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Table 2 Stage progression rates and incidence rates of stage progression of NF1 from 2009 to 2012 by age and clinical stage at registration in 2008

From: Evaluation of neurofibromatosis type 1 progression using a nationwide registry of patients who submitted claims for medical expense subsidies in Japan between 2008 and 2012

  No. of cases (A) No. of cases with renewal claim (B) No. of cases with no renewal claims Renewal rate (B/A) No. of cases with stage progression (C) No. of cases with dermatological progression No. of cases with neurological progression No. of cases with bone progression Person-years (D) a) Stage progression rate (C/A) b) Incidence rate per 100 person-years (C/D)
Total 342 205 137 60% 30 13 16 8 245.0 19% 12.2
Age group
 0–19 yrs 74 47 27 64% 7 1 4 4 28.0 26% 25.0
 20–39 yrs 109 65 44 60% 10 6 7 1 89.0 19% 11.2
 40–59 yrs 89 53 36 60% 6 4 2 1 77.5 12% 7.7
  > 60 yrs 70 40 30 57% 7 2 3 2 50.5 21% 13.9
Clinical stage
 Stage 1, 2 57 19 38 33% 10 6 7 2 63.0 18% 15.9
 Stage 3, 4 105 67 38 64% 20 7 9 6 182.0 19% 11.0
 Stage 5 180 119 61 66%      
Age×clinical stage
 0–19 yrs            
  Stage 1, 2 18 7 11 39% 3 0 2 1 20.0 17% 15.0
  Stage 3, 4 9 5 4 56% 4 1 2 3 8.0 44% 50.0
  Stage 5 47 35 12 74%      
 20–39 yrs
  Stage 1, 2 24 9 15 38% 6 5 4 1 26.5 25% 22.6
  Stage 3, 4 29 20 9 69% 4 1 3 0 62.5 14% 6.4
  Stage 5 56 36 20 64%      
 40–59 yrs
  Stage 1, 2 8 2 6 25% 1 1 1 0 10.5 13% 9.5
  Stage 3, 4 41 23 18 56% 5 3 1 1 67.0 12% 7.5
  Stage 5 40 28 12 70%      
> 60 yrs
  Stage 1, 2 7 1 6 14% 0 6.0 0% 0.0
  Stage 3, 4 26 19 7 73% 7 2 3 2 44.5 27% 15.7
  Stage 5 37 20 17 54%      
  1. a) Sum of observation periods of Stage 1 to Stage 4 patients at registration
  2. b) Total number of Stage 1 to Stage 4 patients at registration was used as the denominator to calculate the rate