Correlation of time to institution of disease modifying antirheumatic drugs with radiological outcome in rheumatoid arthritis

Background Disease modifying antirheumatic drug (DMARD) therapy is believed to retard the radiological progression of disease in rheumatoid arthritis (RA) patients. Sooner the treatment is introduced, better is the expected outcome. This concept was formally tested in this retrospective study by analyzing the relationship between time to institution of DMARDs in the first 5 years of RA and its radiological outcome. Methods Two hundred adults with RA of more than 5 years duration taking DMARDs for at least 1 year were recruited in the study. Work up included detailed clinical evaluation, X-rays of both hands and feet AP view, assessment of rheumatoid factor (RF) titres, and calculation of van der Heijde-modified Sharp score, HAQ-DI and deformity score. Radiological score was correlated with the time to institution of DMARDs. Results The mean age of study patients was 43.7 years and 92% were women. Median duration of disease was 7 years (IQR 5, 10) and 83% were RF positive. Time lag before starting DMARDs was divided into < 3 months, 3–12 months, 1–3 years and 3–5 years and the number of patients in these subgroups was 16, 86, 63 and 35 respectively. The corresponding median radiological scores were 5 (IQR 0, 30), 9.5 (IQR 0, 27), 22 (IQR 16, 36) and 36 (IQR 26, 56) respectively. There was a significant rise in radiological score with increasing time lag but the difference between < 3 months and 3–12 months categories was not statistically significant. Radiological score correlated significantly with RA articular damage index, HAQ score and total duration of RA but it did correlate with RF positivity. Conclusion Crucial therapeutic window in RA appears to be the first year, after which the radiological score tends to rise sharply.