A prospective study of the incidence, prevalence and mortality of multiple sclerosis in Leeds

Objective: To establish the prospective incidence of multiple sclerosis and mortality rates of people with multiple sclerosis in Leeds Health Authority and an updated prevalence of multiple sclerosis on 31 October 1999. Methods: A population based prevalence register established on 30 April 1996 was maintained by prospectively registering all new cases of multiple sclerosis, flagging all cases with the National Health Service Central Register for notification of deaths and by registering all new clinical events. General practitioners notified patients with multiple sclerosis moving into or out of the area. Results 136 incident cases were prospectively registered from 30 April 1996 living in Leeds Health Authority (with an estimated resident population of 728 840). 57 deaths were notified. 792 people with multiple sclerosis were identified living in Leeds on 31 October 1999. The mean annual incidence rate for the three-year period 1996-1998 was 6.1/10(5) (95 % CI: 5.1-7.2). The sex ratio of incident cases was 2.3 to 1 women to men. On 31 October 1999 the prevalence of multiple sclerosis in the Leeds Health Authority was 108.7/10(5) (95 % CI: 101.2-116.5). This compares with a prevalence of 97.3/10(5) (95 % CI: 90.3 -104.7) on 30 April 1996. The prevalence of definite and probable multiple sclerosis was 93.3/10(5) (95 % Cl: 86.4-100.6) and of suspected multiple sclerosis was 15.4/10(5) (95 % CI 12.7-18.5). Crude annual mortality rates of people with multiple sclerosis for 1997 and 1998 were 1.9/10(5) (95 % CI: 1.1 to 3.2) and 3.2/10(5) (95 % Cl: 2.0 to 4.7). Multiple sclerosis was noted as the underlying cause of death in 8 (14 %) cases. Conclusion The incidence of multiple sclerosis in the Leeds Health Authority is similar to that in the south of the United Kingdom. The difference in successive prevalence figures is less than that published in other serial studies. Multiple sclerosis was notified as the underlying cause of death in a minority of deaths in people with multiple sclerosis.