Wednesday, June 27, 2012

Extending the c-statistic to nominal polytomous outcomes: the Polytomous Discrimination Index.




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Extending the c-statistic to nominal polytomous outcomes: the Polytomous Discrimination Index.



Stat Med. 2012 Jun 26;
Calster BV, Belle VV, Vergouwe Y, Timmerman D, Huffel SV, Steyerberg EW

Diagnostic problems in medicine are sometimes polytomous, meaning that the outcome has more than two distinct categories. For example, ovarian tumors can be benign, borderline, primary invasive, or metastatic. Extending the main measure of binary discrimination, the c-statistic or area under the ROC curve, to nominal polytomous settings is not straightforward. This paper reviews existing measures and presents the polytomous discrimination index (PDI) as an alternative. The PDI assesses all sets of k cases consisting of one case from each outcome category. For each category i (i = 1, … ,k), it is assessed whether the risk of category i is highest for the case from category i. A score of 1∕k is given per category for which this holds, yielding a set score between 0 and 1 to indicate the level of discrimination. The PDI is the average set score and is interpreted as the probability to correctly identify a case from a randomly selected category within a set of k cases. This probability can be split up by outcome category, yielding k category-specific values that result in the PDI when averaged. We demonstrate the measures on two diagnostic problems (residual mass histology after chemotherapy for testicular cancer; diagnosis of ovarian tumors). We compare the behavior of the measures on theoretical data, showing that PDI is more strongly influenced by simultaneous discrimination between all categories than by partial discrimination between pairs of categories. In conclusion, the PDI is attractive because it better matches the requirements of a measure to summarize polytomous discrimination. Copyright © 2012 John Wiley & Sons, Ltd.








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Laser Liposuction and Shoulder treatment- patient dropped 2 pant sizes with the Erchonia laser









Steve Lopez describes how cold laser therapy at Laser Chiropractic initially fixed his shoulder injury, and how the non-surgical Erchonia lipolaser helped with fat loss and helped him drop 2 pant sizes.

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Complementary and alternative medicine in osteoarthritis.



PM R. 2012 May; 4(5 Suppl): S122-33
De Luigi AJ

The intent of this focused clinical review is to assess the current literature on a variety of complementary and alternative medicine treatments for osteoarthritis. This review assesses acupuncture techniques, moxibustion, transcutaneous electrical nerve stimulation, low-level laser therapy, and massage. These treatment methods are growing in popularity among the general public. It is important that providers become aware of the existing literature regarding the efficacy of these alternative methods for the treatment of osteoarthritis to adequately respond to the inquiries of our patients.








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Exploration of new electroacupuncture needle material.



Evid Based Complement Alternat Med. 2012; 2012: 612545
Lee S, Choi GH, Lee CH, Kim YK, Lee S, Cho S, Yeon S, Choi SM, Ryu YH

Background. Electro Acupuncture (EA) uses the acupuncture needle as an electrode to apply low-frequency stimulation. For its safe operation, it is essential to prevent any corrosion of the acupuncture needle. Objective. The aim of this study is to find an available material and determine the possibility of producing a standard EA needle that is biocompatible. Methods. Biocompatibility was tested by an MTT assay and cytotoxicity testing. Corrosion was observed with a scanning electron microscope (SEM) after 0.5 mA, 60 min stimulation. The straightness was measured using a gap length of 100 mm, and tensile testing was performed by imposing a maximum tensile load. Results. Phosphor bronze, Ni coated SS304, were deemed inappropriate materials because of mild-to-moderate cytotoxicity and corrosion. Ti-6Al-4V and SS316 showed no cytotoxicity or corrosion. Ti-6Al-4V has a 70 times higher cost and 2.5 times lower conductivity than SS316. The results of both straightness and tensile testing confirmed that SS316 can be manufactured as a standard product. Conclusion. As a result, we confirmed that SS316 can be used a new EA electrode material. We hope that a further study of the maximum capacity of low-frequency stimulation using an SS316 for safe operation.







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