Supplementary Table 1 Definitions and codes used to identify rheumatoid arthritis in the provincial administrative data
Definition 1 Resident of Manitoba ≥ 2 years with ≥ 5
physician visits or hospitalizations with ICD9CM/ICD-10 CA codes 714/M05, M06.
If resident for < 2 years, ≥ 3 claims
Definition 2 ≥ 2 physician visits ≥2 months apart with an RA diagnostic code (ICD9 714.X), excluded if for ≥2 visits, after second RA visit, had diagnoses of other inflammatory arthritis (systemic lupus erythematosus, other
connective tissue diseases, psoriatic arthritis, ankylosing spondylitis, and other
spondyloarthropathies
Definition 3 Definition 3a: ≥1 physician visits for 1 year;
Definition 3b: ≥2 physician visits for 1 year;
Diagnosis codes ICD-9-CM/ICD-10-CA codes 714/MO5, M06
Drug claims codes based on the World Health Organization’s Anatomic Therapeutic
Chemical (ATC) Classification System:
Disease-Modifying Anti-Rheumatic Drugs (DMARDs) and biologics available at time of data extraction:
A07EC01 sulfasalazine J01AA08 minocycline L01AA01 cyclophosphamide L01BA01 methotrexate L04AA01 cyclosporine L04AA13 leflunomide L04AX01 azathioprine L04AX03 methotrexate
M01CB01 sodium aurothiomalate M01CB03 auranofin
M01CB04 aurothioglucose M01CC01 penicillamine P01BA02 hydroxychloroquine L04AA11 etanercept
L04AA12 infliximab L04AA14 anakinra
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Supplementary Table 2: Validation of the rheumatoid arthritis administrative definition in Manitoba’s administrative data
Definition Kappa
(95% CI) Sensitivity
(95% CI) Specificity
(95% CI) PPV
(95% CI) NPV
(95% CI) Youden’s J All
Manitoba
Definition 1 65.9 (64.1-67.6)
77.1 (75.4-78.8)
90.3 (89.6-91.0)
72.0 (70.3-73.8)
92.4
(91.8-93.0) 67.4 Definition 2 67.1
(65.4-68.8)
80.4 (78.7-82.0)
89.6 (88.9-90.3)
71.4 (69.6-73.1)
93.4
(92.8-94.0) 69.9 Definition
3a
60.4 (58.5-62.3)
68.0 (66.0-69.9)
91.4 (90.7-92.0)
71.8 (69.9-73.7)
89.8
(89.1-90.5) 59.3 Definition
3b
62.00 (60.1-63.9)
71.6 (69.7-73.4)
90.6 (89.9-91.2)
71.1 (69.2-72.9)
90.8
(90.1-91.5) 62.2 Non-FN
only
Definition 1 66.3 (64.4-68.3)
77.7 (75.8-79.6)
90.8 (90.1-91.5)
71.2 (69.3-73.2)
93.3
(92.6-93.9) 68.4 Definition 2 67.2
(65.3-69.1)
80.7 (78.9-82.5)
90.0 (89.2-90.8)
70.3 (68.4-72.3)
94.1
(93.5-94.7) 70.7 FN only
Definition 1 61.4 (56.8-66.0)
74.8 (70.9-78.9)
86.4 (84.0-88.8)
75.7 (71.7-79.7)
85.9 (83.4-88.3)
61.3 Definition 2 64.6
(60.2-69.1)
79.0 75.1-82.8)
86.2 (83.7-88.6)
76.3 (72.4-80.3)
87.9 (85.5-90.2)
65.1 Note: CI = confidence interval; PPV = positive predictive value; NPV = negative predictive
value
Supplementary Table 3 Description of the “false positive” rheumatoid arthritis (RA) cases identified using Definition 1
Characteristic Numeric Value
(N=681) Persistence of false diagnosis/ change in diagnosis
Number false RA claims/individual Mean (SD)
Median (range)
20.2 (26.7) 11 (1-253) Duration of continued false RA claims (months)
Mean (SD) Median (range)
65.2 (35.9) 66.4 (0.03-121.5) Number false RA claims/month
Mean (SD) /individual Median (range)
0.5 (1.8) 0.3 (0.03-30.0) All RA claim after 1st rheumatology visit (n=635)
Mean (SD) /individual
Median (range) /individual 18.4(26.6)
9(1-243) Other RA claim by rheumatology after 1st visit (n=444)
Mean (SD) /individual
Median (range) /individual 7.0(7.3)
4(1-62) RA claim by non-rheumatologist after 1st rheum visits (n=596)
Mean (SD) /individual Median (range) /individual
14.4(23.7) 7(1-233) Diagnosis assigned by rheumatology in UMRC database N Censored /No rheumatologic diagnosis/ unknown‡ 247
Other inflammatory arthropathy 250
Non-inflammatory arthropathy 91
Connective tissue disease 93
Drugs used after nonRA diagnosis DMARD
Number individuals receiving
Number prescriptions/individual (median (range)
580 28 (1-292) Biologics
Number individuals receiving
Number prescriptions/individual (median (range)
73 24 (1-91) Corticosteroids
Number individuals receiving
Number prescriptions/individual (median (range) 488 6(1-298)
‡ nonRA diagnoses could not be categorized due to less than 6 individuals with the UMRC diagnosis and thus diagnostic category censored due to health privacy legislation requirements.
Diagnoses include: undiagnosed arthropathy, undifferentiated arthritis, enteropathic arthropathy, palindromic rheumatism, reactive arthritis, infection-related arthritis, seronegative arthritis, back pain, diffuse idiopathic skeletal hyperostosis, other soft tissue, other non-inflammatory,
dermatomyositis, myalgias, polymyositis, Giant cell arteritis, granulomatous polyangiitis, Stills disease, Raynaud’s, sarcoid, and Sjogren’s
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Supplementary Table 4 Crude prevalence and incidence rates of rheumatoid arthritis in First Nations versus non-First Nations populations.
Crude Prevalence (%)
Crude Incidence (per 100,000 population)
Year All First
Nations
Non-First Nations
All First
Nations
Non First Nations
2000 0.34 0.50 0.33 46.62 51.16 46.16
2001 0.39 0.54 0.37 43.68 66.71 41.30
2002 0.42 0.59 0.41 42.21 70.67 39.22
2003 0.43 0.59 0.41 37.40 55.89 35.42
2004 0.50 0.69 0.48 39.27 55.66 37.48
2005 0.54 0.73 0.52 36.25 52.03 34.50
2006 0.57 0.77 0.55 33.46 41.81 32.52
2007 0.60 0.80 0.58 33.99 39.31 33.38
2008 0.62 0.82 0.61 28.36 39.35 27.10
2009
† 0.65 0.85 0.63 13.41 21.55 12.48
† 2009 crude prevalence (%) First Nations females 1.3, First Nations males 0.4, non-First Nations females 0.9, and non-First Nations males 0.3
Supplementary Table 5 Age-adjusted and age-specific relative rates (RRs) and 95% confidence intervals (95% CIs) of rheumatoid arthritis in First Nations (FN) versus non-First Nations (non- FN) populations. All comparisons significant with probability Chi squared p<0.0001 unless * p>0.05. Rates adjusted for sex and location of residence (based on assignment to health region of residence using postal code)
NA: Not Available. Annual prevalence data sufficient to compare FN and non-FN each year Incidence reported in 5 year blocks due to low numbers for some years.
Incidence Prevalence
Age Group RR 95% CI RR 95% CI
2000-2001 All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
1.53 1.43 3.62 4.37 2.12 0.59 0.99 0.69
0.97 2.39 0.56 3.65 1.27 10.28 2.26 8.46 1.05 4.26 0.17 1.98 0.29 3.34 0.09 5.19
2.63 0.85 4.37 5.65 4.61 3.40 2.49 1.06
2.08 3.32 0.42 1.77 2.33 8.19 3.24 9.85 2.76 7.73 2.02 5.71 1.44 4.33 0.50 2.26 2001-2002
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs >68 yrs
1.88 0.42 2.75 5.94 3.93 2.37 1.87 0.68
1.21 2.90 0.09 1.88 1.17 6.49 2.90 12.14 2.21 7.00 1.17 4.78 0.70 5.00 0.09 5.10
2.56 0.72 4.56 5.57 4.29 3.20 2.16 1.31
2.05 3.19 0.36 1.48 2.48 8.37 3.25 9.55 2.61 7.06 1.94 5.29 1.26 3.70 0.67 2.55 2002-2003
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
2.79 1.69 8.78 4.81 2.79 1.73 2.41 1.59
1.90 4.10 0.56 5.07 3.34 23.05 2.23 10.36 1.38 5.63 0.77 3.87 0.84 6.92 0.35 7.25
2.44 0.64 3.87 5.15 4.23 3.41 2.18 1.28
1.96 3.03 0.32 1.31 2.13 7.03 3.00 8.86 2.58 6.94 2.07 5.61 1.28 3.70 0.69 2.38 2003-2004
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs
2.17 1.83 2.28 5.37 3.52
1.45 3.25 0.74 4.55 0.88 5.88 2.92 9.89 1.92 6.46
2.49 0.76 3.83 4.64 4.27
2.01 3.07 0.38 1.49 2.12 6.90 2.75 7.82 2.61 6.96 6
49-58 yrs 59-68 yrs
>68 yrs
1.72 2.09 0.81
0.76 3.87 0.81 5.39 0.11 5.91
3.08 2.61 1.28
1.88 5.03 1.56 4.36 0.70 2.33 2004-2005
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
0.10 0.64 3.20 4.51 2.93 2.15 2.17 0
0.07 0.15 0.18 2.32 1.19 8.63 2.26 8.98 1.46 5.86 1.05 4.41 0.91 5.18
0 0
2.49 0.82 2.97 4.76 4.52 3.16 2.42 1.45
2.03 3.05 0.43 1.59 1.67 5.29 2.87 7.90 2.81 7.27 1.96 5.10 1.47 3.99 0.84 2.52 2005-2006
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
2.48 1.350 1.83 8.45 3.40 1.59 2.10 2.42
1.70 3.61 0.45 4.10 0.56 6.04 3.71 19.27 1.71 6.77 0.65 3.86 0.86 5.12 0.69 8.49
2.38 0.79 2.532 4.82 4.25 3.16 2.59 1.31
1.94 2.93 0.41 1.53 1.41 4.54 2.90 8.01 2.63 6.88 1.96 5.12 1.57 4.26 0.75 2.27 2006-2007
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
2.42 1.56 8.74 4.10 1.14 2.32 1.62 2.01
1.64 3.57 0.54 4.49 2.80 27.28 1.73 9.70 0.46 2.81 1.04 5.18 0.53 4.95 0.57 7.01
2.41 0.92 2.00 4.85 4.47 3.25 2.37 1.54
1.97 2.96 0.47 1.79 1.11 3.60 2.91 8.07 2.76 7.23 2.01 5.24 1.44 3.90 0.90 2.61 2007-2008
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
1.77 0.80 4.58 3.43 2.67 1.39 1.24 0.93
1.14 2.74 0.25 2.49 1.79 11.69 1.50 7.88 1.26 5.65 0.59 3.30 0.42 3.66 0.12 7.02
2.50 1.09 2.18 4.73 4.53 3.26 2.36 1.57
2.05 3.06 0.55 2.14 1.22 3.91 2.86 7.81 2.83 7.26 2.04 5.21 1.45 3.82 0.94 2.62 2008-2009
All ages 0-18 yrs 19-28 yrs
0.09 1.03 1.64
0.06 0.14 0.31 3.35 0.43 6.27
2.48 0.94 2.45
2.02 3.04 0.47 1.88 1.39 4.35
29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
5.13 3.12 2.45 3.59 0
2.11 12.45 1.53 6.36 1.08 5.54 1.38 9.35
0 0
4.30 4.59 3.35 2.37 1.60
2.58 7.15 2.85 7.38 2.09 5.36 1.46 3.84 0.96 2.66 2009-2010
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
2.23 0.74 3.47 2.66 3.49 4.61 1.45 1.75
1.26 3.97 0.08 6.51 1.04 11.51 0.78 9.15 1.30 9.40 1.76 12.12 0.31 6.71 0.22 13.73
2.55 1.12 2.14 4.52 4.51 3.45 2.33 1.77
2.08 3.12 0.55 2.28 1.21 3.81 2.71 7.56 2.80 7.28 2.15 5.54 1.43 3.78 1.07 2.94 2000-2004
All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
2.01 1.13 3.69 4.69 3.04 1.64 1.85 0.75
1.58 2.56 0.60 2.12 2.06 6.61 2.87 7.68 1.89 4.89 0.97 2.76 1.02 3.34 0.28 2.03
NA NA
2005-2010 All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
2.22 1.12 3.83 4.64 2.49 2.09 1.81 1.43
1.74 2.85 0.56 2.23 1.97 7.44 2.60 8.27 1.46 4.25 1.20 3.66 0.97 3.40 0.61 3.39
NA NA
2000-2010 All ages 0-18 yrs 19-28 yrs 29-38 yrs 39-48 yrs 49-58 yrs 59-68 yrs
>68 yrs
2.10 1.11 3.80 4.61 2.74 1.77 1.80 1.05
1.70 2.58 0.63 1.95 2.21 6.52 2.86 7.45 1.72 4.36 1.09 2.87 1.06 3.05 0.51 2.17
NA NA
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