PURPOSE We wanted to summarize evidence about the diagnostic accuracy of the 5.07/10-g monofi lament test in peripheral neuropathy. METHODSWe conducted a systematic review of studies in which the accuracy of the 5.07/10-g monofi lament was evaluated to detect peripheral neuropathy of any cause using nerve conduction as reference standard. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. RESULTSWe reviewed 173 titles and abstracts of articles to identify 54 potentially eligible studies, of which 3 were fi nally selected for data synthesis. All studies were limited to patients with diabetes mellitus and showed limitations according to the QUADAS tool. Sensitivity ranged from 41% to 93% and specifi city ranged from 68% to 100%. Because of the heterogenous nature of the studies, a meta-analysis could not be accomplished.CONCLUSIONS Despite the frequent use of monofi lament testing, little can be said about the test accuracy for detecting neuropathy in feet without visible ulcers. Optimal test application and defi ning a threshold should have priority in evaluating monofi lament testing, as this test is advocated in many clinical guidelines. Accordingly, we do not recommend the sole use of monofi lament testing to diagnose peripheral neuropathy. 2009;7:555-558. doi:10.1370/afm.1016. Ann Fam Med INTRODUCTIONP eripheral neuropathy causes loss of sensation and increases the risk of ulceration of the feet. Timely identifi cation of loss of protective sensation may allow preventive intervention. Peripheral neuropathy is a complication in approximately 50% of patients with diabetes, and up to 50% of patients with peripheral neuropathy may not have symptoms. [1][2][3] Several tests are used to detect peripheral neuropathy, including vibration perception, application of warmth and cold, and nerve conduction studies, which are assumed to be the reference standard.4 Electrodiagnostic tests can be complex, expensive, and time consuming, which hampers their widespread use, especially in primary care, where for most patients peripheral neuropathy is diagnosed and treated.Monofi lament testing is an inexpensive, easy-to-use, and portable test for assessing the loss of protective sensation, and it is recommended by several practice guidelines to detect peripheral neuropathy in otherwise normal feet. 1,5,6 Monofi laments, often called Semmes-Weinstein monofi laments, are calibrated, single-fi ber nylon threads, identifi ed by values ranging from 1.65 to 6.65, that generate a reproducible buckling stress. The higher the value of the monofi lament, the stiffer and more diffi cult it is to bend. Three monofi laments commonly used to diagnose periph- M ONO FIL A MEN T T ES T ING F OR PER IPHER A L NEUROPAT HYeral neuropathy are the 4.17, 5.07 and 6.10.7-9 Forces required to bend these monofi laments are 1, 10, and 75 g, respectively. The fi lament is placed on the patient's skin (usually the feet); when there is considerable loss of sensation, the patient will not be...