Pathologic fractures: should these be included in epidemiologic studies of osteoporotic fractures?

Pathologic fractures are often excluded in epidemiologic studies of osteoporosis. Using Medicare administrative data, we identified persons with vertebral and hip fractures. Among these, 48% (vertebral) and 3% (hip) of the fractures were coded as pathologic. Only 25% and 66% of persons with these pathologic fractures had evidence for malignancy. Analyses of osteoporosis-related fractures that use administrative data often exclude pathologic fractures (ICD-9 733.1x) due to concern that these are caused by cancer. We examined pathologic fractures of the vertebrae and hip to evaluate their contribution to fracture incidence and assessed the evidence for a malignancy. We studied US Medicare beneficiaries age a parts per thousand yen65 with new fractures identified using ICD-9 diagnosis codes 733.13 (pathologic vert), 805.0, 805.2, 805.4, 805.8 (nonpathologic vert); and 733.14 (pathologic hip), 820.0, 820.2, 820.8 (nonpathologic hip). We further examined the proportion of cases with a diagnosis of a malignancy proximate to the fracture. We identified 44,120 individuals with a vertebral fracture and 60,354 with a hip fracture. Approximately 48% of vertebral fractures and 3% of hip fractures were coded as pathologic. For only approximately 25% of persons with a pathologic vertebral fracture ICD-9 code, but 66% of persons with a pathologic hip fracture, there was evidence of a possible cancer diagnosis. Among US Medicare beneficiaries, one fourth of pathologic vertebral fracture and two thirds of pathologic hip fracture cases had evidence for a malignancy. Particularly for vertebral fractures, excluding persons with pathologic fractures in epidemiologic analyses that utilize administrative claims data substantially underestimates the burden of fractures due to osteoporosis.