Table 3 Intensity weighted lifetime days of pesticide use and risk of specialist-confirmed RA among AHS applicators with ≥ 24 months continuous FFS Medicare coverage (1999–2016).

From: Associations between pesticide use and rheumatoid arthritis among older farmers in the Agricultural Health Study

IWLD categories 1

Non-cases

Cases2

Relative Risk

(N = 22,084)

N (%)

(N = 161)

N (%)

(95% CI) 3

Insecticides

Organochlorine

DDT*

None

6161 (63)

46 (60)

Reference

M1

1784 (18)

16 (21)

1.01 (0.57–1.80)

M2

1796 (18)

15 (19)

0.85 (0.47–1.54)

p-trend

  

0.63

Organophosphate

Chlorpyrifos

None

10,333 (56)

72 (56)

Reference

M1

3999 (22)

24 (19)

0.92 (0.58–1.45)

M2

3990 (22)

32 (25)

1.23 (0.81–1.86)

p-trend

  

0.42

Malathion*

None

3193 (31)

22 (*)

Reference

T1

2418 (23)

< 11

0.55 (0.25–1.25)

T2

2370 (23)

18 (*)

1.19 (0.64–2.24)

T3

2378 (23)

28 (*)

1.67 (0.95–2.94)

p-trend

  

0.03

Terbufos

None

10,886 (61)

75 (63)

Reference

M1

3437 (19)

18 (15)

0.97 (0.57–1.64)

M2

3429 (19)

27 (23)

1.39 (0.89–2.18)

p-trend

  

0.19

Carbamates

Carbaryl*

None

5205 (49)

31 (38)

Reference

T1

1803 (17)

18 (22)

1.75 (0.97–3.16)

T2

1810 (17)

15 (18)

1.35 (0.71–2.58)

T3

1802 (17)

18 (22)

1.36 (0.69–2.69)

p-trend

  

0.34

Carbofuran

None

11,958 (68)

75 (61)

Reference

M1

2827 (16)

20 (16)

1.26 (0.77–2.08)

M2

2824 (16)

27 (22)

1.53 (0.99–2.37)

p-trend

  

0.05

Herbicides

Anilids/anilines

Alachlor

None

7700 (43)

51 (41)

Reference

T1

3334 (19)

22 (18)

1.18 (0.71–1.96)

T2

3346 (19)

28 (23)

1.45 (0.91–2.30)

T3

3342 (19)

23 (19)

1.11 (0.68–1.81)

p-trend

  

0.38

Metolachlor

None

9493 (54)

59 (46)

Reference

T1

2742 (15)

26 (20)

1.87 (1.17-3.00)

T2

2747 (16)

19 (15)

1.38 (0.82–2.33)

T3

2725 (15)

23 (18)

1.60 (0.98–2.59)

p-trend

  

0.04

Pendimethalin*

None

6270 (61)

52 (*)

Reference

M1

1996 (19)

< 11

0.47 (0.21–1.04)

M2

1991 (19)

19 (*)

1.18 (0.70-2.00)

p-trend

  

0.92

Trifluralin

None

8003 (45)

56 (46)

Reference

T1

3237 (18)

19 (16)

1.06 (0.62–1.80)

T2

3214 (18)

21 (17)

1.27 (0.75–2.14)

T3

3240 (18)

25 (21)

1.46 (0.89–2.38)

p-trend

  

0.12

Phenoxy

2,4-D

None

4034 (21)

32 (23)

Reference

Q1

3870 (20)

29 (21)

1.07 (0.65–1.78)

Q2

3878 (20)

23 (17)

0.92 (0.53–1.60)

Q3

3878 (20)

23 (17)

0.92 (0.53–1.61)

Q4

3866 (20)

30 (22)

1.19 (0.71-2.00)

p-trend

  

0.71

Thiocarbamate

Butylate*

None

7051 (73)

54 (*)

Reference

M1

1327 (14)

< 11

0.52 (0.20–1.33)

M2

1315 (14)

17 (*)

1.74 (0.97–3.11)

p-trend

  

0.16

Triazine/Triazinone

Atrazine

None

5027 (26)

31 (23)

Reference

Q1

3506 (18)

23 (17)

1.20 (0.69–2.11)

Q2

3513 (18)

26 (20)

1.34 (0.77–2.33)

Q3

3507 (18)

25 (19)

1.30 (0.74–2.28)

Q4

3506 (18)

27 (20)

1.33 (0.76–2.32)

p-trend

  

0.31

Cyanazine

None

10,157 (57)

77 (61)

Reference

M1

3827 (21)

25 (20)

1.18 (0.73–1.92)

M2

3825 (21)

25 (20)

1.19 (0.74–1.94)

p-trend

  

0.43

Metribuzin*

None

6061 (61)

48 (*)

Reference

M1

1926 (19)

20 (*)

1.82 (1.03–3.21)

M2

1946 (20)

< 11

0.89 (0.44–1.80)

p-trend

  

0.83

Other

Dicamba

None

8472 (48)

72 (56)

Reference

T1

3069 (17)

22 (17)

1.21 (0.71–2.06)

T2

3055 (17)

19 (15)

1.06 (0.61–1.86)

T3

3067 (17)

16 (12)

0.89 (0.49–1.60)

p-trend

  

0.75

Glyphosate

None

4031 (21)

30 (21)

Reference

Q1

3857 (20)

24 (17)

0.84 (0.49–1.45)

Q2

3856 (20)

22 (16)

0.77 (0.44–1.34)

Q3

3857 (20)

28 (20)

0.99 (0.59–1.67)

Q4

3844 (20)

37 (26)

1.27 (0.77–2.08)

p-trend

  

0.25

Imazethapyr

None

10,811 (60)

83 (66)

Reference

M1

3645 (20)

25 (20)

1.27 (0.75–2.13)

M2

3648 (20)

17 (14)

0.92 (0.51–1.64)

p-trend

  

0.92

  1. 1As reported in 1993-97 and updated 1999–2003. Scores are grouped based on percent exposed cases: median (30 < 50%), tertiles (50 < 70%), or quartiles (≥ 70%) as intensity-weighted lifetime days (IWLD) use of specific pesticides up through enrollment (1993–1997) or first follow-up (1999–2003) prior to RA diagnosis; *Enrollment IWLD based on the take home questionnaire.
  2. 2Among participants with ≥ 24 months continuous fee for service (FFS) coverage (Parts A and B without Part C), including an initial ≥ 12-month clean period with no RA claims; specialist-confirmed cases had ≥ 2 claims for RA ≥ 30 days apart, plus ≥ 1 claim from a rheumatologist. Asterix (*) indicates percent not shown if number or percent not shown due to < 11 in a cell or ability to infer the count of groups with < 11 exposed cases.
  3. 3Relative Risk (RR) and 95% Confidence Intervals (CI) calculated using log binomial regression. Models adjust for categorical age at enrollment (40–49, 50–59, 60–69, 70+), state (NC, IA) state, (NC, IA)-education (≤ high school, > high school), smoking pack years, and correlated pesticides (R2 > 0.350) [aldicarb (chlorothalonil and benomyl)-chlorothalonil (aldicarb and benomyl)-atrazine (alachlor)-butylate (cyanazine and metribuzin)].
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