PONM20 Should acetylcholine receptor antibody requesting be restricted to hospital clinicians? No difference demonstrated in the proportion of positive assay results between primary and secondary care

Methods We retrospectively analysed Ach receptor antibody requests and assay records from the Royal Bournemouth Hospital between September 2007 and August 2009. We categorised clinical indication for request (MG, diplopia, ptosis, ophthalmoplegia, fatigue, dysphagia, weakness, other and unclear clinical details), speciality of requesting clinician (GP, Neurology, Medicine, Elderly Care, Ophthalmology and Other) and the test result (positive or negative). There were 296 requests. Eight were not analysed by the laboratory and excluded from our results. Results There were no statistically significant differences between the proportion of positive assays requested by different specialities. Overall 17% of tests were positive, ranging from 20% (10/50) in General Practice and 18.6% (8/34) in Neurology and 13% (9/69) in Medicine. There were no statistically significant differences between positive test results categorised by clinical indication of requests. The majority of requests were for “myasthenia gravis” (85), with 20% of results positive (17). Results requested for ptosis yielded the greatest proportion of positive assays (26%, 5/19), and ophthalmoplegia (0%, 0/7) the least. Conclusion Perhaps surprisingly, we found no difference between positive acetylcholine receptor antibody assay results requested by different specialities. On the basis of this study we cannot recommend that Ach assay requests are restricted to secondary care services.