Incidence of adult Huntington's disease in the UK: a UK-based primary care study and a systematic review

Abstract

ObjectivesThe prevalence of Huntington's disease (HD) recorded in the UK primary care records has increased twofold between 1990 and 2010. This investigation was undertaken to assess whether this might be due to an increased incidence. We have also undertaken a systematic review of published estimates of the incidence of HD.SettingIncident patients with a new diagnosis of HD were identified from the primary care records of the Clinical Practice Research Datalink (CPRD). The systematic review included all published estimates of the incidence of HD in defined populations.ParticipantsA total of 393 incident cases of HD were identified from the CPRD database between 1990 and 2010 from a total population of 9 282 126 persons.Primary and secondary outcome measuresThe incidence of HD per million person-years was estimated. From the systematic review, the extent of heterogeneity of published estimates of the incidence of HD was examined using the I2 statistic.ResultsThe data showed that the incidence of HD has remained constant between 1990 and 2010 with an overall rate of 7.2 (95% CI 6.5 to 7.9) per million person-years. The systematic review identified 14 independent estimates of incidence with substantial heterogeneity and consistently lower rates reported in studies from East Asia compared with those from Australia, North America and some—though not all—those from Europe. Differences in incidence estimates did not appear to be explained solely by differences in case ascertainment or diagnostic methods.ConclusionsThe rise in the prevalence of diagnosed HD in the UK, between 1990 and 2010, cannot be attributed to an increase in incidence. Globally, estimates of the incidence of HD show evidence of substantial heterogeneity with consistently lower rates in East Asia and parts of Europe. Modifiers may play an important role in determining the vulnerability of different populations to expansions of the HD allele.

Epidemiological Study of Huntington's Disease in the Province of Ferrara, Italy

“…The mean annual incidence estimate of 0.3 per 100,000 calculated for the province of Ferrara in the period 1990-2009, was lower than what was reported in north-western European countries, for example, in the United Kingdom where it ranged from 0.7 to 0.8 per 100,000 in the period 1990-2010 [11]. …”

“…The introduction of genetic tests has represented a turning point in diagnostic work-up, making it possible to perform preclinical and antenatal diagnoses. HD appears to have an uneven distribution in the world [8,9,10,11,12]. However, an increase in prevalence of HD has been observed in Italian [8] and European population ascribable to the new diagnostic era [13,14,15] pointing out how the lack of a specific test had led to an underestimation of the actual disease burden.…”

The Prevalence of Huntington's Disease

“…Third, the increased prevalence might be due to increased mutation rates, with a corresponding increase in incidence. A recent study by us, however, based on data from the United Kingdom [44] suggests that the incidence of HD between 1990 and 2010 has remained unchanged. Fourth, it is likely that the general increase in population survival will have had some effect on the longevity of those with HD, thus increasing prevalence even in the absence of a rise in incidence.…”

Epidemiology of Huntington disease in Cyprus: A 20‐year retrospective study

“…9 Several studies on the HD prevalence have been published indicating that the prevalence of HD varies widely between different geographical regions. 10,11 However, overall, western European countries and countries with populations of western European descent, such as the United States, Canada and Australia, display higher incidence and prevalence rates, while overall prevalence of the condition has increased over the past 50+ years. [10][11][12][13] On the other hand, Asian populations display lower prevalence.…”

“…10,11 However, overall, western European countries and countries with populations of western European descent, such as the United States, Canada and Australia, display higher incidence and prevalence rates, while overall prevalence of the condition has increased over the past 50+ years. [10][11][12][13] On the other hand, Asian populations display lower prevalence. 10,11,13 Incidence rates for HD in European countries vary from 0.11 to 0.8 cases per 100 000 population per year.…”