 It has been proposed that one of the underlying mechanisms of BPs-related AFF was the accumulation of microcracks in a bone ‘frozen’ by the long-term and highly compliant use of the drug.…”

Fusion of Electronic Health Records and Radiographic Images for a Multimodal Deep Learning Prediction Model of Atypical Femur Fractures

“…Much attention has been focused on these fractures because of the paradoxical causal relationship between the most commonly used drugs to treat osteoporosis (bisphosphonates) and a dramatically increased risk for AFF [10][11][12][13][14]. With a yearly incidence of 1.1-2.2 AFF per 100,000 inhabitants in Sweden [15], AFF comprise only about 4% of all fractures of the femoral shaft and less than 0.25% of all fractures of the femur. Since AFF are so rare, clinicians might overlook this fracture pattern among the abundance of other fractures [16,17].…”