Extended report patients not receiving treatment, highlighting the fact that treat- ment was more likely to be given to patients with more severe disease. Change in HAQ over 10 years and treatment, with adjustment by time-dependent confounders When adjusted for baseline HAQ only, those ever treated with DMARD/S had a signiﬁcantly greater deterioration in function over 10 years, than those never treated (adjusted mean differ- ence in change (adj_MDIC) in HAQ 0.30, 95% CI 0.18 to 0.42) Table 2 Baseline characteristics of the cohort Baseline characteristics Age at symptom onset (years), median (IQR) Female, n (%) Symptom duration at registration (months), median (IQR) HAQ score, median (IQR)* CRP (mg/dl), median (IQR)† DAS28 score, median (IQR)† Swollen joint count, median (IQR) Tender joint count, median (IQR) Swollen and tender joint count, median (IQR) Satisﬁed 1987 ACR criteria for RA, n (%) Presence of nodules, n (%) Smoking status at baseline, n (%) Never smoked Ex-smoker ≥10 years Ex-smoker <10 years Current smoker IP cohort (n=1084) 53 (41–66) 709 (65.4) 4 (2–10) 0.75 (0.25–1.375) 5 (0–16) 3.93 (2.89–5.01) 6 (2–13) 7 (3–16) 3 (0–8) 493 (45.5) 72 (6.6) 353 (32.6) 282 (26) 161 (14.9) 288 (26.6) *HAQ completed by 1072 subjects; †CRP measured on 866 subjects. ACR, American College of Rheumatology; CRP, C-reactive protein; DAS28, 28 joint count Disease Activity Score; HAQ, Health Assessment Questionnaire; IP, inﬂammatory polyarthritis; RA, rheumatoid arthritis. 0* 1 2 3 5 7 10 692 Year of follow-up 0 1 2 3 5 7 10 *Treated since symptom onset to baseline. 1084 1025 961 924 855 732 664 Cohort (n) 1084 1025 961 924 855 732 664 226 (21) 450 (44) 418 (43) 396 (43) 374 (44) 305 (42) 293 (44) Ever treated by follow-up, n (%) 226 (21) 453 (44) 464 (48) 466 (50) 444 (52) 374 (51) 361 (54) (table 5). However, after adjustment for the time-dependent confounders there was no signiﬁcant difference in the change in HAQ between those ever treated and those not treated (–0.01, 95% CI –0.20 to 0.19). In other words, after allowing for the fact that treatment is more likely to be given to those with severe and active IP, treatment has been shown to move patients onto a trajectory that they would have followed if they had had milder disease not requiring treatment. On adjustment those treated early (<6 months) experienced an improvement in func- tional disability over the 10 years (–0.24, 95% CI –0.58 to 0.09), although this was not signiﬁcant. Of the 345 subjects treated over the 10 years, 290 (84%) were no longer receiving their ﬁrst treatment by 10 years of follow-up. Patients who discontinued their ﬁrst treatment (either stopped, change or added another DMARD/S) within 6 months of start- ing, experienced a signiﬁcant deterioration in functional disabil- ity (adj_MDIC 0.28, 95% CI 0.04 to 0.52); those who continued to receive their ﬁrst treatment for >36 months experienced an Table 3 Disease-modifying antirheumatic drug (DMARD)/steroid treatment received over 10 years of follow-up Year of follow-up Cohort (n) Treated between previous and current follow-up, n (%) Figure 1 No adjustment for confounders may lead to the incorrect inference that those patients who were receiving disease-modifying antirheumatic drug treatment at each follow-up experienced poorer function, compared with those patients not receiving treatment. HAQ, Health Assessment Questionnaire; IP, inﬂammatory polyarthritis. DMARD/steroid treatment between previous and current follow-up, n (%) Sulfasalazine (SSZ) Methotrexate (MTX) Steroid (Ss) 135 (60) 15 (7) 283 (63) 69 (15) 225 (54) 91 (22) 194 (49) 114 (29) 164 (44) 144 (39) 113 (37) 150 (49) 108 (37) 159 (54) Ever DMARD/steroid treatment by follow-up, n (%) Sulfasalazine (SSZ) 135 (60) 285 (63) 298 (64) 308 (66) 294 (66) 255 (68) 255 (71) Methotrexate (MTX) 15 (7) 70 (15) 101 (22) 134 (29) 170 (38) 182 (49) 192 (53) 72 (32) 139 (31) 128 (31) 124 (31) 127 (34) 98 (32) 95 (32) Steroid (Ss) 72 (32) 139 (31) 151 (33) 156 (33) 161 (36) 142 (38) 142 (39) Other 17 (8) 36 (8) 40 (10) 38 (10) 32 (9) 25 (8) 22 (8) Other 17 (8) 41 (9) 56 (12) 60 (13) 64 (14) 58 (16) 62 (17) Ann Rheum Dis 2010;69:689–695. doi:10.1136/ard.2009.108639