Table 1.
Characteristics at time of blood draw according to pre-RA ACPA results for women who developed RA and their matched controls in the Nurses’ Health Studies.
| COPD analysis (n=1,125) | Pre-RA ACPA+ (n=59) |
Matched controls (n=176) |
p value |
Pre-RA ACPA− (n=224) |
Matched controls (n=666) |
p value |
|---|---|---|---|---|---|---|
| Mean age, years (SD) | 51.5 (7.6) | 51.2 (7.8) | 0.93 | 51.5 (8.0) | 51.5 (7.9) | 0.87 |
| Mean time to RA diagnosis or matched index date for controls, years (SD) | 6.4 (5.3) | 6.4 (5.3) | 0.92 | 10.6 (5.6) | 10.6 (5.6) | 0.96 |
| Median time to RA diagnosis of matched index date for controls, years (IQR) | 4.8 (2.2, 9.6) | 4.8 (2.2, 9.6) | 0.92 | 10.5 (6.1, 13.9) | 10.6 (6.1, 13.9) | 0.96 |
| CCP+ at diagnosis by medical record review, % | 81.6 | N/A | N/A | 8.7 | N/A | N/A |
| RF+ at diagnosis by medical record review, % | 76.3 | N/A | N/A | 54.0 | N/A | N/A |
| CCP+ or RF+ by medical record review at diagnosis, % | 88.1 | N/A | N/A | 55.4 | N/A | N/A |
| White race, % | 98.3 | 97.2 | 1.00 | 92.9 | 96.6 | 0.02 |
| Mean household income, $USD (SD) | 59,775 (20,555) | 62,154 (22,195) | 0.58 | 63,778 (25,889) | 63,886 (23,575) | 0.51 |
| Mean body mass index, kg/m2 (SD) | 26.8 (5.9) | 24.8 (4.3) | 0.02 | 25.5 (4.5) | 25.1 (4.6) | 0.10 |
| Mean pack-years (SD) | 12.7 (16.1) | 11.2 (16.5) | 0.49 | 11.5 (15.5) | 8.9 (15.2) | 0.01 |
| Mean pack-years among smokers (SD) | 21.5 (15.8) | 19.3 (17.7) | 0.26 | 21.6 (15.4) | 19.6 (17.4) | 0.06 |
| Smoking pack-year category, % | ||||||
| Never | 40.7 | 42.1 | 0.43 | 46.9 | 54.8 | 0.01 |
| >0 to 10 | 17.0 | 25.6 | 14.7 | 18.3 | ||
| >10 to 20 | 15.3 | 10.8 | 14.3 | 9.3 | ||
| >20 | 27.1 | 21.6 | 24.1 | 17.6 | ||
| Parent(s) smoked at home during childhood, % | 74.6 | 68.8 | 0.40 | 62.1 | 63.1 | 0.79 |
| Ever lived with a smoker, % | 67.8 | 55.1 | 0.09 | 58.0 | 56.8 | 0.74 |
| Asthma analysis (n=951) | Pre-RA ACPA+ (n=49) |
Matched controls (n=136) |
p value |
Pre-RA ACPA− (n=203) |
Matched controls (n=563) |
p value |
| Mean age, years (SD) | 52.6 (7.7) | 52.5 (8.0) | 0.89 | 51.9 (8.0) | 52.1 (7.9) | 0.75 |
| Mean time to RA diagnosis or matched index date for controls, years (SD) | 6.3 (5.3) | 6.3 (5.3) | 0.96 | 10.8 (5.6) | 10.8 (5.7) | 0.98 |
| Median time to RA diagnosis of matched index date for controls, years (IQR) | 4.4 (1.6, 9.6) | 4.4 (1.9, 9.6) | 0.96 | 11.1 (6.1, 14.2) | 11.0 (6.0, 14.4) | 0.98 |
| CCP+ at diagnosis by medical record review, % | 81.0 | N/A | N/A | 9.4 | N/A | N/A |
| RF+ at diagnosis by medical record review, % | 75.5 | N/A | N/A | 53.2 | N/A | N/A |
| CCP+ or RF+ by medical record review at diagnosis, % | 87.8 | N/A | N/A | 54.7 | N/A | N/A |
| White race, % | 98.0 | 96.3 | 1.00 | 93.6 | 97.7 | 0.01 |
| Mean household income, $USD (SD) | 61,867 (20,872) | 63,101 (23,406) | 0.93 | 64,446 (26,508) | 63,377 (23,079) | 0.90 |
| Mean body mass index, kg/m2 (SD) | 25.4 (4.2) | 25.0 (4.3) | 0.31 | 25.3 (4.4) | 25.0 (4.4) | 0.32 |
| Mean pack-years (SD) | 13.5 (17.0) | 12.9 (18.6) | 0.61 | 11.4 (15.8) | 8.9 (15.4) | 0.02 |
| Mean pack-years among smokers (SD) | 22.1 (16.8) | 21.9 (19.8) | 0.61 | 21.8 (15.8) | 19.8 (17.7) | 0.09 |
| Smoking pack-year category, % | ||||||
| Never | 38.8 | 41.2 | 0.29 | 47.8 | 55.2 | 0.05 |
| >0 to 10 | 16.3 | 25.0 | 14.8 | 17.8 | ||
| >10 to 20 | 16.3 | 8.1 | 13.3 | 9.2 | ||
| >20 | 28.6 | 25.7 | 24.1 | 17.8 | ||
| Parent(s) smoked at home during childhood, % | 71.4 | 67.7 | 0.62 | 61.6 | 63.6 | 0.61 |
| Ever lived with a smoker, % | 67.4 | 58.8 | 0.29 | 56.2 | 57.4 | 0.76 |
ACPA, anti-citrullinated protein antibodies (research tested); CCP, cyclic citrullinated peptide (clinically tested); COPD, chronic obstructive pulmonary disease; IQR, interquartile range; N/A; not applicable; RA, rheumatoid arthritis; RF, rheumatoid factor; SD, standard deviation.