title: Rheumatoid arthritis is getting less frequent-results of a nationwide population-based cohort study.
abstract: The objectives of this study were to examine changes in the incidence and prevalence of RA between 1990 and 2014 and to explore if there is any geographic variation in the incidence and prevalence of RA in the UK.
  
  
  
  This was a primary care-based prospective cohort study. People contributing acceptable data to Clinical Practice Research Datalink between 1 January 1990 and 31 December 2014 were included. Read codes were used to identify RA cases ⩾18 years of age. The prevalence and incidence rates for each year were standardized to the 2014 population and the regional incidence and prevalence of RA for the year 2014 were standardized to the overall population.
  
  
  
  The incidence and prevalence of RA was 3.81/10 000 person-years and 0.67%, respectively, in 2014. The annual incidence of RA decreased by 1.6% (95% CI 0.8, 2.5) between 1990 and 2014, with significant joinpoints at 1994 and 2002. The prevalence of RA increased by 3.7%/year (95% CI 3.2, 4.1) from 1990 to 2005 and decreased by 1.1%/year (95% CI 2.0, 0.2) between 2005 and 2014. There were significant differences in the occurrence of RA throughout different regions of the UK, with the highest incidence in East Midlands, Yorkshire and Humber and the highest prevalence in North East, Yorkshire and Humber.
  
  
  
  The incidence of RA is decreasing, with a reduction in prevalence in recent years. There is significant geographic variation in the occurrence of RA in the UK. Further research is required to identify the reasons underlying this phenomenon so that public health interventions can be designed to further reduce the incidence of RA.
authors.affiliation: Academic Rheumatology, School of Medicine, Clinical Sciences Building, City Hospital Nottingham, Nottingham.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Abhishek
authors.affiliation: Academic Rheumatology, School of Medicine, Clinical Sciences Building, City Hospital Nottingham, Nottingham.
authors.forename: Michael
authors.initials: M
authors.lastname: Doherty
authors.affiliation: Academic Rheumatology, School of Medicine, Clinical Sciences Building, City Hospital Nottingham, Nottingham.
authors.forename: Chang-Fu
authors.initials: CF
authors.lastname: Kuo
authors.affiliation: Primary Care and Health Sciences, Keele University, Keele.
authors.forename: Christian D
authors.initials: CD
authors.lastname: Mallen
authors.affiliation: Academic Rheumatology, School of Medicine, Clinical Sciences Building, City Hospital Nottingham, Nottingham.
authors.forename: Weiya
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Division of Epidemiology and Public Health, School of Medicine, Clinical Sciences Building, City Hospital Nottingham, Nottingham, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Grainge
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012111:Residence Characteristics / Q000706:statistics & numerical data; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
keywords: geographic variation; incidence; prevalence; rheumatoid arthritis