Table 1.
Characteristics two years prior to index date according to smoking behaviors during the smoking cessation period in the Nurses’ Health Study.
| RA cohort (n=938) | Current – continue (n=41) | Current – quit (n=90) | Variable smoking* (n=119) | Past – past (n=370) | Never – never (n=318) |
|---|---|---|---|---|---|
| Mean age, years (SD) | 52.8 (9.0) | 54.1 (8.0) | 50.4 (8.9) | 57.7 (9.1) | 55.4 (10.3) |
| Mean household income, $1000 USD (SD) | 65.8 (23.1) | 60.5 (23.7) | 62.9 (20.4) | 66.3 (25.1) | 63.2 (24.1) |
| Moderate to vigorous physical activity, hours per week (SD)** | 1.6 (2.5) | 2.3 (2.4) | 2.6 (3.1) | 2.5 (3.1) | 2.2 (2.7) |
| Mean body mass index, kg/m2 (SD) | 23.1 (4.1) | 25.9 (5.1) | 26.0 (4.7) | 26.3 (5.3) | 25.6 (4.5) |
| Body mass index category, % | |||||
| Underweight (<18.5 kg/m2) | 8.5 | 1.8 | 1.2 | 1.1 | 2.0 |
| Normal (18.5 to 24.9 kg/m2) | 69.7 | 46.4 | 45.4 | 49.0 | 49.4 |
| Overweight (25.0 to 29.9 kg/m2) | 12.9 | 30.9 | 41.2 | 29.7 | 34.1 |
| Obese (≥30.0 kg/m2) | 8.9 | 18.5 | 12.3 | 20.2 | 14.5 |
| Alternative Healthy Eating Index tertiles, %*** | |||||
| Tertile 1 – least healthy | 35.0 | 27.3 | 26.4 | 23.4 | 31.3 |
| Tertile 2 | 26.0 | 27.1 | 27.0 | 35.3 | 30.4 |
| Tertile 3 – most healthy | 12.3 | 30.9 | 31.2 | 33.5 | 25.6 |
| Pack-years of cigarette smoking, % | |||||
| Never | 0.0 | 1.3 | 7.2 | 0.0 | 100.0 |
| >0 to ≤10 | 1.5 | 4.9 | 7.6 | 37.1 | 0.0 |
| >10–20 | 6.5 | 14.1 | 15.9 | 20.6 | 0.0 |
| >20 | 92.0 | 79.0 | 66.3 | 38.2 | 0.0 |
| Cancer, % | 10.9 | 7.1 | 8.3 | 11.4 | 7.7 |
| Diabetes, % | 4.3 | 5.4 | 4.0 | 3.5 | 3.7 |
| Cardiovascular disease, % | 0.0 | 3.3 | 2.3 | 3.9 | 2.1 |
| Chronic obstructive pulmonary disease, % | 7.1 | 10.9 | 5.5 | 7.8 | 3.3 |
| Asthma, % | 2.1 | 7.9 | 6.1 | 8.1 | 7.8 |
| Mean Multimorbidity Weighted Index (SD)**** | 2.1 (2.8) | 3.1 (3.4) | 3.1 (4.1) | 3.7 (4.0) | 3.1 (3.4) |
| Seropositive, % | 64.2 | 68.6 | 57.2 | 58.0 | 59.5 |
| Rheumatoid nodules, % | 18.6 | 21.7 | 15.1 | 10.2 | 10.3 |
| Radiographic changes/erosions, % | 19.9 | 30.0 | 42.1 | 29.4 | 30.0 |
| Comparison cohort (n=8,951) | Current – continue (n=460) | Current – quit (n=717) | Variable smoking* (n=988) | Past – past (n=2,899) | Never – never (n=3,887) |
|---|---|---|---|---|---|
| Mean age, years (SD) | 53.2 (9.2) | 53.6 (9.0) | 49.7 (8.4) | 57.1 (9.4) | 55.6 (9.7) |
| Mean household income, $1000 USD (SD) | 59.8 (21.6) | 63.4 (25.0) | 63.2 (26.3) | 65.8 (25.1) | 62.6 (24.8) |
| Moderate to vigorous physical activity, hours per week (SD)** | 1.9 (2.7) | 2.0 (2.5) | 2.4 (2.8) | 2.6 (3.2) | 2.5 (3.2) |
| Mean body mass index, kg/m2 (SD) | 24.0 (4.4) | 24.4 (4.3) | 24.6 (4.6) | 25.9 (5.2) | 25.7 (5.0) |
| Body mass index category, % | |||||
| Underweight (<18.5 kg/m2) | 4.5 | 2.8 | 3.4 | 1.0 | 1.6 |
| Normal (18.5 to 24.9 kg/m2) | 62.9 | 60.1 | 59.3 | 51.5 | 50.6 |
| Overweight (25.0 to 29.9 kg/m2) | 22.0 | 27.1 | 26.0 | 29.9 | 29.9 |
| Obese (≥30.0 kg/m2) | 10.6 | 10.0 | 10.8 | 17.3 | 17.3 |
| Alternative Healthy Eating Index tertiles, %*** | |||||
| Tertile 1 – least healthy | 33.5 | 28.8 | 29.0 | 22.0 | 26.7 |
| Tertile 2 | 24.2 | 24.7 | 26.8 | 27.3 | 25.4 |
| Tertile 3 – most healthy | 16.3 | 24.3 | 23.4 | 33.0 | 25.0 |
| Pack-years of cigarette smoking, % | |||||
| Never | 0.0 | 1.6 | 7.5 | 0.0 | 100.0 |
| >0 to ≤10 | 2.9 | 14.9 | 11.0 | 47.3 | 0.0 |
| >10–20 | 11.2 | 14.1 | 12.6 | 21.2 | 0.0 |
| >20 | 83.4 | 66.4 | 67.4 | 28.2 | 0.0 |
| Cancer, % | 8.7 | 6.8 | 9.3 | 9.1 | 7.8 |
| Diabetes, % | 2.2 | 4.9 | 6.6 | 5.2 | 4.8 |
| Cardiovascular disease, % | 3.2 | 4.5 | 1.9 | 3.3 | 2.6 |
| Chronic obstructive pulmonary disease, % | 8.7 | 6.7 | 4.8 | 4.4 | 2.6 |
| Asthma, % | 3.8 | 5.8 | 5.4 | 7.2 | 5.0 |
| Mean Multimorbidity Weighted Index (SD)**** | 2.7 (3.2) | 2.6 (3.8) | 2.3 (3.3) | 2.8 (3.6) | 2.4 (3.1) |
Each RA case was matched with up to 10 women without RA on age and calendar year at index date to form the comparison cohort.
Missing values are not reported.
“Variable smoking” includes current smokers at RA diagnosis then quit >4 years after RA diagnosis/index date (n=66 in RA cohort; n=514 in comparison cohort), quit at RA diagnosis/index date then later started smoking again (n=1 in RA cohort; n=18 in comparison cohort), or quit/relapsed smoking (n=27 in RA cohort; n=278 in comparison cohort); past smokers at RA diagnosis who later started smoking again (n=19 in RA cohort; n=135 in comparison cohort); and never smokers at RA diagnosis/index date who later started smoking (n=6 in RA cohort; n=43 in comparison cohort).
Physical activity was first assessed in 1980.
Alternative Healthy Eating Index was first assessed in 1984.
The previously validated Multimorbidity Weighted Index (MWI) is composed of prevalent/serious conditions, each condition weighted by the effect on physical health-related quality of life. We did not include rheumatoid arthritis and other connective tissue diseases, male conditions, and premenopausal female conditions that were not assessed so the MWI included a total of 64 conditions for these analyses.
RA, rheumatoid arthritis; SD, standard deviation.