Assessment of site-specific X-ray procedure codes for fracture ascertainment: a registry-based cohort study.

Site-specific X-ray procedure codes are a useful ancillary source of information for identifying fractures in healthcare administrative and claims data. Real-world evaluation of fracture epidemiology at the population level from electronic healthcare information, such as administrative data, requires comprehensive data sources and validated case definitions. Only hip fractures are routinely hospitalized, and the identification of most osteoporosis-related fractures which are non-hospitalized fractures remains challenging. Plain X-rays (radiographs) are first-line tests for fracture diagnosis and are frequently repeated to monitor fracture healing, and claims data related to radiologic procedures are available in many healthcare systems. We hypothesized that temporal clustering in plain X-ray procedure codes might be an ancillary source of fracture data. We identified individuals age 40 years and older in Manitoba Bone Mineral Density (BMD) Registry with a fracture diagnosis (hip, forearm, humerus, clinical vertebral) before or following a BMD test. A subset underwent detailed review of X-rays to verify an acute fracture. We examined the association between fracture diagnosis and numbers of site-specific X-ray procedures. The registry cohort included 7793 individuals with a fracture in the previous 5 years and 8417 incident fractures. The X-ray review cohort included 167 radiologically-verified fractures. The number of site-specific X-ray codes was greater in those with vs without fracture (all P < 0.001). The number of days with site-specific X-rays was strongly associated with a fracture diagnosis (area under the curve 0.90 to 0.99 for all non-vertebral fractures, 0.66 to 0.75 for clinical vertebral fractures). There was good agreement between the date of fracture diagnosis and the first X-ray at all non-vertebral fracture sites (Spearman correlation range 0.65 to 0.99), but this was lower for clinical vertebral fractures (range 0.29 to 0.59). Temporal clustering in site-specific X-ray procedures was associated with a corresponding fracture diagnosis in administrative medical records. Non-vertebral fracture sites were more strongly associated with X-ray procedures than clinical vertebral fractures.