Epidemiology

The incidence of acute anaesthetic-associated MH varied from 1 in 4000 to 1 in 250,000 anaesthetics over a 6.5-year period, depending on the details of the clinical definition of MH and the type of anaesthetic drugs to which the patient was exposed.[1][16] It has been estimated that the prevalence of a genetic substrate responsible for susceptibility to MH is present in at least 1 in 3000 people.[17][18][19][20] This is based in part on the observation of compound heterozygotes of ryanodine receptor gene type 1 (RYR1) variants that have been found in people susceptible to MH in Europe, North America, and Japan.[21] RYR1 variants have also been found in families where MH events and deaths occurred in South America, South Africa, Australia, New Zealand, Korea, and China.[22][23] However, RYR1 mutations may account for only 50% of MH cases, so measures of MH susceptibility prevalence obtained using RYR1 mutations alone are likely to be underestimates.[24][25] The reported yields vary with the population selected and the details of the genetic test.[20]

MH, on average, presents during the second or third exposure to a triggering agent and in patients in their late teenage years. MH episodes are reported more often in men than women.[5][6][26][27] The North American Malignant Hyperthermia Registry Opens in new window Males are more likely than females to be diagnosed with MH by the caffeine halothane contracture test (CHCT).[28]

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