Several studies evaluated hip fracture incidences and its predictors and trends using hospital discharge registries. However, this source does not provide patient-related data, therefore the hospital changes or re-hospitalisations cannot be identified as "double counting". If double counting differs with age, sex, region, and time, the estimates may be biased. Aim of our study was to evaluate the magnitude of multiple counting and, in particular, its variation with age, sex, region, and calendar year. We used data of a German-wide health insurance (1.6 million members). Between 1998 and 2009, we assessed all hip fractures (ICD 9: 820, ICD 10: S.72.0-2) in individuals aged 50 years or older and calculated the probability to be a patient's "first" fracture in each calendar year. Using multiple logistic regressions, we estimated the influence of age, sex, region, and calendar year. The probabilities of a "first fracture" per patient and year varied between 86.7 % (95 % confidence interval 83.9-89.2 %, year 2003) and 93.9 % (90.9-96.2 %, year 1998). Age (odds ratio per 5 years 0.89; 95 % CI 0.86-0.92), region (East vs. West Germany: 0.65; 0.52-0.81), and calendar year (per year 0.97; 0.95-0.99) were significantly associated in the multiple regression. The probability to have multiple counting of hip fracture events varied significantly with age, region, and calendar year. It should be discussed that analyses which do not account for this may provide invalid estimates and conclusions when differences between age groups and regions or trends are analyzed.
Some evidence suggests a daily dose of bisphosphonates improves fixation of cementless metal implants by enhancing osseointegration. Because the necessity of daily administration may result in suboptimal adherence to therapy, single- dose administration is desirable. We examined whether a dose-equivalent single injection of the nitrogen-containing bisphosphonate ibandronate is as effective as a daily injection in improving the osseointegrated surface and enhancing periprosthetic bone mineralization (bone volume to tissue volume) of cementless metal implants. Uncoated titanium and hydroxyapatite-coated titanium implants were surgically inserted into the femoral medullary canal of 55 female Sprague Dawley rats. The animals were randomly assigned subcutaneous treatments with 25 microg/kg body weight ibandronate per day, a dose-equivalent single injection of 28 x 25 microg/kg body weight, or saline solution for control. Histomorphometric evaluation revealed an enhanced osseointegrated surface for hydroxyapatite-coated implants in both treatment groups, but only for daily injections for uncoated titanium implants. Bone volume to tissue volume was improved in both treatment groups. Our results suggest that an equivalent-dose single injection of ibandronate is as effective as a daily dose in improving osseointegration and stabilization of hydroxyapatite-coated titanium implants in this rat model.
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