The validity of self-reported fractures among Danish female nurses: comparison with fractures registered in the Danish National Hospital Register

Background: The authors compared self-reported non-spine fractures obtained from a cohort of Danish female nurses with fracture diagnoses registered in the Danish National Hospital Register (DNHR). Method: The self-reported fracture history was obtained from a questionnaire and was related to fracture information registered with the DNHR by means of the unique person identification code of Danish citizens. A total of 166 self-reported hip fractures, 391 self-reported wrist fractures, and 121 self-reported upper arm fractures were available for the comparison. The self-reported fractures were initially compared with the anatomic specific fracture diagnoses registered in the DNHR. Second, the comparison also included fracture diagnoses of adjacent skeletal sites (unspecific fracture diagnoses). Results: The positive predictive value of a positive report of hip fracture was 89%. Inclusion of unspecific registered hip fractures increased the positive predictive value to 94%. The same figures for wrist fractures were 75% and 84%, respectively, and for upper arm fractures 54% and 83%, respectively. The predictive value of a negative report of hip fracture was 99.5%. The fracture year was correctly reported in 76% of the hip fracture cases, 81% of the wrist fracture cases, and 82% of the upper arm fracture cases. . Predictors of false-positive report of fractures were young age (