How to Establish Clinical Prediction Models

A clinical prediction model can be applied to several challenging clinical scenarios: screening high-risk individuals for asymptomatic disease, predicting future events such as disease or death, and assisting medical decision-making and health education. Despite the impact of clinical prediction models on practice, prediction modeling is a complex process requiring careful statistical analyses and sound clinical judgement. Although there is no definite consensus on the best methodology for model development and validation, a few recommendations and checklists have been proposed. In this review, we summarize five steps for developing and validating a clinical prediction model: preparation for establishing clinical prediction models; dataset selection; handling variables; model generation; and model evaluation and validation. We also review several studies that detail methods for developing clinical prediction models with comparable examples from real practice. After model development and vigorous validation in relevant settings, possibly with evaluation of utility/usability and fine-tuning, good models can be ready for the use in practice. We anticipate that this framework will revitalize the use of predictive or prognostic research in endocrinology, leading to active applications in real clinical practice.

Utilidad clínica de las pruebas hormonales e inmunológicas en la evaluación de las enfermedades del tiroides / Clinical usefulness of hormonal and immunological tests for the evaluation of thyroid diseases

Las enfermedades tiroideas son un importante problema de salud que afecta a un gran porcentaje de la población. Las pruebas bioquímicas constituyen el pilar fundamental para su diagnóstico y seguimiento. El desarrollo de ensayos de segunda y tercera generación ha supuesto un gran avance en el diagnóstico de estas enfermedades. El texto incluye los ensayos utilizados para diagnosticar y tratar las diferentes enfermedades tiroideas, provee información bioquímica y clínica actualizada contenida en secciones referidas a la utilidad clínica de las determinaciones de hormonas tiroideas totales y libres, anticuerpos antitiroideos, tirotropina humana y tiroglobulina, de manera que pueda ofrecer, tanto al laboratorio como al médico, un panorama general de la utilidad y la capacidad actual de estas pruebas(AU)

Thyroid diseases are a significant health problem affecting a high percentage of the population. The biochemical tests are the fundamental pillar for diagnosis and follow-up. The development of second and third-generation assays has represented a great advance in diagnosing these diseases. The text covers the tests to diagnose and treat a number of thyroid diseases, and provides the reader with updated biochemical and clinical information in sections about the clinical usefulness of total and free thyroid hormone determinations, antithyroid antibodies, human thyrotropin and thyroglobulin. In this way, it can offer both the lab and the physician a general overview of the usefulness and the current capability of these tests(AU)

Clinical Usefulness and the Accuracy of Korean Reference Equation for Diffusing Capacity / 결핵및호흡기질환

BACKGROUND: Park et al. developed the Korean reference equation for the measurement of diffusing capacity in 1985. However, the equation has not been widely used in Korea and foreign reference equations have been popularly used. We intended to compare the clinical usefulness and the accuracy of the the Korean reference equation (Park's equation) with that of the foreign equation (Burrows' equation) that is commonly used in Korea. METHODS: 1. Evaluation of clinical usefulness; Among 1,584 patients who underwent diffusing capacity (D(L)CO) at the Asan Medical Center from July to December 2006, group A subjects included 276 patients who had different interpretations of D(L)CO in trials employing Burrows' equation and Park's equation. Clinical assessment was decided by consensus of two respiratory physicians. In order to evaluate the clinical usefulness of Burrows' equation and Park's equation, agreement of clinical assessment and DLCO interpretation were measured. 2. Evaluation of accuracy; Group B subjects were 81 patients with interstitial lung disease (ILD) and 39 normal subjects. The 81 ILD patients were diagnosed following a surgical lung biopsy. The accuracy of diagnosing ILD as well as sensitivity and specificity were evaluated according to the use of the reference equations (Burrows' equation and Park's equation) for DLCO. RESULTS: Agreement between clinical assessment and interpretation of D(L)CO was 22% for the use of Burrows' equation and 78% for the use of Park's equation. The sensitivity and specificity of the Burrows' equation for diagnosing ILD were 64.2% and 100%. The sensitivity and specificity of the Park's equation for diagnosing ILD were 90.1% and 100%. The sensitivity of the Park's equation for diagnosing ILD was significantly higher than that of Burrows' equation (p<0.001). CONCLUSION: The Korean reference equation (Park's equation) was more clinically useful and had higher sensitivity for diagnosing ILD than the foreign reference equation (Burrows' equation).

A Study on the Clinical Usefullness of Digitalized Random-dot Stereoacuity Test

Existing methods of stereoacuity testing need specific glasses or optical device for use. We have designed a new stereoacuity test for the digitalized, random-dot stereogram and researched its clinical usefulness. A digitalized, random-dot, stereoacuity test card was created with a computer program that used a preferred symbol and the designed system was tested along with the Randot preschool stereoacuity, Titmus-fly and Lang tests to compare their sensitivity and specificity. The mean success rate of the digitalized, random-dot test was 98.2%, while the rates of the Randot preschool stereoacuity, Titmus-fly and Lang tests were 89.3%, 74.2% and 86.1%, respectively. Sensitivity and specificity of the new test were 100% and 95.3%, respectively, which were not that different from those of the Randot preschool stereoacuity, Titmus-fly and Lang tests. We found that the digitalized, random-dot, stereoacuity test has a high success rate and can be appropriately used in medical examinations and follow-up tests for strabismus patients.

Clinical Significance of Axonal Stimulation Single Fiber Electromyography in Patients with Myasthenia Gravis

BACKGROUND: The axonal stimulation single fiber electromyography (S-SFEMG) is a relatively new electrophysio-logical technique and has several advantages over conventional voluntarily activated single fiber electromyography (V-SFEMG). This study was performed in patients with myasthenia gravis (MG) in order to analyze their neuromuscular transmission defects and thus to verify the usefulness of the S-SFEMG technique. METHODS: In 44 patients with MG, S-SFEMG was performed on the extensor digitorum communis muscle. The repetitive nerve stimulation test (RNST) on orbicularis oculi, trapezius, flexor carpi ulnaris, and abductor digiti quinti muscles was also performed at the same time. The results of the RNS and S-SFEMG were then analysed in detail. RESULTS: The S-SFEMG was found abnormal in 84.1%, while RNST was found abnormal in 75.0% of the patients tested. The normal S-SFEMG result was observed exclusively among 7 ocular type MG patients. The mean of the mean consecutive difference (MCD) value, % of fibers with blocking and % of fibers with abnormal jitter, was more increased in patients with generalized type MG than those with ocular type MG. This difference was statistically significant (P<0.01) in all 3 variables. CONCLUSIONS The S-SFEMG is a highly sensitive and useful diagnostic tool in MG. Although it demands more strict technical consideration than V-SFEMG, it is less time-consuming and applicable to uncooperative patients including children. Our study shows S-SFEMG to be especially useful in patients with ocular type MG whose RNST results do not show definite decremen-tal responses.