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Table 1 Incidence rates and incidence rate ratios of CFS/ME in the Norwegian population according to year, sex and age in 2008 (categorized), 2008 to 2012

From: Two age peaks in the incidence of chronic fatigue syndrome/myalgic encephalomyelitis: a population-based registry study from Norway 2008-2012

Variable Number of cases Number of person years Incidence rate per 100,000 person years (95% CI) Incidence rate ratio (95% CI)
Year
  2008 1,172 4,494,062 26.1 (24.6 to 27.6) 1.0 (ref.)
  2009 1,113 4,491,822 24.8 (23.3 to 26.3) 0.9 (0.9 to 1.0)
  2010 1,104 4,449,683 24.8 (23.4 to 26.3) 0.9 (0.9 to 1.0)
  2011 1,222 4,395,325 27.8 (26.3 to 29.4) 1.0 (1.0 to 1.1)
  2012 1,198 4,342,818 27.6 (26.1 to 29.2) 0.9 (0.9 to 1.1)
Sex
  Male 1,430 11,050,966 12.9 (12.3 to 13.6) 1.0 (ref.)
  Female 4,379 11,122,744 39.4 (38.2 to 40.6) 3.2 (3.0 to 3.4)
Age category (years)
  5 to 9 121 1,497,289 8.1 (6.7 to 9.7) 1.3 (1.1 to 1.6)
  10 to 14 690 1,578,106 43.7 (40.5 to 47.1) 7.1 (6.3 to 8.1)
  15 to 19 689 1,598,802 43.1 (39.9 to 46.4) 7.0 (6.2 to 8.0)
  20 to 24 473 1,481,322 31.9 (29.1 to 34.9) 5.2 (4.5 to 5.9)
  25 to 29 492 1,523,923 32.3 (29.5 to 35.3) 5.2 (4.6 to 6.0)
  30 to 34 688 1,603,520 42.9 (39.6 to 46.2) 7.0 (6.1 to 7.9)
  35 to 39 771 1,809,970 42.6 (39.6 to 45.7) 6.9 (6.1 to 7.8)
  40 to 44 614 1,797,270 34.2 (31.5 to 37.0) 5.6 (4.9 to 6.3)
  45 to 49 496 1,636,483 30.3 (27.7 to 33.1) 4.9 (4.3 to 5.6)
  50 to 54 383 1,564,478 24.5 (22.1 to 27.1) 4.0 (3.4 to 4.6)
  55+ 392 6,082,547 6.2 (5.6 to 6.9) 1.0 (ref.)
  1. CFS/ME, chronic fatigue syndrome/myalgic encephalomyelitis; CI, confidence interval.