Prediction of insufficient serum vitamin D status in older women: a validated model.

We developed an externally validated simple prediction model to predict serum 25(OH)D levels < 30, < 40, < 50 and 60 nmol/L in older women with risk factors for fractures. The benefit of the model reduces when a higher 25(OH)D threshold is chosen. INTRODUCTION: Vitamin D deficiency is associated with increased fracture risk in older persons. General supplementation of all older women with vitamin D could cause medicalization and costs. We developed a clinical model to identify insufficient serum 25-hydroxyvitamin D (25(OH)D) status in older women at risk for fractures. METHODS: In a sample of 2689 women ≥ 65 years selected from general practices, with at least one risk factor for fractures, a questionnaire was administered and serum 25(OH)D was measured. Multivariable logistic regression models with backward selection were developed to select predictors for insufficient serum 25(OH)D status, using separate thresholds 30, 40, 50 and 60 nmol/L. Internal and external model validations were performed. RESULTS: Predictors in the models were as follows: age, BMI, vitamin D supplementation, multivitamin supplementation, calcium supplementation, daily use of margarine, fatty fish ≥ 2×/week, ≥ 1 hours/day outdoors in summer, season of blood sampling, the use of a walking aid and smoking. The AUC was 0.77 for the model using a 30 nmol/L threshold and decreased in the models with higher thresholds to 0.72 for 60 nmol/L. We demonstrate that the model can help to distinguish patients with or without insufficient serum 25(OH)D levels at thresholds of 30 and 40 nmol/L, but not when a threshold of 50 nmol/L is demanded. CONCLUSIONS: This externally validated model can predict the presence of vitamin D insufficiency in women at risk for fractures. The potential clinical benefit of this tool is highly dependent of the chosen 25(OH)D threshold and decreases when a higher threshold is used.

A new method for automatic recognition of the radiographic trabecular pattern.

This study reports a method to describe and analyze the structure of the trabecular pattern seen on radiographs of the distal radius. The structure is measured and related to the bone mineral density (BMD) of the lumbar spine measured by dual-photon absorptiometry. Radiographs of hand and wrist combined with additional information of the bone mineral density of the vertebrae serve as testing material. With a computer-aided imaging system, a part of the depicted radius is scanned. The image is filtered and segmented into a bilevel picture consisting of a light network with dark meshes. Seven features of the bilevel picture are measured and analyzed. It is shown that six features correlate significantly with the bone mineral density measured at the lumbar spine, although the correlations between the trabecular pattern and the BMD are too weak to allow precise predictions of BMD values for individuals. Nevertheless, the correlations confirm the existence of a relationship between the radiographic trabecular pattern and the bone mineral density of the lumbar spine. The method is worth being further developed for use on individual patients. It provides a noninvasive tool to make an objective and quantitative assessment of the trabecular pattern.