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We describe a case of delayed onset, acute demyelinating neuropathy secondary to novel SARS-CoV-2 infection. A previously healthy 46-year-old man presented with bilateral leg pain and loss of sensation in his feet 53 days after having COVID-19 pneumonitis. He developed painful sensory symptoms followed by a rapidly progressive lower motor neuron weakness involving all limbs, face and respiratory muscles, needing ventilatory support. In keeping with a diagnosis of Guillain-Barré syndrome, cerebrospinal fluid examination showed albuminocytologic dissociation and nerve conduction studies supported the diagnosis of an acute inflammatory demyelinating polyradiculoneuropathy. The delayed neurological dysfunction seen in our patient following SARS-CoV-2 infection may indicate a novel mechanism of disease that is part of the emerging ‘long COVID-19 syndrome’.

BackgroundWhile the importance of record linkage is widely recognised, few studies have attempted to quantify how linkage errors may have impacted on their own findings and outcomes. Even where authors of linkage studies have attempted to estimate sensitivity and specificity based on subjects with known status, the effects of false negatives and positives on event rates and estimates of effect are not often described.MethodsWe present quantification of the effect of sensitivity and specificity of the linkage process on event rates and incidence, as well as the resultant effect on relative risks. Formulae to estimate the true number of events and estimated relative risk adjusted for given linkage sensitivity and specificity are then derived and applied to data from a prisoner mortality study. The implications of false positive and false negative matches are also discussed.DiscussionComparisons of the effect of sensitivity and specificity on incidence and relative risks indicate that it is more important for linkages to be highly specific than sensitive, particularly if true incidence rates are low. We would recommend that, where possible, some quantitative estimates of the sensitivity and specificity of the linkage process be performed, allowing the effect of these quantities on observed results to be assessed.