[{"id":464,"title":"Report a relative proportion of patients ruled-out or ruled-in with a diagnostic test","sha":"69b4588b9c1ebd5cd438e1b67e8169de","user_id":null,"state":"published","body":"One measure of the performance of a diagnostic test is the proportion of patients the test stratifies as likely not to have the condition (ruled-out:RO) or to have the condition (ruled-in:RI). This proportion depends on the prevalence of the disease in the cohort. This means that it is not valid to compare tests performed in cohorts with differing prevalences.  However, this is exactly what is often done in the discussion section of academic papers.  Usually there is a target sensitivity (t_sn) for the test which means that the maximum proportion ruled-out at that sensitivity is:\r\n\r\n```\r\nROmax=(TN + TP(1/t_sn -1))/(TN + TP/t_sn)\r\n```\r\n\r\nWhere TN=True Negative, TP=True Positive. Note for ROmax, there are zero False Positives (FP). Also, in the case where t_sn=1 (False Negatives, FN=0), R0max=1-prevalence.\r\n\r\nSimilarly, if there is a target specificity (t_sp) the maximum proportion ruled-in is:\r\n\r\n```\r\nRImax=(TP + TN(1/t_sp -1))/(TP + TN/t_sp)                                            \r\n```\r\nNote, in the case where t_sp=1 (FP=0), RImax=prevalence.\r\n\r\nTherefore, to better be able to compare between studies, both the measured proportion of those ruled-out and those ruled-in should be normalised to their maximum possible values:\r\n\r\n```\r\nAdjusted proportion ruled-out = measured proportion ruled-out / ROmax\r\n\r\nAdjusted proportion ruled-in = measured proportion ruled-in / RImax\r\n```\r\n","created_at":"2018-06-26T00:16:49.505Z","updated_at":"2018-06-26T06:00:32.943Z","zenodo_id":1297700,"doi":"https://doi.org/10.5281/zenodo.1297700","subject":null,"tags":["diagnosis","test","sensitivity","specificity","prevalence"],"vote_count":0,"view_count":1,"score":0.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null},{"id":252,"title":"Rabies Virus: Toward Ante-Mortem, Sub-Clinical Diagnosis by Electron Microscopy","sha":"5ed5cdad04e7ecb9d898274de0e95fc8","user_id":null,"state":"published","body":"According to the Centers for Disease Control and Prevention (CDC), Rabies is the cause of approximately 59,000 deaths annually worldwide. Rabies is 100% fatal and with no approved treatment or survivability upon clinical symptom presentation. With the low-efficacy and general irreproducibility of the “Milwaukee protocol,” post-exposure prophylaxis (PEP) is essential in preventing disease onset through multiple rounds of vaccine alongside rabies immunoglobulin. There remains no single test to diagnose rabies infection sub-clinically in humans, with the gold standard being brain tissue analysis via animal host necropsy.\r\n\r\nElectron Microscopy (EM) appears a reliable option for early diagnostics given its ability to image Rhabdoviridae. Limitations include equipment size, expense, and technical expertise essential for operation. This can be partially addressed by the use of the Low-Voltage electron microscope (6-25kV). Such is functionally compact and does not require staining given its enhanced contrast, provided tissue samples are thin enough for examination (20-65nm).\r\n\r\nRabies virus is known to initially replicate in infected muscle tissue of bite wounds. This could be the basis for aforementioned diagnosis via muscle biopsy by simple viral load presence. Combined with EM (having been used in rabies imaging previously), further research is necessary to determine the viability of this approach.\r\n","created_at":"2015-11-01T06:41:42.650Z","updated_at":"2015-11-02T06:00:40.491Z","zenodo_id":66918,"doi":"http://dx.doi.org/10.5281/zenodo.33000","subject":null,"tags":["rabies","diagnosis","electron","microscopy","early","low","voltage","imaging","rhabdovirus","lyssavirus"],"vote_count":0,"view_count":1,"score":0.1,"deleted":false,"muted":false,"tweeted":false,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null}]