You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Meta-analysis of vertebral augmentation compared with conservative treatment for osteoporotic spinal fractures. Cement augmentation is a controversial treatment for painful vertebral compression fractures (VCF). Our research questions for the meta-analysis were: Is there a clinical and statistical difference in pain relief, functional improvement, and quality of life between conservative care and cement augmentation for VCF and, if so, are they maintained at longer time points? We conducted a search of MEDLINE from January 1980 to July 2011 using PubMed, Cochrane Database of Systematic Reviews and Controlled Trials, CINAHL, and EMBASE. Searches were performed from medical subject headings. Terms "vertebroplasty" and "compression fracture" were used. The outcome variables of pain, functional measures, health-related quality of life (HRQOL), and new fracture risk were analyzed. A random effects model was chosen. Continuous variables were calculated using the standardized mean difference comparing improvement from baseline of the experimental group with the control group. New vertebral fracture risk was calculated using log odds ratio. Six studies met the criteria. The pain visual analog scale (VAS) mean difference was 0.73 (confidence interval [CI] 0.35, 1.10) for early (<12 weeks) and 0.58 (CI 0.19, 0.97) for late time points (6 to 12 months), favoring vertebroplasty (p < 0.001). The functional outcomes at early and late time points were statistically significant with 1.08 (CI 0.33, 1.82) and 1.16 (CI 0.14, 2.18), respectively. The HRQOL showed superior results of vertebroplasty compared with conservative care at early and late time points of 0.39 (CI 0.16, 0.62) and 0.33 (CI 0.16, 0.51), respectively. Secondary fractures were not statistically different between the groups, 0.065 (CI -0.57, 0.70). This meta-analysis showed greater pain relief, functional recovery, and health-related quality of life with cement augmentation compared with controls. Cement augmentation results were significant in the early (<12 weeks) and the late time points (6 to 12 months). This meta-analysis provides strong evidence in favor of cement augmentation in the treatment of symptomatic VCF fractures.
{"Chemical": []}