OBJECTIVE: To identify different trajectories of disease activity in patients with RA following initiation of a first anti-TNF.
METHODS: Patients with RA starting their first anti-TNF between 2001 and 2013 were selected from the British Society for Rheumatology Biologics Register for RA. Six-monthly DAS28-ESR scores were used to identify trajectories of disease activity using latent class modelling. Data were included for six follow-ups after registration (approximately 3 years). Subgroup analysis examined changes in disease activity profiles over time.
RESULTS: A total of 14 436 patients with RA starting their first anti-TNF were enrolled between 2001 and 2013 (13 115 between 2001 and 2008, 1321 between 2010 and 2013). The mean number of DAS28-ESR scores was 3.5/patient (s.d. 2.1), with a mean of 184.9 days (s.d. 69.9) between scores. The DAS28-ESR nadir was achieved within 250 days of commencing anti-TNF, although apparent trajectory divergence emerged by first 6-monthly follow-up at 180 days. Four distinct response trajectories comprised the most stable model. Most patients fitted into 'modest' (7986 patients; 55.3%) or 'substantial' (4676 patients; 32.4%) response trajectories. Of the remainder, 1254 (8.7%) and 520 (3.6%) fitted 'maximal' and 'minimal' response trajectories, respectively. There was a significant (P < 0.01) increase in proportion achieving 'maximal' response between 2001-2008 and 2010-2013.
CONCLUSION: This is the largest study to identify long-term response trajectories with anti-TNF. By 6 months, longer-term trajectory profiles of DAS28 could already be identified, with many patients identified earlier. The majority of patients had persistent moderate response, equivalent to maintained DAS28-ESR moderate disease activity. The maximal response trajectory (equivalent to sustained DAS2-ESR remission) was only achieved by approximately one-third of patients.