A new prevalence study of multiple sclerosis in Orkney, Shetland and Aberdeen city
- 1Division of Applied Health Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK
- 2University of Aberdeen, Foresterhill, Aberdeen, UK
- 3Centre for Population Health Sciences, University of Edinburgh, Edinburgh, UK
- 4Aberdeen Royal Infirmary, NHS Grampian, Foresterhill, Aberdeen, UK
- Correspondence to Dr E M Visser, Division of Applied Health Sciences, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD, UK;
Contributors This study was designed, performed and analysed by EMV and CEC. KW designed, maintained and helped with analysis of the data on a master database. JFW supplied information on patients from Orkney and Shetland, also included in the Northern Isles of Genetics of MS study. KKY assisted in data extraction from patient records and data entry on the master database. All of the authors were involved in the drafting and approval of the manuscript. CEC is the guarantor.
- Received 14 October 2011
- Revised 11 April 2012
- Accepted 12 April 2012
- Published Online First 10 May 2012
Background 30 years ago very high multiple sclerosis (MS) prevalence rates were recorded in northern Scotland. A prevalence study was repeated in Aberdeen, Orkney and Shetland to see if prevalence rates had changed, assess which factors affect prevalence and record disability status.
Methods Hospital, general practice and laboratory records were searched to identify prevalent MS patients (alive and registered with a participating general practice on 24 September 2009). Records were reviewed to confirm diagnoses applying Poser definite and probable and McDonald diagnostic criteria. Disability status (Expanded Disability Status Scale) was recorded from records and questionnaires. Rates were standardised to the Scottish population.
Results 590 patients were found (Aberdeen 442, Orkney 82, Shetland 66). Mean age and disease duration were 53 and 19.4 years, respectively. The standardised prevalence rates for Poser probable/definite MS per 100 000 were: combined area 248 (95% CI 229 to 269), Orkney 402 (95% CI 319 to 500), Shetland 295 (95% CI 229 to 375) and Aberdeen 229 (95% CI 208 to 250). McDonald diagnostic criteria gave a lower prevalence (202, 95% CI 198 to 206). Prevalence was highest in women (2.55:1, 95% CI 2.26 to 2.89) with about 1 in 170 women in Orkney affected. Prevalence was lowest in the most deprived socioeconomic group. 45% had significant disability (Expanded Disability Status Scale ≥6).
Conclusion The prevalence of MS has increased in the overall area, most markedly in Orkney, then Shetland, over the past 30 years. This increase could be due to a number of factors, but rising incidence as reflected by a rising sex ratio, influenced by gene–environment interaction, is the most likely. Orkney has the highest prevalence rate recorded worldwide.
Funding The Chief Scientists Office, Scottish Government, funded this project (grant No CZG/2/419), with additional support from the NHS Grampian Endowment Fund. The research team also acknowledges the financial support of NHS Research Scotland (NRS), through the Scottish Primary Care Research Network (SPCRN).
Competing interests None.
Ethics approval Ethics approval was provided by the North of Scotland Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement The authors are open to discussion regarding data sharing.