NSW Pop 36,550 32,654 24,306 22,494 36,473 36,551 28,359 21,148 13,874 7,651 4,238 3,037 2,608 1,803 794 273 272,813 238,535 93,510 145,025 179,303 AAI 0–4 5–9 10–14 15–19 20–24 25–29 30–34 35–39 40–44 45–48 50–54 55–59 60–64 65–69 70–74 75–79 Total All 0–39 0–14 15–39 15? Total 696,735 0–14 250,631 15–19 52,335 15–24 131,907 15–29 218,185 15–34 292,784 15–39 350,778 15–44 388,338 15–49 408,856 15–54 420,522 15? 446,104 Table 6 Comparison of absolute risk of MS per 100,000 population with 95% conﬁdence intervals by age at immigration: age 0 to 14 versus older ages AAI At risk population MS Risk 95% CI Signiﬁcance 258 37.03 32.64–41.84 56 22.34 16.88–29.02 Reference 30 57.32 38.68–81.84 ? 73 55.34 43.38–69.60 ? 129 59.12 49.36–70.25 ? 168 57.38 49.03–66.74 ? 189 53.88 46.47–62.13 ? 200 51.50 44.61–59.16 ? 201 49.16 42.60–56.45 ? 202 48.04 41.64–55.14 ? 202 45.28 39.25–51.98 ? UKI immigrants (Group II) with MS onset after migration who entered Australia in or after 1947 and were age 0–79 in 1981, Four States combined the same set of immigrants, those who had entered Aus- tralia in 1947 or later and had survived (at age 0–79) into 1981, and by calculating from special population data the J Neurol (2011) 258:1140–1149 Table 5 Risk of MS per 100,000 population by age at immigration for Group II UKI immigrants, those age 0–79 in 1981 who had immigrated in 1947 or later, by state of residence N 2 14 13 20 26 23 15 5 3 1 0 0 0 0 0 0 122 118 29 89 93 Risk 5.47 42.87 53.48 88.91 71.29 62.93 52.89 23.64 21.62 13.07 – – – – – – 44.72 49.47 31.01 61.37 51.87 QLD Pop 15,857 14,618 10,826 9,111 13,809 15,101 1,293.7 9,995 6,779 3,856 2,209 1,617 1,440 1,057 546 168 119,926 102,254 41,301 60,953 78,625 N 3 5 4 2 4 9 7 5 2 0 0 0 0 0 0 0 41 39 12 27 29 Risk 18.92 34.20 36.95 21.95 28.97 59.61 54.11 50.03 29.50 – – – – – – – 34.19 38.14 29.01 44.30 36.88 SA Pop 20,921 20,482 145.21 9,297 11,497 14,607 15,459 13,023 8,321 4,261 2,278 1,768 1,572 1,076 417 111 139,611 119,807 55,924 63,883 83,687 N 0 4 2 3 6 11 6 6 1 0 0 0 0 0 0 0 39 38 6 32 33 Risk 19.53 13.77 32.27 52.19 75.31 38.81 46.07 12.02 – – – – – – – 27.93 31.72 10.73 50.09 39.43 WA Pop 22,928 21,636 15,332 11,433 17,793 20,019 17,844 13,828 8,586 4,750 2,941 2,460 2,272 1,642 723 198 164,385 140,613 59,896 80,917 104,489 N 1 3 5 5 7 13 11 5 5 0 1 0 0 0 0 0 56 50 9 41 47 1147 Risk 4.36 13.87 32.61 43.73 39.34 64.94 61.65 36.16 58.23 – 34.00 – – – – – 34.07 35.56 15.03 50.67 44.98 actual denominator, the number of such immigrants by each year of age at immigration. This revealed in addition that the UKI MS cases comprised two subsets, deﬁned as those with entry before and at/after 1947. They had been combined in the earlier assessment, and this is the main reason why a differential age at immigration was not then demonstrated. There had also been an inadvertent double- counting of 21 cases from NSW, most of whom had had young ages at immigration. The previous study of MS in UKI migrants to Australia [1] demonstrated that with the exception of Hobart the prevalence of MS was less than that in their country of origin—due, in part at least, to the exclusion of cases with onset before migration. Among the native-born Australians there was then reported a higher prevalence of MS in NSW and lower prevalence in QLD. This has been conﬁrmed in the present analysis. In fact, there is a highly signiﬁcant gradient of prevalence rates from NSW to SA to WA to QLD for the native born. Possible reasons for this gradient will be explored in the third of our reassessments, that for the native-born Australians. Prevalence rates of MS in UKI up to 1980 have been reviewed [16–18]. It is difﬁcult to compare the prevalence 123