Characteristics of patients with SLE at the research visit compared across smoking status
| Overall | Current smoker | Not currently smoking | OR (95% CI) | P value | |
| Participants, n | 99 | 35 | 64 | ||
| Age, mean±SD | 48.48±15.75 | 46.91±13.49 | 49.33±16.89 | – | 0.941 |
| Male, n (%) | 13 (13.1) | 7 (20.0) | 6 (9.4) | – | 0.135 |
| Female, n (%) | 86 (86.9) | 28 (80.0) | 58 (90.6) | – | |
| Years of follow-up, median (IQR) | 10.42 (5.08–17.67) | 10.42 (5.08–16.75) | 10.46 (4.92–17.67) | – | 0.941 |
| Smoking details | |||||
| Ex-smoker, n (%) | 25 (39.1) | – | 25 (39.1) | – | |
| Cigarettes per day, median (IQR) | 7 (3–10) | 7 (3–10) | 9 (4–10) | – | 0.428 |
| Years of consistent daily smoking, median (IQR) | 20.0 (13.0–28.00) | 24.0 (18.0–30.0) | 15.0 (5.0–23.0) | – | 0.064 |
| Pack-years, median (IQR) | 5.0 (3.0–12.25) | 9.00 (3.75–14.00) | 3.5 (2.0–5.0) | – | 0.003 |
| Years since quit smoking, median (IQR) | 10 (6–18) | – | 10 (6–18) | – | – |
| Cumulative ACR97 classification criteria | |||||
| Cumulative ACR97 items, median (IQR) | 5 (4–7) | 6 (4–7) | 5 (4–7) | – | 0.651 |
| Positive ANA, n (%) | 97 (97.9) | 35 (100.0) | 62 (96.9) | – | – |
| Mucosal-cutaneous features*, n (%) | 95 (96.0) | 34 (97.1) | 61 (95.3) | 1.67 (0.17 to 16.71) | 0.662 |
| Malar rash, n (%) | 66 (67.3) | 29 (82.9) | 37 (58.7) | 3.40 (1.23 to 9.34) | 0.018 |
| Photosensitivity, n (%) | 59 (60.2) | 23 (65.7) | 36 (57.1) | 1.44 (0.61 to 3.39) | 0.407 |
| Discoid lupus, n (%) | 42 (42.9) | 18 (51.4) | 24 (38.1) | 1.72 (0.75 to 3.97) | 0.203 |
| Mucosal ulcers, n (%) | 31 (31.6) | 17 (48.6) | 14 (22.2) | 3.31 (1.36 to 8.05) | 0.008 |
| Disease activity at the research visit (SLEDAI) | |||||
| Clinical disease activity, n (%) | 84 (84.8) | 28 (28.0) | 56 (56.5) | 0.57 (0.19 to 1.74) | 0.324 |
| Migraine, n (%) | 22 (22.2) | 12 (12.3) | 10 (10.6) | 2.82 (1.07 to 7.44) | 0.037 |
| Arthritis, n (%) | 21 (21.2) | 12 (34.3) | 9 (14.1) | 3.19 (1.19 to 8.60) | 0.022 |
| Clinical SLEDAI score, median (IQR) | 6 (2–12) | 6 (2–14) | 6 (2–10) | – | 0.981 |
| Total SLEDAI score, median (IQR) | 8 (2–14) | 8 (4–16) | 8 (2–11) | – | 0.998 |
| Patient GDA VAS, median (IQR) | 3 (1–5) | 4 (3–6) | 2 (1–5) | – | 0.003 |
| Physician GDA VAS, median (IQR) | 2 (1–4) | 3 (2–4) | 2 (1–3) | – | 0.046 |
| LDAS-50 | 35 (37.2) | 13 (37.1) | 22 (37.3) | 0.99 (0.42 to 2.36) | 0.989 |
| LDAS-30 | 62 (66.0) | 21 (60.0) | 41 (69.5) | 0.66 (0.28 to 1.58) | 0.349 |
| LDAS-70 | 17 (18.1) | 8 (22.9) | 9 (15.3) | 1.65 (0.57 to 4.78) | 0.357 |
| Secondary conditions | |||||
| Raynaud’s phenomenon, n (%) | 25 (25.3) | 16 (16.7) | 9 (9.1) | 5.15 (1.95 to 13.56) | 0.001 |
| Medication requirement | |||||
| Prednisone, n (%) | 50 (50.5) | 18 (51.4) | 32 (50.0) | 1.06 (0.46 to 2.41) | 0.892 |
| Prednisone dose (mg), median (IQR) | 5.00 (5.00–7.50) | 5.00 (5.00–7.50) | 5.00 (5.00–10.00) | 0.898 | |
| Non-steroidal anti-inflammatories, n (%) | 15 (15.2) | 11 (31.4) | 4 (6.3) | 6.88 (1.99 to 23.72) | 0.002 |
| Hydroxychloroquine, n (%) | 58 (58.6) | 19 (54.3) | 39 (60.9) | 0.76 (0.33 to 1.75) | 0.521 |
| Immunosuppressants, n (%) | 36 (36.4) | 13 (37.1) | 23 (35.9) | 1.05 (0.45 to 2.48) | 0.905 |
| Comorbidity | |||||
| Metabolic disorder, n (%) | 61 (61.2) | 20 (57.1) | 41 (68.3) | 0.62 (0.26 to 1.46) | 0.274 |
| Dyslipidaemia, n (%) | 49 (49.1) | 15 (42.9) | 34 (57.6) | 0.55 (0.24 to 1.28) | 0.168 |
| BMI ≥30, n (%) | 12 (12.9) | 3 (8.6) | 9 (15.5) | 0.51 (0.13 to 2.03) | 0.340 |
| Diabetes, n (%) | 3 (3.2) | 3 (8.6) | 0 (0.0) | – | – |
| Hypertension, n (%) | 49 (49.6) | 15 (42.9) | 34 (56.7) | 0.57 (0.25 to 1.33) | 0.196 |
| Cardiovascular disease, n (%) | 31 (31.1) | 12 (34.3) | 19 (29.7) | 1.24 (0.51 to 2.98) | 0.637 |
| Heart attack, n (%) | 13 (13.8) | 6 (17.1) | 7 (11.9) | 1.54 (0.47 to 5.01) | 0.476 |
| Thromboembolic disease, n (%) | 13 (13.8) | 4 (11.4) | 9 (15.3) | 0.72 (0.20 to 2.53) | 0.605 |
| Stroke, n (%) | 5 (5.3) | 2 (5.7) | 3 (5.1) | 1.13 (0.18 to 7.13) | 0.895 |
| Cancer, n (%) | 11 (11.7) | 1 (2.9) | 10 (16.9) | 0.14 (0.02 to 1.18) | 0.071 |
| Pulmonary diseases†, n (%) | 13 (13.1) | 6 (17.1) | 7 (10.9) | 1.69 (0.52 to 5.48) | 0.386 |
| Damage accrual (SDI >0), n (%) | 59 (59.6) | 24 (68.6) | 35 (54.7) | 1.81 (0.76 to 4.30) | 0.181 |
| Total SDI score, median (IQR) | 2.00 (1.00–3.00) | 1.00 (1.00–2.00) | 2.00 (2.00–4.00) | 0.140 | |
| Skin damage, n (%) | 3 (3.0) | 2 (5.7) | 1 (1.6) | 3.82 (0.33 to 43.68) | 0.281 |
| Pulmonary damage, n (%) | 7 (7.1) | 4 (11.4) | 3 (4.7) | 2.62 (0.55 to 12.46) | 0.225 |
| Malignancy damage, n (%) | 14 (14.1) | 3 (8.6) | 11 (17.2) | 0.45 (0.12 to 1.74) | 0.249 |
Bolded findings are significantly different across current and those not currently smoking.
*Also includes alopecia.
†Pulmonary diseases include fibrotic and obstructive diseases (asthma n=6).
ACR97, American College of Rheumatology Classification Criteria for SLE; BMI, body mass index (kg/m2); GDA, global disease activity; LDAS-50, Low Disease Activity State-50; SDI, Systemic Lupus International Collaborating Clinics/ACR Damage Index; SLEDAI, SLE Disease Activity Index; VAS, visual analogue scale.