Multiple sclerosis incidence in the Faroe Islands 1986-2007

Trend in the Incidence and Prevalence of Dementia in the Faroe Islands

Background:

Dementia has become an important public health, economic, and social issue. Knowledge about prevalence, incidence, and trends of dementia in a country is of crucial importance. However, no studies of incidence or prevalence of dementia have been undertaken in the Faroe Islands.

Objectives:

The aim was to estimate the overall and trend in incidence and prevalence of dementia among individuals ≥60 years in the Faroe Islands from 2010-2017.

Methods:

Population-based register study where all individuals ≥60 years with a dementia diagnosis from January 2010 to December 2017 were identified. The overall crude and age-and-sex-specific incidence and prevalence was assessed.

Results:

The overall crude incidence among individuals ≥60 years from 2010 to 2017 was 5.1 per 1000 individuals and the prevalence 22.5 per 1000 individuals. The age-and sex-standardized annual incidence of dementia fluctuated between 4.8 and 6.7 per 1000, with no clear secular trend while the age-and sex-standardized prevalence increased steadily from 14.5 in 2010 to 30.8 per 1000 individuals in 2017.

Conclusion:

The age-standardized incidence or prevalence estimates in the Faroes seem to be lower than in other countries. The incidence was relatively stable in the period while the prevalence of dementia simultaneously increased.

Assessing the Prevalence of Undetected Possible Dementia in Faroese Nursing Homes

INTRODUCTION

To assess the prevalence of possible dementia among nursing home residents in the Faroe Islands.

METHOD

This cross-sectional study, undertaken in 2017, included all nursing homes in the Faroe Islands (n = 30), housing 591 residents. All residents were invited to participate, except those with an existing clinical diagnosis of dementia or living in dementia units (n = 207). A total of 232 residents participated, while 39 declined and 113 were unable to give consent, had died, or were not permanent residents at the time of examination. Cognitive screening was carried out using the Mini-Mental State Examination (MMSE) and the Informant Questionnaire on Cognitive Decline (IQCODE).

RESULTS

Possible dementia was found in 49% to 78% of the participants depending on the method used. According to both MMSE and IQCODE (AND rule), possible dementia was present in 105 participants (49%). According only to IQCODE, 119 participants (55%) scored above the cut-off (≥3.6), according to MMSE alone, 162 participants (72%) scored below the cut-off (≤24 on MMSE), while 175 participants (78%) screened positive according to either MMSE or IQCODE (OR rule). A rough estimate of the prevalence of possible dementia in the entire nursing home population (n = 591) including residents with known dementia and those with possible dementia from this study was between 61% and 73%.

CONCLUSION

A high percentage (49-78%) of the participating nursing home residents without a pre-dementia diagnosis were assessed to have possible dementia based on screening with standardized tools, indicating a high degree of dementia underdiagnoses in Faroese nursing homes. This high prevalence of dementia is of significance for the clinical practice, running, and planning of nursing homes and pinpoints a need to act upon this, not only in the Faroes but also worldwide.

Tremor in normal adults: A population-based study of 1158 adults in the Faroe Islands

There are virtually no population-based data on tremor in normal individuals. Using a population-based sample of 1158 normal adults ages 40-98 years in the Faroe Islands, we characterized the extent of normal action tremor across age and gender strata. Participants drew two Archimedes spirals with each hand, and tremor was systematically quantified by a senior movement disorder neurologist using a reliable and valid ordinal rating scale (ratings = 0-3). Tremor was nearly universal - 1145 (98.9%) participants had a total mean spiral score > 0. Older age was associated with more tremor (p < .001) and spiral scores were higher in males than females (p < .001). The proportion of individuals with a spiral rating ≥ 1.5 (i.e., more than mild tremor) was low (1.8% - 8.5%); however, this value reached 19.6% in left-hand spirals of males ≥70 years old. In this population-based study of more than one thousand normal adults, the vast bulk (i.e., 98.9%) had tremor on spiral drawing. In general, the tremor was mild. The proportion of individuals with tremor above the mild range varied across age and gender strata. These extensive data may be used as a gold standard for defining normal levels of tremor within adult populations.

High prevalence of primary focal dystonia in the Faroe Islands

OBJECTIVE

There are no previous studies undertaken about primary focal dystonia in the Faroe Islands. The aim of this study was to establish the prevalence of these diseases in the Faroese population.

METHODS

Patients were ascertained and registered prospectively from January 1, 1994, through 2013 when they were examined at the Neurological Clinic of the Faroese National Hospital or at a private neurological practice, which together constitutes all the available neurological services in the Faroe Islands.

RESULT

On January 1, 2014, there were 29 individuals within the entire Faroese population of 48,100 with primary focal dystonia: 23 with torticollis, four with writer's cramp, one with oromandibular dystonia, and one with laryngeal dystonia; no one had blepharospasm. The prevalence of primary focal dystonia was 602 per million (395-873) (95% confidence limit). The most common subtype was cervical dystonia with a prevalence of 478 (332-728) per million.

CONCLUSION

The study yielded that (i) the prevalence of primary focal dystonia of 602 (395-873) per million is far higher in the Faroe Islands than that revealed in most other regions studied and (ii) the prevalence of the cervical dystonia subtype is far more common than elsewhere with the highest prevalence of 478 (332-728), which is higher than described in any previously published survey. As the study is serviced-based, the result may underestimate actual occurrence; thus, prevalence rates may be even higher.

Myasthenia gravis incidence in a general North Atlantic isolated population

OBJECTIVE

There are no previous studies undertaken about myasthenia gravis in the Faroe Islands. The aim of this study was to establish the incidence of onset of this disease in the Faroese population.

METHOD

Patients were ascertained and registered prospectively from 1986 to 2013 when they were examined at the Neurological Clinic of the Faroese National Hospital or at a private neurological practice, which constitutes all the available neurological services in the Faroe Islands.

RESULT

Twelve new diagnoses were made over a 27-year period, providing an incidence density rate of 9.4 per million person-years (95% confidence limit 4.9-16.5). At presentation, nine of 12 patients had generalized myasthenia gravis and two patients had pure ocular disease, and in one patient, the symptoms were restricted to the bulbo-facial muscles. The sex ratio was 2:1, F/M. In nine of the cases, a positive result of acetylcholine receptor antibody assay was documented. In all patients, there was a beneficial response to anticholinesterase administration.

CONCLUSION

The result yielded no strong evidence of a difference in incidence between that found in the Faroe Islands and those in most European studies, apart from recent studies from London, UK; Norway; Spain, and Italy in which incidences from 21 to 30 per million person-years had been reported.

Incidence and prevalence of multiple sclerosis in Europe: a systematic review

BACKGROUND

Multiple sclerosis (MS) is the most common cause of neurological disability in young adults worldwide and approximately half of those affected are in Europe. The assessment of differential incidence and prevalence across populations can reveal spatial, temporal and demographic patterns which are important for identifying genetic and environmental factors contributing to MS. However, study methodologies vary and the quality of the methods can influence the estimates. This study aimed to systematically review European studies of incidence and prevalence of MS and to provide a quantitative assessment of their methodological quality.

METHODS

A comprehensive literature search was performed to obtain all original population-based studies of MS incidence and prevalence in European populations conducted and published between January 1985 and January 2011. Only peer-reviewed full-text articles published in English or French were included. All abstracts were screened for eligibility and two trained reviewers abstracted the data and graded the quality of each study using a tool specifically designed for this study.

RESULTS

There were 123 studies that met the inclusion criteria. The study estimates were highly heterogeneous, even within regions or countries. Quality was generally higher in the more recent studies, which also tended to use current diagnostic criteria. Prevalence and incidence estimates tended to be higher in the more recent studies and were higher in the Nordic countries and in northern regions of the British Isles. With rare exceptions, prevalence and incidence estimates were higher in women with ratios as high as 3:1. Few studies examined ethnicity. Epidemiological data at the national level was uncommon and there were marked geographical disparities in available data, with large areas of Europe unrepresented and other regions well-represented in the literature. Only 37% of the studies provided standardized estimates.

CONCLUSIONS

Despite the breadth of the literature on the epidemiology of MS in Europe, inter-study comparisons are hampered by the lack of standardization. Further research should focus on regions not yet studied and the evaluation of ethnic differences in MS prevalence and incidence. National-level studies using current diagnostic criteria, validated case definitions and similar age- and sex-standardization would allow better geographical comparisons.

Incidence of multiple sclerosis among European Economic Area populations, 1985-2009: the framework for monitoring

Background

A debate surrounding multiple sclerosis epidemiology has centred on time-related incidence increases and the need of monitoring. The purpose of this study is to reassess multiple sclerosis incidence in the European Economic Area.

Methods

We conducted a systematic review of literature from 1965 onwards and integrated elements of original research, including requested or completed data by surveys authors and specific analyses.

Results

The review of 5323 documents yielded ten studies for age- and sex-specific analyses, and 21 studies for time-trend analysis of single data sets. After 1985, the incidence of multiple sclerosis ranged from 1.12 to 6.96 per 100,000 population, was higher in females, tripled with latitude, and doubled with study midpoint year. The north registered increasing trends from the 1960s and 1970s, with a historic drop in the Faroe Islands, and fairly stable data in the period 1980-2000; incidence rose in Italian and French populations in the period 1970-2000, in Evros (Greece) in the 1980s, and in the French West Indies in around 2000.

Conclusions

We conclude that the increase in multiple sclerosis incidence is only apparent, and that it is not specific to women. Monitoring of multiple sclerosis incidence might be appropriate for the European Economic Area.

Incidence of multiple sclerosis in Chile. A hospital registry study

OBJECTIVE

To study the incidence of MS in Chile by examining the hospitalizations across all geographical regions of the country and to examine whether there is a correlation between these rates and the latitude or ultraviolet radiation.

METHODS

This is a descriptive study examining the national registry of hospitalizations because of MS (code G35 in ICD-10) from January 1, 2001, to December 31, 2006. Incidence rates were calculated by gender and geographical region and standardized to the world population estimated for 2010.

RESULTS

A total of 6857 hospitalizations were analyzed. There were 935 individuals; 63.9% were women. The mean incidence rate for 2002-2006 period was 0,90 (95% CI: 0.75-1.05). The annualized incidence rates for regions from North to South were as follows: I Tarapaca 0.54 (95% CI: 0.0-1.21), II Antofagasta 0,93 (0.10-1.75), III Atacama 1.07 (0.0-2.31), IV Coquimbo 0.63 (0.01-1.24), V Valparaiso 0.83 (0.38-1.27), VI O'Higgins 0.72 (0.14-1.30), VII Maule 0.52 (0.06-0.98), VIII BIO BIO 0.81 (0.41-1.21), IX Araucanía 0.43 (0.0-0.86), X Los Lagos 0.91 (0.35-1.46), XI Aysen 0.99 (0.0-2.98), XII Magallanes 3.54 (0.57-6.51), and XIII Metropolitana 1.10 (0.84-1.36). There were no significant correlations between hospitalization rates and latitude, except for region XII. UV radiation levels showed significant differences only for region XII.

CONCLUSION

There is a moderate risk of MS in Chile. The southernmost region showed significantly higher incidence rates than those in the rest of the country (a cluster zone). We did not find any correlation between incidence rates and latitude or UV radiation.

Prevalence and incidence of multiple sclerosis in Oppland County: a cross-sectional population-based study in a landlocked county of Eastern Norway

OBJECTIVES - We report the prevalence and incidence rates of multiple sclerosis (MS) in Oppland County, Norway. METHODS - Records from all patients diagnosed with MS at the two Oppland County hospitals, Gjøvik and Lillehammer during 1989-2001 were evaluated. In addition, all general practitioners in Oppland County reported their patients into the study. RESULTS - The age-adjusted prevalence rate of definite MS was 174.4/ 100 000 on the prevalence day 1 January 2002. When the probable cases were included, the prevalence rate rose to 185.6/100 000. The highest prevalence rates were detected in the northern mountain areas, thus corroborating the results from previous local surveys 30-50 years ago. The prevalence of MS was statistically significantly associated with climatic, socioeconomic and geographic variables in the county. The age-adjusted incidence of definite and probable MS in Oppland County was 6.6/100 000 during 1989-1993 increasing to 7.6/100 000 during 1994-1998. DISCUSSION - We found the highest prevalence rates of MS ever reported in Norway. Our findings indicate a possible influence of environmental factors.

Multiple sclerosis: variation of incidence of onset over time in the Faroe Islands

Epidemiological studies of multiple sclerosis (MS) conducted in the Faroe Islands identified 10 annual incidences per 100,000 in 1945 and 4.5 in the period 1986-2007. The aim of this study was to estimate the annual incidence of onset of MS in the Faroe Islands in the six decades from 1943 to 2002 and during the period 2003-7.All patients diagnosed with MS between 1943 and 2007 were documented. The incidence of MS before 1943 was around 0.2 per 100,000 annually. During the period 1943-62, an annual incidence rate of 4.4 [confidence interval (CI) 2.9-6.1] per 100,000 was observed. During the 20-year period 1963-82, the level declined significantly (p < 0.001) to around 0.6 (0.3-1.5). Thereafter, an increase was seen during the period 1983-2002, evidencing a significant (p < 0.001) sevenfold increase in the annual incidence to 4.6 (3.2-6.2) per 100,000. Subsequently, for the period 2003-7, there was again a decline to 2.4 (2.1-3.3) (p = 0.003). This study confirms that significant variation in the incidence of MS has occurred in the Faroes over time. Because the rate of genetic change within the Faroese population is relatively slow, the study suggests environmental factors as a contributing cause of MS. If only genetic factors for susceptibility were important, the incidence rate should not wax and wane over time, as is observed.